U.S. patent application number 15/139364 was filed with the patent office on 2016-08-18 for process for encapsulating a solar cell in a polymer matrix.
The applicant listed for this patent is SolarWorld Innovations GmbH. Invention is credited to Matthias Georgi, Harald Hahn.
Application Number | 20160240712 15/139364 |
Document ID | / |
Family ID | 48985018 |
Filed Date | 2016-08-18 |
United States Patent
Application |
20160240712 |
Kind Code |
A1 |
Hahn; Harald ; et
al. |
August 18, 2016 |
PROCESS FOR ENCAPSULATING A SOLAR CELL IN A POLYMER MATRIX
Abstract
The present invention relates to a process for encapsulating one
or more solar cell(s) in a polymer matrix, said process comprising:
(a) applying a matrix composition comprising at least one
polymerizable compound to the surface of a first solid carrier
material, the matrix composition being a structurally viscous
liquid having a yield point; (b) placing the one or more solar
cell(s) onto the matrix composition applied to the surface of the
first carrier material; (c) applying the matrix composition to the
surface of the solar cell; (d) placing a second solid carrier
material onto the matrix composition applied to the surface of the
solar cell; (e) pressing the structure composed of solar cell,
matrix composition, and first and second carrier materials, such
that the one or more solar cell(s) is/are surrounded by a
continuous layer of matrix composition; and (f) polymerizing the
matrix composition in order to form the polymer matrix, and to the
use of this process for producing solar modules and to the solar
modules obtainable by means of this process.
Inventors: |
Hahn; Harald; (Dresden,
DE) ; Georgi; Matthias; (Dresden, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SolarWorld Innovations GmbH |
Freiberg |
|
DE |
|
|
Family ID: |
48985018 |
Appl. No.: |
15/139364 |
Filed: |
April 27, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13781787 |
Mar 1, 2013 |
9356180 |
|
|
15139364 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08L 75/04 20130101;
Y02P 70/521 20151101; H01L 31/048 20130101; Y02P 70/50 20151101;
H02S 30/10 20141201; H01L 31/1876 20130101; Y02E 10/50
20130101 |
International
Class: |
H01L 31/048 20060101
H01L031/048; H01L 31/18 20060101 H01L031/18; H02S 30/10 20060101
H02S030/10 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 1, 2012 |
DE |
10 2012 101 710.7 |
Claims
1. A process for producing a solar module, comprising: a. applying
a matrix composition comprising at least one polymerizable compound
to a surface of a first solid carrier material, b. placing one or
more solar cell(s) onto the matrix composition applied to the
surface of the first carrier material; c. applying the matrix
composition to the surface of the one or more solar cell(s); d.
placing one or more spacers with projections disposed between the
first and a second carrier material, such that a first distance
between the first and second carrier materials is maintained at
least at the edge of the structure composed of solar cell, matrix
composition, and first and second carrier materials; e. placing the
second solid carrier material onto the matrix composition applied
to the surface of the one or more solar cell(s); f. pressing the
structure composed of solar cell(s), matrix composition, and first
and second carrier materials, such that the one or more solar
cell(s) is/are surrounded by a layer of matrix composition and a
second distance is achieved between the first and second carrier
materials; and g. polymerizing the matrix composition in order to
form a polymer matrix encapsulating the one or more solar
cell(s).
2. The process of claim 1, wherein the second distance is smaller
than the first distance.
3. The process of claim 1, wherein the one or more spacers are
formed from at least one first element and at least one second
element joined to the first element, the first element engaging
with an assembly formed from solar cell(s), polymer matrix, first
carrier material and second carrier material so as to form the
first distance between first and second carrier materials, and the
second element being arranged such that it at least partly overlaps
an outer edge of the assembly.
4. The process of claim 1, wherein the one or more spacers further
comprise at least one positional protruding element which aligns
and holds a position of the second carrier material prior to
pressing, and maintains the position of the second carrier material
after pressing.
5. The process of claim 1, wherein the one or more spacers have a
first geometry configured to provide the first distance between the
first and second carrier materials prior to pressing, and wherein
the first geometry is configured to transform into a second
geometry to provide the second distance between the first and
second carrier materials after pressing.
6. The process of claim 1, wherein the matrix composition is
structurally viscous and imparts a yield point thereto prior
polymerization.
7. A solar module, comprising: a. a first transparent solid carrier
material; b. a second solid carrier material; c. a polymer matrix
between the first and the second solid carrier materials; d. one or
more solar cell(s) encapsulated within the polymer matrix; and e. a
frame profile extending along one edge of the first and the second
solid carrier materials with one or more spacers with projections
disposed between the first and the second solid carrier
materials.
