JP2018133468A - Solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar cell module in which solar cell is rarely damaged or inter-connector is rarely broken even when temperature difference is generated.SOLUTION: A solar cell module 100 includes: a solar cell 10; a surface protection layer 20 which is formed of a resin and disposed at the light-receiving surface side of the solar cell 10; and a gel sealing layer 30 which is disposed between the solar cell 10 and the surface protection layer 20 and formed of acrylic gel with a storage modulus of 0.1 MPa or less, and a glass transition temperature of -30°C or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a solar cell module. Specifically, the present invention relates to a solar cell module using a resin surface protective layer.

  In recent years, photovoltaic power generation that converts light energy into electrical energy has attracted attention from the viewpoint of environmental protection. Conventionally, glass has been used as the surface protective layer of the solar cell module, but recently, in order to reduce the weight of the solar cell module, a resin such as polycarbonate has been used instead of glass.

  For example, Patent Document 1 describes a front sheet for a solar cell module in which the main component of a base material layer is polycarbonate. And by setting it as such a structure, the front sheet | seat for solar cell modules which is lightweight and has high impact resistance is implement | achieved.

  Moreover, in patent document 1, in order to protect a photovoltaic cell, the filler layer formed with the sealing material of synthetic resins, such as ethylene-vinyl acetate type-resin, is described.

JP 2013-145807 A

  However, in general, the linear expansion coefficient of resin is larger than that of glass, and the influence of thermal expansion and contraction due to temperature change is large. When the surface protective layer is thermally expanded and contracted, stress is applied to the filler layer that adheres to the surface protective layer. Therefore, the thermal stress of the surface protective layer and the filler layer tends to increase in proportion to the temperature difference generated in the solar cell module.

  And, when a large thermal stress is applied to the filler layer due to the temperature difference that occurs in the solar cell module, the solar cells in contact with the filler layer are damaged, or the interconnector that electrically connects the solar cells is cut There is a risk of doing so.

  The present invention has been made in view of such problems of the prior art. An object of the present invention is to provide a solar cell module in which damage to solar cells and disconnection of an interconnector are unlikely to occur when a temperature difference occurs.

  In order to solve the above-described problems, a solar cell module according to an aspect of the present invention includes a solar cell, a surface protective layer that is disposed on the light-receiving surface side of the solar cell and is formed of a resin, the solar cell, and the surface And a gel sealing layer formed of an acrylic gel having a storage elastic modulus of 0.1 MPa or less and a glass transition temperature of −30 ° C. or less.

  ADVANTAGE OF THE INVENTION According to this invention, when a temperature difference arises, the solar cell module which cannot damage a photovoltaic cell and a disconnection of an interconnector can be provided.

It is sectional drawing which shows an example of the solar cell module which concerns on this embodiment. It is a top view which shows an example of the solar cell module which concerns on this embodiment.

  Hereinafter, the solar cell module according to the present embodiment will be described in detail with reference to the drawings. In addition, the dimension ratio of drawing is exaggerated on account of description, and may differ from an actual ratio. Further, for the sake of convenience, the drawings are described using a rectangular coordinate system including an x-axis, a y-axis, and a z-axis, and the direction of each arrow is a positive direction. For convenience, a light source side such as sunlight is referred to as a light receiving surface side and a side opposite to the light receiving surface is referred to as a back surface side with respect to the solar cell module.

[Solar cell module 100]
FIG. 1 is a cross-sectional view showing an example of a solar cell module 100 according to this embodiment. As shown in FIG. 1, the solar battery module 100 of the present embodiment includes a solar battery cell 10, a surface protective layer 20, and a gel sealing layer 30. And the surface protective layer 20 is arrange | positioned at the light-receiving surface side of the photovoltaic cell 10, and is formed with resin.

  However, in general, the linear expansion coefficient of resin is larger than that of glass, and the influence of thermal expansion and contraction due to temperature change is large. When the resin substrate thermally expands and contracts, thermal stress is applied to the sealing material in conjunction with the surface protective layer 20.

  Therefore, in this embodiment, the gel sealing layer 30 is disposed between the solar battery cell 10 and the surface protective layer 20, and an acrylic gel having a storage elastic modulus of 0.1 MPa or less and a glass transition temperature of −30 ° C. or less. It is formed by. As a result, even if a temperature difference occurs in the solar cell module 100 and the surface protective layer 20 is thermally expanded and contracted, the thermal stress of the surface protective layer 20 is relaxed by the gel sealing layer 30.

  Therefore, according to the solar cell module 100 of this embodiment, even if the surface protective layer 20 is formed of resin, the solar cell 10 is not easily damaged or the interconnector 12 is not cut. In the following, these components will be described.

(Solar cell 10)
The solar battery cell 10 converts light energy into electric energy. Examples of the solar battery cell 10 include a silicon solar battery, a compound solar battery, and an organic solar battery. Examples of silicon solar cells include single crystal silicon solar cells, polycrystalline silicon solar cells, microcrystalline silicon solar cells, and amorphous silicon solar cells. Examples of compound solar cells include GaAs solar cells, CIS solar cells, CIGS solar cells, and CdTe solar cells. Examples of the organic solar cell include a dye-sensitized solar cell and an organic thin film solar cell. Further, as the solar battery cell 10, a heterojunction solar battery or a multijunction solar battery can be used.

  The solar battery cell 10 is not particularly limited, but includes a front surface portion that forms the light receiving surface side of the solar cell module 100, a back surface portion that faces the front surface portion, and a side surface portion that connects the end portions of the front surface portion and the back surface portion. Can be formed. Specifically, the shape of the solar battery cell 10 is not particularly limited, but may be a rectangular flat plate.

