U.S. patent application number 14/566278 was filed with the patent office on 2015-12-03 for shingled solar cell module.
The applicant listed for this patent is COGENRA SOLAR, INC.. Invention is credited to Gilad ALMOGY, Nathan BECKETT, John GANNON, Jean HUMMEL, Yafu LIN, Dan MAYDAN, Ratson MORAD, Itai SUEZ.
Application Number | 20150349703 14/566278 |
Document ID | / |
Family ID | 54702762 |
Filed Date | 2015-12-03 |
United States Patent
Application |
20150349703 |
Kind Code |
A1 |
MORAD; Ratson ; et
al. |
December 3, 2015 |
SHINGLED SOLAR CELL MODULE
Abstract
A high efficiency configuration for a solar cell module
comprises solar cells arranged in a shingled manner to form super
cells, which may be arranged to efficiently use the area of the
solar module, reduce series resistance, and increase module
efficiency.
Inventors: |
MORAD; Ratson; (Palo Alto,
CA) ; ALMOGY; Gilad; (Palo Alto, CA) ; SUEZ;
Itai; (Santa Cruz, CA) ; HUMMEL; Jean; (San
Carlos, CA) ; BECKETT; Nathan; (Oakland, CA) ;
LIN; Yafu; (Santa Clara, CA) ; MAYDAN; Dan;
(Los Altos Hills, CA) ; GANNON; John; (Oakland,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
COGENRA SOLAR, INC. |
Fremont |
CA |
US |
|
|
Family ID: |
54702762 |
Appl. No.: |
14/566278 |
Filed: |
December 10, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14530405 |
Oct 31, 2014 |
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14566278 |
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29506415 |
Oct 15, 2014 |
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14530405 |
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62003223 |
May 27, 2014 |
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62036215 |
Aug 12, 2014 |
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62042615 |
Aug 27, 2014 |
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62048858 |
Sep 11, 2014 |
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62064260 |
Oct 15, 2014 |
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62064834 |
Oct 16, 2014 |
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Current U.S.
Class: |
136/251 ;
136/244 |
Current CPC
Class: |
H01L 31/0488 20130101;
H02S 50/00 20130101; H01L 31/186 20130101; H01L 31/044 20141201;
H01L 31/068 20130101; H02S 30/00 20130101; H01L 31/042 20130101;
H02S 30/10 20141201; H01L 31/0508 20130101; H02S 40/30 20141201;
H01L 31/02008 20130101; Y02E 10/547 20130101; H01L 31/18 20130101;
H01L 31/1876 20130101; H02S 40/32 20141201; Y02B 10/10 20130101;
H01L 31/0516 20130101; Y02E 10/50 20130101; H01L 27/1421 20130101;
H01L 31/022433 20130101; H01L 31/0481 20130101; H01L 31/0203
20130101; H01L 31/022425 20130101; H01L 31/048 20130101; H01L
31/049 20141201; H01L 31/05 20130101; H02S 50/10 20141201; H02S
20/25 20141201; H01L 31/0504 20130101; H02S 40/34 20141201; H01L
31/1804 20130101; H02S 40/36 20141201; H01L 31/0201 20130101; H01L
31/043 20141201 |
International
Class: |
H02S 20/25 20060101
H02S020/25; H01L 31/048 20060101 H01L031/048; H02S 40/30 20060101
H02S040/30; H01L 31/068 20060101 H01L031/068; H02S 40/34 20060101
H02S040/34; H02S 40/36 20060101 H02S040/36; H01L 31/05 20060101
H01L031/05; H01L 31/028 20060101 H01L031/028 |
Claims
1. An apparatus comprising: a solar module comprising a front
surface including series connected silicon solar cells grouped into
a first super cell comprising a first cut strip having a front side
metallization pattern along a first outside edge overlapped by a
second cut strip.
2. An apparatus as in claim 1 wherein the first cut strip and the
second cut strip have a length reproducing a shape of a wafer from
which the first cut strip is divided.
3. An apparatus as in claim 2 wherein the length is 156 mm.
4. An apparatus as in claim 2 wherein the length is 125 mm.
5. An apparatus as in claim 2 wherein an aspect ratio between a
width of the first cut strip and the length is between about 1:2 to
about 1:20.
6. An apparatus as in claim 2 wherein the first cut strip includes
a first chamfered corner.
7. An apparatus as in claim 6 wherein the first chamfered corner is
along the first outside edge.
8. An apparatus as in claim 6 wherein the first chamfered corner is
not along the first outside edge.
9. An apparatus as in claim 6 wherein the second cut strip includes
a second chamfered corner.
10. An apparatus as in claim 9 wherein an overlapping edge of the
second cut strip includes the second chamfered corner.
11. An apparatus as in claim 9 wherein an overlapping edge of the
second cut strip does not include the second chamfered corner.
12. An apparatus as in claim 6 wherein the length reproduces a
shape of a pseudo-square wafer from which the first cut strip is
divided.
13. An apparatus as in claim 6 wherein a width of the first cut
strip is different from a width of the second cut strip such that
the first cut strip and the second cut strip have approximately a
same area.
14. An apparatus as in claim 1 wherein the second cut strip
overlaps the first cut strip by between about 1-5 mm.
15. An apparatus as in claim 1 wherein the front side metallization
pattern comprises a bus bar.
16. An apparatus as in claim 15 wherein bus bar includes a tapered
portion.
17. An apparatus as in claim 1 wherein the front side metallization
pattern comprises a discrete contact pad.
18. An apparatus as in claim 17 wherein: second cut strip is bonded
to the first cut strip by adhesive; and the discrete contact pad
further comprises a feature to confine adhesive spreading.
19. An apparatus as in claim 18 wherein the feature comprises a
moat.
20. An apparatus as in claim 1 wherein the front side metallization
pattern comprises a bypass conductor.
21. An apparatus as in claim 1 wherein the front side metallization
pattern comprises a finger.
22. An apparatus as in claim 1 wherein the first cut strip further
comprises a rear side metallization pattern along a second outside
edge opposite to the first outside edge.
23. An apparatus as in claim 22 wherein the rear side metallization
pattern comprises a contact pad.
24. An apparatus as in claim 22 wherein the rear side metallization
pattern comprises a bus bar.
25. An apparatus as in claim 1 wherein the super cell comprises at
least nineteen silicon cut strips each having a breakdown voltage
greater than about 10 volts.
26. An apparatus as in claim 1 wherein the super cell is connected
with another super cell on the module front surface.
27. An apparatus as in claim 26 wherein the module front surface
comprises a white backing featuring darkened stripes corresponding
to gaps between the super cell and the other super cell.
28. An apparatus as in claim 26 wherein: the solar module front
surface comprises a backing sheet; and the backing sheet, the
interconnect, the super cell, and an encapsulant comprise a
laminated structure.
29. An apparatus as in claim 28 wherein the encapsulant comprises a
thermoplastic polymer.
30. An apparatus as in claim 29 wherein the thermoplastic polymer
comprises a thermoplastic olefin polymer.
31. An apparatus as in claim 26 further comprising an interconnect
between the super cell and the other super cell.
32. An apparatus as in claim 31 wherein a portion of the
interconnect is covered by a dark film.
33. An apparatus as in claim 31 wherein a portion of the
interconnect is colored.
34. An apparatus as in claim 31 further comprising a ribbon
conductor electrically connecting the super cell to an electrical
component.
35. An apparatus as in claim 34 wherein the ribbon conductor is
conductively bonded to a rear side of the first cut strip.
36. An apparatus as in claim 34 wherein the electrical component
comprises a bypass diode.
37. An apparatus as in claim 34 wherein the electrical component
comprises a switch.
38. An apparatus as in claim 34 wherein the electrical component
comprises a junction box.
39. An apparatus as in claim 38 wherein the junction box overlaps
and is in mating arrangement with another junction box.
40. An apparatus as in claim 26 wherein the super cell and the
other super cell are connected in series.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This non-provisional patent application is a continuation of
U.S. patent application Ser. No. 14/530,405 titled "Shingled Solar
Cell Module" and filed Oct. 31, 2014, and also claims priority to
U.S. Provisional Patent Application No. 62/003,223 titled "Shingled
Solar Cell Module" filed May 27, 2014, to U.S. Provisional Patent
Application No. 62/036,215 titled "Shingled Solar Cell Module"
filed Aug. 12, 2014, to U.S. Provisional Patent Application No.
62/042,615 titled "Shingled Solar Cell Module" filed Aug. 27, 2014,
to U.S. Provisional Patent Application No. 62/048,858 titled
"Shingled Solar Cell Module" filed Sep. 11, 2014, to U.S.
Provisional Patent Application No. 62/064,260 titled "Shingled
Solar Cell Module" filed Oct. 15, 2014, to U.S. Provisional Patent
Application No. 62/064,834 titled "Shingled Solar Cell Module"
filed Oct. 16, 2014, and to U.S. Design patent application No.
29/506,415 filed Oct. 15, 2014. Each of the patent applications in
the preceding list is incorporated herein by reference in its
entirety for all purposes.
FIELD OF THE INVENTION
[0002] The invention relates generally to solar cell modules in
which the solar cells are arranged in a shingled manner.
BACKGROUND
[0003] Alternate sources of energy are needed to satisfy ever
increasing world-wide energy demands. Solar energy resources are
sufficient in many geographical regions to satisfy such demands, in
part, by provision of electric power generated with solar (e.g.,
photovoltaic) cells.
SUMMARY
[0004] High efficiency arrangements of solar cells in a solar cell
module, and methods of making such solar modules, are disclosed
herein.
[0005] In one aspect, a solar module comprises a series connected
string of N.gtoreq.25 rectangular or substantially rectangular
solar cells having on average a breakdown voltage greater than
about 10 volts. The solar cells are grouped into one or more super
cells each of which comprises two or more of the solar cells
arranged in line with long sides of adjacent solar cells
overlapping and conductively bonded to each other with an
electrically and thermally conductive adhesive. No single solar
cell or group of <N solar cells in the string of solar cells is
individually electrically connected in parallel with a bypass
diode. Safe and reliable operation of the solar module is
facilitated by effective heat conduction along the super cells
through the bonded overlapping portions of adjacent solar cells,
which prevents or reduces formation of hot spots in reverse biased
solar cells. The super cells may be encapsulated in a thermoplastic
olefin polymer sandwiched between glass front and back sheets, for
example, further enhancing the robustness of the module with
respect to thermal damage. In some variations, N is .gtoreq.30,
.gtoreq.50, or .gtoreq.100.
[0006] In another aspect, a super cell comprises a plurality of
silicon solar cells each comprising rectangular or substantially
rectangular front (sun side) and back surfaces with shapes defined
by first and second oppositely positioned parallel long sides and
two oppositely positioned short sides. Each solar cell comprises an
electrically conductive front surface metallization pattern
comprising at least one front surface contact pad positioned
adjacent to the first long side, and an electrically conductive
back surface metallization pattern comprising at least one back
surface contact pad positioned adjacent the second long side. The
silicon solar cells are arranged in line with first and second long
sides of adjacent silicon solar cells overlapping and with front
surface and back surface contact pads on adjacent silicon solar
cells overlapping and conductively bonded to each other with a
conductive adhesive bonding material to electrically connect the
silicon solar cells in series. The front surface metallization
pattern of each silicon solar cell comprises a barrier configured
to substantially confine the conducive adhesive bonding material to
the at least one front surface contact pads prior to curing of the
conductive adhesive bonding material during manufacturing of the
super cell.
[0007] In another aspect, a super cell comprises a plurality of
silicon solar cells each comprising rectangular or substantially
rectangular front (sun side) and back surfaces with shapes defined
by first and second oppositely positioned parallel long sides and
two oppositely positioned short sides. Each solar cell comprises an
electrically conductive front surface metallization pattern
comprising at least one front surface contact pad positioned
adjacent to the first long side, and an electrically conductive
back surface metallization pattern comprising at least one back
surface contact pad positioned adjacent the second long side. The
silicon solar cells are arranged in line with first and second long
sides of adjacent silicon solar cells overlapping and with front
surface and back surface contact pads on adjacent silicon solar
cells overlapping and conductively bonded to each other with a
conductive adhesive bonding material to electrically connect the
silicon solar cells in series. The back surface metallization
pattern of each silicon solar cell comprises a barrier configured
to substantially confine the conducive adhesive bonding material to
the at least one back surface contact pads prior to curing of the
conductive adhesive bonding material during manufacturing of the
super cell.
[0008] In another aspect, a method of making a string of solar
cells comprises dicing one or more pseudo square silicon wafers
along a plurality of lines parallel to a long edge of each wafer to
form a plurality of rectangular silicon solar cells each having
substantially the same length along its long axis. The method also
comprises arranging the rectangular silicon solar cells in line
with long sides of adjacent solar cells overlapping and
conductively bonded to each other to electrically connect the solar
cells in series. The plurality of rectangular silicon solar cells
comprises at least one rectangular solar cell having two chamfered
corners corresponding to corners or to portions of corners of the
pseudo square wafer, and one or more rectangular silicon solar
cells each lacking chamfered corners. The spacing between parallel
lines along which the pseudo square wafer is diced is selected to
compensate for the chamfered corners by making the width
perpendicular to the long axis of the rectangular silicon solar
cells that comprise chamfered corners greater than the width
perpendicular to the long axis of the rectangular silicon solar
cells that lack chamfered corners, so that each of the plurality of
rectangular silicon solar cells in the string of solar cells has a
front surface of substantially the same area exposed to light in
operation of the string of solar cells.
[0009] In another aspect, a super cell comprises a plurality of
silicon solar cells arranged in line with end portions of adjacent
solar cells overlapping and conductively bonded to each other to
electrically connect the solar cells in series. At least one of the
silicon solar cells has chamfered corners that correspond to
corners or portions of corners of a pseudo square silicon wafer
from which it was diced, at least one of the silicon solar cells
lacks chamfered corners, and each of the silicon solar cells has a
front surface of substantially the same area exposed to light
during operation of the string of solar cells.
[0010] In another aspect, a method of making two or more super
cells comprises dicing one or more pseudo square silicon wafers
along a plurality of lines parallel to a long edge of each wafer to
form a first plurality of rectangular silicon solar cells
comprising chamfered corners corresponding to corners or portions
of corners of the pseudo square silicon wafers and a second
plurality of rectangular silicon solar cells each of a first length
spanning a full width of the pseudo square silicon wafers and
lacking chamfered corners. The method also comprises removing the
chamfered corners from each of the first plurality of rectangular
silicon solar cells to form a third plurality of rectangular
silicon solar cells each of a second length shorter than the first
length and lacking chamfered corners. The method further comprises
arranging the second plurality of rectangular silicon solar cells
in line with long sides of adjacent rectangular silicon solar cells
overlapping and conductively bonded to each other to electrically
connect the second plurality of rectangular silicon solar cells in
series to form a solar cell string having a width equal to the
first length, and arranging the third plurality of rectangular
silicon solar cells in line with long sides of adjacent rectangular
silicon solar cells overlapping and conductively bonded to each
other to electrically connect the third plurality of rectangular
silicon solar cells in series to form a solar cell string having a
width equal to the second length.
[0011] In another aspect, a method of making two or more super
cells comprises dicing one or more pseudo square silicon wafers
along a plurality of lines parallel to a long edge of each wafer to
form a first plurality of rectangular silicon solar cells
comprising chamfered corners corresponding to corners or portions
of corners of the pseudo square silicon wafers and a second
plurality of rectangular silicon solar cells lacking chamfered
corners, arranging the first plurality of rectangular silicon solar
cells in line with long sides of adjacent rectangular silicon solar
cells overlapping and conductively bonded to each other to
electrically connect the first plurality of rectangular silicon
solar cells in series, and arranging the second plurality of
rectangular silicon solar cells in line with long sides of adjacent
rectangular silicon solar cells overlapping and conductively bonded
to each other to electrically connect the second plurality of
rectangular silicon solar cells in series.
[0012] In another aspect, a super cell comprises a plurality of
silicon solar cells arranged in line in a first direction with end
portions of adjacent silicon solar cells overlapping and
conductively bonded to each other to electrically connect the
silicon solar cells in series, and an elongated flexible electrical
interconnect with its long axis oriented parallel to a second
direction perpendicular to the first direction, conductively bonded
to a front or back surface of an end one of the silicon solar cells
at a plurality of discrete locations arranged along the second
direction, running at least the full width of the end solar cell in
the second direction, having a conductor thickness less than or
equal to about 100 microns measured perpendicularly to the front or
rear surface of the end silicon solar cell, providing a resistance
to current flow in the second direction of less than or equal to
about 0.012 Ohms, and configured to provide flexibility
accommodating differential expansion in the second direction
between the end silicon solar cell and the interconnect for a
temperature range of about -40.degree. C. to about 85.degree.
C.
[0013] The flexible electrical interconnect may have a conductor
thickness less than or equal to about 30 microns measured
perpendicularly to the front and rear surfaces of the end silicon
solar cell, for example. The flexible electrical interconnect may
extend beyond the super cell in the second direction to provide for
electrical interconnection to at least a second super cell
positioned parallel to and adjacent the super cell in a solar
module. In addition, or alternatively, the flexible electrical
interconnect may extend beyond the super cell in the first
direction to provide for electrical interconnection to a second
super cell positioned parallel to and in line with the super cell
in a solar module.
[0014] In another aspect, a solar module comprises a plurality of
super cells arranged in two or more parallel rows spanning a width
of the module to form a front surface of the module. Each super
cell comprises a plurality of silicon solar cells arranged in line
with end portions of adjacent silicon solar cells overlapping and
conductively bonded to each other to electrically connect the
silicon solar cells in series. At least an end of a first super
cell adjacent an edge of the module in a first row is electrically
connected to an end of a second super cell adjacent the same edge
of the module in a second row via a flexible electrical
interconnect that is bonded to the front surface of the first super
cell at a plurality of discrete locations with an electrically
conductive adhesive bonding material, runs parallel to the edge of
the module, and at least a portion of which folds around the end of
the first super cell and is hidden from view from the front of the
module.
[0015] In another aspect, a method of making a super cell comprises
laser scribing one or more scribe lines on each of one or more
silicon solar cells to define a plurality of rectangular regions on
the silicon solar cells, applying an electrically conductive
adhesive bonding material to the one or more scribed silicon solar
cells at one or more locations adjacent a long side of each
rectangular region, separating the silicon solar cells along the
scribe lines to provide a plurality of rectangular silicon solar
cells each comprising a portion of the electrically conductive
adhesive bonding material disposed on its front surface adjacent a
long side, arranging the plurality of rectangular silicon solar
cells in line with long sides of adjacent rectangular silicon solar
cells overlapping in a shingled manner with a portion of the
electrically conductive adhesive bonding material disposed in
between, and curing the electrically conductive bonding material,
thereby bonding adjacent overlapping rectangular silicon solar
cells to each other and electrically connecting them in series.
[0016] In another aspect, a method of making a super cell comprises
laser scribing one or more scribe lines on each of one or more
silicon solar cells to define a plurality of rectangular regions on
the silicon solar cells, applying an electrically conductive
adhesive bonding material to portions of the top surfaces of the
one or more silicon solar cells, applying a vacuum between the
bottom surfaces of the one or more silicon solar cells and a curved
supporting surface to flex the one or more silicon solar cells
against the curved supporting surface and thereby cleave the one or
more silicon solar cells along the scribe lines to provide a
plurality of rectangular silicon solar cells each comprising a
portion of the electrically conductive adhesive bonding material
disposed on its front surface adjacent a long side, arranging the
plurality of rectangular silicon solar cells in line with long
sides of adjacent rectangular silicon solar cells overlapping in a
shingled manner with a portion of the electrically conductive
adhesive bonding material disposed in between, and curing the
electrically conductive bonding material, thereby bonding adjacent
overlapping rectangular silicon solar cells to each other and
electrically connecting them in series.
[0017] In another aspect, a method of making a solar module
comprises assembling a plurality of super cells, with each super
cell comprising a plurality of rectangular silicon solar cells
arranged in line with end portions on long sides of adjacent
rectangular silicon solar cells overlapping in a shingled manner.
The method also comprises curing an electrically conductive bonding
material disposed between the overlapping end portions of adjacent
rectangular silicon solar cells by applying heat and pressure to
the super cells, thereby bonding adjacent overlapping rectangular
silicon solar cells to each other and electrically connecting them
in series. The method also comprises arranging and interconnecting
the super cells in a desired solar module configuration in a stack
of layers comprising an encapsulant, and applying heat and pressure
to the stack of layers to form a laminated structure.
[0018] Some variations of the method comprise curing or partially
curing the electrically conductive bonding material by applying
heat and pressure to the super cells prior to applying heat and
pressure to the stack of layers to form the laminated structure,
thereby forming cured or partially cured super cells as an
intermediate product before forming the laminated structure. In
some variations, as each additional rectangular silicon solar cell
is added to a super cell during assembly of the super cell, the
electrically conductive adhesive bonding material between the newly
added solar cell and its adjacent overlapping solar cell is cured
or partially cured before any other rectangular silicon solar cell
is added to the super cell. Alternatively, some variations comprise
curing or partially curing all of the electrically conductive
bonding material in a super cell in the same step.
[0019] If the super cells are formed as partially cured
intermediate products, the method may comprise completing the
curing of the electrically conductive bonding material while
applying heat and pressure to the stack of layers to form the
laminated structure.
[0020] Some variations of the method comprise curing the
electrically conductive bonding material while applying heat and
pressure to the stack of layers to form a laminated structure,
without forming cured or partially cured super cells as an
intermediate product before forming the laminated structure.
[0021] The method may comprise dicing one or more standard size
silicon solar cells into rectangular shapes of smaller area to
provide the rectangular silicon solar cells. The electrically
conductive adhesive bonding material may be applied to the one or
more silicon solar cells before dicing the one or more silicon
solar cells to provide the rectangular silicon solar cells with
pre-applied electrically conductive adhesive bonding material.
Alternatively, the electrically conductive adhesive bonding
material may be applied to the rectangular silicon solar cells
after dicing the one or more silicon solar cells to provide the
rectangular silicon solar cells.
[0022] These and other embodiments, features and advantages of the
present invention will become more apparent to those skilled in the
art when taken with reference to the following more detailed
description of the invention in conjunction with the accompanying
drawings that are first briefly described.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 shows a cross-sectional diagram of a string of
series-connected solar cells arranged in a shingled manner with the
ends of adjacent solar cells overlapping to form a shingled super
cell.
[0024] FIG. 2A shows a diagram of the front (sun side) surface and
front surface metallization pattern of an example rectangular solar
cell that may be used to form shingled super cells.
[0025] FIGS. 2B and 2C show diagrams of the front (sun side)
surface and front surface metallization patterns of two example
rectangular solar cells having rounded corners that may be used to
form shingled super cells
[0026] FIGS. 2D and 2E show diagrams of the rear surfaces and
example rear surface metallization patterns for the solar cell
shown in FIG. 2A.
[0027] FIGS. 2F and 2G show diagrams of the rear surfaces and
example rear surface metallization patterns for the solar cells
shown in FIGS. 2B and 2C, respectively.
[0028] FIG. 2H shows a diagram of the front (sun side) surface and
front surface metallization pattern of another example rectangular
solar cell that may be used to form shingled super cells. The front
surface metallization pattern comprises discrete contact pads each
of which is surrounded by a barrier configured to prevent uncured
conductive adhesive bonding material deposited on its contact pad
from flowing away from the contact pad.
[0029] FIG. 2I shows a cross-sectional view of the solar cell of
FIG. 2H and identifies detail of the front surface metallization
pattern shown in expanded view in FIGS. 2J and 2K that includes a
contact pad and portions of a barrier surrounding the contact
pad.
[0030] FIG. 2J shows an expanded view of detail from FIG. 2I.
[0031] FIG. 2K shows an expanded view of detail from FIG. 2I with
uncured conductive adhesive bonding material substantially confined
to the location of the discrete contact pad by the barrier.
[0032] FIG. 2L shows a diagram of the rear surface and an example
rear surface metallization pattern for the solar cell of FIG. 2H.
The rear surface metallization pattern comprises discrete contact
pads each of which is surrounded by a barrier configured to prevent
uncured conductive adhesive bonding material deposited on its
contact pad from flowing away from the contact pad.
[0033] FIG. 2M shows a cross-sectional view of the solar cell of
FIG. 2L and identifies detail of the rear surface metallization
pattern shown in expanded view in FIG. 2N that includes a contact
pad and portions of a barrier surrounding the contact pad.
[0034] FIG. 2N shows an expanded view of detail from FIG. 2M.
[0035] FIG. 2O shows another variation of a metallization pattern
comprising a barrier configured to prevent uncured conductive
adhesive bonding material from flowing away from a contact pad. The
barrier abuts one side of the contact pad and is taller than the
contact pad.
[0036] FIG. 2P shows another variation of the metallization pattern
of FIG. 2O, with the barrier abutting at least two sides of the
contact pad
[0037] FIG. 2Q shows a diagram of the rear surface and an example
rear surface metallization pattern for another example rectangular
solar cell. The rear surface metallization pattern comprises a
continuous contact pad running substantially the length of a long
side of the solar cell along an edge of the solar cell. The contact
pad is surrounded by a barrier configured to prevent uncured
conductive adhesive bonding material deposited on the contact pad
from flowing away from the contact pad.
[0038] FIG. 2R shows a diagram of the front (sun side) surface and
front surface metallization pattern of another example rectangular
solar cell that may be used to form shingled super cells. The front
surface metallization pattern comprises discrete contact pads
arranged in a row along an edge of the solar cell and a long thin
conductor running parallel to and inboard from the row of contact
pads. The long thin conductor forms a barrier configured to prevent
uncured conductive adhesive bonding material deposited on its
contact pads from flowing away from the contact pads and onto
active areas of the solar cell.