8. The solar module of claim 7, wherein the frame profile provides
a cavity for excess of polymer matrix material.
9. The solar module of claim 7, wherein the spacer projections are
discontinuing and separated from each other, wherein two separated
spacer projections form a channel for excess flow of polymer matrix
material into the frame profile cavity.
10. The solar module of claim 7, wherein at least one spacer
projection comprises an undercut configured to prevent the frame
profile from slipping off the first and second solid carrier
materials during lamination.
11. The solar module of claim 7, wherein the spacer projections are
collapsed from a first position into a second position, wherein the
second position maintains a smaller distance between the first and
the second solid carrier materials than the first position.
12. The solar module of claim 7, wherein the one or more spacers
are formed from at least one first element and at least one second
element joined to the first element, the first element engaging
with an assembly formed from solar cell(s), polymer matrix, first
carrier material and second carrier material so as to form a first
distance between first and second carrier materials, and the second
element being arranged such that it at least partly overlaps an
outer edge of the assembly.
13. The solar module of claim 7, wherein the one or more spacers
have a first geometry configured to provide a first distance
between the first and second carrier materials prior to pressing,
wherein the first geometry is configured to transform into a second
geometry to provide a second distance between the first and second
carrier materials after pressing.
14. The solar module of claim 7, wherein the polymer matrix
comprises at least one polymerizable compound and is produced by
curing a matrix composition, wherein the matrix composition had
been a structurally viscous liquid having a yield point prior to
polymerization.
15. The solar module of claim 7, wherein at least one spacer
comprises a positional protruding element which is elastically
biased to secure the first and second carrier materials at a second
position from a first position, wherein the second position
maintains a smaller distance between the first and second carrier
materials than the first position.
16. The solar module of claim 7, wherein the projections maintain a
separation between the one or more solar cells and both the first
and second carrier materials.
17. The solar cell module of claim 7, wherein the spacers are
arranged in at least one corner of the solar module.
18. The solar cell module of claim 7, wherein the spacers are
arranged in at least part of one side of the solar module.
19. The solar cell module of claim 7, wherein the spacers are
arranged in at least two sides of the solar module.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This is a continuation of application Ser. No. 13/781,787,
filed on Mar. 1, 2013, which claims priority to German Patent
Application Serial No. 10 2012 101 710.7, which was filed on Mar.
1, 2012, all of which are hereby incorporated herein by reference
in their entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to a process for encapsulating
one or more solar cell(s) in a polymer matrix, wherein the matrix
composition used is a structurally viscous liquid which comprises a
polymerizable compound for forming the matrix and has a yield
point, and to the thus obtainable solar modules.
BACKGROUND
[0003] The solar cells present in conventional solar modules are
typically embedded in a polymer material in order to protect them
from environmental influences. The embedded solar cells are usually
disposed between an upper glass layer and a backside layer,
consisting of glass (double glass modules) or of a sealing film
(glass-film modules). The material for embedding the solar cells is
typically ethylene-vinyl acetate (EVA), which is used in the form
of a film. Overall, customary polymers used for embedding of solar
cells (EVA, PVB, polyolefins) have only low UV stability and have
to be protected from the harmful effects of UV radiation by means
of UV absorber substances. As a result, however, some of the light
(up to 3%) is lost unutilized. More particularly, for novel cell
concepts such as selective emitter cells, it is essential to be
able to better exploit this component of light than is possible
with conventional embedding materials.
[0004] There exist only a few inherently UV-stable polymers which
do not need these protective absorbers. One example of such
inherently UV-stable polymers are silicones. Three-dimensionally
crosslinked silicone elastomers additionally have very good
thermomechanical properties which make them suitable for the
encapsulation of solar cells. For instance, the glass transition
point is below -40.degree. C. and they generally exhibit a small
change in the mechanical properties with temperature.
[0005] However, these materials can be processed only in liquid
form, more particularly as addition-crosslinking 2-component
materials (liquid encapsulation). This involves bonding the two
components, by means of an added catalyst, permanently to give a
rubber-elastic polymer. The necessity of processing these materials
in liquid form, however, complicates the use thereof in solar
module construction, especially for mass production. A known liquid
encapsulation process with liquid silicone is performed with an
exceptionally slow-curing 2K system, by securing the cell matrix
vertically between two glass plates, sealing the edges of the layup
and slowly introducing the silicone from the bottom. However, this
process is unsuitable for automated mass production with high
throughput.
