U.S. patent application number 11/877632 was filed with the patent office on 2008-05-01 for flexible high-voltage adaptable current photovoltaic modules and associated methods.
This patent application is currently assigned to Ascent Solar Technologies, Inc.. Invention is credited to Joseph H. Armstrong, Matthew B. Foster, Douglas G. Jensen, Jonathan S. Port.
Application Number | 20080099063 11/877632 |
Document ID | / |
Family ID | 39322802 |
Filed Date | 2008-05-01 |
United States Patent
Application |
20080099063 |
Kind Code |
A1 |
Armstrong; Joseph H. ; et
al. |
May 1, 2008 |
Flexible High-Voltage Adaptable Current Photovoltaic Modules And
Associated Methods
Abstract
A flexible photovoltaic module for converting light into an
electric current includes a plurality of electrically
interconnected flexible photovoltaic submodules monolithically
integrated onto a common flexible substrate. Each photovoltaic
submodule includes a plurality of electrically interconnected
flexible thin-film photovoltaic cells monolithically integrated
onto the flexible substrate. A flexible photovoltaic module for
converting light into an electric current includes a backplane
layer for supporting the photovoltaic module. A first pottant layer
is disposed on the backplane layer, and a photovoltaic submodule
assembly is disposed on the first pottant layer. The photovoltaic
submodule assembly has at least one photovoltaic submodule, where
each photovoltaic submodule includes a plurality of thin-film
photovoltaic cells. A second pottant layer is disposed on the
photovoltaic submodule assembly, and a upper laminate layer
disposed on the second pottant layer.
Inventors: |
Armstrong; Joseph H.;
(Littleton, CO) ; Foster; Matthew B.; (Lone Tree,
CO) ; Port; Jonathan S.; (Pacific Palisades, CA)
; Jensen; Douglas G.; (Lakewood, CO) |
Correspondence
Address: |
LATHROP & GAGE LC
4845 PEARL EAST CIRCLE
SUITE 300
BOULDER
CO
80301
US
|
Assignee: |
Ascent Solar Technologies,
Inc.
Littleton
CO
|
Family ID: |
39322802 |
Appl. No.: |
11/877632 |
Filed: |
October 23, 2007 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60853609 |
Oct 23, 2006 |
|
|
|
60853610 |
Oct 23, 2006 |
|
|
|
Current U.S.
Class: |
136/249 |
Current CPC
Class: |
H01L 31/02008 20130101;
H02S 10/00 20130101; Y02E 10/50 20130101; H01L 31/0504 20130101;
H02S 40/36 20141201; Y10T 29/49355 20150115; H01L 31/02021
20130101; H01L 31/048 20130101; Y10S 136/293 20130101 |
Class at
Publication: |
136/249 |
International
Class: |
H02N 6/00 20060101
H02N006/00 |
Claims
1. A flexible photovoltaic module for converting light into an
electric current, comprising a plurality of electrically
interconnected flexible photovoltaic submodules monolithically
integrated on a common flexible substrate, each photovoltaic
submodule including a plurality of electrically interconnected
flexible thin-film photovoltaic cells monolithically integrated
onto the flexible substrate.
2. The photovoltaic module of claim 1, further comprising at least
one bus bar electrically connecting at least two of the
photovoltaic submodules.
3. The photovoltaic module of claim 1, further comprising at least
one conductor formed of conductive ink electrically connecting at
least two of the photovoltaic submodules.
4. The photovoltaic module of claim 1, at least two of the
photovoltaic submodules being electrically connected in series.
5. The photovoltaic module of claim 4, further comprising a
flexible bus bar electrically connecting the two photovoltaic
submodules in series.
6. The photovoltaic module of claim 1, at least two of the
photovoltaic submodules being electrically connected in
parallel.
7. The photovoltaic module of claim 6, further comprising a
flexible bus bar electrically connecting the two photovoltaic
modules in parallel.
8. The photovoltaic module of claim 1, wherein: the plurality of
photovoltaic submodules comprises a first, second, third, and
fourth photovoltaic submodule; the first and second photovoltaic
submodules are electrically connected in series to form a first
string of photovoltaic submodules; the third and fourth
photovoltaic submodules are electrically connected in series to
form a second string of photovoltaic submodules; and the first
string of photovoltaic submodules is electrically connected in
parallel to the second string of photovoltaic submodules.
9. The photovoltaic module of claim 1, wherein: the plurality of
photovoltaic submodules comprises a first, second, third, and
fourth photovoltaic submodule; the first and second photovoltaic
submodules are electrically connected in parallel to form a first
group of photovoltaic submodules; the third and fourth photovoltaic
submodules are electrically connected in parallel to form a second
group of photovoltaic submodules; and the first group of
photovoltaic submodules is electrically connected in series with
the second group of photovoltaic submodules.
10. The photovoltaic module of claim 1, the photovoltaic module
having a length and a width, a plurality of photovoltaic submodules
being disposed along both the length and the width of the
photovoltaic module.
11. The photovoltaic module of claim 1, at least two adjacent
photovoltaic submodules having opposite electrical polarity.
12. A flexible photovoltaic module for converting light into an
electric current, comprising: a backplane layer for supporting the
photovoltaic module; a first pottant layer disposed on the
backplane layer; a photovoltaic submodule assembly disposed on the
first pottant layer, the photovoltaic submodule assembly having at
least one photovoltaic submodule, each photovoltaic submodule
having a plurality of thin-film photovoltaic cells; a second
pottant layer disposed on the photovoltaic submodule assembly; and
a upper laminate layer disposed on the second pottant layer.
13. The photovoltaic module of claim 12, the photovoltaic submodule
assembly comprising a plurality of photovoltaic submodules and a
plurality of bus bars, the bus bars electrically interconnecting
the plurality of photovoltaic submodules.
14. The photovoltaic module of claim 12, at least one or both of
the first and second pottant layers comprising an additive.