[0039] FIG. 3A shows a diagram illustrating an example method by
which a standard size and shape pseudo square silicon solar cell
may be separated (e.g., cut, or broken) into rectangular solar
cells of two different lengths that may be used to form shingled
super cells.
[0040] FIGS. 3B and 3C show diagrams illustrating another example
method by which a pseudo square silicon solar cell may be separated
into rectangular solar cells. FIG. 3B shows the front surface of
the wafer and an example front surface metallization pattern. FIG.
3C shows the rear surface of the wafer and an example rear surface
metallization pattern.
[0041] FIGS. 3D and 3E show diagrams illustrating an example method
by which a square silicon solar cell may be separated into
rectangular solar cells. FIG. 3D shows the front surface of the
wafer and an example front surface metallization pattern. FIG. 3E
shows the rear surface of the wafer and an example rear surface
metallization pattern.
[0042] FIG. 4A shows a fragmentary view of the front surface of an
example rectangular super cell comprising rectangular solar cells
as shown for example in FIG. 2A arranged in a shingled manner as
shown in FIG. 1.
[0043] FIGS. 4B and 4C show front and rear views, respectively, of
an example rectangular super cell comprising "chevron" rectangular
solar cells having chamfered corners, as shown for example in FIG.
2B, arranged in a shingled manner as shown in FIG. 1.
[0044] FIG. 5A shows a diagram of an example rectangular solar
module comprising a plurality of rectangular shingled super cells,
with the long side of each super cell having a length of
approximately half the length of the short sides of the module.
Pairs of the super cells are arranged end-to-end to form rows with
the long sides of the super cells parallel to the short sides of
the module.
[0045] FIG. 5B shows a diagram of another example rectangular solar
module comprising a plurality of rectangular shingled super cells,
with the long side of each super cell having a length of
approximately the length of the short sides of the module. The
super cells are arranged with their long sides parallel to the
short sides of the module.
[0046] FIG. 5C shows a diagram of another example rectangular solar
module comprising a plurality of rectangular shingled super cells,
with the long side of each super cell having a length of
approximately the length of the long side of the module. The super
cells are arranged with their long sides parallel to the sides of
the module.
[0047] FIG. 5D shows a diagram of an example rectangular solar
module comprising a plurality of rectangular shingled super cells,
with the long side of each super cell having a length of
approximately half the length of the long sides of the module.
Pairs of the super cells are arranged end-to-end to form rows with
the long sides of the super cells parallel to the long sides of the
module.
[0048] FIG. 5E shows a diagram of another example rectangular solar
module similar in configuration to that of FIG. 5C, in which all of
the solar cells from which the super cells are formed are chevron
solar cells having chamfered corners corresponding to corners of
pseudo-square wafers from which the solar cells were separated.
[0049] FIG. 5F shows a diagram of another example rectangular solar
module similar in configuration to that of FIG. 5C, in which the
solar cells from which the super cells are formed comprise a
mixture of chevron and rectangular solar cells arranged to
reproduce the shapes of the pseudo-square wafers from which they
were separated.
[0050] FIG. 5G shows a diagram of another example rectangular solar
module similar in configuration to that of FIG. 5E, except that
adjacent chevron solar cells in a super cell are arranged as mirror
images of each other so that their overlapping edges are of the
same length.
[0051] FIG. 6 shows an example arrangement of three rows of super
cells interconnected with flexible electrical interconnects to put
the super cells within each row in series with each other, and to
put the rows in parallel with each other. These may be three rows
in the solar module of FIG. 5D, for example.
[0052] FIG. 7 shows example flexible interconnects that may be used
to interconnect super cells in series or in parallel. Some of the
examples exhibit patterning that increase their flexibility
(mechanical compliance) along their long axes, along their short
axes, or along their long axes and their short axes.
[0053] FIG. 8A shows Detail A from FIG. 5D: a cross-sectional view
of the example solar module of FIG. 5D showing cross-sectional
details of flexible electrical interconnects bonded to the rear
surface terminal contacts of the rows of super cells.
[0054] FIG. 8B shows Detail C from FIG. 5D: a cross-sectional view
of the example solar module of FIG. 5D showing cross-sectional
details of flexible electrical interconnects bonded to the front
(sunny side) surface terminal contacts of the rows of super
cells.
[0055] FIG. 8C shows Detail B from FIG. 5D: a cross-sectional view
of the example solar module of FIG. 5D showing cross-sectional
details of flexible interconnects arranged to interconnect two
super cells in a row in series.
[0056] FIG. 8D-8G show additional examples of electrical
interconnects bonded to a front terminal contact of a super cell at
an end of a row of super cells, adjacent an edge of a solar module.
The example interconnects are configured to have a small foot print
on the front surface of the module.
[0057] FIG. 9A shows a diagram of another example rectangular solar
module comprising six rectangular shingled super cells, with the
long side of each super cell having a length of approximately the
length of the long side of the module. The super cells are arranged
in six rows that are electrically connected in parallel with each
other and in parallel with a bypass diode disposed in a junction
box on the rear surface of the solar module. Electrical connections
between the super cells and the bypass diode are made through
ribbons embedded in the laminate structure of the module.
[0058] FIG. 9B shows a diagram of another example rectangular solar
module comprising six rectangular shingled super cells, with the
long side of each super cell having a length of approximately the
length of the long side of the module. The super cells are arranged
in six rows that are electrically connected in parallel with each
other and in parallel with a bypass diode disposed in a junction
box on the rear surface and near an edge of the solar module. A
second junction box is located on the rear surface near an opposite
edge of the solar module. Electrical connection between the super
cells and the bypass diode are made through an external cable
between the junction boxes.
[0059] FIG. 9C shows an example glass-glass rectangular solar
module comprising six rectangular shingled super cells, with the
long side of each super cell having a length of approximately the
length of the long side of the module. The super cells are arranged
in six rows that are electrically connected in parallel with each
other. Two junction boxes are mounted on opposite edges of the
module, maximizing the active area of the module.
[0060] FIG. 9D shows a side view of the solar module illustrated in
FIG. 9C.
[0061] FIG. 9E shows another example solar module comprising six
rectangular shingled super cells, with the long side of each super
cell having a length of approximately the length of the long side
of the module. The super cells are arranged in six rows, with three
pairs of rows individually connected to a power management device
on the solar module.
[0062] FIG. 9F shows another example solar module comprising six
rectangular shingled super cells, with the long side of each super
cell having a length of approximately the length of the long side
of the module. The super cells are arranged in six rows, with each
row individually connected to a power management device on the
solar module.
[0063] FIGS. 9G and 9H show other embodiments of architectures for
module level power management using shingled super cells.
[0064] FIG. 10A shows an example schematic electrical circuit
diagram for a solar module as illustrated in FIG. 5B.
[0065] FIGS. 10B-1 and 10B-2 show an example physical layout for
various electrical interconnections for a solar module as
illustrated in FIG. 5B having the schematic circuit diagram of FIG.
10A.
[0066] FIG. 11A shows an example schematic electrical circuit
diagram for a solar module as illustrated in FIG. 5A.
[0067] FIGS. 11B-1 and 11B-2 show an example physical layout for
various electrical interconnections for a solar module as
illustrated in FIG. 5A having the schematic electrical circuit
diagram of FIG. 11A.
[0068] FIGS. 11C-1 and 11C-2 show another example physical layout
for various electrical interconnections for a solar module as
illustrated in FIG. 5A having the schematic electrical circuit
diagram of FIG. 11A.
[0069] FIG. 12A shows another example schematic circuit diagram for
a solar module as illustrated in FIG. 5A.
[0070] FIGS. 12B-1 and 12B-2 show an example physical layout for
various electrical interconnections for a solar module as
illustrated in FIG. 5A having the schematic circuit diagram of FIG.
12A.
[0071] FIGS. 12C-1, 12C-2, and 12C-3 show another example physical
layout for various electrical interconnections for a solar module
as illustrated in FIG. 5A having the schematic circuit diagram of
FIG. 12A.
[0072] FIG. 13A shows another example schematic circuit diagram for
a solar module as illustrated in FIG. 5A.
[0073] FIG. 13B shows another example schematic circuit diagram for
a solar module as illustrated in FIG. 5B.
[0074] FIGS. 13C-1 and 13C-2 show an example physical layout for
various electrical interconnections for a solar module as
illustrated in FIG. 5A having the schematic circuit diagram of FIG.
13A. Slightly modified, the physical layout of FIGS. 13C-1 and
13C-2 is suitable for a solar module as illustrated in FIG. 5B
having the schematic circuit diagram of FIG. 13B.
[0075] FIG. 14A shows a diagram of another example rectangular
solar module comprising a plurality of rectangular shingled super
cells, with the long side of each super cell having a length of
approximately half the length of the short side of the module.
Pairs of the super cells are arranged end-to-end to form rows with
the long sides of the super cells parallel to the short side of the
module.
[0076] FIG. 14B shows an example schematic circuit diagram for a
solar module as illustrated in FIG. 14A.
[0077] FIGS. 14C-1 and 14C-2 show an example physical layout for
various electrical interconnections for a solar module as
illustrated in FIG. 14A having the schematic circuit diagram of
FIG. 14B.
[0078] FIG. 15 shows another example physical layout for various
electrical interconnections for a solar module as illustrated in
FIG. 5B having the schematic circuit diagram of FIG. 10A.
[0079] FIG. 16 shows an example arrangement of a smart switch
interconnecting two solar modules in series.
[0080] FIG. 17 shows a flow chart for an example method of making a
solar module with super cells.
[0081] FIG. 18 shows a flow chart for another example method of
making a solar module with super cells.
[0082] FIGS. 19A-19D show example arrangements by which super cells
may be cured with heat and pressure.
[0083] FIGS. 20A-20C schematically illustrate an example apparatus
that may be used to cleave scribed solar cells. The apparatus may
be particularly advantageous when used to cleave scribed super
cells to which conductive adhesive bonding material has been
applied.
[0084] FIG. 21 shows an example white back sheet "zebra striped"
with dark lines that may be used in solar modules comprising
parallel rows of super cells to reduce visual contrast between the
super cells and portions of the back sheet visible from the front
of the module.
[0085] FIG. 22A shows a plan view of a conventional module
utilizing traditional ribbon connections under hot spot conditions.
FIG. 22B shows a plan view of a module utilizing thermal spreading
according to embodiments, also under hot spot conditions.
[0086] FIGS. 23A-B show examples of super cell string layouts with
chamfered cells.
[0087] FIGS. 24-25 show simplified cross-sectional views of arrays
comprising a plurality of modules assembled in shingled
configurations.
[0088] FIG. 26 shows a diagram of the rear (shaded) surface of a
solar module illustrating an example electrical interconnection of
the front (sun side) surface terminal electrical contacts of a
shingled super cell to a junction box on the rear side of the
module.
[0089] FIG. 27 shows a diagram of the rear (shaded) surface of a
solar module illustrating an example electrical interconnection of
two or more shingled super cells in parallel, with the front (sun
side) surface terminal electrical contacts of the super cells
connected to each other and to a junction box on the rear side of
the module.
[0090] FIG. 28 shows a diagram of the rear (shaded) surface of a
solar module illustrating another example electrical
interconnection of two or more shingled super cells in parallel,
with the front (sun side) surface terminal electrical contacts of
the super cells connected to each other and to a junction box on
the rear side of the module.
[0091] FIG. 29 shows fragmentary cross-sectional and perspective
diagrams of two super cells illustrating the use of a flexible
interconnect sandwiched between overlapping ends of adjacent super
cells to electrically connect the super cells in series and to
provide an electrical connection to a junction box. FIG. 29A shows
an enlarged view of an area of interest in FIG. 29.
[0092] FIG. 30A shows an example super cell with electrical
interconnects bonded to its front and rear surface terminal
contacts. FIG. 30B shows two of the super cells of FIG. 30A
interconnected in parallel.
DETAILED DESCRIPTION
[0093] The following detailed description should be read with
reference to the drawings, in which identical reference numbers
refer to like elements throughout the different figures. The
drawings, which are not necessarily to scale, depict selective
embodiments and are not intended to limit the scope of the
invention. The detailed description illustrates by way of example,
not by way of limitation, the principles of the invention. This
description will clearly enable one skilled in the art to make and
use the invention, and describes several embodiments, adaptations,
variations, alternatives and uses of the invention, including what
is presently believed to be the best mode of carrying out the
invention.
[0094] As used in this specification and the appended claims, the
singular forms "a," "an," and "the" include plural referents unless
the context clearly indicates otherwise. Also, the term "parallel"
is intended to mean "parallel or substantially parallel" and to
encompass minor deviations from parallel geometries rather than to
require that any parallel arrangements described herein be exactly
parallel. The term "perpendicular" is intended to mean
"perpendicular or substantially perpendicular" and to encompass
minor deviations from perpendicular geometries rather than to
require that any perpendicular arrangement described herein be
exactly perpendicular. The term "square" is intended to mean
"square or substantially square" and to encompass minor deviations
from square shapes, for example substantially square shapes having
chamfered (e.g., rounded or otherwise truncated) corners. The term
"rectangular" is intended to mean "rectangular or substantially
rectangular" and to encompass minor deviations from rectangular
shapes, for example substantially rectangular shapes having
chamfered (e.g., rounded or otherwise truncated) corners.
[0095] This specification discloses high-efficiency shingled
arrangements of silicon solar cells in solar cell modules, as well
as front and rear surface metallization patterns and interconnects
for solar cells that may be used in such arrangements. This
specification also discloses methods for manufacturing such solar
modules. The solar cell modules may be advantageously employed
under "one sun" (non-concentrating) illumination, and may have
physical dimensions and electrical specifications allowing them to
be substituted for conventional silicon solar cell modules.
[0096] FIG. 1 shows a cross-sectional view of a string of
series-connected solar cells 10 arranged in a shingled manner with
the ends of adjacent solar cells overlapping and electrically
connected to form a super cell 100. Each solar cell 10 comprises a
semiconductor diode structure and electrical contacts to the
semiconductor diode structure by which electric current generated
in solar cell 10 when it is illuminated by light may be provided to
an external load.
[0097] In the examples described in this specification, each solar
cell 10 is a crystalline silicon solar cell having front (sun side)
surface and rear (shaded side) surface metallization patterns
providing electrical contact to opposite sides of an n-p junction,
the front surface metallization pattern is disposed on a
semiconductor layer of n-type conductivity, and the rear surface
metallization pattern is disposed on a semiconductor layer of
p-type conductivity. However, any other suitable solar cells
employing any other suitable material system, diode structure,
physical dimensions, or electrical contact arrangement may be used
instead of or in addition to solar cells 10 in the solar modules
described in this specification. For example, the front (sun side)
surface metallization pattern may be disposed on a semiconductor
layer of p-type conductivity, and the rear (shaded side) surface
metallization pattern disposed on a semiconductor layer of n-type
conductivity.
[0098] Referring again to FIG. 1, in super cell 100 adjacent solar
cells 10 are conductively bonded to each other in the region in
which they overlap by an electrically conducting bonding material
that electrically connects the front surface metallization pattern
of one solar cell to the rear surface metallization pattern of the
adjacent solar cell. Suitable electrically conducting bonding
materials may include, for example, electrically conducting
adhesives and electrically conducting adhesive films and adhesive
tapes, and conventional solders. Preferably, the electrically
conducting bonding material provides mechanical compliance in the
bond between the adjacent solar cells that accommodates stress
arising from mismatch between the coefficient of thermal expansion
(CTE) of the electrically conducting bonding material and that of
the solar cells (e.g., the CTE of silicon). To provide such
mechanical compliance, in some variations the electrically
conducting bonding material is selected to have a glass transition
temperature of less than or equal to about 0.degree. C. To further
reduce and accommodate stress parallel to the overlapping edges of
the solar cells arising from CTE mismatch, the electrically
conductive bonding material may optionally be applied only at
discrete locations along the overlapping regions of the solar cells
rather than in a continuous line extending substantially the length
of the edges of the solar cells
[0099] The thickness of the electrically conductive bond between
adjacent overlapping solar cells formed by the electrically
conductive bonding material, measured perpendicularly to the front
and rear surfaces of the solar cells, may be for example less than
about 0.1 mm. Such a thin bond reduces resistive loss at the
interconnection between cells, and also promotes flow of heat along
the super cell from any hot spot in the super cell that might
develop during operation. The thermal conductivity of the bond
between solar cells may be, for example, .gtoreq.about 1.5
Watts/(meter K).
[0100] FIG. 2A shows the front surface of an example rectangular
solar cell 10 that may be used in a super cell 100. Other shapes
for solar cell 10 may also be used, as suitable. In the illustrated
example the front surface metallization pattern of solar cell 10
includes a bus bar 15 positioned adjacent to the edge of one of the
long sides of solar cell 10 and running parallel to the long sides
for substantially the length of the long sides, and fingers 20
attached perpendicularly to the bus bar and running parallel to
each other and to the short sides of solar cell 10 for
substantially the length of the short sides.
[0101] In the example of FIG. 2A solar cell 10 has a length of
about 156 mm, a width of about 26 mm, and thus an aspect ratio
(length of short side/length of long side) of about 1:6. Six such
solar cells may be prepared on a standard 156 mm.times.156 mm
dimension silicon wafer, then separated (diced) to provide solar
cells as illustrated. In other variations, eight solar cells 10
having dimensions of about 19.5 mm.times.156 mm, and thus an aspect
ratio of about 1:8, may be prepared from a standard silicon wafer.
More generally, solar cells 10 may have aspect ratios of, for
example, about 1:2 to about 1:20 and may be prepared from standard
size wafers or from wafers of any other suitable dimensions.
[0102] FIG. 3A shows an example method by which a standard size and
shape pseudo square silicon solar cell wafer 45 may be cut, broken,
or otherwise divided to form rectangular solar cells as just
described. In this example several full width rectangular solar
cells 10L are cut from the central portion of the wafer, and in
addition several shorter rectangular solar cells 10S are cut from
end portions of the wafer and the chamfered or rounded corners of
the wafer are discarded. Solar cells 10L may be used to form
shingled super cells of one width, and solar cells 10S may be used
to form shingled super cells of a narrower width.
[0103] Alternatively, the chamfered (e.g., rounded) corners may be
retained on the solar cells cut from end portions of the wafer.
FIGS. 2B-2C show the front surfaces of example "chevron"
rectangular solar cells 10 substantially similar to that of FIG.
2A, but having chamfered corners retained from the wafer from which
the solar cells were cut. In FIG. 2B, bus bar 15 is positioned
adjacent to and runs parallel to the shorter of the two long sides
for substantially the length of that side, and further extends at
both ends at least partially around the chamfered corners of the
solar cell. In FIG. 2C, bus bar 15 is positioned adjacent to and
runs parallel to the longer of the two long sides for substantially
the length of that side. FIGS. 3B-3C show front and rear views of a
pseudo square wafer 45 that may be diced along the dashed lines
shown in FIG. 3C to provide a plurality of solar cells 10 having
front surface metallization patterns similar to that shown in FIG.
2A, and two chamfered solar cells 10 having front surface
metallization patterns similar to that shown in FIG. 2B.
[0104] In the example front surface metallization pattern shown in
FIG. 2B, the two end portions of bus bar 15 that extend around the
chamfered corners of the cell may each have a width that tapers
(gradually narrows) with increasing distance from the portion of
the bus bar located adjacent the long side of the cell. Similarly,
in the example front surface metallization pattern shown in FIG.
3B, the two end portions of the thin conductor that interconnects
discrete contact pads 15 extend around the chambered corners of the
solar cell and taper with increasing distance from the long side of
the solar cell along which the discrete contact pads are arranged.
Such tapering is optional, but may advantageously reduce metal use
and shading of the active region of the solar cell without
significantly increasing resistive loss.
[0105] FIGS. 3D-3E show front and rear views of a perfect square
wafer 47 that may be diced along the dashed lines shown in FIG. 3E
to provide a plurality of solar cells 10 having front surface
metallization patterns similar to that shown in FIG. 2A.
[0106] Chamfered rectangular solar cells may be used to form super
cells comprising only chamfered solar cells. Additionally or
alternatively, one or more such chamfered rectangular solar cells
may be used in combination with one or more unchamfered rectangular
solar cells (e.g., FIG. 2A) to form a super cell. For example, the
end solar cells of a super cell may be chamfered solar cells, and
the middle solar cells unchamfered solar cells. If chamfered solar
cells are used in combination with unchamfered solar cells in a
super cell, or more generally in a solar module, it may be
desirable to use dimensions for the solar cells that result in the
chamfered and unchamfered solar cells having the same front surface
area exposed to light during operation of the solar cells. Matching
the solar cell areas in this manner matches the current produced in
the chamfered and unchamfered solar cells, which improves the
performance of a series connected string that includes both
chamfered and unchamfered solar cells. The areas of chamfered and
unchamfered solar cells cut from the same pseudo square wafer may
be matched, for example, by adjusting locations of the lines along
which the wafer is diced to make the chamfered solar cells slightly
wider than the unchamfered solar cells in the direction
perpendicular to their long axes, to compensate for the missing
corners on the chamfered solar cells.
[0107] A solar module may comprise only super cells formed
exclusively from unchamfered rectangular solar cells, or only super
cells formed from chamfered rectangular solar cells, or only super
cells that include chamfered and unchamfered solar cells, or any
combination of these three variations of super cell.
[0108] In some instances portions of a standard size square or
pseudo square solar cell wafer (e.g., wafer 45 or wafer 47) near
the edges of the wafer may convert light to electricity with lower
efficiency than portions of the wafer located away from the edges.
To improve the efficiency of the resulting rectangular solar cells,
in some variations one or more edges of the wafer are trimmed to
remove the lower efficiency portions before the wafer is diced. The
portions trimmed from the edges of the wafer may have widths of
about 1 mm to about 5 mm, for example. Further, as shown in FIGS.
3B and 3D, the two end solar cells 10 to be diced from a wafer may
be oriented with their front surface bus bars (or discrete contact
pads) 15 along their outside edges and thus along two of the edges
of the wafer. Because in the super cells disclosed in this
specification bus bars (or discrete contact pads) 15 are typically
overlapped by an adjacent solar cell, low light conversion
efficiency along those two edges of the wafer typically does not
affect performance of the solar cells. Consequently, in some
variations edges of a square or pseudo square wafer oriented
parallel to the short sides of the rectangular solar cells are
trimmed as just described, but edges of the wafer oriented parallel
to the long sides of rectangular solar cells are not. In other
variations, one, two, three, or four edges of a square wafer (e.g.,
wafer 47 in FIG. 3D) are trimmed as just described. In other
variations, one, two, three, or four of the long edges of a
pseudo-square wafer are trimmed as just described.
[0109] Solar cells having long and narrow aspect ratios and areas
less than that of a standard 156 mm.times.156 mm solar cell, as
illustrated, may be advantageously employed to reduce I.sup.2R
resistive power losses in the solar cell modules disclosed in this
specification. In particular, the reduced area of solar cells 10
compared to standard size silicon solar cells decreases the current
produced in the solar cell, directly reducing resistive power loss
in the solar cell and in a series connected string of such solar
cells. In addition, arranging such rectangular solar cells in a
super cell 100 so that current flows through the super cell
parallel to the short sides of the solar cells may reduce the
distance that the current must flow through the semiconductor
material to reach fingers 20 in the front surface metallization
pattern and reduce the required length of the fingers, which may
also reduce resistive power loss.
[0110] As noted above, bonding overlapped solar cells 10 to each
other in their overlapping region to electrically connect the solar
cells in series reduces the length of the electrical connection
between adjacent solar cells, compared to conventionally tabbed
series-connected strings of solar cells. This also reduces
resistive power loss.
[0111] Referring again to FIG. 2A, in the illustrated example the
front surface metallization pattern on solar cell 10 comprises an
optional bypass conductor 40 running parallel to and spaced apart
from bus bar 15. (Such a bypass conductor may also optionally be
used in the metallization patterns shown in FIGS. 2B-2C, 3B, and
3D, and is also shown in FIG. 2Q in combination with discrete
contact pads 15 rather than a continuous bus bar). Bypass conductor
40 interconnects fingers 20 to electrically bypass cracks that may
form between bus bar 15 and bypass conductor 40. Such cracks, which
may sever fingers 20 at locations near to bus bar 15, may otherwise
isolate regions of solar cell 10 from bus bar 15. The bypass
conductor provides an alternative electrical path between such
severed fingers and the bus bar. The illustrated example shows a
bypass conductor 40 positioned parallel to bus bar 15, extending
about the full length of the bus bar, and interconnecting every
finger 20. This arrangement may be preferred but is not required.
If present, the bypass conductor need not run parallel to the bus
bar and need not extend the full length of the bus bar. Further, a
bypass conductor interconnects at least two fingers, but need not
interconnect all fingers. Two or more short bypass conductors may
be used in place of a longer bypass conductor, for example. Any
suitable arrangement of bypass conductors may be used. The use of
such bypass conductors is described in greater detail in U.S.
patent application Ser. No. 13/371,790, titled "Solar Cell With
Metallization Compensating For Or Preventing Cracking," and filed
Feb. 13, 2012, which is incorporated herein by reference in its
entirety.
[0112] The example front surface metallization pattern of FIG. 2A
also includes an optional end conductor 42 that interconnects
fingers 20 at their far ends, opposite from bus bar 15. (Such an
end conductor may also optionally be used in the metallization
patterns shown in FIGS. 2B-2C, 3B, and 3D, and 2Q). The width of
conductor 42 may be about the same as that of a finger 20, for
example. Conductor 42 interconnects fingers 20 to electrically
bypass cracks that may form between bypass conductor 40 and
conductor 42, and thereby provides a current path to bus bar 15 for
regions of solar cell 10 that might otherwise be electrically
isolated by such cracks.