[0006] Other processes make use of horizontal encapsulation
techniques, but these are problematic particularly with regard to
the demands on the encapsulation material used. For example, DE 20
2010 005555 U1 describes a solar module and a production apparatus,
wherein the solar module is produced with a bonding material for
embedding of solar-active elements, which replaces the conventional
EVA films. The bonding material described may have a pasty or
liquid consistency and be cured after embedding. Examples mentioned
for a suitable bonding material are silicone or silicone-containing
compounds. DE 20 2010 005555 U1, however, does not mention the
disadvantages and difficulties associated with the use of such
liquid or pasty materials, nor does it disclose strategies by which
these can be overcome.
[0007] There is therefore still a need for improved liquid
encapsulation processes which partially or completely overcome the
known disadvantages.
SUMMARY OF THE INVENTION
[0008] In a first aspect, the present invention therefore relates
to a process for encapsulating one or more solar cell(s) in a
polymer matrix, said process comprising: [0009] (a) applying a
matrix composition comprising at least one polymerizable compound
to the surface of a first solid carrier material, the matrix
composition being a structurally viscous liquid having a yield
point; [0010] (b) placing the one or more solar cell(s) onto the
matrix composition applied to the surface of the first carrier
material; [0011] (c) applying the matrix composition to the surface
of the solar cell; [0012] (d) placing a second solid carrier
material onto the matrix composition applied to the surface of the
solar cell; [0013] (e) pressing the structure composed of solar
cell, matrix composition, and first and second carrier materials,
such that the one or more solar cell(s) is/are surrounded by a
continuous layer of matrix composition; and [0014] (f) polymerizing
the matrix composition in order to form the polymer matrix.
[0015] The process can be used for production of a solar cell. The
process can be used in automated form and in mass production.
[0016] In a further aspect, the invention relates to the use of a
matrix composition which comprises at least one polymerizable
compound and is in the form of a structurally viscous liquid having
a yield point for encapsulation of a solar cell.
[0017] In yet a further aspect, the invention likewise relates to a
solar module obtainable by the process according to the
invention.
[0018] In yet another aspect, the invention relates to a solar
module comprising [0019] (a) a first solid carrier material; [0020]
(b) a second solid carrier material; and [0021] (c) one or more
solar cell(s) encapsulated in a polymer matrix and arranged between
the first carrier material and the second carrier material, wherein
the polymer matrix is produced by curing a matrix composition which
comprises at least one polymerizable compound and is a structurally
viscous liquid having a yield point.
[0022] Finally, the invention, in yet a further aspect, relates to
a solar module comprising [0023] (a) a first solid carrier
material; [0024] (b) a second solid carrier material; [0025] (c)
one or more solar cell(s) encapsulated in a polymer matrix and
arranged between the first carrier material and the second carrier
material; and [0026] (d) one or more spacers formed from at least
one first element and at least one second element joined to the
first element, the first element engaging with an assembly formed
from solar cell(s), polymer matrix, first carrier material and
second carrier material so as to form a defined distance between
first and second carrier materials, and the at least one second
element being arranged such that it at least partly overlaps an
outer edge of the assembly.
DESCRIPTION OF THE FIGURES
[0027] FIG. 1 shows a schematic of the cross section of the layup
in the different phases of the process according to the invention.
(A) Matrix composition (102) applied to a first carrier material
(101). (B) First carrier material (101) and matrix composition
(102) with solar cells (103) placed on. (C) First carrier material
(101) and solar cells (103) with applied matrix composition (102).
(D) First carrier material (101), matrix composition (102) and
solar cells (103) with second solid carrier material (104) placed
on. (E) The complete layup after pressing.
[0028] FIG. 2 shows a schematic of the scatter of incident light
(205) at particles of the thickener in the matrix composition
(202). Likewise shown are first carrier material (201), solar cells
(203) and conductor tracks (204).
[0029] FIG. 3 shows a schematic of a top view of the first carrier
material (301) with matrix composition applied in various
forms/various patterns (302).
[0030] FIG. 4 shows a schematic of two alternative options for the
pressing. (A) shows the pressing of the layup composed of first
carrier material (401), matrix composition (402), solar cells (403)
and backside film (404a) by means of a roller (405). (B) shows the
pressing of the layup composed of first carrier material (401),
matrix composition (402), solar cells (403) and backside glass
(404b) by virtue of the weight of the backside glass itself.
[0031] FIG. 5 shows a schematic of the cross section through the
layup composed of first carrier material (501), matrix composition
(502), solar cells (503), backside material (504) and edge
protection frame (505) before and after pressing.