15. The photovoltaic module of claim 12, the first pottant layer
comprising: a first pottant sublayer disposed on the backplane
layer; a first additive layer disposed on the first pottant
sublayer; and a second pottant sublayer disposed on the first
additive layer.
16. The photovoltaic module of claim 12, the second pottant layer
comprising: a third pottant sublayer disposed on the photovoltaic
submodule assembly; a second additive layer disposed on the third
pottant sublayer; and a fourth pottant sublayer disposed on the
second additive layer.
17. The photovoltaic module of claim 12, the photovoltaic submodule
assembly comprising a common flexible substrate, each photovoltaic
submodule being monolithically integrated on the common flexible
substrate.
18. The photovoltaic module of claim 12, further comprising a
flexible wiring harness including a plurality of electrical
conductors, each electrical conductor being electrically isolated
within the wiring harness, the photovoltaic submodule assembly
being selectively connectable to one of the electrical
conductors.
19. The photovoltaic module of claim 12, the backplane layer
comprising a fastener for fastening the photovoltaic module to a
supporting structure.
20. The photovoltaic module of claim 12, at least one of the first
and second pottant layers being formed of one of ethylene vinyl
acetate and polyvinyl butyral.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit of priority to U.S.
Provisional Patent Application Ser. No. 60/853,609 filed 23 Oct.
2006 and U.S. Provisional Patent Application Ser. No. 60/853,610
filed 23 Oct. 2006. Each of the aforementioned applications are
incorporated herein by reference.
BACKGROUND
[0002] The conversion of sunlight into electrical power by
photovoltaic cells provides a share of the world's renewable
energy. However, widespread use of photovoltaic cells to generate
electricity has been limited by issues such as the relatively high
cost of manufacturing and installing photovoltaic cells as well as
the relatively low efficiency of photovoltaic cells.
[0003] Traditional photovoltaic electric generation systems require
the installation of numerous photovoltaic modules, cabling,
junction boxes, and other circuitry to connect the photovoltaic
modules in series and parallel to produce a desired voltage and
current output. Installing the numerous photovoltaic modules and
associated cabling is a time-consuming and expensive process.
Furthermore, the photovoltaic modules of these traditional systems
have fixed sizes and electrical characteristics, which impedes
their ability to meet system design requirements. For example, such
photovoltaic modules cannot be sized to accommodate roof
obstructions.
SUMMARY
[0004] A flexible photovoltaic module for converting light into an
electric current includes a plurality of electrically
interconnected flexible photovoltaic submodules monolithically
integrated onto a common flexible substrate. Each photovoltaic
submodule includes a plurality of electrically interconnected
flexible thin-film photovoltaic cells monolithically integrated
onto the flexible substrate.
[0005] A flexible photovoltaic module for converting light into an
electric current includes a backplane layer for supporting the
photovoltaic module. A first pottant layer is disposed on the
backplane layer, and a photovoltaic submodule assembly is disposed
on the first pottant layer. The photovoltaic submodule assembly has
at least one photovoltaic submodule, where each photovoltaic
submodule includes a plurality of thin-film photovoltaic cells. A
second pottant layer is disposed on the photovoltaic submodule
assembly, and an upper laminate layer disposed on the second
pottant layer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a top plan view of one solar power generation
system for generating electricity from light, according to an
embodiment.
[0007] FIG. 2 is a top plan view of one flexible photovoltaic
submodule, according to an embodiment.
[0008] FIG. 3 is a top plan view of one flexible photovoltaic
module, according to an embodiment.
[0009] FIG. 4 is a top plan view of one flexible photovoltaic
module, according to an embodiment.
[0010] FIG. 5 is a top plan view of two flexible photovoltaic
modules, according to an embodiment.
[0011] FIG. 6 is a top plan view of three flexible photovoltaic
modules, according to an embodiment.
[0012] FIG. 7 is a top plan view of three flexible photovoltaic
modules, according an embodiment.
[0013] FIG. 8 is a top plan view of three flexible photovoltaic
modules, according to an embodiment.
[0014] FIG. 9 is a top plan view of four flexible photovoltaic
modules, according to an embodiment.
[0015] FIG. 10 is an exploded side perspective view of a
photovoltaic module, according to an embodiment.
[0016] FIG. 11 is an exploded side perspective view of a
photovoltaic module, according to an embodiment.
[0017] FIG. 12 is a side perspective view of one solar power
generation system, according to an embodiment.
[0018] FIG. 13 is a side perspective view of a photovoltaic module
installed on a support structure, according to an embodiment.
[0019] FIG. 14 is a side perspective view of photovoltaic modules
installed on support structures, according to an embodiment.
DETAILED DESCRIPTION
[0020] It is noted that, for purposes of illustrative clarity,
certain elements in the drawings may not be drawn to scale.
Specific instances of an item may be referred to by use of a
numeral in parentheses (e.g., photovoltaic module 102(1)) while
numerals without parentheses refer to any such item (e.g.,
photovoltaic module 102). In the present disclosure disclosure,
"cm" refers to centimeters, "m" refers to meters, "A" refers to
amperes, "mA" refers to miliamperes, and "V" refers to volts.
[0021] FIG. 1 is a top plan view of one solar power generation
system 100 for generating electricity from light (e.g., sunlight).
Solar power generation system 100 includes a plurality of
photovoltaic modules 102. Photovoltaic modules 102 are electrically
interconnected; however the electrical connections are not shown in
FIG. 1 in order to promote illustrative clarity.
[0022] Photovoltaic modules 102 are manufacturable in various sizes
to accommodate the size of an installation site as well as
obstructions 104 such as roof vents and skylights. In the example
illustrated in FIG. 1, photovoltaic modules 102(1)-102(5) are full
length, while photovoltaic modules 102(6)-102(10) are reduced
length in order to accommodate obstructions 104.