  Finger electrodes (not shown) can be arranged on the light receiving surface side and the back surface side of the solar battery cell 10. The finger electrode is formed by arranging a plurality of metal wires substantially in parallel. The finger electrode can have a height of 10 μm to 30 μm and a width of 100 μm to 500 μm, for example. The finger electrode collects current generated by light such as sunlight and supplies it to a bus bar electrode (not shown).

  The bus bar electrode is usually formed by two to three metal wires, and is arranged so as to intersect the finger electrode substantially perpendicularly. The bus bar electrode is not particularly limited, but can have a height of 10 μm to 30 μm and a width of 100 μm to 500 μm. The bus bar electrode supplies the current collected from the finger electrodes to the interconnector 12.

  In the embodiment of FIG. 1, the solar cell string 16 includes a plurality of solar cells 10 and an interconnector 12 that electrically connects the plurality of solar cells 10. The solar cell string 16 electrically connects the bus bar electrode provided on the light receiving surface side of one solar cell 10 and the bus bar electrode provided on the back surface side of the other solar cell 10 with an interconnector 12. It can form by connecting to.

  Resin or solder can be used for connection between the interconnector 12 and the bus bar electrode. This resin may be either conductive or non-conductive. In the case of a non-conductive resin, the interconnector 12 and the bus bar electrode are electrically connected by being directly connected.

  The interconnector 12 is not particularly limited as long as the solar cells 10 can be electrically connected to each other. For example, the interconnector 12 may be an interconnector 12 formed of an elongated foil-shaped metal substrate.

  It does not specifically limit as a material which forms a metal base material, Metals, such as gold | metal | money, silver, copper, platinum, aluminum, nickel, can be used. Among these, it is preferable that the material forming the metal substrate is copper from the viewpoints of workability, durability, and economy.

  The metal base material is preferably used by coating at least one metal selected from the group consisting of tin, lead, silver and gold, and alloys thereof. By forming such a coating layer on the metal substrate, the discoloration of the sealing material covering the periphery of the interconnector 12 is suppressed, and / or the light reflectance of the interconnector 12 itself is increased to increase the solar cell module 100. It is possible to improve the power generation efficiency.

  Although the thickness of a coating layer is not specifically limited, It is preferable that it is 5-40 micrometers. By setting the thickness of the coating layer in such a range, the reflectance of light on the surface of the metal substrate can be improved while suppressing the amount of the coating layer used.

  The width of the metal substrate is preferably 0.5 mm to 10 mm, and more preferably 1 mm to 3 mm. Moreover, it is preferable that it is 0.01 mm-3.0 mm, and, as for the thickness of a metal base material, it is more preferable that it is 0.05 mm-1.0 mm.

  FIG. 2 is a top view showing an example of the solar cell module 100 of the present embodiment. In the embodiment of FIG. 2, five solar cells 10 arranged side by side in the y-axis direction are electrically connected in series by an interconnector 12 to form one solar cell string 16.

  Moreover, the interconnector 12 can electrically connect two adjacent photovoltaic cell strings 16. In the embodiment of FIG. 2, the four solar cell strings 16 arranged in parallel in the x-axis direction are electrically connected in series by the interconnector 12. In addition, although an example was shown in FIG. 2, the number, arrangement | positioning, etc. of the photovoltaic cell 10 and the photovoltaic cell string 16 which are arrange | positioned at a photovoltaic module are not specifically limited.

(Surface protective layer 20)
The surface protective layer 20 is disposed on the light receiving surface side of the solar battery cell 10. And the surface protective layer 20 has a role which protects the surface of the solar cell module 100 from a foreign material etc. The shape of the surface protective layer 20 is not particularly limited, and may be a polygon such as a circle, an ellipse, or a rectangle depending on the application. Moreover, the cross-sectional shape of the surface protective layer 20 may be rectangular or may be curved in the stacking direction (z-axis direction) of each layer of the solar cell module 100.

  The surface protective layer 20 is formed of a resin. By forming the surface protective layer 20 with a resin instead of the conventionally used glass, the solar cell module 100 can be lightened. By reducing the weight of the solar cell module 100 as described above, it is possible to reduce a load applied to an installation part such as a roof to which the solar cell module 100 is attached, and it is possible to widen the application range of the solar cell module 100.

  The surface protective layer 20 is preferably translucent. Although not particularly limited, the total light transmittance of the surface protective layer 20 is preferably 80% to 100%, and more preferably 85% to 95%. By setting the total light transmittance of the surface protective layer 20 in such a range, light can efficiently reach the solar battery cell 10. The total light transmittance is measured by a method such as, for example, Japanese Industrial Standard JIS K7361-1: 1997 (ISO 13468-1: 1996) (Plastic-Test method for total light transmittance of transparent material-Part 1: Single beam method). Can be measured.

  Examples of the resin for forming the surface protective layer 20 include polycarbonate (PC), polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN), amorphous polyarylate, and polyacetal (POM). ), Polyether ketone (PEK), polyether ether ketone (PEEK), polyether sulfone, modified polyphenylene ether, and the like. Among these, it is preferable that the material which forms the surface protective layer 20 is a polycarbonate (PC) from a viewpoint of impact resistance and translucency.

  Although the thickness of the surface protective layer 20 is not specifically limited as long as it plays the role which protects the surface of the solar cell module 100, it is preferable that it is 0.1 mm-100 mm, and it is more preferable that it is 0.5 mm-50 mm. By setting the thickness of the surface protective layer 20 in such a range, the solar cell module 100 can be appropriately protected and light can efficiently reach the solar cells 10.