[0032] FIG. 6 shows a schematic of the cross section through the
layup composed of first carrier material (601), matrix composition
(602), solar cells (603), backside material (604) and edge
protection frame (605) before and after pressing, the backside
material (604) being placed on the latching elements (605a) of the
edge protection frame (605) and then being moved over the latching
position by the pressing.
[0033] FIG. 7 shows a schematic of the cross section through the
layup composed of first carrier material (701), matrix composition
(702), solar cells (703), backside material (704) and spacers (705)
before and after pressing. The spacers (705) shown have a U-shaped
profile and are deformed in the course of pressing such that the
two projections (705a) come into contact with one another.
[0034] FIG. 8 shows (A) a schematic of the cross section through
the layup composed of first carrier material (801), matrix
composition (802), solar cells (803), backside material (804) and
edge protection frame (805) with projections (805a) before and
after pressing, and (B) a schematic of various suitable projection
forms in top view.
DETAILED DESCRIPTION OF THE INVENTION
[0035] The present invention is based on the finding that the
rheological properties of the base polymers used for embedding can
be altered such that the problems which occur in the processing of
medium-viscosity, free-flowing materials can be avoided.
[0036] In a first aspect, the present invention therefore relates
to a process for encapsulating one or more solar cell(s) in a
polymer matrix. This involves applying a matrix composition
comprising at least one polymerizable compound to the surface of a
first solid carrier material. The matrix composition from which the
polymer matrix forms through polymerization is a liquid composition
which is structurally viscous and has a yield point.
[0037] "Polymer matrix" as used herein relates to a solid material
which comprises polymers and into which the solar cells are
embedded. The polymer matrix material may be elastic or inelastic
in the fully cured state.
[0038] "Structural viscosity", as used herein interchangeably with
"pseudoplasticity" or "shear thinning", relates to the property of
non-newtonian liquids that exhibit a decrease in viscosity with
increasing shear force.
[0039] "Yield point" as used herein relates to the property of a
liquid or dispersion to exhibit severe restriction of flow at low
shear levels, which prevents flow, this restriction of flow only
being eliminated under the action of a force exceeding the yield
point.
[0040] In the process according to the invention, after the
application of the matrix composition to a solid substrate, i.e.
the first solid carrier material, for example a front glass, one or
more solar cell(s) is/are placed onto the matrix composition. The
placing-on is effected in such a way that there is at least some
matrix composition between solar cell(s) and carrier material so
that the solar cell(s) do(es) not come into direct contact with the
carrier material.
[0041] In a next step, matrix composition is then applied to the
surface of the solar cell, and then a second solid carrier
material, for example a backside film or a backside glass, is
placed onto the matrix composition. The placing-on is again
effected in such a way that there is at least some matrix
composition between solar cell(s) and second carrier material ao
that there is no direct contact between solar cell(s) and carrier
material.
[0042] The dimensions of the carrier materials are typically such
that they project beyond the one or more solar cells on all sides
and thus allow complete encapsulation of the solar cells.
[0043] After these steps have formed the layup consisting of first
carrier material, matrix composition, solar cell(s), matrix
composition and second carrier material, the layup structure is
pressed. The pressing is effected in such a way that the matrix
composition flows and forms a layer which surrounds the one or more
solar cell(s) and is free of air inclusions. "Pressing" thus means
herein that first and second carrier materials are pressed
together, thus forming a continuous layer of matrix composition
which encapsulates the solar cells. The pressure used in the
pressing is selected such that the force applied to the matrix
composition is above the yield point of the matrix composition and
therefore leads to flow of the matrix composition. This makes it
possible to form a polymer layer completely surrounding the solar
cells.
[0044] The matrix composition can be cured in order to form the
polymer matrix during any step in the process. For example, the
polymerization may already be initiated with the production of the
matrix composition. Such a procedure requires, depending on the
time required for the complete polymerization, correspondingly
rapid processing of the matrix composition. Alternatively, the
polymerization can also be initiated during the pressing or
thereafter. Curing may for example be effected by heating the layup
structure.
[0045] An illustrative embodiment of the various steps of the
process according to the invention is shown schematically in FIG.