[0023] Photovoltaic modules 102 may be manufactured with a desired
open circuit output voltage to match the designated system voltage
for a planned installation, thereby obviating any need for series
interconnections between photovoltaic modules 102. For example,
each of photovoltaic modules 102 may have the same open circuit
output voltage and may be connected in parallel. Furthermore, a
desired maximum current capability of solar power generation system
100 may be achieved by combining photovoltaic modules 102 in
parallel.
[0024] Each photovoltaic modules 102 includes one or more
photovoltaic submodules. An example of such photovoltaic submodule
is shown in FIG. 2, which is a top plan view of one photovoltaic
submodule 200. Photovoltaic submodule 200 has a flexible web
substrate 202 that is, for example, a metal foil such as stainless
steel or a polyimide sheet material. Accordingly, photovoltaic
submodules 200 are flexible, and photovoltaic module 102 may also
be flexible.
[0025] A plurality of photovoltaic cells 204 are disposed on and
defined by monolithic integration on substrate 202, and thereby
occupy a portion of submodule area 206. Photovoltaic cells 204 are
thin-film devices that are sequentially deposited by a variety of
means to achieve desired electrical and mechanical properties. Cell
dimensions are defined by monolithic integration which includes
patterning by mechanical, chemical etch, laser, and/or direct write
means that also define a series of electrical interconnects.
[0026] Photovoltaic cells 204 are defined, for example, by creating
a plurality of scribes and electrical connections in a stack of
thin-film layers. The stack of thin-film layers includes, for
example, a back contact layer formed on substrate 202, a solar
absorber layer formed on the back contact layer, a window layer
formed on the solar absorber layer, and a top contact layer formed
on the solar absorber layer. The solar absorber layer includes, for
example, one of copper-indium-gallium-selenium (CIGS),
copper-indium-gallium-selenium-sulfur (CIGSS),
copper-indium-aluminum-selenium (CIAS),
copper-indium-gallium-aluminum-selenium (CIGAS),
copper-indium-gallium-aluminum-selenium-sulphur (CIGASS),
cadmium-telluride (CdTe), polycrystalline silicon, and amorphous
silicon (a-Si) or combinations thereof. As described herein below,
cell type (e.g., solar absorber material) may govern or affect
length, quantity, and electrical characteristics of photovoltaic
cells 204 and photovoltaic submodule 200.
[0027] The number of photovoltaic cells 204 of photovoltaic
submodule 200 is for example determined by a web width 208 and a
minimum or maximum desired cell breadth 210 when cells are scribed
along a web transport direction, indicated by arrow 212, or by the
length of the web along web transport direction 212 in the event
cells are patterned perpendicular to the web length. The cell
breadth 210 varies according to photovoltaic cell manufacturing
technique and/or design, which may also affect the open circuit
output voltage and maximum current generated by each photovoltaic
cell 204. A maximum quantity of photovoltaic cells 204 may be
limited by minimum per-cell active area requirements which
constrain the minimum surface area of photovoltaic cells 204. The
breadth 210 of photovoltaic cells 204 may likewise be constrained
by conductivity limitations of thin films conductors that are part
of the photovoltaic cells. For example, if the electrical
conductivity of the connecting films is low, the films may
dissipate power generated by photovoltaic cells 204--in such case,
it may be desirable to reduce the breadth of photovoltaic cells 204
to reduce maximum current output, reduce the current path distance
from the top of one cell to the bottom of the adjacent cell, and
thus minimize power loss in connections between photovoltaic cells
204.
[0028] Thin-film photovoltaic cells 204 may be formed on or with
substrate 202 by deposition, printing, or other continuous web,
roll-to-roll, processing techniques. Photovoltaic cells 204 are,
for example, deposited or printed parallel to web transport
direction 212.
[0029] The current generated by a photovoltaic cell 204 depends in
part on the photovoltaic material in the photovoltaic cell and the
material's current density, and thus, the total area of the cell.
Where cell breadth 210 is fixed, current density of the cell
material may be considered and cell width 214 adjusted to produce
desired current-generating characteristics. In one example, cell
breadth 210 is 0.4 cm, and the current density of photovoltaic cell
204 is 30 mA/cm.sup.2. Assuming a desired current output of 10 A,
the required area of each cell 204 in the series string is 333
cm.sup.2. Based on the given cell breadth 210 of 0.4 cm, cell width
214 is 833 cm. In another example, cell breadth 210 is 0.4 cm, and
the current density of photovoltaic cell 204 is 30 mA/cm.sup.2.
Assuming a desired current output of 5 A, the required area of each
photovoltaic cell 204 is 167 cm.sup.2. Based upon the given 0.4 cm
breadth 210, the cell width 214 is 417 cm. In this example,
although the 5 A photovoltaic cell is half the length of the 10 A
cell, both photovoltaic cells produce approximately the same output
voltage.
[0030] The quantity of series connected photovoltaic cells 204 in
photovoltaic submodule 200 is determinable during manufacture,
e.g., by inputting specifications into a computer controlled
roll-to-roll continuous web processing system to determine the open
circuit output voltage generated by photovoltaic submodule 200.
Open circuit output voltage ratings of photovoltaic submodules 200
are therefore customizable to meet specifications of an
installation site and/or for compliance with building codes. For a
given photovoltaic submodule/module width, the open circuit output
voltage produced by photovoltaic module 102 is dictated by the
number of photovoltaic cells that are electrically connected in
series--such series connection of photovoltaic cells may be
referred to as a string of photovoltaic cells. Module open circuit
output voltage realistically ranges, for example, from a minimum of
7 V to as high as 1,000 V according to application, associated
codes, and design requirements. Thus, embodiments of photovoltaic
modules 102 may have a significantly higher open circuit output
voltage than prior art photovoltaic modules. Accordingly, such
embodiments may be referred to as high voltage photovoltaic
modules.