[0113] Although some of the illustrated examples show a front bus
bar 15 extending substantially the length of the long sides of
solar cell 10 with uniform width, this is not required. For
example, as alluded to above front bus bar 15 may be replaced by
two or more front surface discrete contact pads 15 which may be
arranged, for example, in line with each other along a side of
solar cell 10 as shown in FIGS. 2H, 2Q, and 3B for example. Such
discrete contact pads may optionally be interconnected by thinner
conductors running between them, as shown for example in the
figures just mentioned. In such variations, the width of the
contact pads measured perpendicularly to the long side of the solar
cell may be for example about 2 to about 20 times that of the thin
conductors interconnecting the contact pads. There may be a
separate (e.g., small) contact pad for each finger in the front
surface metallization pattern, or each contact pad may be connected
to two or more fingers. Front surface contact pads 15 may be square
or have a rectangular shape elongated parallel to the edge of the
solar cell, for example. Front surface contact pads 15 may have
widths perpendicular to the long side of the solar cell of about 1
mm to about 1.5 mm, for example, and lengths parallel to the long
side of the solar cell of about 1 mm to about 10 mm for example.
The spacing between contact pads 15 measured parallel to the long
side of the solar cell may be about 3 mm to about 30 mm, for
example.
[0114] Alternatively, solar cell 10 may lack both a front bus bar
15 and discrete front contact pads 15 and include only fingers 20
in the front surface metallization pattern. In such variations, the
current-collecting functions that would otherwise be performed by a
front bus bar 15 or contact pads 15 may instead be performed, or
partially performed, by the conductive material used to bond two
solar cells 10 to each other in the overlapping configuration
described above.
[0115] Solar cells lacking both a bus bar 15 and contact pads 15
may either include bypass conductor 40, or not include bypass
conductor 40. If bus bar 15 and contact pads 15 are absent, bypass
conductor 40 may be arranged to bypass cracks that form between the
bypass conductor and the portion of the front surface metallization
pattern that is conductively bonded to the overlapping solar
cell.
[0116] The front surface metallization patterns, including bus bar
or discrete contact pads 15, fingers 20, bypass conductor 40 (if
present), and end conductor 42 (if present) may be formed, for
example, from silver paste conventionally used for such purposes
and deposited, for example, by conventional screen printing
methods. Alternatively, the front surface metallization patterns
may be formed from electroplated copper. Any other suitable
materials and processes may be also used. In variations in which
the front surface metallization pattern is formed from silver, the
use of discrete front surface contact pads 15 rather than a
continuous bus bar 15 along the edge of the cell reduces the amount
of silver on the solar cell, which may advantageously reduce cost.
In variations in which the front surface metallization pattern is
formed from copper or from another conductor less expensive than
silver, a continuous bus 15 may be employed without a cost
disadvantage.
[0117] FIGS. 2D-2G, 3C, and 3E show example rear surface
metallization patterns for a solar cell. In these examples the rear
surface metallization patterns include discrete rear surface
contact pads 25 arranged along one of the long edges of the rear
surface of the solar cell and a metal contact 30 covering
substantially all of the remaining rear surface of the solar cell.
In a shingled super cell, contact pads 25 are bonded for example to
a bus bar or to discrete contact pads arranged along the edge of
the upper surface of an adjacent overlapping solar cell to
electrically connect the two solar cells in series. For example,
each discrete rear surface contact pad 25 may be aligned with and
bonded to a corresponding discrete front surface contact pad 15 on
the front surface of the overlapping solar cell by electrically
conductive bonding material applied only to the discrete contact
pads. Discrete contact pads 25 may be square (FIG. 2D) or have a
rectangular shape elongated parallel to the edge of the solar cell
(FIGS. 2E-2G, 3C, 3E), for example. Contact pads 25 may have widths
perpendicular to the long side of the solar cell of about 1 mm to
about 5 mm, for example, and lengths parallel to the long side of
the solar cell of about 1 mm to about 10 mm for example. The
spacing between contact pads 25 measured parallel to the long side
of the solar cell may be about 3 mm to about 30 mm, for
example.
[0118] Contact 30 may be formed, for example, from aluminum and/or
electroplated copper. Formation of an aluminum back contact 30
typically provides a back surface field that reduces back surface
recombination in the solar cell and thereby improves solar cell
efficiency. If contact 30 is formed from copper rather than
aluminum, contact 30 may be used in combination with another
passivation scheme (e.g., aluminum oxide) to similarly reduce back
surface recombination. Discrete contact pads 25 may be formed, for
example, from silver paste. The use of discrete silver contact pads
25 rather than a continuous silver contact pad along the edge of
the cell reduces the amount of silver in the rear surface
metallization pattern, which may advantageously reduce cost.
[0119] Further, if the solar cells rely on a back surface field
provided by formation of an aluminum contact to reduce back surface
recombination, the use of discrete silver contacts rather than a
continuous silver contact may improve solar cell efficiency. This
is because the silver rear surface contacts do not provide a back
surface field and therefore tend to promote carrier recombination
and produce dead (inactive) volumes in the solar cells above the
silver contacts. In conventionally ribbon-tabbed solar cell strings
those dead volumes are typically shaded by ribbons and/or bus bars
on the front surface of the solar cell, and thus do not result in
any extra loss of efficiency. In the solar cells and super cells
disclosed herein, however, the volume of the solar cell above rear
surface silver contact pads 25 is typically unshaded by any front
surface metallization, and any dead volumes resulting from use of
silver rear surface metallization reduce the efficiency of the
cell. The use of discrete silver contact pads 25 rather than a
continuous silver contact pad along the edge of the rear surface of
the solar cell thus reduces the volume of any corresponding dead
zones and increases the efficiency of the solar cell.
[0120] In variations not relying on a back surface field to reduce
back surface recombination, the rear surface metallization pattern
may employ a continuous bus bar 25 extending the length of the
solar cell rather than discrete contact pads 25, as shown for
example in FIG. 2R. Such a bus bar 25 may be formed for example,
from tin or silver.
[0121] Other variations of the rear surface metallization patterns
may employ discrete tin contact pads 25. Variations of the rear
surface metallization patterns may employ finger contacts similar
to those shown in the front surface metallization patterns of FIGS.
2A-2C and may lack contact pads and a bus bar.
[0122] Although the particular example solar cells shown in the
figures are described as having particular combinations of front
and rear surface metallization patterns, more generally any
suitable combination of front and rear surface metallization
patterns may be used. For example, one suitable combination may
employ a silver front surface metallization pattern comprising
discrete contact pads 15, fingers 20, and an optional bypass
conductor 40, and a rear surface metallization pattern comprising
an aluminum contact 30 and discrete silver contact pads 25. Another
suitable combination may employ a copper front surface
metallization pattern comprising a continuous bus bar 15, fingers
20, and an optional bypass conductor 40, and a rear surface
metallization pattern comprising a continuous bus bar 25 and a
copper contact 30.
[0123] In the super cell manufacturing process (described in more
detail below) the electrically conductive bonding material used to
bond adjacent overlapping solar cells in a super cell may be
dispensed only onto (discrete or continuous) contact pads at the
edge of the front or rear surface of the solar cell, and not onto
the surrounding portions of the solar cell. This reduces use of
material and, as described above, may reduce or accommodate stress
arising from CTE mismatch between the electrically conductive
bonding material and the solar cell. However, during or after
deposition and prior to curing, portions of the electrically
conductive bonding material may tend to spread beyond the contact
pads and onto surrounding portions of the solar cell. For example,
a binding resin portion of the electrically conductive bonding
material may be drawn off of a contact pad onto textured or porous
adjacent portions of the solar cell surface by capillary forces. In
addition, during the deposition process some of the conductive
bonding material may miss the contact pad and instead be deposited
on adjacent portions of the solar cell surface, and possibly spread
from there. This spreading and/or inaccurate deposition of the
conductive bonding material may weaken the bond between the
overlapping solar cells and may damage the portions of the solar
cell onto which the conductive bonding material has spread or been
mistakenly deposited. Such spreading of the electrically conductive
bonding material may be reduced or prevented, for example, with a
metallization pattern that forms a dam or barrier near or around
each contact pad to retain the electrically conductive bonding
material substantially in place.
[0124] As shown in FIGS. 2H-2K, for example, the front surface
metallization pattern may comprise discrete contact pads 15,
fingers 20, and barriers 17, with each barrier 17 surrounding a
corresponding contact pad 15 and acting as a dam to form a moat
between the contact pad and the barrier. Portions 19 of uncured
conductive adhesive bonding material 18 that flow off of the
contact pads, or that miss the contact pads when dispensed onto the
solar cell, may be confined by barriers 17 to the moats. This
prevents the conductive adhesive bonding material from spreading
further from the contact pads onto surrounding portions of the
cell. Barriers 17 may be formed from the same material as fingers
20 and contact pads 15 (e.g., silver), for example, may have
heights of about 10 microns to about 40 microns, for example, and
may have widths of about 30 microns to about 100 microns, for
example. The moat formed between a barrier 17 and a contact pad 15
may have a width of about 100 microns to about 2 mm, for example.
Although the illustrated examples comprise only a single barrier 17
around each front contact pad 15, in other variations two or more
such barriers may be positioned concentrically, for example, around
each contact pad. A front surface contact pad and its one or more
surrounding barriers may form a shape similar to a "bulls-eye"
target, for example. As shown in FIG. 2H, for example, barriers 17
may interconnect with fingers 20 and with the thin conductors
interconnecting contact pads 15.
[0125] Similarly, as shown in FIGS. 2L-2N, for example, the rear
surface metallization pattern may comprise (e.g., silver) discrete
rear contact pads 25, (e.g., aluminum) contact 30 covering
substantially all of the remaining rear surface of the solar cell,
and (e.g., silver) barriers 27, with each barrier 27 surrounding a
corresponding rear contact pad 25 and acting as a dam to form a
moat between the contact pad and the barrier. A portion of contact
30 may fill the moat, as illustrated. Portions of uncured
conductive adhesive bonding material that flow off of contact pads
25, or that miss the contact pads when dispensed onto the solar
cell, may be confined by barriers 27 to the moats. This prevents
the conductive adhesive bonding material from spreading further
from the contact pads onto surrounding portions of the cell.
Barriers 27 may have heights of about 10 microns to about 40
microns, for example, and may have widths of about 50 microns to
about 500 microns, for example. The moat formed between a barrier
27 and a contact pad 25 may have a width of about 100 microns to
about 2 mm, for example. Although the illustrated examples comprise
only a single barrier 27 around each rear surface contact pad 25,
in other variations two or more such barriers may be positioned
concentrically, for example, around each contact pad. A rear
surface contact pad and its one or more surrounding barriers may
form a shape similar to a "bulls-eye" target, for example.
[0126] A continuous bus bar or contact pad running substantially
the length of the edge of a solar cell may also be surrounded by a
barrier that prevents spreading of the conductive adhesive bonding
material. For example, FIG. 2Q shows such a barrier 27 surrounding
a rear surface bus bar 25. A front surface bus bar (e.g., bus bar
15 in FIG. 2A) may be similarly surrounded by a barrier. Similarly,
a row of front or rear surface contact pads may be surrounded as a
group by such a barrier, rather than individually surrounded by
separate barriers.
[0127] Rather than surrounding a bus bar or one or more contact
pads as just described, a feature of the front or rear surface
metallization pattern may form a barrier running substantially the
length of the solar cell parallel to the overlapped edge of the
solar cell, with the bus bar or contact pads positioned between the
barrier and the edge of the solar cell. Such a barrier may do
double duty as a bypass conductor (described above). For example,
in FIG. 2R bypass conductor 40 provides a barrier that tends to
prevent uncured conductive adhesive bonding material on contact
pads 15 from spreading onto the active area of the front surface of
the solar cell. A similar arrangement may be used for rear surface
metallization patterns.
[0128] Barriers to the spread of conductive adhesive bonding
material may be spaced apart from contact pads or bus bars to form
a moat as just described, but this is not required. Such barriers
may instead abut a contact pad or bus bar, as shown in FIG. 2O or
2P for example. In such variations the barrier is preferably taller
than the contact pad or bus bar, to retain the uncured conductive
adhesive bonding material on the contact pad or bus bar. Although
FIGS. 2O and 2P show portions of a front surface metallization
pattern, similar arrangements may be used for rear surface
metallization patterns.
[0129] Barriers to the spread of conductive adhesive bonding
material and/or moats between such barriers and contact pads or bus
bars, and any conductive adhesive bonding material that has spread
into such moats, may optionally lie within the region of the solar
cell surface overlapped by the adjacent solar cell in the super
cell, and thus be hidden from view and shielded from exposure to
solar radiation.
[0130] Alternatively or in addition to the use of barriers as just
described, the electrically conductive bonding material may be
deposited using a mask or by any other suitable method (e.g.,
screen printing) allowing accurate deposition and thus requiring
reduced amounts of electrically conductive bonding material that
are less likely to spread beyond the contact pads or miss the
contact pads during deposition.
[0131] More generally, solar cells 10 may employ any suitable front
and rear surface metallization patterns.
[0132] FIG. 4A shows a portion of the front surface of an example
rectangular super cell 100 comprising solar cells 10 as shown in
FIG. 2A arranged in a shingled manner as shown in FIG. 1. As a
result of the shingling geometry, there is no physical gap between
pairs of solar cells 10. In addition, although bus bar 15 of the
solar cell 10 at one end of super cell 100 is visible, the bus bars
(or front surface contact pads) of the other solar cells are hidden
beneath overlapping portions of adjacent solar cells. As a
consequence, super cell 100 efficiently uses the area it takes up
in a solar module. In particular, a larger portion of that area is
available to produce electricity than is the case for
conventionally tabbed solar cell arrangements and solar cell
arrangements including numerous visible bus bars on the illuminated
surface of the solar cells. FIGS. 4B-4C show front and rear views,
respectively, of another example super cell 100 comprising
primarily chamfered chevron rectangular silicon solar cells but
otherwise similar to that of FIG. 4A.
[0133] In the example illustrated in FIG. 4A, bypass conductors 40
are hidden by overlapping portions of adjacent cells.
Alternatively, solar cells comprising bypass conductors 40 may be
overlapped similarly to as shown in FIG. 4A without covering the
bypass conductors.
[0134] The exposed front surface bus bar 15 at one end of super
cell 100 and the rear surface metallization of the solar cell at
the other end of super cell 100 provide negative and positive
(terminal) end contacts for the super cell that may be used to
electrically connect super cell 100 to other super cells and/or to
other electrical components as desired.
[0135] Adjacent solar cells in super cell 100 may overlap by any
suitable amount, for example by about 1 millimeter (mm) to about 5
mm.
[0136] As shown in FIGS. 5A-5G, for example, shingled super cells
as just described may efficiently fill the area of a solar module.
Such solar modules may be square or rectangular, for example.
Rectangular solar modules as illustrated in FIGS. 5A-5G may have
shorts sides having a length, for example, of about 1 meter and
long sides having a length, for example, of about 1.5 to about 2.0
meters. Any other suitable shapes and dimensions for the solar
modules may also be used. Any suitable arrangement of super cells
in a solar module may be used.
[0137] In a square or rectangular solar module, the super cells are
typically arranged in rows parallel to the short or long sides of
the solar module. Each row may include one, two, or more super
cells arranged end-to-end. A super cell 100 forming part of such a
solar module may include any suitable number of solar cells 10 and
be of any suitable length. In some variations super cells 100 each
have a length approximately equal to the length of the short sides
of a rectangular solar module of which they are a part. In other
variations super cells 100 each have a length approximately equal
to one half the length of the short sides of a rectangular solar
module of which they are a part. In other variations super cells
100 each have a length approximately equal to the length of the
long sides of a rectangular solar module of which they are a part.
In other variations super cells 100 each have a length
approximately equal to one half the length of the long sides of a
rectangular solar module of which they are a part. The number of
solar cells required to make super cells of these lengths depends
of course on the dimensions of the solar module, the dimensions of
the solar cells, and the amount by which adjacent solar cells
overlap. Any other suitable lengths for super cells may also be
used.
[0138] In variations in which a super cell 100 has a length
approximately equal to the length of the short sides of a
rectangular solar module, the super cell may include, for example,
56 rectangular solar cells having dimensions of about 19.5
millimeters (mm) by about 156 mm, with adjacent solar cells
overlapped by about 3 mm. Eight such rectangular solar cells may be
separated from a conventional square or pseudo square 156 mm wafer.
Alternatively such a super cell may include, for example, 38
rectangular solar cells having dimensions of about 26 mm by about
156 mm, with adjacent solar cells overlapped by about 2 mm. Six
such rectangular solar cells may be separated from a conventional
square or pseudo square 156 mm wafer. In variations in which a
super cell 100 has a length approximately equal to half the length
of the short sides of a rectangular solar module, the super cell
may include, for example, 28 rectangular solar cells having
dimensions of about 19.5 millimeters (mm) by about 156 mm, with
adjacent solar cells overlapped by about 3 mm. Alternatively, such
a super cell may include, for example, 19 rectangular solar cells
having dimensions of about 26 mm by about 156 mm, with adjacent
solar cells overlapped by about 2 mm.
[0139] In variations in which a super cell 100 has a length
approximately equal to the length of the long sides of a
rectangular solar module, the super cell may include, for example,
72 rectangular solar cells having dimensions of about 26 mm by
about 156 mm, with adjacent solar cells overlapped by about 2 mm.
In variations in which a super cell 100 has a length approximately
equal to one half the length of the long sides of a rectangular
solar module, the super cell may include, for example, 36
rectangular solar cells having dimensions of about 26 mm by about
156 mm, with adjacent solar cells overlapped by about 2 mm.
[0140] FIG. 5A shows an example rectangular solar module 200
comprising twenty rectangular super cells 100, each of which has a
length approximately equal to one half the length of the short
sides of the solar module. The super cells are arranged end-to-end
in pairs to form ten rows of super cells, with the rows and the
long sides of the super cells oriented parallel to the short sides
of the solar module. In other variations, each row of super cells
may include three or more super cells. Also, a similarly configured
solar module may include more or fewer rows of super cells than
shown in this example. (FIG. 14A for example shows a solar module
comprising twenty-four rectangular super cells arranged in twelve
rows of two super cells each).
[0141] Gap 210 shown in FIG. 5A facilitates making electrical
contact to front surface end contacts (e.g., exposed bus bars or
discrete contacts 15) of super cells 100 along the center line of
the solar module, in variations in which the super cells in each
row are arranged so that at least one of them has a front surface
end contact on the end of the super cell adjacent to the other
super cell in the row. For example, the two super cells in a row
may be arranged with one super cell having its front surface
terminal contact along the center line of the solar module and the
other super cell having its rear surface terminal contact along the
center line of the solar module. In such an arrangement the two
super cells in a row may be electrically connected in series by an
interconnect arranged along the center line of the solar module and
bonded to the front surface terminal contact of one super cell and
to the rear surface terminal contact of the other super cell. (See
e.g. FIG. 8C discussed below). In variations in which each row of
super cells includes three or more super cells, additional gaps
between super cells may be present and may similarly facilitate
making electrical contact to front surface end contacts that are
located away from the sides of the solar module.
[0142] FIG. 5B shows an example rectangular solar module 300
comprising ten rectangular super cells 100, each of which has a
length approximately equal to the length of the short sides of the
solar module. The super cells are arranged as ten parallel rows
with their long sides oriented parallel to the short sides of the
module. A similarly configured solar module may include more or
fewer rows of such side-length super cells than shown in this
example.
[0143] FIG. 5B also shows what solar module 200 of FIG. 5A looks
like when there are no gaps between adjacent super cells in the
rows of super cells in solar module 200. Gap 210 of FIG. 5A can be
eliminated, for example, by arranging the super cells so that both
super cells in each row have their back surface end contacts along
the center line of the module. In this case the super cells may be
arranged nearly abutting each other with little or no extra gap
between them because no access to the front surface of the super
cell is required along the center of the module. Alternatively, two
super cells 100 in a row may be arranged with one having its front
surface end contact along a side of the module and its rear surface
end contact along the center line of the module, the other having
its front surface end contact along the center line of the module
and its rear surface end contact along the opposite side of the
module, and the adjacent ends of the super cells overlapping. A
flexible interconnect may be sandwiched between the overlapping
ends of the super cells, without shading any portion of the front
surface of the solar module, to provide an electrical connection to
the front surface end contact of one of the super cells and the
rear surface end contact of the other super cell. For rows
containing three or more super cells these two approaches may be
used in combination.
[0144] The super cells and rows of super cells shown in FIGS. 5A-5B
may be interconnected by any suitable combination of series and
parallel electrical connections, for example as described further
below with respect to FIGS. 10A-15. The interconnections between
super cells may be made, for example, using flexible interconnects
similarly to as described below with respect to FIGS. 5C-5G and
subsequent figures.
[0145] FIG. 5C shows an example rectangular solar module 350
comprising six rectangular super cells 100, each of which has a
length approximately equal to the length of the long sides of the
solar module. The super cells are arranged as six parallel rows
with their long sides oriented parallel to the long sides of the
module. A similarly configured solar module may include more or
fewer rows of such side-length super cells than shown in this
example. Each super cell in this example (and in several of the
following examples) comprises 72 rectangular solar cells each
having a width approximately equal to 1/6 the width of a 156 mm
square or pseudo square wafer. Any other suitable number of
rectangular solar cells of any other suitable dimensions may also
be used. In this example the front surface terminal contacts of the
super cells are electrically connected to each other with flexible
interconnects 400 positioned adjacent to and running parallel to
the edge of one short side of the module. The rear surface terminal
contacts of the super cells are similarly connected to each other
by flexible interconnects positioned adjacent to and running
parallel to the edge of the other short side, behind the solar
module. The rear surface interconnects are hidden from view in FIG.
5C. This arrangement electrically connects the six module-length
super cells in parallel. Details of the flexible interconnects and
their arrangement in this and other solar module configurations are
discussed in more detail below with respect to FIGS. 6-8G.
[0146] FIG. 5D shows an example rectangular solar module 360
comprising twelve rectangular super cells 100, each of which has a
length approximately equal to one half the length of the long sides
of the solar module. The super cells are arranged end-to-end in
pairs to form six rows of super cells, with the rows and the long
sides of the super cells oriented parallel to the long sides of the
solar module. In other variations, each row of super cells may
include three or more super cells. Also, a similarly configured
solar module may include more or fewer rows of super cells than
shown in this example. Each super cell in this example (and in
several of the following examples) comprises 36 rectangular solar
cells each having a width approximately equal to 1/6 the width of a
156 mm square or pseudo square wafer. Any other suitable number of
rectangular solar cells of any other suitable dimensions may also
be used. Gap 410 facilitates making electrical contact to front
surface end contacts of super cells 100 along the center line of
the solar module. In this example, flexible interconnects 400
positioned adjacent to and running parallel to the edge of one
short side of the module electrically interconnect the front
surface terminal contacts of six of the super cells. Similarly,
flexible interconnects positioned adjacent to and running parallel
to the edge of the other short side of the module behind the module
electrically connect the rear surface terminal contacts of the
other six super cells. Flexible interconnects (not shown in this
figure) positioned along gap 410 interconnect each pair of super
cells in a row in series and, optionally, extend laterally to
interconnect adjacent rows in parallel. This arrangement
electrically connects the six rows of super cells in parallel.
Optionally, in a first group of super cells the first super cell in
each row is electrically connected in parallel with the first super
cell in each of the other rows, in a second group of super cells
the second super cell is electrically connected in parallel with
the second super cell in each of the other rows, and the two groups
of super cells are electrically connect in series. The later
arrangement allows each of the two groups of super cells to be
individually put in parallel with a bypass diode.
[0147] Detail A in FIG. 5D identifies the location of a
cross-sectional view shown in FIG. 8A of the interconnection of the
rear surface terminal contacts of super cells along the edge of one
short side of the module. Detail B similarly identifies the
location of a cross-sectional view shown in FIG. 8B of the
interconnection of the front surface terminal contacts of super
cells along the edge of the other short side of the module. Detail
C identifies the location of a cross-sectional view shown in FIG.
8C of series interconnection of the super cells within a row along
gap 410.
[0148] FIG. 5E shows an example rectangular solar module configured
similarly to that of FIG. 5C, except that in this example all of
the solar cells from which the super cells are formed are chevron
solar cells having chamfered corners corresponding to corners of
pseudo-square wafers from which the solar cells were separated.
[0149] FIG. 5F shows another example rectangular solar module
configured similarly to that of FIG. 5C, except that in this
example the solar cells from which the super cells are formed
comprise a mixture of chevron and rectangular solar cells arranged
to reproduce the shapes of the pseudo-square wafers from which they
were separated. In the example of FIG. 5F, the chevron solar cells
may be wider perpendicular to their long axes than are the
rectangular solar cells to compensate for the missing corners on
the chevron cells, so that the chevron solar cells and the
rectangular solar cells have the same active area exposed to solar
radiation during operation of the module and therefore matched
current.
[0150] FIG. 5G shows another example rectangular solar module
configured similarly to that of FIG. 5E (i.e., including only
chevron solar cells) except that in the solar module of FIG. 5G
adjacent chevron solar cells in a super cell are arranged as mirror
images of each other so that their overlapping edges are of the
same length. This maximizes the length of each overlapping joint,
and thereby facilitates heat flow through the super cell.