(Gel sealing layer 30)
The gel sealing layer 30 is disposed between the solar battery cell 10 and the surface protective layer 20. When the solar cell module 100 includes such a gel sealing layer 30, the solar cell 10 can be protected from external impacts and the like. The shape of the gel sealing layer 30 is not particularly limited as in the case of the surface protective layer 20, and may be a polygon such as a circle, an ellipse, or a rectangle depending on the application. Similarly to the surface protective layer 20, the gel sealing layer 30 may have a rectangular cross-sectional shape or may be curved in the stacking direction (z-axis direction) of each layer of the solar cell module 100.

  The gel sealing layer 30 is formed of an acrylic gel. The acrylic gel is less likely to discolor even after the solar cell module 100 has been operated for a long period of time, compared to urethane gel or the like. For this reason, it is possible to suppress a decrease in design properties accompanying discoloration of the gel sealing layer 30 and a decrease in power generation efficiency due to a decrease in total light transmittance. In addition, since the acrylic gel theoretically does not contain a siloxane component, when the siloxane is scattered to the outside air and adheres to the surface protective layer 20 like a silicone gel, the adhesion with other adjacent members is unlikely to decrease. preferable.

  The storage elastic modulus of the acrylic gel that forms the gel sealing layer 30 is 0.1 MPa or less. By setting the storage elastic modulus of the acrylic gel forming the gel sealing layer 30 in such a range, when the temperature difference occurs in the solar cell module 100, the thermal stress of the surface protective layer 20 is changed to the gel sealing layer 30. Can be effectively relieved.

  The storage elastic modulus can be obtained by measuring dynamic viscoelasticity using a rotary rheometer. The storage elastic modulus can be 0.1 MPa or less at 30 ° C., but is preferably 0.1 MPa or less in all regions in the range of −30 ° C. to 85 ° C.

The storage modulus is the real part of the complex modulus and is proportional to the maximum energy stored throughout the load cycle and represents the stiffness of the viscoelastic material. The complex elastic modulus is the ratio of the dynamic stress σ (t) to the dynamic strain ε (t) when sinusoidal vibration is applied to the viscoelastic material. The dynamic strain ε (t) is expressed by ε (t) = ε _A exp {i (2πft−δ)}, and the dynamic stress σ (t) is σ (t) = σ _A exp (i2πft). expressed. In the above equation, ε _A is the strain amplitude, σ _A is the stress amplitude, f is the frequency, t is time, and δ is the phase angle between the stress and strain.

  The glass transition temperature of the acrylic gel forming the gel sealing layer 30 is −30 ° C. or lower. By setting the glass transition temperature of the acrylic gel forming the gel sealing layer 30 in such a range, even when the solar cell module 100 is placed at a low temperature of −30 ° C. or less, surface protection is achieved. The thermal stress of the layer 20 can be effectively relieved by the gel sealing layer 30. Therefore, it becomes difficult to apply thermal stress directly to the solar battery cell 10 and the interconnector 12.

The glass transition temperature can be measured in accordance with the provisions of JIS K7121-1987 (plastic transition temperature measurement method). In the DSC curve obtained by differential scanning calorimetry (DSC), the glass transition temperature is directly equal to the vertical line from the extended straight line of each base line, and the curve of the step change portion of the glass transition. It can be the intermediate glass transition temperature (T _mg ) that intersects.

  The acrylic gel forming the gel sealing layer 30 is a resin obtained by polymerizing at least one (meth) acrylate. Here, (meth) acrylate means acrylate or (meth) acrylate.

  The (meth) acrylate has a monofunctional (meth) acrylate having one carbon-carbon unsaturated bond, a bifunctional (meth) acrylate having two carbon-carbon unsaturated bonds, and three carbon-carbon unsaturated bonds. Trifunctional (meth) acrylate and polyfunctional (meth) acrylate having 4 or more carbon-carbon unsaturated bonds are included. Among these, the (meth) acrylate is preferably at least one of monofunctional (meth) acrylate and bifunctional (meth) acrylate. This is because these (meth) acrylates do not have a relatively large cross-linking density even when polymerized, and therefore tend to improve the buffering effect of the acrylic gel. The (meth) acrylate is more preferably a monofunctional (meth) acrylate.

Monofunctional acrylate _is a compound represented by CH 2 = CH-COOR ^1, monofunctional _{methacrylate,} a compound represented by _{CH 2 = C (CH 3)} -COOR 2.

_That, CH 2 = CH-COOR ¹ and _CH 2 ₌ C (CH 3) acrylic gel obtained by polymerizing a monomer represented in -COOR ² is represented by each following chemical formula (1) and the following formula (2) It is preferable that the repeating unit is included.

R ¹ in the chemical formula (1) and R ² in the chemical formula (2) are particularly limited as long as the storage modulus of the acrylic gel obtained by polymerization is 0.1 MPa or less and the glass transition temperature is −30 ° C. or less. Not. R ¹ and R ² are each an organic group such as a saturated chain hydrocarbon group, an unsaturated chain hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, an ether group, an ester group, or an acyl group. Is mentioned. Some of these organic groups may be partially substituted with a substituent containing oxygen, nitrogen, sulfur, fluorine, chlorine, bromine, iodine, or the like.

  The acrylic gel is preferably a polymer of a monomer including at least one of a monofunctional (meth) acrylate having a branched alkyl group and a monofunctional (meth) acrylate having an alkylene oxide chain.

  An acrylic gel obtained by polymerizing a monofunctional (meth) acrylate having a branched alkyl group is difficult to crystallize even at low temperatures and has flexibility. Therefore, even when a temperature difference occurs in the solar battery module 100, it is preferable because damage to the solar battery cell 10 and disconnection of the interconnector 12 hardly occur.