[0031] Each photovoltaic submodule 200 may be an independent,
monolithically-integrated thin-film photovoltaic device with
multiple photovoltaic cells 204. Photovoltaic submodule 200 is, for
example, structurally separate from adjacent submodules or other
structures. In one embodiment, each photovoltaic cell 204 is 0.4
centimeters in breadth 210 and generates an open circuit output
voltage of 0.5 V. Flexible web substrate 202 has a web width 208,
for example, of one meter. Web width 208 and cell breadth 210
permit, for example, 240 cells across the web (in the direction of
web width 208), providing an open circuit output voltage of 120 V
across photovoltaic submodule 200.
[0032] In one embodiment, a plurality of photovoltaic submodules
200 are monolithically integrated on a continuous web substrate 202
to form photovoltaic module 102. Each photovoltaic submodule 200
has, for example, 120 photovoltaic cells 204, such that the
photovoltaic submodule produces an open circuit output voltage of
60 V. Adjacent photovoltaic submodules 200 are connected in series
or in parallel such that photovoltaic module 102 has a desired open
circuit output voltage. The quantity of photovoltaic submodules 200
may be determined by overall output requirements for photovoltaic
module 102; for example, if a 600 V open circuit output voltage
photovoltaic module is desired, five 120 V photovoltaic submodules
200 are monolithically integrated and interconnected in series on
one continuous flexible web substrate 202. Various numbers of
photovoltaic submodules 200 per module 102, as well as numbers
photovoltaic cells 204 per photovoltaic submodule, may be used to
achieve the same approximate open circuit output voltage and
maximum current capability for a given surface area of photovoltaic
module 102. The configuration of submodule 200 may be determined by
considering factors such as the available area for placement of the
submodule, how configuration affects cost and speed of fabricating
the submodule, and how configuration affects the submodule's
reliability. It should be noted that the magnitude of current
required to be generated by submodule 200 also affects the
configuration of submodule 200 because the maximum current
generated by a string of series-connected photovoltaic cells 204 is
equal to the smallest current produced by a single photovoltaic
cell 204 in the string. Thus, to maximize the efficiency of
photovoltaic submodule 200, each photovoltaic cell 204 is, for
example, designed to produce the same current.
[0033] Each photovoltaic module 102 of solar power generation
system 100, has for example, the same open circuit output voltage.
Accordingly, in such example, photovoltaic modules 102 are combined
in parallel, with each module and its adjacent modules being
connected by a single parallel connection. Photovoltaic module
102's size may be modified, as described above, without changing
the desired open circuit output voltage. A complete solar power
generation system (e.g., system 100) may include custom-sized
photovoltaic modules to fit around, for example, rooftop
obstructions or to better contour to irregular areas of the roof,
thereby optimizing the available space on the roof. Installation of
solar power generation system 100 is greatly simplified, as
photovoltaic modules 202 require only parallel connection to one
another, as opposed to parallel and series connections required by
conventional solar power devices.
[0034] FIG. 3 is a top plan view of one flexible photovoltaic
module 300, which is an embodiment of photovoltaic module 102 of
FIG. 1. Photovoltaic module 300 is formed on a continuous flexible
web substrate 302. Photovoltaic module 300 is a thin-film
photovoltaic module including at least one
monolithically-integrated photovoltaic submodule 304. Monolithic
integration utilizes a process by which mechanical, chemical etch,
laser and/or direct write means are employed to define individual
photovoltaic cells and electrically interconnect adjacent
photovoltaic cells to create a submodule (e.g., submodule 304).
Each monolithically integrated photovoltaic module includes a
plurality of thin-film photovoltaic submodule monolithically
integrated on the common substrate.
[0035] Each photovoltaic submodule 304 includes a plurality of
photovoltaic cells 312. The photovoltaic cells 312 are formed, for
example, by creating a plurality of scribes and electrical
connections in a stack of thin film layers. The stack of thin film
layers may include at least one back contact layer, at least one
solar absorber layer formed on the back contact layer, at least one
window layer formed on the solar absorber layer, and a top contact
layer formed on the window layer.
[0036] In the example of FIG. 3, five photovoltaic submodules 304
are interconnected in series by electrically conductive flexible
bus bars 306 within photovoltaic module 300. However, bus bars 306
may electrically connect to each other and to photovoltaic
submodules 304 to create series or parallel electrical connections
between photovoltaic submodules 304, as desired. Each photovoltaic
submodule 304 is monolithically integrated in this example with the
same polarity where all submodules 304 have either the same
positive or negative terminals on the same side. The approach
afforded by bus bar 306 contacting the top contact of one submodule
to the bottom contact of the adjacent submodule 304 provides a
series interconnect between the two submodules, thereby adding the
voltage of the submodules. Photovoltaic module 300 also has two
output terminals 308 and 310. As described above with respect to
FIGS. 1 and 2, output (e.g., open circuit output voltage and
maximum current capability) of photovoltaic module 300 may be
customized during manufacture, e.g., by altering submodule 304's
cell interconnections or interconnections of photovoltaic cells 312
within submodule 304.
[0037] As discussed above, a photovoltaic module (e.g.,
photovoltaic module 102, 300) may be optimized by adjusting the
quantity and/or size of the module's constituent photovoltaic
cells. Additionally, it is possible to provide photovoltaic
submodules with scribing cells perpendicular to those shown above
(i.e., perpendicular to the web transport direction) but still on
the same common substrate. The relative direction of scribing is,
for example, dictated by the manufacturing equipment used to
manufacture the photovoltaic modules/submodules. FIG. 4 is a top
plan view of one flexible photovoltaic module 400, which is an
embodiment of photovoltaic module 102 of FIG. 1. Photovoltaic
module 400 has photovoltaic cells 402 disposed perpendicularly to
the web transport direction, indicated by arrow 404. Photovoltaic
cells 402 may formed, for example, by a monolithic integration
process including creating a plurality of scribes and electrical
connections in a stack of thin-film layers formed on a substrate.
In such example, the stack of thin-film layers may include a back
contact layer formed on the substrate, a solar absorber layer
formed on the back contact layer, a window layer formed on the
solar absorber layer, and a top contact layer formed on the window
layer.