[0151] Other configurations of rectangular solar modules may
include one or more rows of super cells formed only from
rectangular (non-chamfered) solar cells, and one or more rows of
super cells formed only from chamfered solar cells. For example, a
rectangular solar module may be configured similarly to that of
FIG. 5C, except having the two outer rows of super cells each
replaced by a row of super cells formed only from chamfered solar
cells. The chamfered solar cells in those rows may be arranged in
mirror image pairs as shown in FIG. 5G, for example.
[0152] In the example solar modules shown in FIGS. 5C-5G, the
electric current along each row of super cells is about 1/6 of that
in a conventional solar module of the same area because the
rectangular solar cells from which the super cells are formed has
an active area of about 1/6 that of a conventionally sized solar
cell. Because in these examples the six rows of super cells are
electrically connected in parallel, however, the example solar
modules may generate a total electric current equal to that
generated by a conventional solar module of the same area. This
facilitates substation of the example solar modules of FIGS. 5C-5G
(and other examples described below) for conventional solar
modules.
[0153] FIG. 6 shows in more detail than FIGS. 5C-5G an example
arrangement of three rows of super cells interconnected with
flexible electrical interconnects to put the super cells within
each row in series with each other, and to put the rows in parallel
with each other. These may be three rows in the solar module of
FIG. 5D, for example. In the example of FIG. 6, each super cell 100
has a flexible interconnect 400 conductively bonded to its front
surface terminal contact, and another flexible interconnect
conductively bonded to its rear surface terminal contact. The two
super cells within each row are electrically connected in series by
a shared flexible interconnect conductively bonded to the front
surface terminal contact of one super cell and to the rear surface
terminal contact of the other super cell. Each flexible
interconnect is positioned adjacent to and runs parallel to an end
of a super cell to which it is bonded, and may extend laterally
beyond the super cell to be conductively bonded to a flexible
interconnect on a super cell in an adjacent row, electrically
connecting the adjacent rows in parallel. Dotted lines in FIG. 6
depict portions of the flexible interconnects that are hidden from
view by overlying portions of the super cells, or portions of the
super cells that are hidden from view by overlying portions of the
flexible interconnects.
[0154] Flexible interconnects 400 may be conductively bonded to the
super cells with, for example, a mechanically compliant
electrically conductive bonding material as described above for use
in bonding overlapped solar cells. Optionally, the electrically
conductive bonding material may be located only at discrete
positions along the edges of the super cell rather than in a
continuous line extending substantially the length of the edge of
the super cell, to reduce or accommodate stress parallel to the
edges of the super cell arising from mismatch between the
coefficient of thermal expansion of the electrically conductive
bonding material or the interconnects and that of the super
cell.
[0155] Flexible interconnects 400 may be formed from or comprise
thin copper sheets, for example. Flexible interconnects 400 may be
optionally patterned or otherwise configured to increase their
mechanical compliance (flexibility) both perpendicular to and
parallel to the edges of the super cells to reduce or accommodate
stress perpendicular and parallel to the edges of the super cells
arising from mismatch between the CTE of the interconnect and that
of the super cells. Such patterning may include, for example,
slits, slots, or holes. Conductive portions of interconnects 400
may have a thickness of, for example, less than about 100 microns,
less than about 50 microns, less than about 30 microns, or less
than about 25 microns to increase the flexibility of the
interconnects. The mechanical compliance of the flexible
interconnect, and its bonds to the super cells, should be
sufficient for the interconnected super cells to survive stress
arising from CTE mismatch during the lamination process described
in more detail below with respect to methods of manufacturing
shingled solar cell modules, and to survive stress arising from CTE
mismatch during temperature cycling testing between about
-40.degree. C. and about 85.degree. C.
[0156] Preferably, flexible interconnects 400 exhibit a resistance
to current flow parallel to the ends of the super cells to which
they are bonded of less than or equal to about 0.015 Ohms, less
than or equal to about 0.012 Ohms, or less than or equal to about
0.01 Ohms.
[0157] FIG. 7 shows several example configurations, designated by
reference numerals 400A-400T, that may be suitable for flexible
interconnect 400,
[0158] As shown in the cross-sectional views of FIGS. 8A-8C, for
example, the solar modules described in this specification
typically comprise a laminate structure with super cells and one or
more encapsulant materials 410 sandwiched between a transparent
front sheet 420 and a back sheet 430. The transparent front sheet
may be glass, for example. Optionally, the back sheet may also be
transparent, which may allow bifacial operation of the solar
module. The back sheet may be a polymer sheet, for example.
Alternatively, the solar module may be a glass-glass module with
both the front and back sheets glass.
[0159] The cross-sectional view of FIG. 8A (detail A from FIG. 5D)
shows an example of a flexible interconnect 400 conductively bonded
to a rear surface terminal contact of a super cell near the edge of
the solar module and extending inward beneath the super cell,
hidden from view from the front of the solar module. An extra strip
of encapsulant may be disposed between interconnect 400 and the
rear surface of the super cell, as illustrated.
[0160] The cross-sectional view of FIG. 8B (Detail B from FIG. 5B)
shows an example of a flexible interconnect 400 conductively bonded
to a front surface terminal contact of a super cell.
[0161] The cross-sectional view of FIG. 8C (Detail C from FIG. 5B)
shows an example of a shared flexible interconnect 400 conductively
bonded to the front surface terminal contact of one super cell and
to the rear surface terminal contact of the other super cell to
electrically connect the two super cells in series.
[0162] Flexible interconnects electrically connected to the front
surface terminal contact of a super cell may be configured or
arranged to occupy only a narrow width of the front surface of the
solar module, which may for example be located adjacent an edge of
the solar module. The region of the front surface of the module
occupied by such interconnects may have a narrow width
perpendicular to the edge of the super cell of, for example,
.ltoreq.about 10 mm, .ltoreq.about 5 mm, or .ltoreq.about 3 mm. In
the arrangement shown in FIG. 8B, for example, flexible
interconnect 400 may be configured to extend beyond the end of the
super cell by no more than such a distance. FIGS. 8D-8G show
additional examples of arrangements by which a flexible
interconnect electrically connected to a front surface terminal
contact of a super cell may occupy only a narrow width of the front
surface of the module. Such arrangements facilitate efficient use
of the front surface area of the module to produce electricity.
[0163] FIG. 8D shows a flexible interconnect 400 that is
conductively bonded to a terminal front surface contact of a super
cell and folded around the edge of the super cell to the rear of
the super cell. An insulating film 435, which may be pre-coated on
flexible interconnect 400, may be disposed between flexible
interconnect 400 and the rear surface of the super cell.
[0164] FIG. 8E shows a flexible interconnect 400 comprising a thin
narrow ribbon 440 that is conductively bonded to a terminal front
surface contact of a super cell and also to a thin wide ribbon 445
that extends behind the rear surface of the super cell. An
insulating film 435, which may be pre-coated on ribbon 445, may be
disposed between ribbon 445 and the rear surface of the super
cell.
[0165] FIG. 8F shows a flexible interconnect 400 bonded to a
terminal front surface contact of a super cell and rolled and
pressed into a flattened coil that occupies only a narrow width of
the solar module front surface.
[0166] FIG. 8G shows a flexible interconnect 400 comprising a thin
ribbon section that is conductively bonded to a terminal front
surface contact of a super cell and a thick cross-section portion
located adjacent to the super cell.
[0167] In FIGS. 8A-8G, flexible interconnects 400 may extend along
the full lengths of the edges of the super cells (e.g., into the
drawing page) as shown in FIG. 6 for example.
[0168] Optionally, portions of a flexible interconnect 400 that are
otherwise visible from the front of the module may be covered by a
dark film or coating or otherwise colored to reduce visible
contrast between the interconnect and the super cell, as perceived
by a human having normal color vision. For example, in FIG. 8C
optional black film or coating 425 covers portions of the
interconnect 400 that would otherwise be visible from the front of
the module. Otherwise visible portions of interconnect 400 shown in
the other figures may be similarly covered or colored.
[0169] Conventional solar modules typically include three or more
bypass diodes, with each bypass diode connected in parallel with a
series connected group of 18-24 silicon solar cells. This is done
to limit the amount of power that may be dissipated as heat in a
reverse biased solar cell. A solar cell may become reverse biased,
for example, because of a defect, a dirty front surface, or uneven
illumination that reduces its ability to pass current generated in
the string. Heat generated in a solar cell in reverse bias depends
on the voltage across the solar cell and the current through the
solar cell. If the voltage across the reverse biased solar cell
exceeds the breakdown voltage of the solar cell, the heat
dissipated in the cell will be equal to the breakdown voltage times
the full current generated in the string. Silicon solar cells
typically have a breakdown voltage of 16-30 Volts. Because each
silicon solar cell produces a voltage of about 0.64 Volts in
operation, a string of more than 24 solar cells could produce a
voltage across a reverse biased solar cell exceeding the breakdown
voltage.
[0170] In conventional solar modules in which the solar cells are
spaced apart from each other and interconnected with ribbons, heat
is not readily transported away from a hot solar cell.
Consequently, the power dissipated in a solar cell at breakdown
voltage could produce a hot spot in the solar cell that causes
significant thermal damage and perhaps a fire. In conventional
solar modules a bypass diode is therefore required for every group
of 18-24 series connected solar cells to insure that no solar cell
in the string can be reverse biased above the breakdown
voltage.
[0171] Applicants have discovered that heat is readily transported
along a silicon super cell through the thin electrically and
thermally conductive bonds between adjacent overlapping silicon
solar cells. Further, the current through a super cell in the solar
modules described herein is typically less than that through a
string of conventional solar cells, because the super cells
described herein are typically formed by shingling rectangular
solar cells each of which has an active area less than (for
example, 1/6) that of a conventional solar cell. Furthermore, the
rectangular aspect ratio of the solar cells typically employed
herein provides extended regions of thermal contact between
adjacent solar cells. As a consequence, less heat is dissipated in
a solar cell reverse biased at the breakdown voltage, and the heat
readily spreads through the super cell and the solar module without
creating a dangerous hot spot. Applicants have therefore recognized
that solar modules formed from super cells as described herein may
employ far fewer bypass diodes than conventionally believed to be
required.
[0172] For example, in some variations of solar modules as
described herein a super cell comprising N>25 solar cells,
N.gtoreq.about 30 solar cells, N.gtoreq.about 50 solar cells,
N.gtoreq.about 70 solar cells, or N.gtoreq.about 100 solar cells
may be employed with no single solar cell or group of <N solar
cells in the super cell individually electrically connected in
parallel with a bypass diode. Optionally, a full super cell of
these lengths may be electrically connected in parallel with a
single bypass diode. Optionally, super cells of these lengths may
be employed without a bypass diode.
[0173] Several additional and optional design features may make
solar modules employing super cells as described herein even more
tolerant to heat dissipated in a reverse biased solar cell.
Referring again to FIGS. 8A-8C, encapsulant 410 may be or comprise
a thermoplastic olefin (TPO) polymer, TPO encapsulants are more
photo-thermal stable than standard ethylene-vinyl acetate (EVA)
encapsulants. EVA will brown with temperature and ultraviolet light
and lead to hot spot issues created by current limiting cells.
These problems are reduced or avoided with TPO encapsulant.
Further, the solar modules may have a glass-glass structure in
which both the transparent front sheet 420 and the back sheet 430
are glass. Such a glass-glass enables the solar module to safely
operate at temperatures greater than those tolerated by a
conventional polymer back sheet. Further still, junction boxes may
be mounted on one or more edges of a solar module, rather than
behind the solar module where a junction box would add an
additional layer of thermal insulation to the solar cells in the
module above it.
[0174] FIG. 9A shows an example rectangular solar module comprising
six rectangular shingled super cells arranged in six rows extending
the length of the long sides of the solar module. The six super
cells are electrically connected in parallel with each other and
with a bypass diode disposed in a junction box 490 on the rear
surface of the solar module. Electrical connections between the
super cells and the bypass diode are made through ribbons 450
embedded in the laminate structure of the module.
[0175] FIG. 9B shows another example rectangular solar module
comprising six rectangular shingled super cells arranged in six
rows extending the length of the long sides of the solar module.
The super cells are electrically connected in parallel with each
other. Separate positive 490P and negative 490N terminal junction
boxes are disposed on the rear surface of the solar module at
opposite ends of the solar module. The super cells are electrically
connected in parallel with a bypass diode located in one of the
junction boxes by an external cable 455 running between the
junction boxes.
[0176] FIGS. 9C-9D show an example glass-glass rectangular solar
module comprising six rectangular shingled super cells arranged in
six rows extending the length of the long sides of the solar module
in a lamination structure comprising glass front and back sheets.
The super cells are electrically connected in parallel with each
other. Separate positive 490P and negative 490N terminal junction
boxes are mounted on opposite edges of the solar module.
[0177] Shingled super cells open up unique opportunities for module
layout with respect to module level power management devices (for
example, DC/AC micro-inverters, DC/DC module power optimizers,
voltage intelligence and smart switches, and related devices). The
key feature of module level power management systems is power
optimization. Super cells as described and employed herein may
produce higher voltages than traditional panels. In addition, super
cell module layout may further partition the module. Both higher
voltages and increased partitioning create potential advantages for
power optimization.
[0178] FIG. 9E shows one example architecture for module level
power management using shingled super cells. In this figure an
example rectangular solar module comprises six rectangular shingled
super cells arranged in six rows extending the length of the long
sides of the solar module. Three pairs of super cells are
individually connected to a power management system 460, enabling
more discrete power optimization of the module.
[0179] FIG. 9F shows another example architecture for module level
power management using shingled super cells. In this figure an
example rectangular solar module comprises six rectangular shingled
super cells arranged in six rows extending the length of the long
sides of the solar module. The six super cells are individually
connected to a power management system 460, enabling yet more
discrete power optimization of the module.
[0180] FIG. 9G shows another example architecture for module level
power management using shingled super cells. In this figure an
example rectangular solar module comprises six or more rectangular
shingled super cells 998 arranged in six or more rows, where the
three or more super cells pairs are individually connected to a
bypass diode or a power management system 460, to allow yet more
discrete power optimization of the module.
[0181] FIG. 9H shows another example architecture for module level
power management using shingled super cells. In this figure an
example rectangular solar module comprises six or more rectangular
shingled super cells 998 arranged in six or more rows, where each
two super cell are connected in series, and all pairs are connected
in parallel. A bypass diode or power management system 460 is
connected in parallel to all pairs, permitting power optimization
of the module.
[0182] In some variations, module level power management allows
elimination of all bypass diodes on the solar module while still
excluding the risk of hot spots. This is accomplished by
integrating voltage intelligence at the module level. By monitoring
the voltage output of a solar cell circuit (e.g., one or more super
cells) in the solar module, a "smart switch" power management
device can determine if that circuit includes any solar cells in
reverse bias. If a reverse biased solar cell is detected, the power
management device can disconnect the corresponding circuit from the
electrical system using, for example, a relay switch or other
component. For example, if the voltage of a monitored solar cell
circuit drops below a predetermined threshold (V.sub.Limit), then
the power management device will shut off (open circuit) that
circuit while ensuring that the module or string of modules remain
connected.
[0183] In certain embodiments, where a voltage of the circuits
drops by more than a certain percentage or magnitude (e.g., 20% or
10V) from the other circuits in same solar array, it will be shut
off. The electronics will detect this change based upon
inter-module communication.
[0184] Implementation of such voltage intelligence may be
incorporated into existing module level power management solutions
(e.g., from Enphase Energy Inc., Solaredge Technologies, Inc., Tigo
Energy, Inc.) or through a custom circuit design.
[0185] One example of how the V.sub.Limit threshold voltage may be
calculated is:
CellVoc.sub.@Low Irr & High Temp.times.N.sub.number of cells in
series-Vrb.sub.Reverse breakdown voltage.ltoreq.V.sub.Limit,
where:
[0186] CellVoc.sub.@Low Irr & High Temp=open circuit voltage of
a cell working at low irradiation and at high temperature (lowest
expected working Voc);
[0187] N.sub.number of cells in series=a number of cells connected
in series in each super cell monitored.
[0188] Vrb.sub.Reverse breakdown voltage=revered polarity voltage
needed to pass current through a cell.
[0189] This approach to module level power management using a smart
switch may allow, for example more than 100 silicon solar cells to
be connected in series within a single module without affecting
safety or module reliability. In addition, such a smart switch can
be used to limit string voltage going to a central inverter. Longer
module strings can therefore be installed without safety or
permitting concerns regarding over voltage. The weakest module can
be bypassed (switched off) if string voltages run up against the
limit.
[0190] FIGS. 10A, 11A, 12A, 13A, 13B, and 14B described below
provide additional example schematic electrical circuits for solar
modules employing shingled super cells. FIGS. 10B-1, 10B-2, 11B-1,
11B-2, 11C-1, 11C-2, 12B-1, 12B-2, 12C-1, 12C-2, 12C-3, 13C-1,
13C-2, 14C-1, and 14C-2 provide example physical layouts
corresponding to those schematic circuits. The description of the
physical layouts assumes that the front surface end contact of each
super cell is of negative polarity and the rear surface end contact
of each super cell is of positive polarity. If instead the modules
employ super cells having front surface end contacts of positive
polarity and rear surface end contacts of negative polarity, then
the discussion of the physical layouts below may be modified by
swapping positive for negative and by reversing the orientation of
the bypass diodes. Some of the various buses referred to in the
description of these figures may be formed, for example, with
interconnects 400 described above. Other buses described in these
figures may be implemented, for example, with ribbons embedded in
the laminate structure of solar module or with external cables.
[0191] FIG. 10A shows an example schematic electrical circuit for a
solar module as illustrated in FIG. 5B, in which the solar module
includes ten rectangular super cells 100 each of which has a length
approximately equal to the length of the short sides of the solar
module. The super cells are arranged in the solar module with their
long sides oriented parallel to the short sides of the module. All
of the super cells are electrically connected in parallel with a
bypass diode 480.
[0192] FIGS. 10B-1 and 10B-2 show an example physical layout for
the solar module of FIG. 10A. Bus 485N connects the negative (front
surface) end contacts of super cells 100 to the positive terminal
of bypass diode 480 in junction box 490 located on the rear surface
of the module. Bus 485P connects the positive (rear surface) end
contacts of super cells 100 to the negative terminal of bypass
diode 480. Bus 485P may lie entirely behind the super cells. Bus
485N and/or its interconnection to the super cells occupy a portion
of the front surface of the module.
[0193] FIG. 11A shows an example schematic electrical circuit for a
solar module as illustrated in FIG. 5A, in which the solar module
includes twenty rectangular super cells 100, each of which has a
length approximately equal to one half the length of the short
sides of the solar module, and the super cells are arranged
end-to-end in pairs to form ten rows of super cells. The first
super cell in each row is connected in parallel with the first
super cells in the other rows and in parallel with a bypass diode
500. The second super cell in each row is connected in parallel
with the second super cells in the other rows and in parallel with
a bypass diode 510. The two groups of super cells are connected in
series, as are the two bypass diodes.
[0194] FIGS. 11B-1 and 11B-2 show an example physical layout for
the solar module of FIG. 11A. In this layout the first super cell
in each row has its front surface (negative) end contact along a
first side of the module and its rear surface (positive) end
contact along the center line of the module, and the second super
cell in each row has its front surface (negative) end contact along
the center line of the module and its rear surface (positive) end
contact along a second side of the module opposite from the first
side. Bus 515N connects the front surface (negative) end contact of
the first super cell in each row to the positive terminal of bypass
diode 500. Bus 515P connects the rear surface (positive) end
contact of the second super cell in each row to the negative
terminal of bypass diode 510. Bus 520 connects the rear surface
(positive) end contact of the first super cell in each row and the
front surface (negative) end contact of the second super cell in
each row to the negative terminal of bypass diode 500 and to the
positive terminal of bypass diode 510.
[0195] Bus 515P may lie entirely behind the super cells. Bus 515N
and/or its interconnection to the super cells occupy a portion of
the front surface of the module. Bus 520 may occupy a portion of
the front surface of the module, requiring a gap 210 as shown in
FIG. 5A. Alternatively, bus 520 may lie entirely behind the super
cells and be electrically connected to the super cells with hidden
interconnects sandwiched between overlapping ends of the super
cells. In such a case little or no gap 210 is required.
[0196] FIGS. 11C-1, 11C-2, and 11C-3 show another example physical
layout for the solar module of FIG. 11A. In this layout the first
super cell in each row has its front surface (negative) end contact
along a first side of the module and its rear surface (positive)
end contact along the center line of the module, and the second
super cell in each row has its rear surface (positive) end contact
along the center line of the module and its front surface
(negative) end contact along a second side of the module opposite
from the first side. Bus 525N connects the front surface (negative)
end contact of the first super cell in each row to the positive
terminal of bypass diode 500. Bus 530N connects the front surface
(negative) end contact of the second cell in each row to the
negative terminal of bypass diode 500 and to the positive terminal
of bypass diode 510. Bus 535P connects the rear surface (positive)
end contact of the first cell in each row to the negative terminal
of bypass diode 500 and to the positive terminal of bypass diode
510. Bus 540P connects the rear surface (positive) end contact of
the second cell in each row to the negative terminal of bypass
diode 510.
[0197] Bus 535P and bus 540P may lie entirely behind the super
cells. Bus 525N and bus 530N and/or their interconnection to the
super cells occupy a portion of the front surface of the
module.
[0198] FIG. 12A shows another example schematic circuit diagram for
a solar module as illustrated in FIG. 5A, in which the solar module
includes twenty rectangular super cells 100, each of which has a
length approximately equal to one half the length of the short
sides of the solar module, and the super cells are arranged
end-to-end in pairs to form ten rows of super cells. In the circuit
shown in FIG. 12A, the super cells are arranged in four groups: in
a first group the first super cells of the top five rows are
connected in parallel with each other and with a bypass diode 545,
in a second group the second super cells of the top five rows are
connected in parallel with each other and with a bypass diode 505,
in a third group the first super cells of the bottom five rows are
connected in parallel with each other and with a bypass diode 560,
and in a fourth group the second super cells of the bottom five
rows are connected in parallel with each other and with a bypass
diode 555. The four groups of super cells are connected in series
with each other. The four bypass diodes are also in series.
[0199] FIGS. 12B-1 and 12B-2 show an example physical layout for
the solar module of FIG. 12A. In this layout the first group of
super cells has its front surface (negative) end contacts along a
first side of the module and its rear surface (positive) end
contacts along the center line of the module, the second group of
super cells has its front surface (negative) end contacts along the
center line of the module and its rear surface (positive) end
contacts along a second side of the module opposite from the first
side, the third group of super cells has its rear surface
(positive) end contacts along the first side of the module and its
front surface (negative) end contacts along the center line of the
module, and the fourth group of super cells has its rear surface
(positive) end contact along the center line of the module and its
front surface (negative) end contact along the second side of the
module.
[0200] Bus 565N connects the front surface (negative) end contacts
of the super cells in the first group of super cells to each other
and to the positive terminal of bypass diode 545. Bus 570 connects
the rear surface (positive) end contacts of the super cells in the
first group of super cells and the front surface (negative) end
contacts of the super cells in the second group of super cells to
each other, to the negative terminal of bypass diode 545, and to
the positive terminal of bypass diode 550. Bus 575 connects the
rear surface (positive) end contacts of the super cells in the
second group of super cells and the front surface (negative) end
contacts of the super cells in the fourth group of super cells to
each other, to the negative terminal of bypass diode 550, and to
the positive terminal of bypass diode 555. Bus 580 connects the
rear surface (positive) end contacts of the super cells in the
fourth group of super cells and the front surface (negative) end
contacts of the super cells in the third group of super cells to
each other, to the negative terminal of bypass diode 555, and to
the positive terminal of bypass diode 560. Bus 585P connects the
rear surface (positive) end contacts of the super cells in the
third group of super cells to each other and to the negative
terminal of bypass diode 560.
[0201] Bus 585P and the portion of bus 575 connecting to the super
cells of the second group of super cells may lie entirely behind
the super cells. The remaining portion of bus 575 and bus 565N
and/or their interconnection to the super cells occupy a portion of
the front surface of the module.
[0202] Bus 570 and bus 580 may occupy a portion of the front
surface of the module, requiring a gap 210 as shown in FIG. 5A.
Alternatively, they may lie entirely behind the super cells and be
electrically connected to the super cells with hidden interconnects
sandwiched between overlapping ends of super cells. In such a case
little or no gap 210 is required.
[0203] FIGS. 12C-1, 12C-2, and 12C-3 show an alternative physical
layout for the solar module of FIG. 12A. This layout uses two
junction boxes 490A and 490B in place of the single junction box
490 shown in FIGS. 12B-1 and 12B-2, but is otherwise equivalent to
that of FIGS. 12B-1 and 12B-2.
[0204] FIG. 13A shows another example schematic circuit diagram for
a solar module as illustrated in FIG. 5A, in which the solar module
includes twenty rectangular super cells 100, each of which has a
length approximately equal to one half the length of the short
sides of the solar module, and the super cells are arranged
end-to-end in pairs to form ten rows of super cells. In the circuit
shown in FIG. 13A, the super cells are arranged in four groups: in
a first group the first super cells of the top five rows are
connected in parallel with each other, in a second group the second
super cells of the top five rows are connected in parallel with
each other, in a third group the first super cells of the bottom
five rows are connected in parallel with each other, and in a
fourth group the second super cells of the bottom five rows are
connected in parallel with each other. The first group and the
second group are connected in series with each other and thus
connected are in parallel with a bypass diode 590. The third group
and the fourth group are connected in series with each other and
thus connected in parallel with another bypass diode 595. The first
and second groups are connected in series with the third and fourth
groups, and the two bypass diodes are in series as well.