Monofunctional (meth) acrylate having a branched alkyl group _is an acrylate ^{of R 2} in CH 2 = ^{R 1} or the ^{_{CH-COOR 1 CH 2 = C}} (CH 3) -COOR 2 is indicated by _C n _{H 2n + 1} It is preferable. That is, the acrylic gel preferably contains repeating units represented by the following chemical formula (3) and the following chemical formula (4), respectively.

  In the chemical formula (3) and the chemical formula (4), n is preferably 3-18. It is preferable to set the range of n to 3 or more because a desired storage elastic modulus and glass transition temperature can be easily obtained. Further, it is preferable that the range of n is 18 or less because steric hindrance in the molecule is alleviated and the reactivity of (meth) acrylate is improved. In the chemical formula (3) and the chemical formula (4), n is more preferably 4-8. Further, by using the acrylic gel in such a range, even when a temperature difference occurs in the solar cell module 100, the solar cell 10 is not easily damaged or the interconnector 12 is not cut.

Containing monofunctional branched alkyl group (meth) ^{_{acrylate, CH 2 = CH-COOR R}} 1 in ^one or _{CH 2 = C (CH 3)} R 2 is _CH 2 _-CH in _{^{-COOR 2 (C n H 2n +}} 1) it is preferably an acrylate represented by -C _m H _{2m + 1.} That is, the acrylic gel preferably includes repeating units represented by the following chemical formula (5) and the following chemical formula (6), respectively.

  In the above chemical formula (5) and chemical formula (6), n is preferably 0 to 18, and more preferably 3 to 10. In the chemical formula (5) and chemical formula (6), m is more preferably a value of n or less.

  Among these, a monofunctional (meth) acrylate having a branched alkyl group is 2-butyldecyl (meth) acrylate (n = 4 and m = 8 in the above chemical formula (5) and chemical formula (6)), 2- Hexyldecyl (meth) acrylate (in the above chemical formula (5) and chemical formula (6), n = 6 and m = 8) and 2-octyldecyl (meth) acrylate (in the above chemical formula (5) and chemical formula (6), n More preferably, the compound is at least one compound selected from the group consisting of = 8 and m = 8).

  In addition, an acrylic gel obtained by polymerizing a monofunctional (meth) acrylate having an alkylene oxide chain is preferable because it has good adhesion to a resin that forms another layer such as the surface protective layer 20.

Monofunctional (meth) acrylate having an alkylene oxide ^{_{chain, CH 2 = CH-COOR R}} 1 in ^one or _{CH 2 = C (CH 3)} R 2 is in the _{^{-COOR 2 (C n H 2n O}} ) m -CH 3 It is preferable that it is an acrylate shown by these. That is, the acrylic gel preferably contains repeating units represented by the following chemical formula (7) and the following chemical formula (8), respectively.

  In the above chemical formula (7) and chemical formula (8), n is preferably 2 to 4, and more preferably 2. That is, the alkylene oxide chain is preferably at least one of an ethylene oxide chain, a propylene oxide chain, and a tetramethylene oxide chain, and more preferably an ethylene oxide chain. This is because these alkylene oxide chains are excellent in curability.

  Moreover, in the said Chemical formula (7) and Chemical formula (8), it is preferable that m is 3-13, and it is more preferable that it is 3-10. That is, the monofunctional (meth) acrylate having an alkylene oxide chain preferably contains 3 to 13 repeating units of the alkylene oxide chain, more preferably 3 to 10. This is because by setting the repeating unit of the alkylene oxide chain in such a range, the storage elastic modulus of the acrylic gel can be lowered and the adhesion with other layers can be improved.

  The acrylic gel is preferably a polymer of monomers including a monofunctional (meth) acrylate having a branched alkyl group and a monofunctional (meth) acrylate having an alkylene oxide chain. That is, the acrylic gel is represented by at least one chemical formula selected from the group consisting of the chemical formula (3) to the chemical formula (6), and at least one of the chemical formula (7) and the chemical formula (8). It is preferable to include a repeating unit. The acrylic gel obtained by polymerizing these acrylates can effectively relieve the thermal stress of the surface protective layer 20 by the gel sealing layer 30 and improve the adhesion to other layers. It is because it can do. The monomer is preferably composed of a monofunctional (meth) acrylate having a branched alkyl group and a monofunctional (meth) acrylate having an alkylene oxide chain.

  The acrylic gel can be formed by polymerizing at least one or more (meth) acrylates described above, and a crosslinking agent and other additives can be added thereto.

  Although it does not specifically limit as a crosslinking agent, It is preferable to use the acrylic oligomer more than bifunctional. That is, the acrylic gel is preferably a polymer of the monomer and a bifunctional or higher functional acrylic oligomer. The acrylic oligomer is a polymer of a dimer or higher of (meth) acrylate, and the number average molecular weight can be less than 10,000. Bifunctional or higher acrylic oligomers include bifunctional (meth) acrylate oligomers having two carbon-carbon unsaturated bonds, trifunctional (meth) acrylate oligomers having three carbon-carbon unsaturated bonds, and carbon-carbon unsaturated bonds. A polyfunctional (meth) acrylate oligomer having 4 or more saturated bonds is included. By using a bifunctional or higher functional acrylic oligomer as a cross-linking agent, the acrylic gel has a cross-linking point, so that creep of the acrylic gel under high temperature can be suppressed, and the durability of the solar cell module 100 can be improved. .

  As described above, the acrylic gel is preferably a polymer of the monomer and a bifunctional or higher functional acrylic oligomer. And the total content of the monofunctional (meth) acrylate having a branched alkyl group and the monofunctional (meth) acrylate having an alkylene oxide chain is 30% by mass or more with respect to a total of 100% by mass of the monomer and the acrylic oligomer. Preferably there is. By setting it as such content, the thermal stress of the surface protective layer 20 can be effectively relieved by the gel sealing layer 30, and adhesiveness with other layers can be improved. is there. In addition, the total content of these monofunctional (meth) acrylates is more preferably 50% by mass or more, and further preferably 80% by mass or more.