[0038] Photovoltaic submodules 406, 408, 410, 412, 414, and 416
are, for example, monolithically integrated onto a common
substrate. The photovoltaic submodules are electrically connected
in series and/or parallel to produce desired output characteristics
(i.e., open circuit output voltage and maximum current capability)
at bus bars 418 and 420. Bus bars 422 connect photovoltaic
submodules 406, 408, 410, 412, 414 and 416 to each other and to bus
bars 418 and 420. In particular, FIG. 4 depicts pairs of adjacent
photovoltaic submodules across web width 424; however, a single
submodule or three or more submodules may span web width 424. In
one embodiment, photovoltaic submodule 406 is connected in series
with photovoltaic submodule 412 by bus bar 422, as are photovoltaic
submodules 408, 414, and photovoltaic submodules 410,416,
respectively. Thus, the top submodules (406, 408, 410) are of
opposite polarity than the bottom submodules (412, 414, 416) to
permit series interconnection. These photovoltaic submodule pairs
are then connected in parallel by bus bars 418 and 420.
[0039] The same open circuit output voltage may be established
regardless of photovoltaic module size, where the maximum size may
be substantially larger than those used in today's prior art
modules. One approach to maintaining a common open circuit output
voltage across a plurality of photovoltaic modules having different
sizes is to vary the size of the photovoltaic module's constituent
submodules while maintaining the same quantity of cells and
consequently, open circuit output voltage in each photovoltaic
submodule. FIG. 5 is a top plan view of two flexible photovoltaic
modules 500 and 502. Photovoltaic module 500 includes five
photovoltaic submodules 504, each including a plurality of
photovoltaic cells (not shown). Photovoltaic submodules 504, are
for example, monolithically integrated on a common substrate.
Photovoltaic module 500 has width 508 of 1 m (39.4 inches) and a
length 510 of 41.7 m (137.7 feet). Each photovoltaic submodule 504
has a width 512 of 8.3 m (27.4 feet).
[0040] In photovoltaic module 500, the five photovoltaic submodules
504 each generate a maximum output current of 10 A and an open
circuit output voltage of 120 V. Each of the photovoltaic
submodules 504 are electrically connected in series such that
photovoltaic module 500 has a maximum current capability of 10 A
and an open circuit output voltage of 600 V.
[0041] Photovoltaic module 502 has five series-connected
photovoltaic submodules 506, each including a plurality of
photovoltaic cells (not shown). Photovoltaic submodules 506, are
for example, monolithically integrated on a common substrate. Each
photovoltaic submodule 506 has a maximum current capability of 5 A
and an open circuit output voltage of 120 V. Accordingly,
photovoltaic module 502 has a maximum current capability of 5 A and
an open circuit output voltage of 600 V. Photovoltaic module 502
has a width 516 of 1 m (39.4 inches) and a length 514 of 21 m (69
feet).
[0042] Photovoltaic modules 500 and 502 may in turn be connected in
parallel to form a complete or partial system for solar power
generation (e.g., an embodiment system 100). Series connections
between photovoltaic modules 500 and 502 are advantageously not
required because of the relatively high open circuit output voltage
of photovoltaic modules 500 and 502. Table 1 below shows
characteristics of an embodiment of photovoltaic module 500;
similarly, Table 2 below shows characteristics of an embodiment of
photovoltaic module 502. It is assumed that current produced, and
hence power output, of module 500 is approximately twice that of
502. TABLE-US-00001 TABLE 1 Module open circuit output voltage 600
V Photovoltaic cell open circuit output voltage 0.5 V Photovoltaic
cell current density at maximum power 30 ma/cm.sup.2 Photovoltaic
cell breadth 0.4 cm Web (substrate) width 1 m Quantity of
photovoltaic cells per string 240 cells/string Photovoltaic cell
length .about.8.3 m
[0043] TABLE-US-00002 TABLE 2 Module open circuit output voltage
600 V Photovoltaic cell open circuit output voltage 0.5 V
Photovoltaic cell current density at maximum power 30 ma/cm.sup.2
Photovoltaic cell breadth 0.4 cm Web width 1 m Quantity of cells
per string 240 cells/string Photovoltaic cell length .about.4.2
m
[0044] The available width on a web for a photovoltaic module may
allow for a large quantity of photovoltaic cells to be connected in
series, thereby allow the photovoltaic module to have a high open
circuit output voltage. However, such large quantity of
photovoltaic cells may be result in the photovoltaic module having
a larger open circuit output voltage than desired. In such case,
the desired open circuit output voltage may be obtained by
decreasing the quantity of photovoltaic cells, such as by
increasing the width of each photovoltaic cell.
[0045] FIG. 6 is a top plan view of three flexible photovoltaic
modules 600, 602 and 604. Each photovoltaic module's open circuit
output voltage may be customized during manufacturing, e.g., by
including a larger or smaller quantity of photovoltaic cells in the
photovoltaic submodule. Each photovoltaic module is illustrated in
FIG. 6 as including a plurality of photovoltaic cells. However, it
should be noted that only a fraction of the photovoltaic cells of
each photovoltaic module are shown in FIG. 6 in order to promote
illustrate clarity.
[0046] Photovoltaic module 600 has five photovoltaic submodules
608, all monolithically integrated on a common substrate, each with
240 series-connected photovoltaic cells 606. Accordingly, each
photovoltaic submodule 608 has an open circuit output voltage of
120 V. The photovoltaic submodules 608 are connected in series to
provide an open circuit output voltage of 600 V between leads 610
and 612.
[0047] Photovoltaic module 602 includes five photovoltaic
submodules 614, each with 120 photovoltaic cells 626 connected in
series, producing 60 V open circuit output voltage per submodule.
Photovoltaic submodules 614 are, for example, monolithically
integrated on a common substrate. Photovoltaic submodules 614 are
connected in series to provide an open circuit output voltage of
300 V between leads 616 and 618. Photovoltaic module 604 has five
photovoltaic submodules 620, with 60 series-connected photovoltaic
cells 628 per submodule. Photovoltaic submodules 620 are, for
example, monolithically integrated on a common substrate.