1. FIG. 1A shows a schematic of a cross section through the first
solid carrier substrate (101) after application of the matrix
composition (102). The application can, as shown by way of example
in FIG. 3, be effected in various patterns or shapes. Both the size
and shape of the component area of the surface to which the
composition is applied and the distance between and the arrangement
of the component areas with matrix composition with respect to one
another can be varied. The selection of suitable application forms
and patterns can be made according to the process utilized for
pressing. FIG. 1B shows a cross section through the layup after the
solar cells (103) have been placed on. FIG. 1C shows a cross
section through the layup after the matrix composition (102) has
been applied to the solar cells (103). FIG. 1D shows a cross
section through the layup after the second solid carrier material
(104) has been placed on. FIG. 1E shows a cross section through the
layup after pressing.
[0046] In various embodiments of the process according to the
invention, the matrix composition comprises at least two, at least
three or more polymerizable compounds.
[0047] "At least one", "at least two", "at least three" etc., as
used herein, means, respectively, one or more, two or more and
three or more, and includes 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or
more.
[0048] The polymerizable compounds present in the matrix
composition may be any known synthetic or natural polymerizable
compound. The terms "polymerisable" and "curable" as well as
"polymerize" and "cure" are used interchangeably herein. More
particularly, these compounds may be monomers of the desired
polymers or prepolymers. If prepolymers are involved, these may
consist of one kind of monomer or of two or more different kinds of
monomers. The polymers formed from the polymerizable compounds may
be linear or branched polymers. The polymer in the polymer matrix
may, for example, be one or more of the polymers from the group
consisting of silicone rubbers, including fluorosilicones,
polyurethanes, poly(meth)acrylates and epoxy resins, or mixtures
thereof. Accordingly, the polymerizable compounds present in the
matrix composition may be precursors of these polymers, for example
silanes, siloxanes, silane-modified polymers, polyesters,
polyurethane resins (polyols, polyisocyanates), especially
aliphatic polyurethane resins, (meth)acrylates and epoxides. The
polymer of the polymer matrix may likewise comprise copolymers and
mixtures of the polymers mentioned.
[0049] In one embodiment of the invention, the at least one
polymerizable compound is a 2-component silicone, preferably an
addition-crosslinking 2-component silicone. In an
addition-crosslinking 2-component silicone, both silicone polymers
having free silane groups and silicone polymers having free vinyl
groups are present, both kinds of silicone prepolymer having a
relatively low viscosity, and these being free-flowing and
pumpable. Both kinds of prepolymer react in an addition reaction in
the presence of a noble metal catalyst to give the desired silicone
rubber.
[0050] Suitable polymerizable compounds or compositions are, for
example, the polyorganosiloxanes described in international patent
publication WO 2011/107592. Further patent specifications which
describe suitable polymerizable materials are U.S. Pat. No.
4,056,405, U.S. Pat. No. 4,093,473, U.S. Pat. No. 4,143,949, U.S.
Pat. No. 4,167,644 and WO 2005/006451. Suitable
addition-crosslinking polyorganosiloxanes are also described in
U.S. Pat. No. 3,699,072, U.S. Pat. No. 3,892,707, U.S. Pat. No.
4,077,943, U.S. Pat. No. 4,082,726, U.S. Pat. No. 4,087,585, U.S.
Pat. No. 4,245,079, U.S. Pat. No. 4,257,936, U.S. Pat. No.
4,677,161, U.S. Pat. No. 4,701,503, U.S. Pat. No. 4,721,764, U.S.
Pat. No. 4,912,188, U.S. Pat. No. 5,051,467, U.S. Pat. No.
5,106,933, U.S. Pat. No. 5,312,855, U.S. Pat. No. 5,364,921, U.S.
Pat. No. 5,438,094, U.S. Pat. No. 5,516,823, U.S. Pat. No.
5,536,803, U.S. Pat. No. 6,743,515, U.S. Pat. No. 7,119,159, U.S.
Pat. No. 7,288,322, US20030236380, US20050089696 and
WO2008103227.
[0051] If the matrix composition does not already have the desired
structural viscosity and yield point by virtue of the selection of
the polymerizable compound, this can be established by the addition
of thickeners to the matrix composition. The thickeners are those
suitable for production of structurally viscous liquids. In various
embodiments of the invention, the matrix composition therefore
comprises at least one thickener. This may be present in a
concentration which makes the matrix composition structurally
viscous and imparts a yield point thereto. The thickener may have a
refractive index similar to that of the polymer of the polymer
matrix. The refractive index may, for example, have a value within
the range of .+-.25% of the refractive index of the polymer.
[0052] As shown schematically in FIG. 2, the thickener in the
embedding material (202) can act as a light-scattering centre.