  As other additives, a polymerization initiator, a viscosity modifier, a flame retardant, a dispersant, a colorant, an antioxidant, and the like can be added without departing from the scope of the present embodiment.

  The polymerization initiator may be a photopolymerization initiator or a thermal polymerization initiator. The photopolymerization initiator generates polymerization active species such as radicals, cations, and anions by light irradiation such as ultraviolet rays and electron beams, and initiates a polymerization reaction of monomers and oligomers. Moreover, the thermal polymerization initiator generates polymerization active species such as radicals and cations by heating to initiate a polymerization reaction of monomers and oligomers.

  Examples of the photopolymerization initiator include benzoin compounds such as benzoin methyl ether, acetophenone compounds such as 2,2-diethoxyacetophenone, benzophenone compounds such as 4,4′-bis (dimethylamino) benzophenone, and 2-isopropylthioxanthone. At least one selected from the group consisting of thioxanthone compounds can be used.

  Examples of the thermal polymerization initiator include azo compounds such as 2,2′-azobisisobutyronitrile and 2,2′-azobis (2-methylbutyronitrile), dibenzoyl peroxide, tert-butyl hydroperoxide, Selected from the group consisting of peroxides such as 1,1-dimethylpropyl 2-ethylhexaneperoxy acid, benzenesulfonates such as cyclohexyl-p-toluenesulfonate, and alkylsulfonium salts such as diphenyl (methyl) sulfonium tetrafluoroborate Can be used.

  The thickness of the gel sealing layer 30 is not particularly limited, but is preferably 0.1 mm or more and 10 mm or less, and more preferably 0.2 mm or more and 1.0 mm or less. By setting the thickness of the gel sealing layer 30 in such a range, the solar battery cell 10 can be appropriately protected, and light can efficiently reach the solar battery cell 10.

  The gel sealing layer 30 is preferably translucent. Although not particularly limited, the total light transmittance of the gel sealing layer 30 is preferably 60% to 100%, and more preferably 70% to 95%. Further, the total light transmittance of the gel sealing layer 30 is more preferably 80% to 95%. By setting the total light transmittance of the gel sealing layer 30 within this range, light can efficiently reach the solar battery cell 10. The total light transmittance can be measured by a method such as JIS K7361-1: 1997 (ISO 13468-1: 1996).

  In addition to the surface protective layer 20, the gel sealing layer 30, and the solar battery cell 10, the solar cell module 100 of the present embodiment has a light receiving surface side sealing layer 40, a back surface side seal, and a range that does not impair the effects of the present embodiment. A stop layer 50, a back surface protective layer 60, a frame (not shown), and the like can be further provided.

  In the embodiment of FIG. 1, the solar cell module 100 includes a surface protective layer 20, a gel sealing layer 30, a light receiving surface side sealing layer 40, a solar cell string 16, a back surface side sealing layer 50, and a back surface protective layer 60. Arranged in order from the top.

(Light-receiving surface side sealing layer 40)
The light-receiving surface side sealing layer 40 is disposed between the gel sealing layer 30 and the solar battery cell, and can protect the solar battery cell 10 from an external impact or the like. The shape of the light-receiving surface side sealing layer 40 is not particularly limited as in the case of the surface protective layer 20, and may be a polygon such as a circle, an ellipse, or a rectangle depending on the application. Similarly to the surface protective layer 20, the light receiving surface side sealing layer 40 may have a rectangular cross-sectional shape or may be curved in the stacking direction (z-axis direction) of each layer of the solar cell module 100.

  The material for forming the light-receiving surface side sealing layer 40 is not particularly limited. For example, ethylene-vinyl acetate copolymer (EVA), polyvinyl butyral (PVB), polyethylene terephthalate (PET), polyolefin (PO), polyimide (PI ) Or the like, or at least one selected from the group consisting of thermosetting resins such as epoxy, urethane, and polyimide can be used. These resins can be modified resins, or can be used in combination. Among these, the material forming the light-receiving surface side sealing layer 40 is preferably at least one of ethylene-vinyl acetate copolymer (EVA) and polyolefin (PO).

  The light-receiving surface side sealing layer 40 is preferably translucent. Although not particularly limited, the total light transmittance of the light-receiving surface side sealing layer 40 is preferably 60% to 100%, and more preferably 70% to 95%. The total light transmittance of the light-receiving surface side sealing layer 40 is more preferably 80% to 95%. By setting the total light transmittance of the light-receiving surface side sealing layer 40 within this range, light can efficiently reach the solar battery cell 10. The total light transmittance can be measured by a method such as JIS K7361-1: 1997 (ISO 13468-1: 1996).

  The thickness of the light-receiving surface side sealing layer 40 is not particularly limited, but is preferably 0.1 mm or more and 10 mm or less, and more preferably 0.2 mm or more and 1.0 mm or less. By setting the thickness of the light-receiving surface side sealing layer 40 in such a range, the solar battery cell 10 can be appropriately protected and light can efficiently reach the solar battery cell 10.

(Back side sealing layer 50)
The back surface side sealing layer 50 can be disposed between the solar battery cell 10 and the back surface protective layer 60. That is, the back surface side sealing layer 50 is disposed under the light receiving surface side sealing layer 40 and the solar cell string 16, and protects the solar cell 10 from an external impact or the like. The material for forming the back surface side sealing layer 50 may be the same material as the light receiving surface side sealing layer 40, but may be formed of a material different from that of the light receiving surface side sealing layer 40.