[0205] FIGS. 13C-1 and 13C-2 show an example physical layout for
the solar module of FIG. 13A. In this layout the first group of
super cells has its front surface (negative) end contact along a
first side of the module and its rear surface (positive) end
contact along the center line of the module, the second group of
super cells has its front surface (negative) end contact along the
center line of the module and its rear surface (positive) end
contact along a second side of the module opposite from the first
side, the third group of super cells has its rear surface
(positive) end contact along the first side of the module and its
front surface (negative) end contact along the center line of the
module, and the fourth group of super cells has its rear surface
(positive) end contact along the center line of the module and its
front surface (negative) end contact along the second side of the
module.
[0206] Bus 600 connects the front surface (negative) end contacts
of the first group of super cells to each other, to the rear
surface (positive) end contacts of the third group of super cells,
to the positive terminal of bypass diode 590, and to the negative
terminal of bypass diode 595. Bus 605 connects the rear surface
(positive) end contacts of the first group of super cells to each
other and to the front surface (negative) end contacts of the
second group of super cells. Bus 610P connects the rear surface
(positive) end contacts of the second group of super cells to each
other and to the negative terminal of bypass diode 590. Bus 615N
connects the front surface (negative) end contacts of the fourth
group of super cells to each other and to the positive terminal of
bypass diode 595. Bus 620 connects the front surface (negative) end
contacts of the third group of super cells to each other and to the
rear surface (positive) end contacts of the fourth group of super
cells.
[0207] Bus 610P and the portion of bus 600 connecting to the super
cells of the third group of super cells may lie entirely behind the
super cells. The remaining portion of bus 600 and bus 615N and/or
their interconnection to the super cells occupy a portion of the
front surface of the module.
[0208] Bus 605 and bus 620 occupy a portion of the front surface of
the module, requiring a gap 210 as shown in FIG. 5A. Alternatively,
they may lie entirely behind the super cells and be electrically
connected to the super cells with hidden interconnects sandwiched
between overlapping ends of super cells. In such a case little or
no gap 210 is required.
[0209] FIG. 13B shows an example schematic electrical circuit for a
solar module as illustrated in FIG. 5B, in which the solar module
includes ten rectangular super cells 100 each of which has a length
approximately equal to the length of the short sides of the solar
module. The super cells are arranged in the solar module with their
long sides oriented parallel to the short sides of the module. In
the circuit shown in FIG. 13B, the super cells are arranged in two
groups: in a first group the top five super cells are connected in
parallel with each other and with bypass diode 590, and in a second
group the bottom five super cells are connected in parallel with
each other and with bypass diode 595. The two groups are connected
in series with each other. The bypass diodes are also connected in
series.
[0210] The schematic circuit of FIG. 13B differs from that of FIG.
13A by replacing each row of two super cells in FIG. 13A with a
single super cell. Consequently, the physical layout for the solar
module of FIG. 13B may be as shown in FIGS. 13C-1, 13C-2, and
13C-3, with the omission of bus 605 and bus 620.
[0211] FIG. 14A shows an example rectangular solar module 700
comprising twenty-four rectangular super cells 100, each of which
has a length approximately equal to one half the length of the
short sides of the solar module. Super cells are arranged
end-to-end in pairs to form twelve rows of super cells, with the
rows and the long sides of the super cells oriented parallel to the
short sides of the solar module.
[0212] FIG. 14B shows an example schematic circuit diagram for a
solar module as illustrated in FIG. 14A. In the circuit shown in
FIG. 14B, the super cells are arranged in three groups: in a first
group the first super cells of the top eight rows are connected in
parallel with each other and with a bypass diode 705, in a second
group the super cells of the bottom four rows are connected in
parallel with each other and with a bypass diode 710, and in a
third group the second super cells of the top eight rows are
connected in parallel with each other and with a bypass diode 715.
The three groups of super cells are connected in series. The three
bypass diodes are also in series.
[0213] FIGS. 14C-1 and 14C-2 show an example physical layout for
the solar module of FIG. 14B. In this layout the first group of
super cells has its front surface (negative) end contacts along a
first side of the module and its rear surface (positive) end
contacts along the center line of the module. In the second group
of super cells, the first super cell in each of the bottom four
rows has its rear surface (positive) end contact along the first
side of the module and its front surface (negative) end contact
along the center line of the module, and the second super cell in
each of the bottom four rows has its front surface (negative) end
contact along the center line of the module and its rear surface
(positive) end contact along a second side of the module opposite
from the first side. The third group of solar cells has its rear
surface (positive) end contacts along the center line of the module
and its rear surface (negative) end contacts along the second side
of the module.
[0214] Bus 720N connects the front surface (negative) end contacts
of the first group of super cells to each other and to the positive
terminal of bypass diode 705. Bus 725 connects the rear surface
(positive) end contacts of the first group of super cells to the
front surface (negative) end contacts of the second group of super
cells, to the negative terminal of bypass diode 705, and to the
positive terminal of bypass diode 710. Bus 730P connects the rear
surface (positive) end contacts of the third group of super cells
to each other and to the negative terminal of bypass diode 715. Bus
735 connects the front surface (negative) end contacts of the third
group of super cells to each other, to the rear surface (positive)
end contacts of the second group of super cells, to the negative
terminal of bypass diode 710, and to the positive terminal of
bypass diode 715.
[0215] The portion of bus 725 connecting to the super cells of the
first group of super cells, bus 730P, and the portion of bus 735
connecting to the super cells of the second group of super cells
may lie entirely behind the super cells. Bus 720N and the remaining
portions of bus 725 and bus 735 and/or their interconnection to the
super cells occupy a portion of the front surface of the
module.
[0216] Some of the examples described above house the bypass diodes
in one or more junction boxes on the rear surface of the solar
module. This is not required, however. For example, some or all of
the bypass diodes may be positioned in-plane with the super cells
around the perimeter of the solar module or in gaps between super
cells, or positioned behind the super cells. In such cases the
bypass diodes may be disposed in a laminate structure in which the
super cells are encapsulated, for example. The locations of the
bypass diodes may thus be decentralized and removed from the
junction boxes, facilitating replacement of a central junction box
comprising both positive and negative module terminals with two
separate single-terminal junction boxes which may be located on the
rear surface of the solar module near to outer edges of the solar
module, for example. This approach generally reduces the current
path length in ribbon conductors in the solar module and in cabling
between solar modules, which may both reduce material cost and
increase module power (by reducing resistive power losses).
[0217] Referring to FIG. 15, for example, the physical layout for
various electrical interconnections for a solar module as
illustrated in FIG. 5B having the schematic circuit diagram of FIG.
10A may employ a bypass diode 480 located in the super cell
laminate structure and two single terminal junction boxes 490P and
490N. FIG. 15 may best be appreciated by comparison to FIGS. 10B-1
and 10B-2. The other module layouts described above may be
similarly modified.
[0218] Use of in-laminate bypass diodes as just described may be
facilitated by the use of reduced current (reduced area)
rectangular solar cells as described above, because the power
dissipated in a forward-biased bypass diode by the reduced current
solar cells may be less than would be the case for conventionally
sized solar cells. Bypass diodes in solar modules described in this
specification may therefore require less heat-sinking than is
conventional, and consequently may be moved out of a junction box
on the rear surface of the module and into the laminate.
[0219] A single solar module may include interconnects, other
conductors, and/or bypass diodes supporting two or more electrical
configurations, for example supporting two or more of the
electrical configurations described above. In such cases a
particular configuration for operation of the solar module may be
selected from the two or more alternatives with the use of switches
and/or jumpers, for example. The different configurations may put
different numbers of super cells in series and/or in parallel to
provide different combinations of voltage and current outputs from
the solar module. Such a solar module may therefore be factory or
field configurable to select from two or more different voltage and
current combinations, for example to select between a high voltage
and low current configuration, and a low voltage and high current
configuration.
[0220] FIG. 16 shows an example arrangement of a smart switch
module level power management device 750, as described above,
between two solar modules.
[0221] Referring now to FIG. 17, an example method 800 for making
solar modules as disclosed in this specification comprises the
following steps. In step 810, conventionally sized solar cells
(e.g., 156 millimeters.times.156 millimeters or 125
millimeters.times.125 millimeters) are cut and/or cleaved to form
narrow rectangular solar cell "strips". (See also FIGS. 3A-3E) and
related description above, for example). The resulting solar cell
strips may optionally be tested and sorted according to their
current-voltage performance. Cells with matching or approximately
matching current-voltage performance may advantageously be used in
the same super cell or in the same row of series connected super
cells. For example, it may be advantageous that cells connected in
series within a super cell or within a row of super cells produce
matching or approximately matching current under the same
illumination.
[0222] In step 815 super cells are assembled from the strip solar
cells, with a conductive adhesive bonding material disposed between
overlapping portions of adjacent solar cells in the super cells.
The conductive adhesive bonding material may be applied, for
example, by ink jet printing or screen printing.
[0223] In step 820 heat and pressure are applied to cure or
partially cure the conductive adhesive bonding material between the
solar cells in the super cells. In one variation, as each
additional solar cell is added to a super cell the conductive
adhesive bonding material between the newly added solar cell and
its adjacent overlapping solar cell (already part of the super
cell) is cured or partially cured, before the next solar cell is
added to the super cell. In another variation, more than two solar
cells or all solar cells in a super cell may be positioned in the
desired overlapping manner before the conductive adhesive bonding
material is cured or partially cured. The super cells resulting
from this step may optionally be tested and sorted according to
their current-voltage performance. Super cells with matching or
approximately matching current-voltage performance may
advantageously be used in the same row of super cells or in the
same solar module. For example, it may be advantageous that super
cells or rows of super cells electrically connected in parallel
produce matching or approximately matching voltages under the same
illumination.
[0224] In step 825 the cured or partially cured super cells are
arranged and interconnected in the desired module configuration in
a layered structured including encapsulant material, a transparent
front (sun side) sheet, and a (optionally transparent) back sheet.
The layered structure may comprise, for example, a first layer of
encapsulant on a glass substrate, the interconnected super cells
arranged sun-side down on the first layer of encapsulant, a second
layer of encapsulant on the layer of super cells, and a back sheet
on the second layer of encapsulant. Any other suitable arrangement
may also be used.
[0225] In lamination step 830 heat and pressure are applied to the
layered structure to form a cured laminate structure.
[0226] In one variation of the method of FIG. 17, the
conventionally sized solar cells are separated into solar cell
strips, after which the conductive adhesive bonding material is
applied to each individual solar cell strip. In an alternative
variation, the conductive adhesive bonding material is applied to
the conventionally sized solar cells prior to separation of the
solar cells into solar cell strips.
[0227] At curing step 820 the conductive adhesive bonding material
may be fully cured, or it may be only partially cured. In the
latter case the conductive adhesive bonding material may be
initially partially cured at step 820 sufficiently to ease handling
and interconnection of the super cells, and fully cured during the
subsequent lamination step 830.
[0228] In some variations a super cell 100 assembled as an
intermediate product in method 800 comprises a plurality of
rectangular solar cells 10 arranged with the long sides of adjacent
solar cells overlapped and conductively bonded as described above,
and interconnects bonded to terminal contacts at opposite ends of
the super cell.
[0229] FIG. 30A shows an example super cell with electrical
interconnects bonded to its front and rear surface terminal
contacts. The electrical interconnects run parallel to the terminal
edges of the super cell and extend laterally beyond the super cell
to facilitate electrical interconnection with an adjacent super
cell.
[0230] FIG. 30B shows two of the super cells of FIG. 30A
interconnected in parallel.
[0231] Portions of the interconnects that are otherwise visible
from the front of the module may be covered or colored (e.g.,
darkened) to reduce visible contrast between the interconnect and
the super cells, as perceived by a human having normal color
vision. In the example illustrated in FIG. 30A, an interconnect 850
is conductively bonded to a front side terminal contact of a first
polarity (e.g., + or -) at one end of the super cell (on the right
side of the drawing), and another interconnect 850 is conductively
bonded to a back side terminal contact of the opposite polarity at
the other end of the super cell (on the left side of the drawing).
Similarly to the other interconnects described above, interconnects
850 may be conductively bonded to the super cell with the same
conductive adhesive bonding material used between solar cells, for
example, but this is not required. In the illustrated example, a
portion of each interconnect 850 extends beyond the edge of super
cell 100 in a direction perpendicular to the long axis of the super
cell (and parallel to the long axes of solar cells 10). As shown in
FIG. 30B, this allows two or more super cells 100 to be positioned
side by side, with the interconnects 850 of one super cell
overlapping and conductively bonded to corresponding interconnects
850 on the adjacent super cell to electrically interconnect the two
super cells in parallel. Several such interconnects 850
interconnected in series as just described may form a bus for the
module. This arrangement may be suitable, for example, when the
individual super cell extends the full width or full length of the
module (e.g., FIG. 5B). In addition, interconnects 850 may also be
used to electrically connect terminal contacts of two adjacent
super cells within a row of super cells in series. Pairs or longer
strings of such interconnected super cells within a row may be
electrically connected in parallel with similarly interconnected
super cells in an adjacent row by overlapping and conductively
bonding interconnects 850 in one row with interconnects 850 in the
adjacent row similarly to as shown in FIG. 30B.
[0232] Interconnect 850 may be die cut from a conducting sheet, for
example, and may be optionally patterned to increase its mechanical
compliance both perpendicular to and parallel to the edge of the
super cell to reduce or accommodate stress perpendicular and
parallel to the edge of the super cell arising from mismatch
between the CTE of the interconnect and that of the super cell.
Such patterning may include, for example, slits, slots, or holes
(not shown). The mechanical compliance of interconnect 850, and its
bond or bonds to the super cell, should be sufficient for the
connections to the super cell to survive stress arising from CTE
mismatch during the lamination process described in more detail
below. Interconnect 850 may be bonded to the super cell with, for
example, a mechanically compliant electrically conductive bonding
material as described above for use in bonding overlapped solar
cells. Optionally, the electrically conductive bonding material may
be located only at discrete positions along the edges of the super
cell rather than in a continuous line extending substantially the
length of the edge of the super cell, to reduce or accommodate
stress parallel to the edges of the super cell arising from
mismatch between the coefficient of thermal expansion of the
electrically conductive bonding material or the interconnects and
that of the super cell.
[0233] Interconnect 850 may be cut from a thin copper sheet, for
example, and may be thinner than conventional conductive
interconnects when super cells 100 are formed from solar cells
having areas smaller than standard silicon solar cells and
therefore operate at lower currents than is conventional. For
example, interconnects 850 may be formed from copper sheet having a
thickness of about 50 microns to about 300 microns. Interconnects
850 may be sufficiently thin and flexible to fold around and behind
the edge of the super cell to which they are bonded, similarly to
the interconnects described above.
[0234] FIGS. 19A-19D show several example arrangements by which
heat and pressure may be applied during method 800 to cure or
partially cure the conductive adhesive bonding material between
adjacent solar cells in the super cells. Any other suitable
arrangement may also be employed.
[0235] In FIG. 19A, heat and localized pressure are applied to cure
or partially cure conductive adhesive bonding material 12 one joint
(overlapping region) at a time. The super cell may be supported by
a surface 1000 and pressure may be mechanically applied to the
joint from above with a bar, pin, or other mechanical contact, for
example. Heat may be applied to the joint with hot air (or other
hot gas), with an infrared lamp, or by heating the mechanical
contact that applies localized pressure to the joint, for
example.
[0236] In FIG. 19B, the arrangement of FIG. 19A is extended to a
batch process that simultaneously applies heat and localized
pressure to multiple joints in a super cell.
[0237] In FIG. 19C, an uncured super cell is sandwiched between
release liners 1015 and reusable thermoplastic sheets 1020 and
positioned on a carrier plate 1010 supported by a surface 1000. The
thermoplastic material of sheets 1020 is selected to melt at the
temperature at which the super cells are cured. Release liners 1015
may be formed from fiberglass and PTFE, for example, and do not
adhere to the super cell after the curing process. Preferably,
release liners 1015 are formed from materials that have a
coefficient of thermal expansion matching or substantially matching
that of the solar cells (e.g., the CTE of silicon). This is because
if the CTE of the release liners differs too much from that of the
solar cells, then the solar cells and the release liners will
lengthen by different amounts during the curing process, which
would tend to pull the super cell apart lengthwise at the joints. A
vacuum bladder 1005 overlies this arrangement. The uncured super
cell is heated from below through surface 1000 and carrier plate
1010, for example, and a vacuum is pulled between bladder 1005 and
support surface 1000. As a result bladder 1005 applies hydrostatic
pressure to the super cell through the melted thermoplastic sheets
1020.
[0238] In FIG. 19D, an uncured super cell is carried by a
perforated moving belt 1025 through an oven 1035 that heats the
super cell. A vacuum applied through perforations in the belt pulls
solar cells 10 toward the belt, thereby applying pressure to the
joints between them. The conductive adhesive bonding material in
those joints cures as the super cell passes through the oven.
Preferably, perforated belt 1025 is formed from materials that have
a CTE matching or substantially matching that of the solar cells
(e.g., the CTE of silicon). This is because if the CTE of belt 1025
differs too much from that of the solar cells, then the solar cells
and the belt will lengthen by different amounts in oven 1035, which
will tend to pull the super cell apart lengthwise at the
joints.
[0239] Method 800 of FIG. 17 includes distinct super cell curing
and lamination steps, and produces an intermediate super cell
product. In contrast, in method 900 shown in FIG. 18 the super cell
curing and lamination steps are combined. In step 910,
conventionally sized solar cells (e.g., 156 millimeters.times.156
millimeters or 125 millimeters.times.125 millimeters) are cut
and/or cleaved to form narrow rectangular solar cell strips. The
resulting solar cell strips may optionally be tested and
sorted.
[0240] In step 915, the solar cell strips are arranged in the
desired module configuration in a layered structured including
encapsulant material, a transparent front (sun side) sheet, and a
back sheet. The solar cell strips are arranged as super cells, with
an uncured conductive adhesive bonding material disposed between
overlapping portions of adjacent solar cells in the super cells.
(The conductive adhesive bonding material may be applied, for
example, by ink jet printing or screen printing). Interconnects are
arranged to electrically interconnect the uncured super cells in
the desired configuration. The layered structure may comprise, for
example, a first layer of encapsulant on a glass substrate, the
interconnected super cells arranged sun-side down on the first
layer of encapsulant, a second layer of encapsulant on the layer of
super cells, and a back sheet on the second layer of encapsulant.
Any other suitable arrangement may also be used.
[0241] In lamination step 920 heat and pressure are applied to the
layered structure to cure the conductive adhesive bonding material
in the super cells and to form a cured laminate structure.
Conductive adhesive bonding material used to bond interconnects to
the super cells may be cured in this step as well.
[0242] In one variation of method 900, the conventionally sized
solar cells are separated into solar cell strips, after which the
conductive adhesive bonding material is applied to each individual
solar cell strips. In an alternative variation, the conductive
adhesive bonding material is applied to the conventionally sized
solar cells prior to separation of the solar cells into solar cell
strips. For example, a plurality of conventionally sized solar
cells may be placed on a large template, conductive adhesive
bonding material then dispensed on the solar cells, and the solar
cells then simultaneously separated into solar cell strips with a
large fixture. The resulting solar cell strips may then be
transported as a group and arranged in the desired module
configuration as described above.
[0243] As noted above, in some variations of method 800 and of
method 900 the conductive adhesive bonding material is applied to
the conventionally sized solar cells prior to separating the solar
cells into solar cell strips. The conductive adhesive bonding
material is uncured (i.e., still "wet") when the conventionally
sized solar cell is separated to form the solar cell strips. In
some of these variations, the conductive adhesive bonding material
is applied to a conventionally sized solar cell (e.g. by ink jet or
screen printing), then a laser is used to scribe lines on the solar
cell defining the locations at which the solar cell is to be
cleaved to form the solar cell strips, then the solar cell is
cleaved along the scribe lines. In these variations the laser power
and/or the distance between the scribe lines and the adhesive
bonding material may be selected to avoid incidentally curing or
partially curing the conductive adhesive bonding material with heat
from the laser. In other variations, a laser is used to scribe
lines on a conventionally sized solar cell defining the locations
at which the solar cell is to be cleaved to form the solar cell
strips, then the conductive adhesive bonding material is applied to
the solar cell (e.g. by ink jet or screen printing), then the solar
cell is cleaved along the scribe lines. In the latter variations it
may be preferable to accomplish the step of applying the conductive
adhesive bonding material without incidentally cleaving or breaking
the scribed solar cell during this step.
[0244] FIG. 20A schematically illustrates a side view of an example
apparatus 1050 that may be used to cleave scribed solar cells to
which conductive adhesive bonding material has been applied.
(Scribing and application of conductive adhesive bonding material
may have occurred in either order). In this apparatus, a scribed
conventionally sized solar cell 45 to which conductive adhesive
bonding material has been applied is carried by a perforated moving
belt 1060 over a curved portion of a vacuum manifold 1070. As solar
cell 45 passes over the curved portion of the vacuum manifold, a
vacuum applied through the perforations in the belt pulls the
bottom surface of solar cell 45 against the vacuum manifold and
thereby flexes the solar cell. The radius of curvature R of the
curved portion of the vacuum manifold may be selected so that
flexing solar cell 45 in this manner cleaves the solar cell along
the scribe lines. Advantageously, solar cell 45 may be cleaved by
this method without contacting the top surface of solar cell 45 to
which the conductive adhesive bonding material has been
applied.
[0245] If it is preferred for cleaving to begin at one end of a
scribe line (i.e., at one edge of solar cell 45), this may be
accomplished with apparatus 1050 of FIG. 20A by for example
arranging for the scribe lines to be oriented at an angle .theta.
to the vacuum manifold so that for each scribe line one end reaches
the curved portion of the vacuum manifold before the other end. As
shown in FIG. 20B, for example, the solar cells may be oriented
with their scribe lines at an angle to the direction of travel of
the belt and the manifold oriented perpendicularly to the direction
of travel of the belt. As another example, FIG. 20C shows the cells
oriented with their scribe lines perpendicular to the direction of
travel of the belt, and the manifold oriented at an angle.
[0246] Any other suitable apparatus may also be used to cleave
scribed solar cells to which conductive adhesive bonding material
has been applied to form strip solar cells with pre-applied
conductive adhesive bonding material. Such apparatus may, for
example, use rollers to apply pressure to the top surface of the
solar cell to which the conductive adhesive bonding material has
been applied. In such cases it is preferable that the rollers touch
the top surface of the solar cell only in regions to which
conductive adhesive bonding material has not been applied.
[0247] In some variations, solar modules comprise super cells
arranged in rows on a white or otherwise reflective back sheet, so
that a portion of solar radiation initially unabsorbed by and
passing through the solar cells may be reflected by the back sheet
back into the solar cells to produce electricity. The reflective
back sheet may be visible through the gaps between rows of super
cells, which may result in a solar module that appears to have rows
of parallel bright (e.g., white) lines running across its front
surface. Referring to FIG. 5B, for example, the parallel dark lines
running between the rows of super cells 100 may appear as white
lines if super cells 100 are arranged on a white back sheet. This
may be aesthetically displeasing for some uses of the solar
modules, for example on roof tops.
[0248] Referring to FIG. 21, to improve the aesthetic appearance of
the solar module, some variations employ a white back sheet 1100
comprising dark stripes 1105 located in positions corresponding to
the gaps between rows of the super cells to be arranged on the back
sheet. Stripes 1105 are sufficiently wide that the white portions
of the back sheet are not visible through gaps between the rows of
super cells in the assembled module. This reduces the visual
contrast between the super cells and the back sheet, as perceived
by a human having normal color vision. The resulting module
includes a white back sheet but may have a front surface similar in
appearance to that of the modules illustrated in FIGS. 5A-5B, for
example. Dark stripes 1105 may be produced with lengths of dark
tape, for example, or in any other suitable manner.
[0249] As previously mentioned, shading of individual cells within
solar modules can create `hotspots`, wherein power of the
non-shaded cells is dissipated in the shaded cell. This dissipated
power creates localized temperature spikes that can degrade the
modules.
[0250] To minimize the potential severity of these hotspots, bypass
diodes are conventionally inserted as part of the module. The
maximal number of cells between bypass diodes is set to limit the
max temperature of the module and prevent irreversible damage on
the module. Standard layouts for silicon cells may utilize a bypass
diode every 20 or 24 cells, a number that is determined by the
typical break down voltage of silicon cells. In certain
embodiments, the breakdown voltage may lie in range between about
10-50V. In certain embodiments, the breakdown voltage may be about
10V, about 15V, about 20V, about 25V, about 30V, or about 35V.
[0251] According to embodiments, the shingling of strips of cut
solar cells with thin thermally conductive adhesives, improves the
thermal contact between solar cells. This enhanced thermal contact
allows higher degree of thermal spreading than traditional
interconnection technologies. Such a thermal heat spreading design
based on shingling allows longer strings of solar cells to be used
than the twenty-four (or fewer) solar cells per bypass diode to
which conventional designs are restricted. Such relaxation in the
requirement for frequent bypass diodes according to the thermal
spreading facilitated by shingling according to embodiments, may
offer one or more benefits. For example, it allows for the creation
of module layouts of a variety of solar cell string lengths,
unhindered by a need to provide for a large number of bypass
diodes.
[0252] According to embodiments, thermal spreading is achieved by
maintaining a physical and thermal bond with the adjacent cell.
This allows for adequate heat dissipation though the bonded
joint.