Photovoltaic submodules 620 each produce an open circuit output
voltage of 30 V. The photovoltaic submodules 620 are connected in
series to provide an open circuit output voltage of 150 V between
leads 622 and 624.
[0048] As described herein above, a photovoltaic module's output
characteristics (i.e., open circuit output voltage and maximum
current capability) are set during manufacture, not only by
changing the quantity of photovoltaic cells per submodule as
illustrated in FIG. 6, but also by changing the quantity of
photovoltaic submodules per module. FIG. 7 is a top plan view of
three photovoltaic modules 700, 702 and 704, each having
photovoltaic submodules 706, 712, and 718, respectively.
Photovoltaic submodules 706, 712, and 718 have an equivalent open
circuit output voltage; however, the maximum current capability of
photovoltaic modules 700, 702 and 704 varies due to variation in
the quantity of photovoltaic submodules per photovoltaic
module.
[0049] Photovoltaic module 700 has five photovoltaic submodules
706, all monolithically integrated on a common substrate, each
producing an open circuit output voltage of 120 V. Photovoltaic
submodules 706 are electrically connected in series to produce an
open circuit output voltage of 600 V between module leads 708 and
710. Photovoltaic module 702 has four photovoltaic submodules 712
each producing an open circuit output voltage 120 V; photovoltaic
submodules 712 are, for example, monolithically integrated on a
common substrate. Photovoltaic submodules 712 are connected in
series to produce an open circuit output voltage of 480 V between
module leads 714 and 716. Photovoltaic module 704 has three
photovoltaic submodules 718, each producing an open circuit output
voltage of 120 V; photovoltaic submodules 718 are, for example,
monolithically integrated on a common substrate. Photovoltaic
submodules 718 are connected in series to produce an open circuit
output voltage 360 V between leads 720 and 722. The quantity of
photovoltaic submodules per module (or photovoltaic cells per
submodule) may be altered according to design preference and/or
power requirements.
[0050] FIG. 8 is a top plan view of three flexible photovoltaic
modules 800, 804 and 808, each having the same open circuit output
voltage and maximum current rating. Photovoltaic module 800 has of
a plurality of photovoltaic submodules 802 formed on separate,
narrow web substrates. Photovoltaic submodules 802 are physically
connected (e.g., via adhesives to common support materials) and
electrically connected (e.g., via wiring or snap-in connections) to
form photovoltaic module 800. In this example, groups of four of
photovoltaic submodules 802 are connected in series to form an
assembly 812 having a desired maximum voltage rating, and five
assemblies 812 are then connected in parallel to achieve a desired
open circuit output current. Embodiments of photovoltaic module 800
may be suitable for early-stage small web width manufacturing, or
in applications where substrate web width is limited.
[0051] Photovoltaic module 804 has of a plurality of photovoltaic
submodules 806, each of which is formed on a substrate having a
larger web width than the substrate used to form photovoltaic
submodules 802 of photovoltaic module 800. As with photovoltaic
module 800, each photovoltaic submodule 806 is supported by a
separate substrate. However, it may not be necessary to
electrically connect photovoltaic submodules 806 in parallel within
photovoltaic module 804 because photovoltaic modules 806 have a
relatively large surface area, and therefore have a relatively
large maximum current capability. Photovoltaic submodules 806 are
physically connected together and are, for example, electrically
connected in series.
[0052] Photovoltaic module 808 has of a plurality of photovoltaic
submodules 810 formed on a single wide web substrate. Photovoltaic
submodules 810 are, for example, monolithically integrated on the
substrate. The polarity of each photovoltaic submodule 810 is
alternated during the monolithic integration process to accommodate
a serpentine interconnect scheme between adjacent photovoltaic
submodules 810, or can maintain the same polarity with an
interconnect running from the top of one submodule 810 to the
bottom of the adjacent submodule. Photovoltaic submodules 810 are
shown as being partially delineated by dashed lines in FIG. 8 in
order to emphasize that the submodules are monolithically
integrated on a common substrate, but each are electrically
independent until they are interconnected as described above.
[0053] FIG. 9 is a top plan view of four flexible photovoltaic
modules 900, 902, 904, and 906, each including a plurality of
photovoltaic cells monolithically integrated onto common
substrates. The monolithic integration scribes of photovoltaic
modules 900, 902, 904, and 906 are oriented substantially parallel
to the direction of web transport, as illustrated by arrow 908.
However, orientation of the scribes with respect to the web
transport direction may change in order to optimize photovoltaic
modules 900, 902, 904, and/or 906 for cost, reliability, and
manufacturing throughput.
[0054] Each of photovoltaic modules 900, 902, 904, and 906 includes
at least two electrical conductors, as discussed below. Such
electrical conductors are, for example, conductive ink deposited
during a monolithic integration process and/or metallic bus
bars.
[0055] In photovoltaic module 900, photovoltaic cells 910 are
electrically connected in series such that current flows from
conductor 912 to conductor 914 in the direction indicated by the
arrow in photovoltaic module 900. The open circuit output voltage
of photovoltaic module 900 is the sum of the open circuit output
voltage of each photovoltaic cell 910. Although photovoltaic module
900 is shown as having 29 photovoltaic cells 910 in order to
promote illustrative clarity, photovoltaic module 900 will commonly
have a different quantity of photovoltaic cells (e.g., many more
than 29 photovoltaic cells 910).
[0056] Photovoltaic module 902 has a plurality of photovoltaic
submodules 920 electrically connected in parallel by conductors 924
and 926. Photovoltaic module 902 has, for example, five
photovoltaic submodules 920(1), 920(2), 920(3), 920(4), and 920(5)
as illustrated in FIG. 9. Although each photovoltaic submodule 920
is illustrated as including five photovoltaic cells 922 in order to
promote illustrative clarity, each photovoltaic submodule may have
a different quantity of photovoltaic cells 922 (e.g., significantly
more than five photovoltaic cells 922). Electric current flows from
conductor 924, through the photovoltaic submodules 920 as indicated
by their respective arrows, and to conductor 926.