  The back side sealing layer 50 preferably has a higher storage elastic modulus than the acrylic gel that forms the gel sealing layer 30. That is, the back surface side sealing layer 50 is disposed between the solar battery cell 10 and the back surface protective layer 60 and preferably has a higher storage elastic modulus than the acrylic gel forming the gel sealing layer 30. By arrange | positioning such a back surface side sealing layer 50, it can fix so that the photovoltaic cell 10 may not move with respect to the back surface side sealing layer 50, and the cutting | disconnection of the interconnector 12 can be suppressed. .

  The material for forming the back side sealing layer 50 is not particularly limited. For example, ethylene-vinyl acetate copolymer (EVA), polyvinyl butyral (PVB), polyethylene terephthalate (PET), polyolefin (PO), polyimide (PI). At least one selected from the group consisting of thermoplastic resins such as epoxy, urethane, polyimide, and other thermosetting resins can be used. These resins can be modified resins, or can be used in combination. Among these, it is preferable that the material forming the back side sealing layer 50 is at least one of ethylene-vinyl acetate copolymer (EVA) and polyolefin (PO).

The tensile modulus of the back side sealing layer 50 is preferably 1 MPa to 1000 MPa, more preferably 10 MPa to 500 MPa. By setting the tensile elastic modulus of the back surface side sealing layer 50 in such a range, an external impact can be effectively absorbed and the solar battery cell 10 can be fixed. The tensile modulus is measured at a test temperature of 25 ° C. and a test speed of 100 mm / min, for example, in accordance with Japanese Industrial Standard JIS K7161-1 (Plastics—Method of obtaining tensile properties—Part 1: General) as follows. can do.
E _t = (σ ₂ −σ ₁ ) / (ε ₂ −ε ₁ )
In the above formula, _Et is the tensile modulus (Pa), σ ₁ is the stress (Pa) at the strain ε ₁ = 0.0005, and σ ₂ is the stress (Pa) at the strain ε ₂ = 0.0025.

The linear expansion coefficient of the back surface side sealing layer 50 is preferably 1 × 10 ⁻⁶ K ^{−1 to} 500 × 10 ⁻⁶ K ⁻¹ , and 100 × 10 ⁻⁶ K ^{−1 to} 300 × 10 ⁻⁶ K ^{−. 1} is more preferable. By setting the linear expansion coefficient of the back surface side sealing layer 50 in such a range, even if a temperature difference occurs in the solar cell module 100, the back surface side sealing layer 50 is unlikely to thermally expand. The disconnection of the connector 12 can be suppressed. The linear expansion coefficient can be measured according to JIS K7197: 2012 (a method for testing the linear expansion coefficient by thermomechanical analysis of plastics). In addition, a linear expansion coefficient can be made into an average linear expansion coefficient, and can be made into the variation | change_quantity of the length of the test piece per 30 degreeC-50 degreeC temperature difference.

When the tensile elastic modulus of the back surface side sealing layer 50 is 1 MPa to 1000 MPa and the linear expansion coefficient is 1 × 10 ⁻⁶ K ^{−1 to} 500 × 10 ⁻⁶ K ⁻¹ , the back surface side sealing layer 50 as will be described later. Has the same effect as that of the back surface protective layer 60, and therefore the necessity of providing the back surface protective layer 60 is reduced. Incidentally, typical ethylene - tensile modulus of the vinyl acetate copolymer (EVA) is 10MPa～50MPa, a linear expansion coefficient ^{200 × 10 -6 K -1 ~300 ×} 10 -6 K -1.

  Although the thickness of the back surface side sealing layer 50 is not specifically limited, It is preferable that they are 0.1 mm or more and 10 mm or less, and it is more preferable that they are 0.2 mm or more and 1.0 mm or less. By making the thickness of the back surface side sealing layer 50 into such a range, the photovoltaic cell 10 and the interconnector 12 can be appropriately protected from an impact or the like.

(Back side protective layer 60)
The back surface protective layer 60 can be disposed on the side opposite to the light receiving surface side of the solar battery cell 10. That is, the back surface protective layer 60 is disposed on the back surface side with respect to the solar battery cell 10. In the embodiment of FIG. 1, the back surface protective layer 60 is disposed under the back surface side sealing layer 50. The back surface protective layer 60 can protect the back surface side of the solar cell module 100.

  The material for forming the back surface protective layer 60 is not particularly limited. For example, an inorganic material such as glass, a metal such as aluminum, polyimide (PI), cyclic polyolefin, polycarbonate (PC), polymethyl methacrylate (PMMA), polyether ether At least one selected from the group consisting of plastics such as ketone (PEEK), polystyrene (PS), polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) and fiber reinforced plastic (FRP) can be used. Examples of the fiber reinforced plastic (FRP) include glass fiber reinforced plastic (GFRP), carbon fiber reinforced plastic (CFRP), aramid fiber reinforced plastic (AFRP), and cellulose fiber reinforced plastic. Examples of the glass fiber reinforced plastic (GFRP) include glass epoxy. The back surface protective layer 60 is preferably formed of glass fiber reinforced plastic. This is because glass fiber reinforced plastic (GFRP) is less likely to bend and is lightweight.

  The back surface protective layer 60 is more preferably at least one selected from the group consisting of a honeycomb structure, a foam, and a porous body. Such a structure can reduce the weight of the solar cell module 100 while maintaining rigidity. The material for forming the honeycomb structure, the foam, and the porous body is not particularly limited, and the above materials can be used. From the viewpoint of rigidity and weight reduction, the honeycomb structure is preferably formed of a material containing aluminum and cellulose. Moreover, it is preferable that at least any one of a foam and a porous body is formed with resin materials, such as a polyurethane, polyolefin, polyester, polyamide, and polyether.