[0253] In certain embodiments this joint is maintained at a
thickness of about 200 micrometers or less, and runs the length of
the solar cell in a segmented pattern. Depending upon the
embodiment, the joint may have a thickness of about 200 micrometers
or less, of about 150 micrometers or less, of about 125 micrometers
or less, of about 100 micrometers or less, of about 90 micrometers
or less, of about 80 micrometers or less, of about 70 micrometers
or less, of about 50 micrometers, or less, or of about 25
micrometers or less.
[0254] An accurate adhesive cure processing may be important to
ensuring that a reliable joint is maintained while a thickness is
reduced in order to promote thermal spreading between bonded
cells.
[0255] Being allowed to run longer strings (e.g., more than 24
cells) affords flexibility in the design of solar cells and
modules. For example, certain embodiments may utilize strings of
cut solar cells that are assembled in a shingled manner. Such
configurations may utilize significantly more cells per module than
a conventional module.
[0256] Absent the thermal spreading property, a bypass diode would
be needed every 24 cells. Where the solar cells are cut by 1/6, the
bypass diodes per module would be 6 times the conventional module
(comprises of 3 uncut cells), adding up to a total of 18 diodes.
Thus thermal spreading affords a significant reduction in the
number of bypass diodes.
[0257] Moreover for every bypass diode, bypass circuitry is needed
to complete the bypass electrical path. Each diode requires two
interconnections points and conductor routing to connect them to
such interconnection points. This creates a complicated circuit,
contributing significant expense over standard layout costs
associated with assembling a solar module.
[0258] By contrast, thermal spreading technology requires only one
or even no bypass diodes per module. Such a configuration
streamlines a module assembly process, allowing simple automation
tools to perform the layout manufacturing steps.
[0259] Avoiding the need to bypass protect every 24 cells thus
renders the cell module easier to manufacture. Complex tap-outs in
the middle of the module and long parallel connections for bypass
circuitry, are avoided. This thermal spreading is implemented by
creating long shingled strips of cells running a width and/or
length of the module.
[0260] In addition to providing thermal heat spreading, shingling
according to embodiments also allows improved hotspot performance
by reducing a magnitude of current dissipated in a solar cell.
Specifically, during a hot spot condition the amount of current
dissipated in a solar cell is dependent upon cell area.
[0261] Since shingling may cut cells to smaller areas, an amount of
current passing through one cell in a hot spot condition is a
function of the cut dimensions. During a hot spot condition, the
current passes through the lowest resistance path which is usually
a cell level defect interface or grain boundary. Reducing this
current is a benefit and minimizes reliability risk failure under
hot spot conditions.
[0262] FIG. 22A shows a plan view of a conventional module 2200
utilizing traditional ribbon connections 2201, under hot spot
conditions. Here, shading 2202 on one cell 2204 results in heat
being localized to that single cell.
[0263] By contrast, FIG. 22B shows a plan view of a module
utilizing thermal spreading, also under hot spot conditions. Here,
shading 2250 on cell 2252 generates heat within that cell. This
heat, however, is spread to other electrically and thermally bonded
cells 2254 within the module 2256.
[0264] It is further noted that the benefit of reduction in
dissipated current is multiplied for multi-crystalline solar cells.
Such multi-crystalline cells are known to perform poorly under hot
spot conditions owing to a high level of defect interfaces.
[0265] As indicated above, particular embodiments may employ
shingling of chamfered cut cells. In such cases, there is a heat
spreading advantage to mirror, along the bond line between each
cell with the adjacent cell.
[0266] This maximizes the bond length of each overlapping joint.
Since the bond joint is major interface for cell-to-cell heat
spreading, maximizing this length may ensure the optimum heat
spreading is obtained.
[0267] FIG. 23A shows one example of a super cell string layout
2300 with chamfered cells 2302. In this configuration, the
chamfered cells are oriented in a same direction, and thus all the
bonded joints conduction paths are the same (125 mm).
[0268] Shading 2306 on one cell 2304 results in reverse biasing of
that cell. Heat is spread to with adjacent cells. Unbonded ends
2304a of the chamfered cell becomes hottest due to a longer
conduction length to the next cell.
[0269] FIG. 23B shows another example of a super cell string layout
2350 with chamfered cells 2352. In this configuration, the
chamfered cells are oriented in different directions, with some of
the long edges of the chamfered cells facing each other. This
results in bonded joint conduction paths of two lengths: 125 mm and
156 mm.
[0270] Where a cell 2354 experiences shading 2356, the
configuration of FIG. 23B exhibits improved thermal spreading along
the longer bond length. FIG. 23B thus shows that the thermal
spreading in a super cell with chamfered cells facing each
other.
[0271] The above discussion has focused upon assembling a plurality
of solar cells (which may be cut solar cells) in a shingled manner
on a common substrate. This results in the formation of a module
having a single electrical interconnect-junction box (or
j-box).
[0272] In order to gather a sufficient amount of solar energy to be
useful, however, an installation typically comprises a number of
such modules that are themselves assembled together. According to
embodiments, a plurality of solar cell modules may also be
assembled in a shingled manner to increase the area efficiency of
an array.
[0273] In particular embodiments, a module may feature a top
conductive ribbon facing a direction of solar energy, and a bottom
conductive ribbon facing away from the direction of solar
energy.
[0274] The bottom ribbon is buried beneath the cells. Thus, it does
not block incoming light and adversely impact an area efficiency of
the module. By contrast, the top ribbon is exposed and can block
the incoming light and adversely impact efficiency.
[0275] According to embodiments the modules themselves can be
shingled, such that the top ribbon is covered by the neighboring
module. FIG. 24 shows a simplified cross-sectional view of such an
arrangement 2400, where an end portion 2401 of an adjacent module
2402, serves to overlap the top ribbon 2404 of an instant module
2406. Each module itself comprises a plurality of shingled solar
cells 2407.
[0276] The bottom ribbon 2408 of the instant module 2406 is buried.
It is located on an elevated side of the instant shingled module in
order to overlap the next adjacent shingled module.
[0277] This shingled module configuration could also provide for
additional area on the module for other elements, without adversely
impacting a final exposed area of the module array. Examples of
module elements that may be positioned in overlapping regions can
include but are not limited to, junction boxes (j-boxes) 2410
and/or bus ribbons.
[0278] FIG. 25 shows another embodiment of a shingled module
configuration 2500. Here, j-boxes 2502, 2504 of the respective
adjacent shingled modules 2506 and 2508 are in a mating arrangement
2510 in order to achieve electrical connection between them. This
simplifies the configuration of the array of shingled modules by
eliminating wiring.
[0279] In certain embodiments, the j-boxes could be reinforced
and/or combined with additional structural standoffs. Such a
configuration could create an integrated tilted module roof mount
rack solution, wherein a dimension of the junction box determines a
tilt. Such an implementation may be particularly useful where an
array of shingled modules is mounted on a flat roof.
[0280] Where the modules comprise a glass substrate and a glass
cover (glass-glass modules), the modules could be used without
additional frame members by shortening an overall module length
(and hence an exposed length L resulting from the shingling). Such
shortening would allow the modules of the tiled array to survive
expected physical loads (e.g., a 5400 Pa snow load limit), without
fracturing under the strain.
[0281] It is emphasized that the use of super cell structures
comprising a plurality of individual solar cells assembled in a
shingled manner, readily accommodates changing the length of the
module to meet a specific length dictated by physical load and
other requirements.
[0282] 1. A solar module comprising:
[0283] a series connected string of N.gtoreq.25 rectangular or
substantially rectangular solar cells having on average a breakdown
voltage greater than about 10 volts, the solar cells grouped into
one or more super cells each of which comprises two or more of the
solar cells arranged in line with long sides of adjacent solar
cells overlapping and conductively bonded to each other with an
electrically and thermally conductive adhesive;
[0284] wherein no single solar cell or group of <N solar cells
in the string of solar cells is individually electrically connected
in parallel with a bypass diode.
[0285] 2. The solar module of clause 1, wherein N is greater than
or equal to 30.
[0286] 3. The solar module of clause 1, wherein N is greater than
or equal to 50.
[0287] 4. The solar module of clause 1, wherein N is greater than
or equal to 100.
[0288] 5. The solar module of clause 1, wherein the adhesive forms
bonds between adjacent solar cells having a thickness perpendicular
to the solar cells less than or equal to about 0.1 mm and a thermal
conductivity perpendicular to the solar cells greater than or equal
to about 1.5 w/m/k.
[0289] 6. The solar module of clause 1, wherein the N solar cells
are grouped into a single super cell.
[0290] 7. The solar module of clause 1, wherein the super cells are
encapsulated in a polymer.
[0291] 7A. The solar module of clause 7 wherein the polymer
comprises a thermoplastic olefin polymer.
[0292] 7B. The solar module of clause 7 wherein the polymer is
sandwiched between a glass front and back sheets.
[0293] 7C. The solar module of clause 7B wherein the back sheets
comprise glass.
[0294] 8. The solar module of clause 1, wherein the solar cells are
silicon solar cells.
[0295] 9. A solar module comprising:
[0296] a super cell substantially spanning a full length or width
of the solar module parallel to an edge of the solar module, the
super cell comprising a series connected string of N rectangular or
substantially rectangular solar cells having on average a breakdown
voltage greater than about 10 volts arranged in line with long
sides of adjacent solar cells overlapping and conductively bonded
to each other with an electrically and thermally conductive
adhesive;
[0297] wherein no single solar cell or group of <N solar cells
in the super cell is individually electrically connected in
parallel with a bypass diode.
[0298] 10. The solar module of clause 9, wherein N>24.
[0299] 11. The solar module of clause 9, wherein the super cell has
a length in the direction of current flow of at least about 500
mm.
[0300] 12. The solar module of clause 9, wherein the super cells
are encapsulated in a thermoplastic olefin polymer sandwiched
between glass front and back sheets.
[0301] 13. A super cell comprising:
[0302] a plurality of silicon solar cells each comprising: [0303]
rectangular or substantially rectangular front and back surfaces
with shapes defined by first and second oppositely positioned
parallel long sides and two oppositely positioned short sides, at
least portions of the front surfaces to be exposed to solar
radiation during operation of the string of solar cells; [0304] an
electrically conductive front surface metallization pattern
disposed on the front surface and comprising at least one front
surface contact pad positioned adjacent to the first long side; and
[0305] an electrically conductive back surface metallization
pattern disposed on the back surface and comprising at least one
back surface contact pad positioned adjacent the second long
side;
[0306] wherein the silicon solar cells are arranged in line with
first and second long sides of adjacent silicon solar cells
overlapping and with front surface and back surface contact pads on
adjacent silicon solar cells overlapping and conductively bonded to
each other with a conductive adhesive bonding material to
electrically connect the silicon solar cells in series; and
[0307] wherein the front surface metallization pattern of each
silicon solar cell comprises a barrier configured to substantially
confine the conductive adhesive bonding material to at least one
front surface contact pad prior to curing of the conductive
adhesive bonding material during manufacturing of the super
cell.
[0308] 14. The super cell of clause 13, wherein for each pair of
adjacent and overlapping silicon solar cells, the barrier on the
front surface of one of the silicon solar cells is overlapped and
hidden by a portion of the other silicon solar cell, thereby
substantially confining the conductive adhesive bonding material to
overlapped regions of the front surface of the silicon solar cell
prior to curing of the conductive adhesive bonding material during
manufacturing of the super cell.
[0309] 15. The super cell of clause 13, wherein the barrier
comprises a continuous conductive line running parallel to and for
substantially the full length of the first long side, with at least
one front surface contact pad located between the continuous
conductive line and the first long side of the solar cell.
[0310] 16. The super cell of clause 15, wherein the front surface
metallization pattern comprises fingers electrically connected to
the at least one front surface contact pads and running
perpendicularly to the first long side, and the continuous
conductive line electrically interconnects the fingers to provide
multiple conductive paths from each finger to at least one front
surface contact pad.
[0311] 17. The super cell of clause 13, wherein the front surface
metallization pattern comprises a plurality of discrete contact
pads arranged in a row adjacent to and parallel to the first long
side, and the barrier comprises a plurality of features forming
separate barriers for each discrete contact pad that substantially
confine the conductive adhesive bonding material to the discrete
contact pads prior to curing of the conductive adhesive bonding
material during manufacturing of the super cell.
[0312] 18. The super cell of clause 17, wherein the separate
barriers abut and are taller than their corresponding discrete
contact pads.
[0313] 19. A super cell comprising:
[0314] a plurality of silicon solar cells each comprising: [0315]
rectangular or substantially rectangular front and back surfaces
with shapes defined by first and second oppositely positioned
parallel long sides and two oppositely positioned short sides, at
least portions of the front surfaces to be exposed to solar
radiation during operation of the string of solar cells; [0316] an
electrically conductive front surface metallization pattern
disposed on the front surface and comprising at least one front
surface contact pad positioned adjacent to the first long side; and
[0317] an electrically conductive back surface metallization
pattern disposed on the back surface and comprising at least one
back surface contact pad positioned adjacent the second long
side;
[0318] wherein the silicon solar cells are arranged in line with
first and second long sides of adjacent silicon solar cells
overlapping and with front surface and back surface contact pads on
adjacent silicon solar cells overlapping and conductively bonded to
each other with a conductive adhesive bonding material to
electrically connect the silicon solar cells in series; and
[0319] wherein the back surface metallization pattern of each
silicon solar cell comprises a barrier configured to substantially
confine the conducive adhesive bonding material to the at least one
back surface contact pads prior to curing of the conductive
adhesive bonding material during manufacturing of the super
cell.
[0320] 20. The super cell of clause 19, wherein the back surface
metallization pattern comprises one or more discrete contact pads
arranged in a row adjacent to and parallel to the second long side,
and the barrier comprises a plurality of features forming separate
barriers for each discrete contact pad that substantially confine
the conductive adhesive bonding material to the discrete contact
pads prior to curing of the conductive adhesive bonding material
during manufacturing of the super cell.
[0321] 21. The super cell of clause 20, wherein the separate
barriers abut and are taller than their corresponding discrete
contact pads.
[0322] 22. A method of making a string of solar cells, the method
comprising:
[0323] dicing one or more pseudo square silicon wafers along a
plurality of lines parallel to a long edge of each wafer to form a
plurality of rectangular silicon solar cells each having
substantially the same length along its long axis; and
[0324] arranging the rectangular silicon solar cells in line with
long sides of adjacent solar cells overlapping and conductively
bonded to each other to electrically connect the solar cells in
series;
[0325] wherein the plurality of rectangular silicon solar cells
comprises at least one rectangular solar cell having two chamfered
corners corresponding to corners or to portions of corners of the
pseudo square wafer, and one or more rectangular silicon solar
cells each lacking chamfered corners; and
[0326] wherein the spacing between parallel lines along which the
pseudo square wafer is diced is selected to compensate for the
chamfered corners by making the width perpendicular to the long
axis of the rectangular silicon solar cells that comprise chamfered
corners greater than the width perpendicular to the long axis of
the rectangular silicon solar cells that lack chamfered corners, so
that each of the plurality of rectangular silicon solar cells in
the string of solar cells has a front surface of substantially the
same area exposed to light in operation of the string of solar
cells.
[0327] 23. A string of solar cells comprising:
[0328] a plurality of silicon solar cells arranged in line with end
portions of adjacent solar cells overlapping and conductively
bonded to each other to electrically connect the solar cells in
series;
[0329] wherein at least one of the silicon solar cells has
chamfered corners that correspond to corners or portions of corners
of a pseudo square silicon wafer from which it was diced, at least
one of the silicon solar cells lacks chamfered corners, and each of
the silicon solar cells has a front surface of substantially the
same area exposed to light during operation of the string of solar
cells.
[0330] 24. A method of making two or more strings of solar cells,
the method comprising:
[0331] dicing one or more pseudo square silicon wafers along a
plurality of lines parallel to a long edge of each wafer to form a
first plurality of rectangular silicon solar cells comprising
chamfered corners corresponding to corners or portions of corners
of the pseudo square silicon wafers and a second plurality of
rectangular silicon solar cells each of a first length spanning a
full width of the pseudo square silicon wafers and lacking
chamfered corners;
[0332] removing the chamfered corners from each of the first
plurality of rectangular silicon solar cells to form a third
plurality of rectangular silicon solar cells each of a second
length shorter than the first length and lacking chamfered
corners;
[0333] arranging the second plurality of rectangular silicon solar
cells in line with long sides of adjacent rectangular silicon solar
cells overlapping and conductively bonded to each other to
electrically connect the second plurality of rectangular silicon
solar cells in series to form a solar cell string having a width
equal to the first length; and arranging the third plurality of
rectangular silicon solar cells in line with long sides of adjacent
rectangular silicon solar cells overlapping and conductively bonded
to each other to electrically connect the third plurality of
rectangular silicon solar cells in series to form a solar cell
string having a width equal to the second length.
[0334] 25. A method of making two or more strings of solar cells,
the method comprising:
[0335] dicing one or more pseudo square silicon wafers along a
plurality of lines parallel to a long edge of each wafer to form a
first plurality of rectangular silicon solar cells comprising
chamfered corners corresponding to corners or portions of corners
of the pseudo square silicon wafers and a second plurality of
rectangular silicon solar cells lacking chamfered corners;
[0336] arranging the first plurality of rectangular silicon solar
cells in line with long sides of adjacent rectangular silicon solar
cells overlapping and conductively bonded to each other to
electrically connect the first plurality of rectangular silicon
solar cells in series; and
[0337] arranging the second plurality of rectangular silicon solar
cells in line with long sides of adjacent rectangular silicon solar
cells overlapping and conductively bonded to each other to
electrically connect the second plurality of rectangular silicon
solar cells in series.
[0338] 26. A method of making a solar module, the method
comprising:
[0339] dicing each of a plurality of pseudo square silicon wafers
along a plurality of lines parallel to a long edge of the wafer to
form from the plurality of pseudo square silicon wafers a plurality
of rectangular silicon solar cells comprising chamfered corners
corresponding to corners of the pseudo square silicon wafers and a
plurality of rectangular silicon solar cells lacking chamfered
corners;
[0340] arranging at least some of the rectangular silicon solar
cells lacking chamfered corners to form a first plurality of super
cells each of which comprises only rectangular silicon solar cells
lacking chamfered corners arranged in line with long sides of the
silicon solar cells overlapping and conductively bonded to each
other to electrically connect the silicon solar cells in
series;
[0341] arranging at least some of the rectangular silicon solar
cells comprising chamfered corners to form a second plurality of
super cells each of which comprises only rectangular silicon solar
cells comprising chamfered corners arranged in line with long sides
of the silicon solar cells overlapping and conductively bonded to
each other to electrically connect the silicon solar cells in
series; and
[0342] arranging the super cells in parallel rows of super cells of
substantially equal length to form a front surface of the solar
module, with each row comprising only super cells from the first
plurality of super cells or only super cells from the second
plurality of super cells.
[0343] 27. The solar module of clause 26, wherein two of the rows
of super cells adjacent to parallel opposite edges of the solar
module comprise only super cells from the second plurality of super
cells, and all other rows of super cells comprise only super cells
from the first plurality of super cells.
[0344] 28. The solar module of clause 27, wherein the solar module
comprises a total of six rows of super cells.
[0345] 29. A super cell comprising:
[0346] a plurality of silicon solar cells arranged in line in a
first direction with end portions of adjacent silicon solar cells
overlapping and conductively bonded to each other to electrically
connect the silicon solar cells in series; and
[0347] an elongated flexible electrical interconnect with its long
axis oriented parallel to a second direction perpendicular to the
first direction, conductively bonded to a front or back surface of
an end one of the silicon solar cells at three or more discrete
locations arranged along the second direction, running at least the
full width of the end solar cell in the second direction, having a
conductor thickness less than or equal to about 100 microns
measured perpendicularly to the front or rear surface of the end
silicon solar cell, providing a resistance to current flow in the
second direction of less than or equal to about 0.012 Ohms, and
configured to provide flexibility accommodating differential
expansion in the second direction between the end silicon solar
cell and the interconnect for a temperature range of about
-40.degree. C. to about 85.degree. C.
[0348] 30. The super cell of clause 29, wherein the flexible
electrical interconnect has a conductor thickness less than or
equal to about 30 microns measured perpendicularly to the front and
rear surfaces of the end silicon solar cell.
[0349] 31. The super cell of clause 29, wherein the flexible
electrical interconnect extends beyond the super cell in the second
direction to provide for electrical interconnection to at least a
second super cell positioned parallel to and adjacent the super
cell in a solar module.
[0350] 32. The super cell of clause 29, wherein the flexible
electrical interconnect extends beyond the super cell in the first
direction to provide for electrical interconnection to a second
super cell positioned parallel to and in line with the super cell
in a solar module.
[0351] 33. A solar module comprising:
[0352] a plurality of super cells arranged in two or more parallel
rows spanning a width of the module to form a front surface of the
module, each super cell comprising a plurality of silicon solar
cells arranged in line with end portions of adjacent silicon solar
cells overlapping and conductively bonded to each other to
electrically connect the silicon solar cells in series;
[0353] wherein at least an end of a first super cell adjacent an
edge of the module in a first row is electrically connected to an
end of a second super cell adjacent the same edge of the module in
a second row via a flexible electrical interconnect that is bonded
to the front surface of the first super cell at a plurality of
discrete locations with an electrically conductive adhesive bonding
material, runs parallel to the edge of the module, and at least a
portion of which folds around the end of the first super cell and
is hidden from view from the front of the module.
[0354] 34. The solar module of clause 33, wherein surfaces of the
flexible electrical interconnect on the front surface of the module
are covered or colored to reduce visible contrast with the super
cells.
[0355] 35. The solar module of clause 33, wherein the two or more
parallel rows of super cells are arranged on a white back sheet to
form a front surface of the solar module to be illuminated by solar
radiation during operation of the solar module, the white back
sheet comprises parallel darkened stripes having locations and
widths corresponding to locations and widths of gaps between the
parallel rows of super cells, and white portions of the back sheets
are not visible through the gaps between the rows.
[0356] 36. A method of making a string of solar cells, the method
comprising:
[0357] laser scribing one or more scribe lines on each of one or
more silicon solar cells to define a plurality of rectangular
regions on the silicon solar cells, applying an electrically
conductive adhesive bonding material to the one or more scribed
silicon solar cells at one or more locations adjacent a long side
of each rectangular region;
[0358] separating the silicon solar cells along the scribe lines to
provide a plurality of rectangular silicon solar cells each
comprising a portion of the electrically conductive adhesive
bonding material disposed on its front surface adjacent a long
side;
[0359] arranging the plurality of rectangular silicon solar cells
in line with long sides of adjacent rectangular silicon solar cells
overlapping in a shingled manner with a portion of the electrically
conductive adhesive bonding material disposed in between; and
[0360] curing the electrically conductive bonding material, thereby
bonding adjacent overlapping rectangular silicon solar cells to
each other and electrically connecting them in series.
[0361] 37. A method of making a string of solar cells, the method
comprising:
[0362] laser scribing one or more scribe lines on each of one or
more silicon solar cells to define a plurality of rectangular
regions on the silicon solar cells, each solar cell comprising a
top surface and an oppositely positioned bottom surface;
[0363] applying an electrically conductive adhesive bonding
material to portions of the top surfaces of the one or more silicon
solar cells;
[0364] applying a vacuum between the bottom surfaces of the one or
more silicon solar cells and a curved supporting surface to flex
the one or more silicon solar cells against the curved supporting
surface and thereby cleave the one or more silicon solar cells
along the scribe lines to provide a plurality of rectangular
silicon solar cells each comprising a portion of the electrically
conductive adhesive bonding material disposed on its front surface
adjacent a long side;
[0365] arranging the plurality of rectangular silicon solar cells
in line with long sides of adjacent rectangular silicon solar cells
overlapping in a shingled manner with a portion of the electrically
conductive adhesive bonding material disposed in between; and
[0366] curing the electrically conductive bonding material, thereby
bonding adjacent overlapping rectangular silicon solar cells to
each other and electrically connecting them in series.
[0367] 38. The method of clause 37, comprising applying the
electrically conductive adhesive bonding material to the one or
more silicon solar cells, then laser scribing the one or more
scribe lines on each of the one or more silicon solar cells.
[0368] 39. The method of clause 37, comprising laser scribing the
one or more scribe lines on each of the one or more silicon solar
cells, then applying the electrically conductive adhesive bonding
material to the one or more silicon solar cells.
[0369] 40. A solar module comprising:
[0370] a plurality of super cells arranged in two or more parallel
rows to form a front surface of the solar module, each super cell
comprising a plurality of silicon solar cells arranged in line with
end portions of adjacent silicon solar cells overlapping and
conductively bonded to each other to electrically connect the
silicon solar cells in series, each super cell comprising a front
surface end contact at one end of the super cell and a back surface
end contact of opposite polarity at an opposite end of the super
cell;
[0371] wherein a first row of super cells comprises a first super
cell arranged with its front surface end contact adjacent and
parallel to a first edge of the solar module, and the solar module
comprises a first flexible electrical interconnect that is
elongated and runs parallel to the first edge of the solar module,
is conductively bonded to the front surface end contact of the
first super cell, and occupies only a narrow portion of the front
surface of the solar module adjacent to the first edge of the solar
module and no wider than about 1 centimeter measured
perpendicularly to the first edge of the solar module.
[0372] 41. The solar module of clause 40, wherein a portion of the
first flexible electrical interconnect extends around the end of
the first super cell nearest to the first edge of the solar module,
and behind the first super cell.
[0373] 42. The solar module of clause 40, wherein the first
flexible interconnect comprises a thin ribbon portion conductively
bonded to the front surface end contact of the first super cell and
a thicker portion running parallel to the first edge of the solar
module.