However, this is uncritical to a certain degree since light
scattering takes place principally in forward direction onto the
solar cell (203), and the much smaller scattered light components
in backward direction are additionally captured again to a certain
degree by total reflection at the surface of the front material
(201). An additional effect of the light scattering is that light
falls at an oblique angle on reflective structures, for example
cell connectors (204), and can then likewise be captured again.
This effect generates additional module power and compensates for
the losses caused by backward scattering.
[0053] In one embodiment of the invention, the thickener comprises
fumed silica. Examples of suitable silicas are the silicas
available under the Aerosil.RTM. brand name, including Aerosil 200
or Aerosil 300. The thickener particles preferably do not have a
hydrophobic coating. The thickener is typically used in solid form,
and the particles have mean diameters of 1 .mu.m or less,
preferably of about 200 nm. The particle size distribution is
preferably essentially monodisperse.
[0054] In various embodiments of the invention, the matrix
composition at room temperature (20.degree. C.) and standard
pressure (1000 mbar) has a dynamic zero viscosity .eta..sub.0 of at
least 10.sup.3 mPas, preferably at least 10.sup.4 mPas, even more
preferably at least 10.sup.5 mPas, most preferably at least
10.sup.6 mPas.
[0055] The yield point .tau..sub.0 of the matrix composition, in
various embodiments of the invention, is at least 30 Pa, preferably
at least 50 Pa, even more preferably at least 100 Pa, most
preferably at least 150 Pa.
[0056] In the process according to the invention, the
polymerization (curing) of the matrix composition can be effected
by heating, UV irradiation, addition of a catalyst or
polymerization initiator, or by mixing two compounds spontaneously
polymerizable with one another. If the polymerization is effected
by adding a catalyst or polymerization initiator to the matrix
composition, this can be added to the matrix composition as early
as prior to the application step, in order to initiate the
polymerization. The process for encapsulation including the
pressing is preferably already complete prior to complete
polymerization. Alternatively, the polymerization can also be
initiated by mixing two compounds spontaneously polymerizable with
one another, optionally with an additional catalyst or
polymerization initiator, in the matrix composition. This
initiation of polymerization can likewise be performed prior to the
application step. If a matrix composition with an already initiated
polymerization reaction is used in the process according to the
invention, the time which is required for complete polymerization
or for a degree of polymerization which increases the viscosity to
such an extent that the composition no longer has suitable
rheological properties is such that processability of the
composition in the process according to the invention is ensured.
For example, the period for complete polymerization or for a degree
of polymerization which increases the viscosity to such an extent
that the composition no longer has rheological properties suitable
for processing in the process, in various embodiments of the
invention, may be up to 24 h, up to 18 h, up to 12 h, up to 6 h, up
to 4 h, up to 3 h, up to 2 h, up to 1 h, preferably up to 30
minutes, up to 20 minutes, or up to 10 minutes, more preferably
about 5 minutes.
[0057] If the polymerization is performed by means of heating or UV
irradiation, the polymerization is preferably not initiated until
the pressing step or thereafter. For example, the heating can be
effected together with the pressing in a suitable laminator. If the
polymerization is effected by heating, the initiation temperature
is preferably at least 50.degree. C., preferably at least
100.degree. C.
[0058] In various embodiments of the invention, the first solid
carrier material is a transparent front material. The material may
be any front material customarily used, including but not limited
to glass or polycarbonate.
[0059] The second solid carrier material may be a backside
material. The backside material may, for example, be glass or a
polymer film. The backside material need not be transparent. In
various embodiments, the backside material is glass. The backside
material may preferably be transparent to UV and/or light, and as a
result allows the curing of the polymerizable compound through
irradiation with UV or visible light through the backside
layer.
[0060] In various embodiments, the second solid carrier material
may have orifices which allow excess amounts of matrix composition
to flow out in the course of pressing. The orifices may take the
form, for example, of spots or strips.
[0061] In order to ensure the formation of encapsulation free of
air inclusions, the matrix composition is preferably applied
locally to at least two spaced-apart component areas of the surface
of the first solid carrier material and/or of the one or more solar
cell(s). The application can be effected, for example, in the form
of spots, strips or beads. Typically, the application is effected
to at least five, at least 10, at least 20 or more component areas
of the surface and/or of the solar cell. The amount applied is such
that the pressing can form a continuous layer around the solar
cells, such that the solar cells are in direct contact neither with
one another nor with the carrier materials. Examples of application
forms and patterns are shown in FIG. 3.
[0062] In various embodiments, the matrix composition is applied in
such a way that air inclusions are avoided in the course of
pressing. In other words, the application pattern of the matrix
composition is selected according to the way in which the pressing
is conducted such that the air present between carrier materials
and solar cells can be removed and no air inclusions are
formed.