[0057] Photovoltaic module 904 has a plurality of sets of
photovoltaic submodules electrically connected in parallel. Each
set of photovoltaic submodules includes two photovoltaic submodules
electrically connected in series. For example, one photovoltaic
submodule in a set 938 includes photovoltaic cells 930(1) and the
other photovoltaic submodule in set 938 includes photovoltaic cells
930(2). Photovoltaic module 904, for example, has five sets of
photovoltaic submodules electrically connected in parallel.
Electric current flows from conductor 932 through the photovoltaic
submodules as indicated by the arrows therein, through conductors
936, and out of conductor 934.
[0058] Similar to photovoltaic module 904, photovoltaic module 906
has a plurality of sets of photovoltaic submodules electrically
connected in parallel. Each set of photovoltaic submodules includes
two photovoltaic submodules electrically connected in series by an
electrical conductor 946. For example, one photovoltaic submodule
includes photovoltaic cells 940(1), and another photovoltaic
submodule includes photovoltaic cells 940(2)--each of these two of
photovoltaic submodules are electrically connected by a conductor
946. Photovoltaic submodule 906 may, for example, include ten
photovoltaic submodules. Although each photovoltaic submodule is
illustrated as including five photovoltaic cells, each photovoltaic
submodule may have a different quantity of photovoltaic cells and
would likely have many more than five photovoltaic cells. Electric
current flows from conductor 942, through the photovoltaic
submodules as indicated by their respective arrows, conductors 946,
and to conductor 944.
[0059] FIG. 10 is an exploded side perspective view of a
photovoltaic module 1000. Photovoltaic module 1000 is, for example,
a hermetically sealed laminate with integrated conductive bus bars
1002 for directing current and voltage to integrated leads 1004(1)
and 1004(2). One lead 1004(1) serves to provide a connection to the
positive node of photovoltaic module 1000; the other lead 1004(2)
serves to provide a connection to the negative node (e.g., ground
node) of photovoltaic module 1000. Module 1000 has a backplane
layer 1006 supporting a pottant layer 1008, a photovoltaic
submodule assembly 1010, bus bars 1002, leads 1004(1) and 1004(2),
a second pottant layer 1012, and an upper laminate 1014.
[0060] Backplane layer 1006 is strong, flexible, and resistant to
thermal and environmental damage, and may be made from any suitably
flexible material, such as stainless steel foil, plastic, or a
polymer. Backplane layer 1006 protects photovoltaic submodule 1000
from thermal and environmental stress and may include or provide a
connection to a fastener for attaching photovoltaic module 1000 to
a support structure. Exemplary fasteners include, but are not
limited to, an adhesive, a tape, one or more screws, nails, straps
or snaps, and Velcro.
[0061] Pottant layer 1008 overlies backplane layer 1006 and
supports photovoltaic submodule assembly 1010. Pottant layer 1008
and a second pottant layer 1012 form an airtight seal around
photovoltaic submodule assembly 1010 to prevent air from being
trapped near active devices (e.g., submodules or photovoltaic
cells). Pottant layer 1012 is optically transparent to allow light
to reach active devices of photovoltaic submodule assembly 1010.
Pottant layers 1008, 1012 may be sticky or tacky, to facilitate
adhesion of module backplane layer 1006 to pottant 1008 and upper
laminate 1014 to pottant layer 1012.
[0062] In one embodiment of photovoltaic module 1000, pottant
layers 1008 and 1012 are formed of ethylene vinyl acetate (EVA) or
polyvinyl butyral (PVB) and are applied as sheets or sprayed onto
photovoltaic submodule assembly 1010. In such embodiment, backplane
1006 and upper laminate 1014 are subsequently pressed or laminated
to the pottant layers. In another embodiment of photovoltaic module
1000, pottant layers 1008 and 1012 are protective laminates applied
to photovoltaic submodule assembly 1010.
[0063] Additives may be combined with the pottant layer material to
increase cut, puncture, or abrasion resistance of the pottant
layers. Additives may likewise be incorporated into the pottant
layer material to change its aesthetic appearance, to increase its
sealing properties, or to enhance overall photovoltaic module 1000
stability and/or performance.
[0064] Optionally, layers of additive may be sandwiched between
pottant layers on either side of photovoltaic submodule assembly
1010. For example, FIG. 11 shows an exploded side view of a
flexible photovoltaic module 1100, which is similar to photovoltaic
module 1000 with the exception that photovoltaic module 1100
contains additive layers and additional pottant layers.
Photovoltaic module 1100 includes four pottant sublayers and two
additive layers. Pottant sublayer 1102 is formed on backplane layer
1006, additive layer 1104 is formed on pottant sublayer 1102, and
pottant sublayer 1106 is formed on additive layer 1104.
Additionally, pottant sublayer 1108 is formed on photovoltaic
submodule assembly 1010, additive layer 1110 is formed on pottant
sublayer 1108, and pottant sublayer 1112 is formed on additive
layer 1110.
[0065] Returning to FIG. 10, upper laminate 1014 protects
photovoltaic module 1000 from wear and tear as well as
environmental stresses such as weather, ultraviolet radiation,
dirt, and debris. Upper laminate 1014 may be a suitable polymer,
plastic, or other optically transparent, protective material. Upper
laminate 1014 may be applied by lamination or spraying. In one
embodiment, upper laminate 1014 is an outer surface of the second
pottant layer 1012.