[0374] 43. The solar module of clause 40, wherein the first
flexible interconnect comprises a thin ribbon portion conductively
bonded to the front surface end contact of the first super cell and
a coiled ribbon portion running parallel to the first edge of the
solar module.
[0375] 44. The solar module of clause 40, wherein a second row of
super cells comprises a second super cell arranged with its front
surface end contact adjacent to and parallel to the first edge of
the solar module, and the front surface end contact of the first
super cell is electrically connected to the front surface end
contact of the second super cell via the first flexible electrical
interconnect.
[0376] 45. The solar module of clause 40, wherein the back surface
end contact of the first super cell is located adjacent to and
parallel to a second edge of the solar module opposite from the
first edge of the solar module, comprising a second flexible
electrical interconnect that is elongated and runs parallel to the
second edge of the solar module, is conductively bonded to the back
surface end contact of the first super cell, and lies entirely
behind the super cells.
[0377] 46. The solar module of clause 45, wherein:
[0378] a second row of super cells comprises a second super cell
arranged with its front surface end contact adjacent to and
parallel to the first edge of the solar module and its back surface
end contact located adjacent to and parallel to the second edge of
the solar module;
[0379] the front surface end contact of the first super cell is
electrically connected to the front surface end contact of the
second super cell via the first flexible electrical interconnect;
and
[0380] the back surface end contact of the first super cell is
electrically connected to the back surface end contact of the
second super cell via the second flexible electrical
interconnect.
[0381] 47. The solar module of clause 40, comprising: [0382] a
second super cell arranged in the first row of super cells in
series with the first super cell and with its back surface end
contact adjacent a second edge of the solar module opposite from
the first edge of the solar module; and
[0383] a second flexible electrical interconnect that is elongated
and runs parallel to the second edge of the solar module, is
conductively bonded to the back surface end contact of the first
super cell, and lies entirely behind the super cells.
[0384] 48. The solar module of clause 47, wherein:
[0385] a second row of super cells comprises a third super cell and
a fourth super cell arranged in series with a front surface end
contact of the third super cell adjacent the first edge of the
solar module and the back surface end contact of the fourth super
cell adjacent the second edge of the solar module; and
[0386] the front surface end contact of the first super cell is
electrically connected to the front surface end contact of the
third super cell via the first flexible electrical interconnect and
the back surface end contact of the second super cell is
electrically connected to the back surface end contact of the
fourth super cell via the second flexible electrical
interconnect.
[0387] 49. The solar module of clause 40, wherein the super cells
are arranged on a white back sheet that comprises parallel darkened
stripes having locations and widths corresponding to locations and
widths of gaps between the parallel rows of super cells, and white
portions of the back sheets are not visible through the gaps
between the rows.
[0388] 50. The solar module of clause 40, wherein all portions of
the first flexible electrical interconnect located on the front
surface of the solar module are covered or colored to reduce
visible contrast with the super cells.
[0389] 51. The solar module of clause 40, wherein: [0390] each
silicon solar cell comprises: [0391] rectangular or substantially
rectangular front and back surfaces with shapes defined by first
and second oppositely positioned parallel long sides and two
oppositely positioned short sides, at least portions of the front
surfaces to be exposed to solar radiation during operation of the
string of solar cells; [0392] an electrically conductive front
surface metallization pattern disposed on the front surface and
comprising a plurality of fingers running perpendicular to the long
sides and a plurality of discrete front surface contact pads
positioned in a row adjacent to the first long side, each front
surface contact pad electrically connected to at least one of the
fingers; and [0393] an electrically conductive back surface
metallization pattern disposed on the back surface and comprising a
plurality of discrete back surface contact pads positioned in a row
adjacent the second long side; and
[0394] within each super cell the silicon solar cells are arranged
in line with first and second long sides of adjacent silicon solar
cells overlapping and with corresponding discrete front surface
contact pads and discrete back surface contact pads on adjacent
silicon solar cells aligned, overlapping, and conductively bonded
to each other with a conductive adhesive bonding material to
electrically connect the silicon solar cells in series.
[0395] 52. The solar module of clause 51, wherein the front surface
metallization pattern of each silicon solar cell comprises a
plurality of thin conductors electrically interconnecting adjacent
discrete front surface contact pads, and each thin conductor is
thinner than the width of the discrete contact pads measured
perpendicularly to the long sides of the solar cells.
[0396] 53. The solar module of clause 51, wherein the conductive
adhesive bonding material is substantially confined to the
locations of the discrete front surface contact pads by features of
the front surface metallization pattern that form one or more
barriers adjacent to the discrete front surface contact pads.
[0397] 54. The solar module of clause 51, wherein the conductive
adhesive bonding material is substantially confined to the
locations of the discrete back surface contact pads by features of
the back surface metallization pattern that form one or more
barriers adjacent to the discrete back surface contact pad.
[0398] 55. A method of making a solar module, the method
comprising:
[0399] assembling a plurality of super cells, each super cell
comprising a plurality of rectangular silicon solar cells arranged
in line with end portions on long sides of adjacent rectangular
silicon solar cells overlapping in a shingled manner;
[0400] curing an electrically conductive bonding material disposed
between the overlapping end portions of adjacent rectangular
silicon solar cells by applying heat and pressure to the super
cells, thereby bonding adjacent overlapping rectangular silicon
solar cells to each other and electrically connecting them in
series;
[0401] arranging and interconnecting the super cells in a desired
solar module configuration in a stack of layers comprising an
encapsulant; and
[0402] applying heat and pressure to the stack of layers to form a
laminated structure.
[0403] 56. The method of clause 55, comprising curing or partially
curing the electrically conductive bonding material by applying
heat and pressure to the super cells prior to applying heat and
pressure to the stack of layers to form the laminated structure,
thereby forming cured or partially cured super cells as an
intermediate product before forming the laminated structure.
[0404] 57. The method of clause 56, wherein as each additional
rectangular silicon solar cell is added to a super cell during
assembly of the super cell, the electrically conductive adhesive
bonding material between the newly added solar cell and its
adjacent overlapping solar cell is cured or partially cured before
another rectangular silicon solar cell is added to the super
cell.
[0405] 58. The method of clause 56, comprising curing or partially
curing all of the electrically conductive bonding material in a
super cell in the same step.
[0406] 59. The method of clause 56, comprising:
[0407] partially curing the electrically conductive bonding
material by applying heat and pressure to the super cells prior to
applying heat and pressure to the stack of layers to form a
laminated structure, thereby forming partially cured super cells as
an intermediate product before forming the laminated structure;
and
[0408] completing curing of the electrically conductive bonding
material while applying heat and pressure to the stack of layers to
form the laminated structure.
[0409] 60. The method of clause 55, comprising curing the
electrically conductive bonding material while applying heat and
pressure to the stack of layers to form a laminated structure,
without forming cured or partially cured super cells as an
intermediate product before forming the laminated structure.
[0410] 61. The method of clause 55, comprising dicing one or more
silicon solar cells into rectangular shapes to provide the
rectangular silicon solar cells.
[0411] 62. The method of clause 61, comprising applying the
electrically conductive adhesive bonding material to the one or
more silicon solar cells before dicing the one or more silicon
solar cells to provide rectangular silicon solar cells with
pre-applied electrically conductive adhesive bonding material.
[0412] 63. The method of clause 62, comprising applying the
electrically conductive adhesive bonding material to the one or
more silicon solar cells, then using a laser to scribe one or more
lines on each of the one or more silicon solar cells, then cleaving
the one or more silicon solar cells along the scribed lines.
[0413] 64. The method of clause 62, comprising using a laser to
scribe one or more lines on each of the one or more silicon solar
cells, then applying the electrically conductive adhesive bonding
material to the one or more silicon solar cells, then cleaving the
one or more silicon solar cells along the scribed lines.
[0414] 65. The method of clause 62, wherein the electrically
conductive adhesive bonding material is applied to a top surface of
each of the one or more silicon solar cells and not to an
oppositely positioned bottom surface of each of the one or more
silicon solar cells, comprising applying a vacuum between the
bottom surfaces of the one or more silicon solar cells and a curved
supporting surface to flex the one or more silicon solar cells
against the curved supporting surface and thereby cleave the one or
more silicon solar cells along scribe lines.
[0415] 66. The method of clause 61, comprising applying the
electrically conductive adhesive bonding material to the
rectangular silicon solar cells after dicing the one or more
silicon solar cells to provide the rectangular silicon solar
cells.
[0416] 67. The method of clause 55, wherein the conductive adhesive
bonding material has a glass transition temperature of less than or
equal to about 0.degree. C.
[0417] FIG. 26 shows a diagram of the rear (shaded) surface of a
solar module illustrating an example electrical interconnection of
the front (sun side) surface terminal electrical contacts of a
shingled super cell to a junction box on the rear side of the
module. The front surface terminal contacts of the shingled super
cell may be located adjacent to an edge of the module.
[0418] FIG. 27 shows a diagram of the rear (shaded) surface of a
solar module illustrating an example electrical interconnection of
two or more shingled super cells in parallel, with the front (sun
side) surface terminal electrical contacts of the super cells
connected to each other and to a junction box on the rear side of
the module. The front surface terminal contacts of the shingled
super cells may be located adjacent to an edge of the module.
[0419] FIG. 28 shows a diagram of the rear (shaded) surface of a
solar module illustrating another example electrical
interconnection of two or more shingled super cells in parallel,
with the front (sun side) surface terminal electrical contacts of
the super cells connected to each other and to a junction box on
the rear side of the module. The front surface terminal contacts of
the shingled super cells may be located adjacent to an edge of the
module.
[0420] FIG. 29 shows fragmentary cross-sectional and perspective
diagrams of two super cells illustrating the use of a flexible
interconnect sandwiched between overlapping ends of adjacent super
cells to electrically connect the super cells in series and to
provide an electrical connection to a junction box. FIG. 29A shows
an enlarged view of an area of interest in FIG. 29.
[0421] FIG. 29 and FIG. 29A show the use of an example flexible
interconnect 2960 partially sandwiched between and electrically
interconnecting the overlapping ends of two super cells 100 to
provide an electrical connection to the front surface end contact
of one of the super cells and to the rear surface end contact of
the other super cell, thereby interconnecting the super cells in
series. In the illustrated example, interconnect 2960 is hidden
from view from the front of the solar module by the upper of the
two overlapping solar cells. In another variation, the adjacent
ends of the two super cells do not overlap and the portion of
interconnect 2960 connected to the front surface end contact of one
of the two super cells may be visible from the front surface of the
solar module. Optionally, in such variations the portion of the
interconnect that is otherwise visible from the front of the module
may be covered or colored (e.g., darkened) to reduce visible
contrast between the interconnect and the super cells, as perceived
by a human having normal color vision. Interconnect 2960 may extend
parallel to the adjacent edges of the two super cells beyond the
side edges of the super cells to electrically connect the pair of
super cells in parallel with a similarly arranged pair of super
cells in an adjacent row.
[0422] A ribbon conductor 2970 may be conductively bonded to
interconnect 2960 as shown to electrically connect the adjacent
ends of the two super cells to electrical components (e.g., bypass
diodes and/or module terminals in a junction box) on the rear
surface of the solar module. In another variation (not shown) a
ribbon conductor 2970 may be electrically connected to the rear
surface contact of one of the overlapping super cells away from
their overlapping ends, instead of being conductively bonded to an
interconnect 2960. That configuration may also provide a hidden tap
to one or more bypass diodes or other electrical components on the
rear surface of the solar module.
[0423] Interconnect 2960 may be die cut from a conducting sheet,
for example, and may be optionally patterned to increase its
mechanical compliance both perpendicular to and parallel to the
edges of the super cells to reduce or accommodate stress
perpendicular and parallel to the edges of the super cells arising
from mismatch between the CTE of the interconnect and that of the
super cells. Such patterning may include, for example, slits, slots
(as shown), or holes. The mechanical compliance of the flexible
interconnect, and its bonds to the super cells, should be
sufficient for the interconnected super cells to survive stress
arising from CTE mismatch during the lamination process described
in more detail below. The flexible interconnect may be bonded to
the super cells with, for example, a mechanically compliant
electrically conductive bonding material as described above for use
in bonding overlapped solar cells. Optionally, the electrically
conductive bonding material may be located only at discrete
positions along the edges of the super cells rather than in a
continuous line extending substantially the length of the edge of
the super cells, to reduce or accommodate stress parallel to the
edge of the super cells arising from mismatch between the
coefficient of thermal expansion of the electrically conductive
bonding material or the interconnect and that of the super cells.
Interconnect 2960 may be cut from a thin copper sheet, for
example.
[0424] 1A. A solar module comprising:
[0425] a plurality of super cells arranged in two or more parallel
rows to form a front surface of the solar module, each super cell
comprising a plurality of silicon solar cells arranged in line with
end portions of adjacent silicon solar cells overlapping and
conductively bonded to each other to electrically connect the
silicon solar cells in series, each super cell comprising a front
surface end contact at one end of the super cell and a back surface
end contact of opposite polarity at an opposite end of the super
cell;
[0426] wherein a first row of super cells comprises a first super
cell arranged with its front surface end contact adjacent and
parallel to a first edge of the solar module, and the solar module
comprises a first flexible electrical interconnect that is
elongated and runs parallel to the first edge of the solar module,
is conductively bonded to the front surface end contact of the
first super cell, and occupies only a narrow portion of the front
surface of the solar module adjacent to the first edge of the solar
module and no wider than about 1 centimeter measured
perpendicularly to the first edge of the solar module.
[0427] 2A. The solar module of clause 1A, wherein a portion of the
first flexible electrical interconnect extends around the end of
the first super cell nearest to the first edge of the solar module,
and behind the first super cell.
[0428] 3A. The solar module of clause 1A, wherein the first
flexible interconnect comprises a thin ribbon portion conductively
bonded to the front surface end contact of the first super cell and
a thicker portion running parallel to the first edge of the solar
module.
[0429] 4A. The solar module of clause 1A, wherein the first
flexible interconnect comprises a thin ribbon portion conductively
bonded to the front surface end contact of the first super cell and
a coiled ribbon portion running parallel to the first edge of the
solar module.
[0430] 5A. The solar module of clause 1A, wherein a second row of
super cells comprises a second super cell arranged with its front
surface end contact adjacent to and parallel to the first edge of
the solar module, and the front surface end contact of the first
super cell is electrically connected to the front surface end
contact of the second super cell via the first flexible electrical
interconnect.
[0431] 6A. The solar module of clause 1A, wherein the back surface
end contact of the first super cell is located adjacent to and
parallel to a second edge of the solar module opposite from the
first edge of the solar module, comprising a second flexible
electrical interconnect that is elongated and runs parallel to the
second edge of the solar module, is conductively bonded to the back
surface end contact of the first super cell, and lies entirely
behind the super cells.
[0432] 7A. The solar module of clause 6A, wherein:
[0433] a second row of super cells comprises a second super cell
arranged with its front surface end contact adjacent to and
parallel to the first edge of the solar module and its back surface
end contact located adjacent to and parallel to the second edge of
the solar module;
[0434] the front surface end contact of the first super cell is
electrically connected to the front surface end contact of the
second super cell via the first flexible electrical interconnect;
and
[0435] the back surface end contact of the first super cell is
electrically connected to the back surface end contact of the
second super cell via the second flexible electrical
interconnect.
[0436] 8A. The solar module of clause 1A, comprising:
[0437] a second super cell arranged in the first row of super cells
in series with the first super cell and with its back surface end
contact adjacent a second edge of the solar module opposite from
the first edge of the solar module; and
[0438] a second flexible electrical interconnect that is elongated
and runs parallel to the second edge of the solar module, is
conductively bonded to the back surface end contact of the first
super cell, and lies entirely behind the super cells.
[0439] 9A. The solar module of clause 8A, wherein:
[0440] a second row of super cells comprises a third super cell and
a fourth super cell arranged in series with a front surface end
contact of the third super cell adjacent the first edge of the
solar module and the back surface end contact of the fourth super
cell adjacent the second edge of the solar module; and
[0441] the front surface end contact of the first super cell is
electrically connected to the front surface end contact of the
third super cell via the first flexible electrical interconnect and
the back surface end contact of the second super cell is
electrically connected to the back surface end contact of the
fourth super cell via the second flexible electrical
interconnect.
[0442] 10A. The solar module of clause 1A, wherein away from outer
edges of the solar module there are no electrical interconnections
between the super cells that reduce the active area of the front
surface of the module.
[0443] 11A. The solar module of clause 1A wherein at least one pair
of super cells is arranged in line in a row with the rear surface
contact end of one of the pair of super cells adjacent to the rear
surface contact end of the other of the pair of super cells.
[0444] 12A. The solar module of clause 1A wherein:
[0445] at least one pair of super cells is arranged in line in a
row with adjacent ends of the two super cells having end contacts
of opposite polarity;
[0446] the adjacent ends of the pair of super cells overlap;
and
[0447] the super cells in the pair of super cells are electrically
connected in series by a flexible interconnect that is sandwiched
between their overlapping ends and that does not shade the front
surface.
[0448] 13A. The solar module of clause 1A, wherein the super cells
are arranged on a white backing sheet that comprises parallel
darkened stripes having locations and widths corresponding to
locations and widths of gaps between the parallel rows of super
cells, and white portions of the backing sheets are not visible
through the gaps between the rows.
[0449] 14A. The solar module of clause 1A, wherein all portions of
the first flexible electrical interconnect located on the front
surface of the solar module are covered or colored to reduce
visible contrast with the super cells.
[0450] 15A. The solar module of clause 1A, wherein:
each silicon solar cell comprises: [0451] rectangular or
substantially rectangular front and back surfaces with shapes
defined by first and second oppositely positioned parallel long
sides and two oppositely positioned short sides, at least portions
of the front surfaces to be exposed to solar radiation during
operation of the string of solar cells; [0452] an electrically
conductive front surface metallization pattern disposed on the
front surface and comprising a plurality of fingers running
perpendicular to the long sides and a plurality of discrete front
surface contact pads positioned in a row adjacent to the first long
side, each front surface contact pad electrically connected to at
least one of the fingers; and [0453] an electrically conductive
back surface metallization pattern disposed on the back surface and
comprising a plurality of discrete back surface contact pads
positioned in a row adjacent the second long side; and within each
super cell the silicon solar cells are arranged in line with first
and second long sides of adjacent silicon solar cells overlapping
and with corresponding discrete front surface contact pads and
discrete back surface contact pads on adjacent silicon solar cells
aligned, overlapping, and conductively bonded to each other with a
conductive adhesive bonding material to electrically connect the
silicon solar cells in series.
[0454] 16A. The solar module of clause 15A, wherein the front
surface metallization pattern of each silicon solar cell comprises
a plurality of thin conductors electrically interconnecting
adjacent discrete front surface contact pads, and each thin
conductor is thinner than the width of the discrete contact pads
measured perpendicularly to the long sides of the solar cells.
[0455] 17A. The solar module of clause 15A, wherein the conductive
adhesive bonding material is substantially confined to the
locations of the discrete front surface contact pads by features of
the front surface metallization pattern that form barriers around
each discrete front surface contact pad.
[0456] 18A. The solar module of clause 15A, wherein the conductive
adhesive bonding material is substantially confined to the
locations of the discrete back surface contact pads by features of
the back surface metallization pattern that form barriers around
each discrete back surface contact pad.
[0457] 19A. The solar module of clause 15A, wherein the discrete
back surface contact pads are discrete silver back surface contact
pads, and except for the discrete silver back surface contact pads
the back surface metallization pattern of each silicon solar cell
does not comprise a silver contact at any location that underlies a
portion of the front surface of the solar cell that is not
overlapped by an adjacent silicon solar cell.
[0458] 20A. A solar module comprising:
[0459] a plurality of super cells, each super cell comprising a
plurality of silicon solar cells arranged in line with end portions
of adjacent silicon solar cells overlapping and conductively bonded
to each other to electrically connect the silicon solar cells in
series;
[0460] wherein each silicon solar cell comprises: [0461]
rectangular or substantially rectangular front and back surfaces
with shapes defined by first and second oppositely positioned
parallel long sides and two oppositely positioned short sides, at
least portions of the front surfaces to be exposed to solar
radiation during operation of the string of solar cells; [0462] an
electrically conductive front surface metallization pattern
disposed on the front surface and comprising a plurality of fingers
running perpendicular to the long sides and a plurality of discrete
front surface contact pads positioned in a row adjacent to the
first long side,
[0463] each front surface contact pad electrically connected to at
least one of the fingers; and [0464] an electrically conductive
back surface metallization pattern disposed on the back surface and
comprising a plurality of discrete back surface contact pads
positioned in a row adjacent the second long side;
[0465] wherein within each super cell the silicon solar cells are
arranged in line with first and second long sides of adjacent
silicon solar cells overlapping and with corresponding discrete
front surface contact pads and discrete back surface contact pads
on adjacent silicon solar cells aligned, overlapping, and
conductively bonded to each other with a conductive adhesive
bonding material to electrically connect the silicon solar cells in
series; and
[0466] wherein the super cells are arranged in a single row or in
two or more parallel rows substantially spanning a length or width
of the solar module to form a front surface of the solar module to
be illuminated by solar radiation during operation of the solar
module.
[0467] 21A. The solar module of clause 20A, wherein the discrete
back surface contact pads are discrete silver back surface contact
pads, and except for the discrete silver back surface contact pads
the back surface metallization pattern of each silicon solar cell
does not comprise a silver contact at any location that underlies a
portion of the front surface of the solar cell that is not
overlapped by an adjacent silicon solar cell.
[0468] 22A. The solar module of clause 20A, wherein the front
surface metallization pattern of each silicon solar cell comprises
a plurality of thin conductors electrically interconnecting
adjacent discrete front surface contact pads, and each thin
conductor is thinner than the width of the discrete contact pads
measured perpendicularly to the long sides of the solar cells.
[0469] 23A. The solar module of clause 20A, wherein the conductive
adhesive bonding material is substantially confined to the
locations of the discrete front surface contact pads by features of
the front surface metallization pattern that form barriers around
each discrete front surface contact pad.
[0470] 24A. The solar module of clause 20A, wherein the conductive
adhesive bonding material is substantially confined to the
locations of the discrete back surface contact pads by features of
the back surface metallization pattern that form barriers around
each discrete back surface contact pad.
[0471] 25A. A super cell comprising:
[0472] a plurality of silicon solar cells each comprising: [0473]
rectangular or substantially rectangular front and back surfaces
with shapes defined by first and second oppositely positioned
parallel long sides and two oppositely positioned short sides, at
least portions of the front surfaces to be exposed to solar
radiation during operation of the string of solar cells; [0474] an
electrically conductive front surface metallization pattern
disposed on the front surface and comprising a plurality of fingers
running perpendicular to the long sides and a plurality of discrete
front surface contact pads positioned in a row adjacent to the
first long side, each front surface contact pad electrically
connected to at least one of the fingers; and [0475] an
electrically conductive back surface metallization pattern disposed
on the back surface and comprising a plurality of discrete silver
back surface contact pads positioned in a row adjacent the second
long side;
[0476] wherein the silicon solar cells are arranged in line with
first and second long sides of adjacent silicon solar cells
overlapping and with corresponding discrete front surface contact
pads and discrete back surface contact pads on adjacent silicon
solar cells aligned, overlapping, and conductively bonded to each
other with a conductive adhesive bonding material to electrically
connect the silicon solar cells in series.
[0477] 26A. The solar module of clause 25A, wherein the discrete
back surface contact pads are discrete silver back surface contact
pads, and except for the discrete silver back surface contact pads
the back surface metallization pattern of each silicon solar cell
does not comprise a silver contact at any location that underlies a
portion of the front surface of the solar cell that is not
overlapped by an adjacent silicon solar cell.
[0478] 27A. The string of solar cells of clause 25A, wherein the
front surface metallization pattern comprises a plurality of thin
conductors electrically interconnecting adjacent discrete front
surface contact pads, and each thin conductor is thinner than the
width of the discrete contact pads measured perpendicularly to the
long sides of the solar cells.
[0479] 28A. The string of solar cells of clause 25A, wherein the
conductive adhesive bonding material is substantially confined to
the locations of the discrete front surface contact pads by
features of the front surface metallization pattern that form
barriers around each discrete front surface contact pad.
[0480] 29A. The string of solar cells of clause 25A, wherein the
conductive adhesive bonding material is substantially confined to
the locations of the discrete back surface contact pads by features
of the back surface metallization pattern that form barriers around
each discrete back surface contact pad.
[0481] 30A. The string of solar cells of clause 25A, wherein the
conductive adhesive bonding material has a glass transition less
than or equal to about 0.degree. C.
[0482] 31. A method of making a solar module, the method
comprising:
[0483] assembling a plurality of super cells, each super cell
comprising a plurality of rectangular silicon solar cells arranged
in line with end portions on long sides of adjacent rectangular
silicon solar cells overlapping in a shingled manner;
[0484] curing an electrically conductive bonding material disposed
between the overlapping end portions of adjacent rectangular
silicon solar cells by applying heat and pressure to the super
cells, thereby bonding adjacent overlapping rectangular silicon
solar cells to each other and electrically connecting them in
series;
[0485] arranging and interconnecting the super cells in a desired
solar module configuration in a stack of layers comprising an
encapsulant; and
[0486] applying heat and pressure to the stack of layers to form a
laminated structure.
[0487] 32A. The method of clause 31A, comprising curing or
partially curing the electrically conductive bonding material by
applying heat and pressure to the super cells prior to applying
heat and pressure to the stack of layers to form the laminated
structure, thereby forming cured or partially cured super cells as
an intermediate product before forming the laminated structure.