[0063] In various embodiments, the process comprises an evacuation
step. This step is intended to prevent the formation of air
inclusions between carrier materials and solar cells, i.e. in the
matrix composition. The evacuation is preferably performed prior to
or in the course of pressing, i.e. at a time when the layup
structure has been formed from solar cell, matrix composition, and
first and second carrier materials. The evacuation can be effected,
for example, by applying a vacuum.
[0064] The pressing step can be effected in different ways commonly
known in the prior art. More particularly, the pressing can be
effected in a laminator, for example a laminator as typically used
for production of solar modules. Alternatively, the layup can also
be performed under a roller, preferably a flexible roller. If such
a roller is used, the second carrier material is preferably a
flexible backside film. Pressing with a roller is shown
schematically in FIG. 4A. This involves pressing the layup composed
of first carrier material (401), matrix composition (402) which has
preferably been applied in bead form parallel to or at a sharp
angle with respect to the roller axis, solar cells (403) and
backside material (404) by means of a roller (405).
[0065] Finally, the pressing can also be effected by the placing-on
of the second carrier material and through its own weight. In this
case, the carrier material can be placed on in bent form, in such a
way that it is first placed on centrally and then laid down toward
the edges. The second carrier material here is preferably composed
of glass. This principle is shown schematically in FIG. 4B. In this
case, the backside material (404) in bent form is placed onto the
layup composed of first carrier material (401), matrix composition
(402) and solar cells (403), and the layup is pressed by the weight
of the backside material itself.
[0066] Possibilities and apparatuses for pressing of the layup,
especially in horizontal alignment, are disclosed, for example,
also in the above-cited utility model specification DE 20 2010
005555 U1.
[0067] In the processes according to the invention, it is possible
to use one or more spacers which engage with the layup composed of
solar cells, matrix composition and carrier materials in such a way
that a defined distance is maintained between first carrier
material and second carrier material in the course of pressing. In
various embodiments, the spacers are formed from at least one first
element and at least one second element joined to the first
element, the first element engaging with the layup and ensuring the
distance between first and second carrier materials, and the second
element being arranged such that it at least partly overlaps the
outer edge of the layup.
[0068] In various embodiments, one spacer in each case may have a
plurality of first elements spaced apart from one another and
joined to a second element. The distance between the individual
first elements may be from 1 mm up to 10 or more cm. The first
elements may be of any desired shape, though they typically have an
essentially rectangular cross section and the thickness thereof
together with the compressibility thereof defines the distance
between the first and second carrier materials. Suitable shapes are
rectangular, triangular, semicircular and the like. The individual
first elements joined to a single second element may independently
be joined to the second element in such a way that they are either
essentially vertical with respect thereto, meaning that the spacer
has a T-shaped profile, or point alternately upward or downward in
a plane, meaning that the first elements are arranged in a V-shaped
cross section. In the latter case, the joint is preferably
configured so as to be movable, such that the individual first
elements are arranged essentially horizontally with respect to the
carrier materials in one plane in the course of pressing.
Illustrative arrangements are shown in the figures.
[0069] The spacers may also be configured so as to be
compressible.
[0070] The first elements typically engage with the layup for about
1 mm up to 5 cm.
[0071] In various embodiments, the second element likewise has an
essentially rectangular cross section. The width of thickness of
the pressed layup may be the same or else lower. The length may be
such that it corresponds to the length of an outer edge of the
module. The thickness is typically a few mm to cm.
[0072] In various embodiments, the spacers may be part of an edge
protection frame. This may simultaneously be adhesive-bonded to the
embedding material in the curing step. Such an edge protection
frame is advantageous especially in the case of solar modules in
which both the frontside material and the backside material is
glass. The advantages of using such an edge protection frame are
protection against slippage of the layup in the course of pressing,
and avoidance of excessive edge pressing or the escape of embedding
material. The edge protection frame may encompass all edges of the
solar module and consists typically of two or more parts. The edge
protection frame may lie on and/or be adhesive-bonded to the edge,
i.e. the cross-sectional face, of the layup.
[0073] The spacers form a defined distance between front- and
backside material and thus prevent damage to the solar cell in the
course of pressing. If they are integrated into an edge protection
frame, the spacers may either be arranged in the module corners or
over all or part of the frame length.
[0074] The edge protection frame/the spacers may consist of any
suitable material. Suitable materials are known in the prior art
and include, for example, aluminium, steel and polymers.