[0066] Photovoltaic submodule assembly 1010 includes a plurality of
thin-film, monolithically-integrated photovoltaic cells, as
described herein above. Photovoltaic submodule assembly 1010 has,
for example, submodules like submodule 200 or submodules like those
of one of photovoltaic modules 300, 400, 500, 502, 600, 602, 604,
700, 702, 704, 800, 804, 808, 900, 902, 904, and 906 discussed
above. In one embodiment, photovoltaic submodule assembly 1010 is a
solar "blanket" with five or fewer monolithically integrated,
interconnected CIGS cell photovoltaic submodules. The photovoltaic
submodules are connected in series or in parallel such that
photovoltaic module 1000 has a desired maximum current capability
and open circuit output voltage. The open circuit output voltage
will be the sum of the open circuit output voltage of each
photovoltaic cell and/or photovoltaic submodule electrically
connected in series. For example, photovoltaic module 1000 may
include five photovoltaic submodules electrically connected in
series. If each photovoltaic submodule has an open circuit output
voltage of 120 V, photovoltaic module 1000 has an open circuit
output voltage of 600 V.
[0067] Bus bars 1002 and leads 1004 may extend from module 1000 for
connection to harnesses containing flexible conductors (e.g.,
conductors 1208 in FIG. 12 below). Such harnesses are for example
seamed to photovoltaic module 1000. In one embodiment, flexible
conductors (e.g., conductors 1208) are incorporated into
photovoltaic module 1000 (with electrical connection points), for
example by extending backplane and top laminate width to account
for such conductors.
[0068] The size and shape of photovoltaic module 1000 may be
modified by computer-aided design to fit the needs of a specific
installation site while maintaining appropriate electrical
characteristics for a given photovoltaic module. In an embodiment,
a roof is measured and an array of photovoltaic modules 1000 is
designed for maximum coverage of the roof. Photovoltaic modules
1000 are manufactured in a variety of custom sizes (e.g., fitted to
optimally surround any obstructions), for example using laser
patterning. Where the roof is free from obstructions, photovoltaic
modules may be manufactured as long as permitted by the maximum
current for each photovoltaic module, e.g., approximately one
hundred and fifty feet when limiting module current to 10 amps.
Embodiments of photovoltaic modules 1000 may rolled up for easy
transportation and placement (unrolling) at an installation site
(e.g., a roof).
[0069] As an example, consider an installation site consisting of a
roof with a length of 150 feet. The roof includes the following
obstructions: (a) two five feet wide vents, each located 20 feet
from opposite ends of the roof, and (b) an eight feet wide skylight
centered between the two vents. Four photovoltaic modules 1000 may
be formed to optimally cover the roof. Two of such photovoltaic
modules have a length of twenty feet, and two of the photovoltaic
modules have a width of 46 feet. Although such photovoltaic modules
have varying lengths, they each have the same open circuit output
voltage allowing them to be electrically connected in parallel.
[0070] FIG. 12 is a side perspective view of a solar power
generation system 1200. Solar power generation system 1200 includes
a plurality of photovoltaic modules 1201, which are, for example,
one or more of the photovoltaic modules discussed above.
Photovoltaic modules 1201 are installed on supports 1202. Supports
1202 are, for example, formed of foam, metal, wood, and/or other
suitable building material. Supports may be solid, partially
filled, and/or frames. Photovoltaic modules 1201 attach to supports
1202 with adhesives, screws, staples, Velcro, zip lock and/or other
fasteners. Photovoltaic modules 1201 are electrically connected in
parallel by control boxes 1204, wiring harnesses 1206 containing
multiple flexible conductors 1208 (shown without shielding, for
clarity), and by harness ground strap or ground jumper 1210 with
molded ground connector 1212. Ground connector 1212, for example,
snaps into ground jumper 1210, and harness 1206 fits, or is trimmed
to fit, control box 1204.
[0071] Control box 1204 houses or supports the following: (a) a
current limiting device such as a fuse, (b) a switch for
disconnecting a respective photovoltaic module, (c) two connection
blocks for connecting wiring harnesses 1206, and (d) a selector
switch for selecting a flexible conductor for connection to the
control box's respective photovoltaic module 1201. Interconnected
photovoltaic modules 1201 are electrically connected to
distribution box 1214, which connects to an inverter, for
example.
[0072] FIG. 13 is a side perspective view of a photovoltaic module
1300 installed on a support structure 1302. Photovoltaic module
1300 is mounted on support structure 1302, which is formed of an
aluminum frame. Photovoltaic module 1300 is electrically connected
to control box 1304, which is mounted to support structure
1300.
[0073] FIG. 14 is a side perspective view of photovoltaic modules
1406(1) and 1406(2) installed on respective support structures
1408(1) and 1408(2). Support structures 1408 are foam wedges.
Photovoltaic module 1406(1) is electrically connected to control
box 1410, and photovoltaic module 1406(2) is also electrically
connected to control box 1410 (and thereby to photovoltaic module
1406(1)) via a wiring harnesses 1412(2). Photovoltaic module
1406(1) includes wiring harness 1412(1) connecting photovoltaic
module 1406(1) to junction box 1414, which interfaces photovoltaic
modules 1406(1) and 1406(2) to an additional system (e.g., a load
consisting of an inverter).
[0074] In one embodiment, harnesses 1412 contain multiple flexible
conductors and include shielding to protect against abrasion,
puncture or other damage. Wiring harness 1412(1) of photovoltaic
module 1406(1), for example, snaps, slides, or plugs into a lead of
wiring harness 1412(2) of photovoltaic module 1406(2), or vice
versa.
[0075] Control box 1410 serves as connection point--that is,
control box 1410 facilitates connection of photovoltaic module
1406(1) to 1406(2). Control box 1410 may also serve to perform
other functions, such as to providing a means to electrically
disconnect photovoltaic module 1406(1) from wiring harnesses
1412(1) and 1412(2).
[0076] Since certain changes may be made in the above apparatus,
systems and methods without departing from the scope hereof, it is
intended that all matter contained in the above description or
shown in the accompanying drawings be interpreted as illustrative
and not in a limiting sense. It is also to be understood that the
following claims are to cover certain generic and specific features
described herein.
* * * * *