[0488] 33A. The method of clause 32A, wherein as each additional
rectangular silicon solar cell is added to a super cell during
assembly of the super cell, the electrically conductive adhesive
bonding material between the newly added solar cell and its
adjacent overlapping solar cell is cured or partially cured before
another rectangular silicon solar cell is added to the super
cell.
[0489] 34A. The method of clause 32A, comprising curing or
partially curing all of the electrically conductive bonding
material in a super cell in the same step.
[0490] 35A. The method of clause 32A, comprising:
[0491] partially curing the electrically conductive bonding
material by applying heat and pressure to the super cells prior to
applying heat and pressure to the stack of layers to form a
laminated structure, thereby forming partially cured super cells as
an intermediate product before forming the laminated structure;
and
[0492] completing curing of the electrically conductive bonding
material while applying heat and pressure to the stack of layers to
form the laminated structure.
[0493] 36A. The method of clause 31A, comprising curing the
electrically conductive bonding material while applying heat and
pressure to the stack of layers to form a laminated structure,
without forming cured or partially cured super cells as an
intermediate product before forming the laminated structure.
[0494] 37A. The method of clause 31A, comprising dicing one or more
silicon solar cells into rectangular shapes to provide the
rectangular silicon solar cells.
[0495] 38A. The method of clause 37A, comprising applying the
electrically conductive adhesive bonding material to the one or
more silicon solar cells before dicing the one or more silicon
solar cells to provide rectangular silicon solar cells with
pre-applied electrically conductive adhesive bonding material.
[0496] 39A. The method of clause 38A, comprising applying the
electrically conductive adhesive bonding material to the one or
more silicon solar cells, then using a laser to scribe one or more
lines on each of the one or more silicon solar cells, then cleaving
the one or more silicon solar cells along the scribed lines.
[0497] 40A. The method of clause 38A, comprising using a laser to
scribe one or more lines on each of the one or more silicon solar
cells, then applying the electrically conductive adhesive bonding
material to the one or more silicon solar cells, then cleaving the
one or more silicon solar cells along the scribed lines.
[0498] 41A. The method of clause 38A, wherein the electrically
conductive adhesive bonding material is applied to a top surface of
each of the one or more silicon solar cells and not to an
oppositely positioned bottom surface of each of the one or more
silicon solar cells, comprising applying a vacuum between the
bottom surfaces of the one or more silicon solar cells and a curved
supporting surface to flex the one or more silicon solar cells
against the curved supporting surface and thereby cleave the one or
more silicon solar cells along scribe lines.
[0499] 42A. The method of clause 37A, comprising applying the
electrically conductive adhesive bonding material to the
rectangular silicon solar cells after dicing the one or more
silicon solar cells to provide the rectangular silicon solar
cells.
[0500] 43A. The method of clause 31A, wherein the conductive
adhesive bonding material has a glass transition temperature of
less than or equal to about 0.degree. C.
[0501] 44A. A method of making a super cell, the method
comprising:
[0502] laser scribing one or more scribe lines on each of one or
more silicon solar cells to define a plurality of rectangular
regions on the silicon solar cells, applying an electrically
conductive adhesive bonding material to the one or more scribed
silicon solar cells at one or more locations adjacent a long side
of each rectangular region;
[0503] separating the silicon solar cells along the scribe lines to
provide a plurality of rectangular silicon solar cells each
comprising a portion of the electrically conductive adhesive
bonding material disposed on its front surface adjacent a long
side;
[0504] arranging the plurality of rectangular silicon solar cells
in line with long sides of adjacent rectangular silicon solar cells
overlapping in a shingled manner with a portion of the electrically
conductive adhesive bonding material disposed in between; and
[0505] curing the electrically conductive bonding material, thereby
bonding adjacent overlapping rectangular silicon solar cells to
each other and electrically connecting them in series.
[0506] 45A. A method of making a super cell, the method
comprising:
[0507] laser scribing one or more scribe lines on each of one or
more silicon solar cells to define a plurality of rectangular
regions on the silicon solar cells, each solar cell comprising a
top surface and an oppositely positioned bottom surface;
[0508] applying an electrically conductive adhesive bonding
material to portions of the top surfaces of the one or more silicon
solar cells;
[0509] applying a vacuum between the bottom surfaces of the one or
more silicon solar cells and a curved supporting surface to flex
the one or more silicon solar cells against the curved supporting
surface and thereby cleave the one or more silicon solar cells
along the scribe lines to provide a plurality of rectangular
silicon solar cells each comprising a portion of the electrically
conductive adhesive bonding material disposed on its front surface
adjacent a long side;
[0510] arranging the plurality of rectangular silicon solar cells
in line with long sides of adjacent rectangular silicon solar cells
overlapping in a shingled manner with a portion of the electrically
conductive adhesive bonding material disposed in between; and
[0511] curing the electrically conductive bonding material, thereby
bonding adjacent overlapping rectangular silicon solar cells to
each other and electrically connecting them in series.
[0512] 46A. A method of making a super cell, the method
comprising:
[0513] dicing one or more pseudo square silicon wafers along a
plurality of lines parallel to a long edge of each wafer to form a
plurality of rectangular silicon solar cells each having
substantially the same length along its long axis; and
[0514] arranging the rectangular silicon solar cells in line with
long sides of adjacent solar cells overlapping and conductively
bonded to each other to electrically connect the solar cells in
series;
[0515] wherein the plurality of rectangular silicon solar cells
comprises at least one rectangular solar cell having two chamfered
comers corresponding to comers or to portions of comers of the
pseudo square wafer, and one or more rectangular silicon solar
cells each lacking chamfered comers; and
[0516] wherein the spacing between parallel lines along which the
pseudo square wafer is diced is selected to compensate for the
chamfered comers by making the width perpendicular to the long axis
of the rectangular silicon solar cells that comprise chamfered
comers greater than the width perpendicular to the long axis of the
rectangular silicon solar cells that lack chamfered comers, so that
each of the plurality of rectangular silicon solar cells in the
string of solar cells has a front surface of substantially the same
area exposed to light in operation of the string of solar
cells.
[0517] 47A. A super cell comprising:
[0518] a plurality of silicon solar cells arranged in line with end
portions of adjacent solar cells overlapping and conductively
bonded to each other to electrically connect the solar cells in
series;
[0519] wherein at least one of the silicon solar cells has
chamfered comers that correspond to comers or portions of comers of
a pseudo square silicon wafer from which it was diced, at least one
of the silicon solar cells lacks chamfered comers, and each of the
silicon solar cells has a front surface of substantially the same
area exposed to light during operation of the string of solar
cells.
[0520] 48A. A method of making two or more super cells, the method
comprising:
[0521] dicing one or more pseudo square silicon wafers along a
plurality of lines parallel to a long edge of each wafer to form a
first plurality of rectangular silicon solar cells comprising
chamfered comers corresponding to comers or portions of comers of
the pseudo square silicon wafers and a second plurality of
rectangular silicon solar cells each of a first length spanning a
full width of the pseudo square silicon wafers and lacking
chamfered comers;
[0522] removing the chamfered comers from each of the first
plurality of rectangular silicon solar cells to form a third
plurality of rectangular silicon solar cells each of a second
length shorter than the first length and lacking chamfered
comers;
[0523] arranging the second plurality of rectangular silicon solar
cells in line with long sides of adjacent rectangular silicon solar
cells overlapping and conductively bonded to each other to
electrically connect the second plurality of rectangular silicon
solar cells in series to form a solar cell string having a width
equal to the first length; and
[0524] arranging the third plurality of rectangular silicon solar
cells in line with long sides of adjacent rectangular silicon solar
cells overlapping and conductively bonded to each other to
electrically connect the third plurality of rectangular silicon
solar cells in series to form a solar cell string having a width
equal to the second length.
[0525] 49A. A method of making two or more super cells, the method
comprising:
[0526] dicing one or more pseudo square silicon wafers along a
plurality of lines parallel to a long edge of each wafer to form a
first plurality of rectangular silicon solar cells comprising
chamfered comers corresponding to comers or portions of comers of
the pseudo square silicon wafers and a second plurality of
rectangular silicon solar cells lacking chamfered comers;
[0527] arranging the first plurality of rectangular silicon solar
cells in line with long sides of adjacent rectangular silicon solar
cells overlapping and conductively bonded to each other to
electrically connect the first plurality of rectangular silicon
solar cells in series; and
[0528] arranging the second plurality of rectangular silicon solar
cells in line with long sides of adjacent rectangular silicon solar
cells overlapping and conductively bonded to each other to
electrically connect the second plurality of rectangular silicon
solar cells in series.
[0529] 50A. A solar module comprising:
[0530] a series connected string of N.gtoreq.than 25 rectangular or
substantially rectangular solar cells having on average a breakdown
voltage greater than about 10 volts, the solar cells grouped into
one or more super cells each of which comprises two or more of the
solar cells arranged in line with long sides of adjacent solar
cells overlapping and conductively bonded to each other with an
electrically and thermally conductive adhesive;
[0531] wherein no single solar cell or group of <N solar cells
in the string of solar cells is individually electrically connected
in parallel with a bypass diode.
[0532] 51A. The solar module of clause 50A, wherein N is greater
than or equal to 30.
[0533] 52A. The solar module of clause 50A, wherein N is greater
than or equal to 50.
[0534] 53A. The solar module of clause 50A, wherein N is greater
than or equal to 100.
[0535] 54A. The solar module of clause 50A, wherein the adhesive
forms bonds between adjacent solar cells having a thickness
perpendicular to the solar cells less than or equal to about 0.1 mm
and a thermal conductivity perpendicular to the solar cells greater
than or equal to about 1.5 w/m/k.
[0536] 55A. The solar module of clause 50A, wherein the N solar
cells are grouped into a single super cell.
[0537] 56A. The solar module of clause 50A, wherein the solar cells
are silicon solar cells.
[0538] 57A. A solar module comprising:
[0539] a super cell substantially spanning a full length or width
of the solar module parallel to an edge of the solar module, the
super cell comprising a series connected string of N rectangular or
substantially rectangular solar cells having on average a breakdown
voltage greater than about 10 volts arranged in line with long
sides of adjacent solar cells overlapping and conductively bonded
to each other with an electrically and thermally conductive
adhesive;
[0540] wherein no single solar cell or group of <N solar cells
in the super cell is individually electrically connected in
parallel with a bypass diode.
[0541] 58A. The solar module of clause 57A, wherein N>24.
[0542] 59A. The solar module of clause 57A, wherein the super cell
has a length in the direction of current flow of at least about 500
mm.
[0543] 60. A super cell comprising:
[0544] a plurality of silicon solar cells each comprising: [0545]
rectangular or substantially rectangular front and back surfaces
with shapes defined by first and second oppositely positioned
parallel long sides and two oppositely positioned short sides, at
least portions of the front surfaces to be exposed to solar
radiation during operation of the string of solar cells; [0546] an
electrically conductive front surface metallization pattern
disposed on the front surface and comprising at least one front
surface contact pad positioned adjacent to the first long side; and
[0547] an electrically conductive back surface metallization
pattern disposed on the back surface and comprising at least one
back surface contact pad positioned adjacent the second long
side;
[0548] wherein the silicon solar cells are arranged in line with
first and second long sides of adjacent silicon solar cells
overlapping and with front surface and back surface contact pads on
adjacent silicon solar cells overlapping and conductively bonded to
each other with a conductive adhesive bonding material to
electrically connect the silicon solar cells in series; and
[0549] wherein the front surface metallization pattern of each
silicon solar cell comprises a barrier configured to substantially
confine the conducive adhesive bonding material to the at least one
front surface contact pads prior to curing of the conductive
adhesive bonding material during manufacturing of the super
cell.
[0550] 61A. The super cell of clause 60A, wherein for each pair of
adjacent and overlapping silicon solar cells, the barrier on the
front surface of one of the silicon solar cells is overlapped and
hidden by a portion of the other silicon solar cell, thereby
substantially confining the conductive adhesive bonding material to
overlapped regions of the front surface of the silicon solar cell
prior to curing of the conductive adhesive bonding material during
manufacturing of the super cell.
[0551] 62A. The super cell of clause 60A, wherein the barrier
comprises a continuous conductive line running parallel to and for
substantially the full length of the first long side, with the at
least one front surface contact pads located between the continuous
conductive line and the first long side of the solar cell.
[0552] 63A. The super cell of clause 62A, wherein the front surface
metallization pattern comprises fingers electrically connected to
the at least one front surface contact pads and running
perpendicularly to the first long side, and the continuous
conductive line electrically interconnects the fingers to provide
multiple conductive paths from each finger to the at least one
front surface contact pads.
[0553] 64A. The super cell of clause 60A, wherein the front surface
metallization pattern comprises a plurality of discrete contact
pads arranged in a row adjacent to and parallel to the first long
side, and the barrier comprises a plurality of features forming
separate barriers for each discrete contact pad that substantially
confine the conductive adhesive bonding material to the discrete
contact pads prior to curing of the conductive adhesive bonding
material during manufacturing of the super cell.
[0554] 65A. The super cell of clause 64A, wherein the separate
barriers abut and are taller than their corresponding discrete
contact pads.
[0555] 66A. A super cell comprising:
[0556] a plurality of silicon solar cells each comprising: [0557]
rectangular or substantially rectangular front and back surfaces
with shapes defined by first and second oppositely positioned
parallel long sides and two oppositely positioned short sides, at
least portions of the front surfaces to be exposed to solar
radiation during operation of the string of solar cells; [0558] an
electrically conductive front surface metallization pattern
disposed on the front surface and comprising at least one front
surface contact pad positioned adjacent to the first long side; and
[0559] an electrically conductive back surface metallization
pattern disposed on the back surface and comprising at least one
back surface contact pad positioned adjacent the second long
side;
[0560] wherein the silicon solar cells are arranged in line with
first and second long sides of adjacent silicon solar cells
overlapping and with front surface and back surface contact pads on
adjacent silicon solar cells overlapping and conductively bonded to
each other with a conductive adhesive bonding material to
electrically connect the silicon solar cells in series; and
[0561] wherein the back surface metallization pattern of each
silicon solar cell comprises a barrier configured to substantially
confine the conducive adhesive bonding material to the at least one
back surface contact pads prior to curing of the conductive
adhesive bonding material during manufacturing of the super
cell.
[0562] 67A. The super cell of clause 66A, wherein the back surface
metallization pattern comprises one or more discrete contact pads
arranged in a row adjacent to and parallel to the second long side,
and the barrier comprises a plurality of features forming separate
barriers for each discrete contact pad that substantially confine
the conductive adhesive bonding material to the discrete contact
pads prior to curing of the conductive adhesive bonding material
during manufacturing of the super cell.
[0563] 68A. The super cell of clause 67A, wherein the separate
barriers abut and are taller than their corresponding discrete
contact pads.
[0564] 69A. A method of making a string of solar cells, the method
comprising:
[0565] dicing one or more pseudo square silicon wafers along a
plurality of lines parallel to a long edge of each wafer to form a
plurality of rectangular silicon solar cells each having
substantially the same length along its long axis; and
[0566] arranging the rectangular silicon solar cells in line with
long sides of adjacent solar cells overlapping and conductively
bonded to each other to electrically connect the solar cells in
series;
[0567] wherein the plurality of rectangular silicon solar cells
comprises at least one rectangular solar cell having two chamfered
comers corresponding to comers or to portions of comers of the
pseudo square wafer, and one or more rectangular silicon solar
cells each lacking chamfered comers; and
[0568] wherein the spacing between parallel lines along which the
pseudo square wafer is diced is selected to compensate for the
chamfered comers by making the width perpendicular to the long axis
of the rectangular silicon solar cells that comprise chamfered
comers greater than the width perpendicular to the long axis of the
rectangular silicon solar cells that lack chamfered comers, so that
each of the plurality of rectangular silicon solar cells in the
string of solar cells has a front surface of substantially the same
area exposed to light in operation of the string of solar
cells.
[0569] 70A. A string of solar cells comprising:
[0570] a plurality of silicon solar cells arranged in line with end
portions of adjacent solar cells overlapping and conductively
bonded to each other to electrically connect the solar cells in
series;
[0571] wherein at least one of the silicon solar cells has
chamfered comers that correspond to comers or portions of comers of
a pseudo square silicon wafer from which it was diced, at least one
of the silicon solar cells lacks chamfered comers, and each of the
silicon solar cells has a front surface of substantially the same
area exposed to light during operation of the string of solar
cells.
[0572] 71A. A method of making two or more strings of solar cells,
the method comprising:
[0573] dicing one or more pseudo square silicon wafers along a
plurality of lines parallel to a long edge of each wafer to form a
first plurality of rectangular silicon solar cells comprising
chamfered comers corresponding to comers or portions of comers of
the pseudo square silicon wafers and a second plurality of
rectangular silicon solar cells each of a first length spanning a
full width of the pseudo square silicon wafers and lacking
chamfered comers;
[0574] removing the chamfered comers from each of the first
plurality of rectangular silicon solar cells to form a third
plurality of rectangular silicon solar cells each of a second
length shorter than the first length and lacking chamfered
comers;
[0575] arranging the second plurality of rectangular silicon solar
cells in line with long sides of adjacent rectangular silicon solar
cells overlapping and conductively bonded to each other to
electrically connect the second plurality of rectangular silicon
solar cells in series to form a solar cell string having a width
equal to the first length; and
[0576] arranging the third plurality of rectangular silicon solar
cells in line with long sides of adjacent rectangular silicon solar
cells overlapping and conductively bonded to each other to
electrically connect the third plurality of rectangular silicon
solar cells in series to form a solar cell string having a width
equal to the second length.
[0577] 72A. A method of making two or more strings of solar cells,
the method comprising:
[0578] dicing one or more pseudo square silicon wafers along a
plurality of lines parallel to a long edge of each wafer to form a
first plurality of rectangular silicon solar cells comprising
chamfered comers corresponding to comers or portions of comers of
the pseudo square silicon wafers and a second plurality of
rectangular silicon solar cells lacking chamfered comers;
[0579] arranging the first plurality of rectangular silicon solar
cells in line with long sides of adjacent rectangular silicon solar
cells overlapping and conductively bonded to each other to
electrically connect the first plurality of rectangular silicon
solar cells in series; and
[0580] arranging the second plurality of rectangular silicon solar
cells in line with long sides of adjacent rectangular silicon solar
cells overlapping and conductively bonded to each other to
electrically connect the second plurality of rectangular silicon
solar cells in series.
[0581] 73A. A method of making a solar module, the method
comprising:
[0582] dicing each of a plurality of pseudo square silicon wafers
along a plurality of lines parallel to a long edge of the wafer to
form from the plurality of pseudo square silicon wafers a plurality
of rectangular silicon solar cells comprising chamfered comers
corresponding to comers of the pseudo square silicon wafers and a
plurality of rectangular silicon solar cells lacking chamfered
comers;
[0583] arranging at least some of the rectangular silicon solar
cells lacking chamfered comers to form a first plurality of super
cells each of which comprises only rectangular silicon solar cells
lacking chamfered comers arranged in line with long sides of the
silicon solar cells overlapping and conductively bonded to each
other to electrically connect the silicon solar cells in
series;
[0584] arranging at least some of the rectangular silicon solar
cells comprising chamfered comers to form a second plurality of
super cells each of which comprises only rectangular silicon solar
cells comprising chamfered comers arranged in line with long sides
of the silicon solar cells overlapping and conductively bonded to
each other to electrically connect the silicon solar cells in
series; and
[0585] arranging the super cells in parallel rows of super cells of
substantially equal length to form a front surface of the solar
module, with each row comprising only super cells from the first
plurality of super cells or only super cells from the second
plurality of super cells.
[0586] 74A. The solar module of clause 73A, wherein two of the rows
of super cells adjacent to parallel opposite edges of the solar
module comprise only super cells from the second plurality of super
cells, and all other rows of super cells comprise only super cells
from the first plurality of super cells.
[0587] 75A. The solar module of clause 74A, wherein the solar
module comprises a total of six rows of super cells.
[0588] 76A. A super cell comprising:
[0589] a plurality of silicon solar cells arranged in line in a
first direction with end portions of adjacent silicon solar cells
overlapping and conductively bonded to each other to electrically
connect the silicon solar cells in series; and
[0590] an elongated flexible electrical interconnect with its long
axis oriented parallel to a second direction perpendicular to the
first direction, conductively bonded to a front or back surface of
an end one of the silicon solar cells at three or more discrete
locations arranged along the second direction, running at least the
full width of the end solar cell in the second direction, having a
conductor thickness less than or equal to about 100 microns
measured perpendicularly to the front or rear surface of the end
silicon solar cell, providing a resistance to current flow in the
second direction of less than or equal to about 0.012 Ohms, and
configured to provide flexibility accommodating differential
expansion in the second direction between the end silicon solar
cell and the interconnect for a temperature range of about
-40.degree. C. to about 85.degree. C.
[0591] 77A. The super cell of clause 76A, wherein the flexible
electrical interconnect has a conductor thickness less than or
equal to about 30 microns measured perpendicularly to the front and
rear surfaces of the end silicon solar cell.
[0592] 78A. The super cell of clause 76A, wherein the flexible
electrical interconnect extends beyond the super cell in the second
direction to provide for electrical interconnection to at least a
second super cell positioned parallel to and adjacent the super
cell in a solar module.
[0593] 79A. The super cell of clause 76A, wherein the flexible
electrical interconnect extends beyond the super cell in the first
direction to provide for electrical interconnection to a second
super cell positioned parallel to and in line with the super cell
in a solar module.
[0594] 80A. A solar module comprising:
[0595] a plurality of super cells arranged in two or more parallel
rows spanning a width of the module to form a front surface of the
module, each super cell comprising a plurality of silicon solar
cells arranged in line with end portions of adjacent silicon solar
cells overlapping and conductively bonded to each other to
electrically connect the silicon solar cells in series;
[0596] wherein at least an end of a first super cell adjacent an
edge of the module in a first row is electrically connected to an
end of a second super cell adjacent the same edge of the module in
a second row via a flexible electrical interconnect that is bonded
to the front surface of the first super cell at a plurality of
discrete locations with an electrically conductive adhesive bonding
material, runs parallel to the edge of the module, and at least a
portion of which folds around the end of the first super cell and
is hidden from view from the front of the module.
[0597] 81A. The solar module of clause 80A, wherein surfaces of the
flexible electrical interconnect on the front surface of the module
are covered or colored to reduce visible contrast with the super
cells.
[0598] 82A. The solar module of clause 80A, wherein the two or more
parallel rows of super cells are arranged on a white backing sheet
to form a front surface of the solar module to be illuminated by
solar radiation during operation of the solar module, the white
backing sheet comprises parallel darkened stripes having locations
and widths corresponding to locations and widths of gaps between
the parallel rows of super cells, and white portions of the backing
sheets are not visible through the gaps between the rows.
[0599] 83A. A method of making a string of solar cells, the method
comprising:
[0600] laser scribing one or more scribe lines on each of one or
more silicon solar cells to define a plurality of rectangular
regions on the silicon solar cells,
[0601] applying an electrically conductive adhesive bonding
material to the one or more scribed silicon solar cells at one or
more locations adjacent a long side of each rectangular region;
separating the silicon solar cells along the scribe lines to
provide a plurality of rectangular silicon solar cells each
comprising a portion of the electrically conductive adhesive
bonding material disposed on its front surface adjacent a long
side;
[0602] arranging the plurality of rectangular silicon solar cells
in line with long sides of adjacent rectangular silicon solar cells
overlapping in a shingled manner with a portion of the electrically
conductive adhesive bonding material disposed in between; and
[0603] curing the electrically conductive bonding material, thereby
bonding adjacent overlapping rectangular silicon solar cells to
each other and electrically connecting them in series.
[0604] 84A. A method of making a string of solar cells, the method
comprising:
[0605] laser scribing one or more scribe lines on each of one or
more silicon solar cells to define a plurality of rectangular
regions on the silicon solar cells, each solar cell comprising a
top surface and an oppositely positioned bottom surface;
[0606] applying an electrically conductive adhesive bonding
material to portions of the top surfaces of the one or more silicon
solar cells;
[0607] applying a vacuum between the bottom surfaces of the one or
more silicon solar cells and a curved supporting surface to flex
the one or more silicon solar cells against the curved supporting
surface and thereby cleave the one or more silicon solar cells
along the scribe lines to provide a plurality of rectangular
silicon solar cells each comprising a portion of the electrically
conductive adhesive bonding material disposed on its front surface
adjacent a long side;
[0608] arranging the plurality of rectangular silicon solar cells
in line with long sides of adjacent rectangular silicon solar cells
overlapping in a shingled manner with a portion of the electrically
conductive adhesive bonding material disposed in between; and
[0609] curing the electrically conductive bonding material, thereby
bonding adjacent overlapping rectangular silicon solar cells to
each other and electrically connecting them in series.
[0610] 85A. The method of clause 84A, comprising applying the
electrically conductive adhesive bonding material to the one or
more silicon solar cells, then laser scribing the one or more
scribe lines on each of the one or more silicon solar cells.
[0611] 86A. The method of clause 84A, comprising laser scribing the
one or more scribe lines on each of the one or more silicon solar
cells, then applying the electrically conductive adhesive bonding
material to the one or more silicon solar cells.
[0612] Embodiments may include one or more features described in
the following U.S. patent Publication documents: U.S. Patent
Publication No. 2014/0124013; and U.S. Patent Publication No.
2014/0124014, both of which are incorporated by reference in their
entireties herein for all purposes.
[0613] This disclosure is illustrative and not limiting. Further
modifications will be apparent to one skilled in the art in light
of this disclosure and are intended to fall within the scope of the
appended claims.
* * * * *