[0075] The use of an edge protection frame with a T-shaped profile
in the region of the spacers is shown schematically in FIG. 5. FIG.
5 shows the cross section through the layup before and after
pressing. This involves pressing the layup composed of first
carrier material (501), matrix composition (502), solar cells
(503), backside material (504) and edge protection frame (505).
[0076] Alternatively or additionally, the edges of the layup can be
sealed with polymer, for example butyl rubber.
[0077] The edge protection/spacer may additionally comprise
latching elements which allow the positioning of the backside
material prior to pressing. In the course of pressing, the backside
material is then pressed over the latching position and the
composite is produced. Such a principle is shown schematically in
FIG. 6. FIG. 6 shows the cross section through the layup in the
region of the spacers before and after pressing. The layup is
produced from first carrier material (601), matrix composition
(602), solar cells (603), backside material (604) and edge
protection frame (605) in such a way that the backside material
(604) is positioned on the latching elements (605a) of the edge
protection frame (605) and is then moved over the latching position
by the pressing.
[0078] As mentioned above, the spacers may be integrated in an edge
protection frame or used separately therefrom. Such a use of
separate spacers which can optionally be removed again is shown
schematically in FIG. 7. FIG. 7 shows the cross section through the
layup in the region of the spacers before and after pressing. The
layup is formed from first carrier material (701), matrix
composition (702), solar cells (703), backside material (704) and
spacers (705), and then pressed. The spacers (705) shown have a
U-shaped profile and are deformed in the course of pressing such
that the two projections (705a) move toward or come into contact
with one another. The resistance of the spacer prevents the layup
from excessive compression and ensures a sufficient distance
between front- and backside material (701, 704), which prevents
damage to the solar cells (703).
[0079] A further embodiment of spacers integrated into an edge
protection frame is shown schematically in FIG. 8A.
[0080] The edge protection frame has spaced-apart projections bent
alternately upward and downward, which engage with the layup and
are also pressed when the laminates are pressed on and prevent
excessive edge pressing. FIG. 8A shows the cross section through
the layup in the region of the spacers before and after pressing.
The layup is produced from first carrier material (801), matrix
composition (802), solar cells (803), backside material (804) and
edge protection frame (805) with projections (805a), in such a way
that, in the unpressed state, the projections of the edge
protection frame (805a) bent alternately upward and downward ensure
a distance between front (801) and backside material (804), which
is reduced by the pressing in such a way that a composite is
obtained. The projections may have various shapes. Examples of
suitable shapes are shown schematically in top view in FIG. 8B.
[0081] The invention further relates to solar modules which are
obtained by the processes according to the invention.
[0082] In yet another aspect, the invention is directed to a solar
module comprising [0083] (a) a first solid carrier material; [0084]
(b) a second solid carrier material; and [0085] (c) one or more
solar cell(s) encapsulated in a polymer matrix and arranged between
the first carrier material and the second carrier material, wherein
the polymer matrix is produced by curing a matrix composition which
comprises at least one polymerizable compound and is a structurally
viscous liquid having a yield point.
[0086] In one embodiment, the solar module further comprises one or
more spacers as defined above. These may, as defined above, also be
part of an edge protection frame.
[0087] Finally, the invention also covers solar modules comprising
[0088] (a) a first solid carrier material; [0089] (b) a second
solid carrier material; [0090] (c) one or more solar cell(s)
encapsulated in a polymer matrix and arranged between the first
carrier material and the second carrier material; and [0091] (d)
one or more spacers formed from at least one first element and at
least one second element joined to the first element, the first
element engaging with an assembly formed from solar cell(s),
polymer matrix, first carrier material and second carrier material
so as to form a defined distance between first and second carrier
materials, and the at least one second element being arranged such
that it at least partly overlaps an outer edge of the assembly. The
terms "carrier material" and "substrate" are used interchangeably
herein.
[0092] In various embodiments, the spacers are as defined above and
may also be part of an edge protection frame.
[0093] In the solar modules of the invention, carrier materials,
solar cells and matrix may be defined as described above in
connection with the processes according to the invention.
[0094] Further embodiments are present in the claims.
[0095] The invention is described herein by reference to particular
embodiments but it is not restricted thereto. More particularly, it
will be immediately apparent to the person skilled in the art that
various changes can be made to the invention described without
departing from the sense and scope of the invention as determined
by the appended claims. The scope of the invention is thus
determined by the claims, and the intention is that the invention
covers all modifications and changes covered by the range of
interpretation and equivalence of the claims.
* * * * *