  The thickness of the back surface protective layer 60 is not particularly limited, but is preferably 0.1 mm or more and 10 mm or less, and more preferably 0.2 mm or more and 5.0 mm or less. By setting the thickness of the back surface protective layer 60 in such a range, the deflection of the back surface protective layer 60 can be suppressed and the solar cell module 100 can be further reduced in weight.

The back surface protective layer 60 preferably has a linear expansion coefficient of 20 × 10 ⁻⁶ K ⁻¹ or less. That is, the back surface protective layer 60 is preferably disposed on the side opposite to the light receiving surface side of the solar battery cell 10 and has a linear expansion coefficient of 20 × 10 ⁻⁶ K ⁻¹ or less. Since the back surface protective layer 60 has such a linear expansion coefficient, the back surface protective layer 60 suppresses thermal expansion and contraction of the back surface side sealing layer 50 even when a temperature difference occurs in the solar cell module 100. Can do. Therefore, damage to the solar battery cell 10 and disconnection of the interconnector 12 can be suppressed. The linear expansion coefficient of the back surface protective layer 60 is more preferably 20 × 10 ⁻⁶ K ⁻¹ or less. Further, the linear expansion coefficient can be measured in accordance with JIS K7197: 2012, similarly to the back side sealing layer 50.

(flame)
The frame is used when the edge of the periphery of the solar cell module 100 is supported and the solar cell module 100 is installed on a roof or the like. Although the material which forms a flame | frame is not specifically limited, From a viewpoint of intensity | strength and weight reduction, it is preferable to form with aluminum.

  The solar cell module 100 of the present embodiment can be mounted on the roof of a vehicle including a building or an automobile. At this time, the shape of the solar cell module 100 may have a curved surface so as to match the shape of the roof.

  As described above, the solar cell module 100 according to the present embodiment includes the solar cell 10, the surface protection layer 20 that is disposed on the light receiving surface side of the solar cell 10 and is formed of resin, the solar cell 10, and the surface. A gel sealing layer 30 disposed between the protective layer 20 and the protective layer 20. And the storage elastic modulus of the acrylic gel which forms the gel sealing layer 30 is 0.1 Mpa or less, and a glass transition temperature is -30 degrees C or less. Therefore, according to the solar cell module of the present embodiment, damage to the solar cells and disconnection of the interconnector can be suppressed when a temperature difference occurs.

[Method for manufacturing solar cell module]
The manufacturing method of the solar cell module 100 of the present embodiment includes the surface protective layer 20, the gel sealing layer 30, the solar cell string 16, the light receiving surface side sealing layer 40, the back surface side sealing layer 50, and the back surface protection layer 60. A step of preparing.

  The solar cell string 16 electrically connects the bus bar electrode provided on the light receiving surface side of one solar cell 10 and the bus bar electrode provided on the back surface side of the other solar cell 10 with an interconnector 12. It can form by connecting to.

  Next, the surface protective layer 20, the gel sealing layer 30, the solar cell string 16, the light-receiving surface side sealing layer 40, the back surface side sealing layer 50, and the back surface protective layer 60 are laminated in this order from above and heated. The solar cell module 100 is formed by compressing while compressing. However, the detailed steps such as compression molding by dividing each layer into several steps are not particularly limited, and molding according to the purpose can be performed.

  The heating conditions are not particularly limited, but may be heated to about 150 ° C. in a vacuum, for example. Heating under vacuum conditions is preferable because the bubble removal properties are further improved. After the vacuum heating, the gel component of the gel sealing layer 30 can be cross-linked by heating with a heater or the like while pressing each layer under atmospheric pressure. Moreover, a frame etc. can also be attached to the laminated body obtained by heating.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to these Examples.

[Example 1]
1 mm thick surface protective layer, 1 mm thick gel sealing layer, 1 mm thick light-receiving surface side sealing layer, solar cell string, 1 mm thick back surface side sealing layer, 2 mm thick back surface protective layer are laminated in order from the top And the solar cell module was produced by compressing and heating at 145 degreeC.

  In the solar cell string, the bus bar electrode provided on the light receiving surface side of one solar cell and the bus bar electrode provided on the back surface side of the other solar cell are electrically connected by an interconnector formed of copper. Formed by connecting them together.

The material of each layer constituting the solar cell module is as follows.
Surface protective layer Polyethylene terephthalate (PET)
Gel sealing layer Acrylic gel Light-receiving surface side sealing layer Ethylene-vinyl acetate copolymer (EVA)
Back side sealing layer Ethylene-vinyl acetate copolymer (EVA)
Back surface protective layer Carbon fiber reinforced plastic (CFRP) (Linear expansion coefficient 2.5 × 10 ⁻⁶ K ⁻¹ )

  As the acrylic gel, an acrylic gel sheet produced by the following procedure was used.

  First, a predetermined amount of the materials described below was placed in a flask, and stirred and mixed in a nitrogen atmosphere at 30 ° C. for 60 hours to prepare an acrylic gel solution.

(Monofunctional (meth) acrylate having branched alkyl group)
70 parts by mass of isostearyl acrylate (S-1800A manufactured by Shin-Nakamura Chemical Co., Ltd.)

(Monofunctional (meth) acrylate having alkylene oxide chain)
29.5 parts by mass of methoxypolyethyleneglycol acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd. AM-30G)

(Bifunctional or higher acrylic oligomer)
0.5 parts by mass of trimethylolpropane triacrylate (Shin-Nakamura Chemical Co., Ltd. A-TMPT)

(Polymerization initiator)
1.0 part by mass of 1,1-dimethylpropyl 2-ethylhexaneperoxyacid (Trigonox (registered trademark) 121 manufactured by Kayaku Akzo Corporation)

  Next, the acrylic gel solution obtained as described above was applied onto a polyethylene terephthalate film so that the thickness after drying was 1.0 mm. And it heated at 100 degreeC for 60 minute (s), and produced the acrylic gel sheet.

  The resulting acrylic gel sheet had a storage modulus of 0.02 MPa and a glass transition temperature of -34 ° C.

[Comparative Example 1]
A solar cell module was produced in the same manner as in Example 1 except that an acrylic gel sheet having a storage elastic modulus of 0.3 MPa and a glass transition temperature of −5 ° C. was used as the acrylic gel sheet.

[Comparative Example 2]
A solar cell module was produced in the same manner as in Example 1 except that an acrylic gel sheet having a storage elastic modulus of 0.01 MPa and a glass transition temperature of −1 ° C. was used as an acrylic gel sheet manufactured by Showa Denko K.K.

[Evaluation]
(Storage modulus)
The storage elastic modulus M ′ was determined by measuring dynamic viscoelasticity using a rotary rheometer (AR2000 manufactured by T.A. Instruments Co., Ltd.) under the following conditions.
Sample: diameter 20 mm, thickness 1.0 mm
Jig: Parallel disk with a diameter of 20 mm Measurement temperature range: 30 ° C to 120 ° C
Temperature increase rate: 3 ° C / min
Frequency: 6 rad / s

(Glass-transition temperature)
The glass transition temperature was measured in accordance with JIS K7121-1987. Specifically, in the DSC curve obtained by differential scanning calorimetry (DSC), the glass transition temperature is a stepwise change of the glass transition directly and equidistantly in the vertical axis direction from the extended straight line of each baseline. The midpoint glass transition temperature (T _mg ) at which the partial curve intersects. Differential scanning calorimetry (DSC) was measured under the following conditions.
Sample weight: 10mg
Inflow gas: Air 100 mL / min Container: Aluminum pan Measurement temperature: -100 ° C to 150 ° C
Heating rate: 5 ° C / min

(Temperature cycle test)
The temperature cycle test is measured in accordance with the provisions of the temperature cycle test of JIS C8990: 2009 (IEC61215: 2005) (Ground-crystalline silicon solar cell (PV) module-requirements for design qualification and type certification) did. Specifically, the solar cell module of each example was installed in a test tank, and the temperature of the solar cell module was periodically changed between −40 ° C. ± 2 ° C. and + 85 ° C. ± 2 ° C. After performing 200 cycles of such a temperature cycle test, it was visually confirmed whether there was any damage to the solar cells or disconnection of the interconnector. And what did not have the damage of a photovoltaic cell and the cutting | disconnection of an interconnector in 200 cycles was made favorable, and what was damaged or the interconnector cut | disconnected in 200 cycles was made into a defect. The temperature change rate between the lower limit and the upper limit is about 1.4 ° C./hour, the lower limit temperature holding time is 60 minutes, the upper limit temperature holding time is 1 hour 20 minutes, and the cycle time is 5 hours 20 hours. Minutes. The temperature cycle test was performed at least three times.

  As shown in Table 1, the solar cell module of Example 1 had good temperature cycle test results. That is, it was found that even when a temperature difference was repeatedly generated in the solar cell module, the solar cell was not easily damaged and the interconnector was not cut. It is considered that the storage elastic modulus of the acrylic gel forming the gel sealing layer of Example 1 is 0.1 MPa or less and the glass transition temperature is −30 ° C. or less.

  On the other hand, the results of the temperature cycle test of the solar cell modules of Comparative Examples 1 to 3 were not sufficient as compared with the solar cell module of Example 1. It is considered that the storage elastic modulus of the acrylic gel forming the gel sealing layer of Comparative Examples 1 to 3 was 0.1 MPa or less and / or the glass transition temperature was not −30 ° C. or less.

  Although the present embodiment has been described above, the present embodiment is not limited to these, and various modifications can be made within the scope of the gist of the present embodiment.

DESCRIPTION OF SYMBOLS 10 Solar cell 20 Surface protective layer 30 Gel sealing layer 50 Back surface side sealing layer 60 Back surface protective layer 100 Solar cell module

Claims (5)

Solar cells,
A surface protective layer disposed on the light receiving surface side of the solar battery cell and formed of a resin;
A gel sealing layer which is disposed between the solar battery cell and the surface protective layer, and is formed of an acrylic gel having a storage elastic modulus of 0.1 MPa or less and a glass transition temperature of −30 ° C. or less;
A solar cell module comprising:   2. The solar cell module according to claim 1, wherein the acrylic gel is a polymer of a monomer including a monofunctional (meth) acrylate having a branched alkyl group and a monofunctional (meth) acrylate having an alkylene oxide chain. The acrylic gel is a polymer of the monomer and a bifunctional or higher functional acrylic oligomer,
The total content of the monofunctional (meth) acrylate having a branched alkyl group and the monofunctional (meth) acrylate having an alkylene oxide chain is 30% by mass or more with respect to a total of 100% by mass of the monomer and the acrylic oligomer. The solar cell module according to claim 2. The back surface protective layer which is arrange ^| positioned on the opposite side to the said light-receiving surface side of the said photovoltaic cell, and further has a linear expansion coefficient of 20 * 10 <^-6> K <^-1> or less is given in any one of Claims 1-3. Solar cell module.   The solar cell according to claim 4, further comprising a back surface side sealing layer that is disposed between the solar battery cell and the back surface protective layer and has a higher storage elastic modulus than an acrylic gel that forms the gel sealing layer. module.

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