JP2014107323A - Sealing film for solar battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing film for solar battery which is capable of manufacturing a solar battery module with an excellent power generation efficiency and which has a resistance to yellow discoloration.SOLUTION: The sealing film for solar battery is a sealing film for solar battery containing ethylene-based copolymer, pigment and metal deactivator. The metal deactivator contains at least one type selected from a group formed from triazole compound, benzotriazole-based compound and hydrazine compound.

Description

  The present invention relates to a solar cell sealing film used when manufacturing a solar cell module.

  A solar cell module is heated while degassing a laminate obtained by laminating a transparent protective material on the upper surface of a solar cell element having a solar cell sealing film laminated on both sides and a back surface protective material on the lower surface. And it manufactures by laminating | stacking and integrating a protective material on the upper and lower surfaces of a solar cell element via an adhesive sheet.

  As a sealing film for a solar cell used in such a solar cell module, for example, in Patent Document 1, it is arranged between a solar cell element of a solar cell and a back surface side protective member, and the solar cell element is sealed. It is a sealing film for backside solar cells for stopping, is a cured film of a composition for sealing film containing an ethylene-vinyl acetate copolymer and a white inorganic pigment, and the content of the white inorganic pigment is Further, a solar cell sealing film having a content of 10 to 30% by mass based on the sealing film composition is disclosed.

  The solar cell sealing film contains a white inorganic pigment at a high concentration of 10 to 30% by mass, and is incident on the solar cell element by highly reflecting light that has passed through the solar cell element toward the solar cell element. The purpose is to improve the power generation efficiency of the solar cell module by increasing the light to be generated.

  On the other hand, a solar cell element is usually configured by connecting a plurality of solar cell cells with metal wiring in order to obtain a high electrical output, but the solar cell sealing film is yellowed in the vicinity of the metal wiring. It is known to occur.

  When the white pigment is contained at a high concentration as in the solar cell sealing film, yellowing of the solar cell sealing film near the metal wiring is more likely to occur, and is incident on the solar cell sealing film. There is a problem that light cannot be reflected well toward the solar cell element, and the power generation efficiency of the solar cell module is lowered.

  In recent years, thin film solar cell elements such as thin film silicon solar cell elements, thin film amorphous silicon solar cell elements, and copper indium selenide (CIS) solar cell elements have been developed as solar cell elements.

  In the thin film solar cell element, a power generation element layer such as a semiconductor layer is formed on the surface of a transparent substrate such as a glass or polyimide substrate by chemical vapor deposition, and a thin film electrode is formed on the power generation element layer. It becomes.

  The corrosion of the thin film electrode also causes a decrease in power generation efficiency of the solar cell module, and a solar cell sealing film that can effectively prevent the corrosion of the thin film electrode is desired.

JP 2012-4146 A

  The present invention provides a solar cell sealing film which can produce a solar cell module having excellent power generation efficiency and hardly causes yellowing.

  The solar cell sealing film of the present invention is a solar cell sealing film containing an ethylene copolymer, a pigment, and a metal deactivator, wherein the metal deactivator is a triazole compound or a benzotriazole compound. And at least one compound selected from the group consisting of hydrazine compounds.

  The ethylene copolymer constituting the sealing film for solar cells of the present invention is a copolymer of ethylene and a copolymerizable monomer that can be copolymerized with ethylene, and such a copolymerizable monomer. There is no particular limitation, and examples thereof include vinyl acetate, acrylic acid, acrylic ester, methacrylic acid, methacrylic ester, maleic acid, maleic anhydride, maleic ester, and propylene, and vinyl acetate is preferred. In addition, the said copolymerizable monomer may be copolymerized with ethylene independently, or 2 or more types may be copolymerized with ethylene.

  If the amount of the copolymerizable monomer contained in the ethylene-based copolymer is small, the transparency of the solar cell sealing film may be lowered. If the amount is large, the solar cell sealing film is formed. Since stability and mechanical strength may become insufficient, it is preferably 5 to 50% by weight, more preferably 10 to 40% by weight, and particularly preferably 14 to 35% by weight.

  If the melt flow rate of the ethylene-based copolymer is small, the film-forming stability of the solar cell sealing film may decrease, and if it is large, the mechanical strength of the solar cell sealing film is insufficient. 1 to 100 g / 10 min is preferable. The melt flow rate of the ethylene copolymer in the present invention refers to a value measured under conditions of a temperature of 190 ° C. and a load of 2.16 kgf (21.18 N) according to JIS K7210.

  The solar cell sealing film of the present invention is used by being disposed on the lower surface of the solar cell element during the production of the solar cell module, and is disposed on the upper surface of the solar cell element by thermocompression bonding under reduced pressure. The solar cell element is sealed and integrated together with the sealing film, and further, the solar cell element and the back surface protective material disposed on the lower surface of the solar cell element via the solar cell sealing film are bonded and integrated. Make it.

  The solar cell sealing film of the present invention uses, as the solar cell element, light that has not been absorbed by the solar cell element by passing between the solar cell elements of the solar cell element among the light incident on the solar cell module. The power generation efficiency of the solar cell module is improved by increasing the amount of light that is reflected toward the solar cell element.

  Therefore, the solar cell sealing film of the present invention contains a pigment in order to reflect the light incident on the solar cell sealing film toward the solar cell element. The pigment is not particularly limited as long as it can reflect the light incident on the sealing film for solar cells. For example, white inorganic pigments such as titanium oxide, calcium carbonate, and aluminum oxide, blue pigments such as ultramarine, and carbon black Black pigments such as glass beads and the like, white inorganic pigments are preferable, and titanium oxide is more preferable.

  If the content of the pigment in the solar cell sealing film is small, the light reflectivity of the solar cell sealing film may decrease and the power generation efficiency of the solar cell module may decrease. Since the adhesion of the sealing film is reduced, or the metal wiring or thin film electrode used in the solar cell element is likely to be corroded, the power generation efficiency of the solar cell module may be reduced. 1-20 weight part is preferable with respect to 100 weight part of unification, and 5-15 weight part is more preferable.

  The sealing film for solar cells contains a metal deactivator. Inclusion of a metal deactivator in the solar cell sealing film prevents yellowing of the solar cell sealing film in the vicinity of the metal wiring of the solar cell element and improves the light reflection efficiency to the solar cell element. In addition, the corrosion of the thin film electrode of the thin film solar cell element is prevented, and the power generation efficiency of the solar cell module is improved.

  As the metal deactivator, at least one compound selected from the group consisting of triazole compounds, benzotriazole compounds and hydrazine compounds is used, and benzotriazole compounds are preferred.

  The triazole-based compound is not particularly limited, and for example, 1- [bis (2-ethylhexyl) aminomethyl] -1H-1,2,4-triazole, N- (2H-1,2,4-triazole-5 -Yl) salicylamide, 1- [2- (2,4-dichlorophenyl-4-propyl-1,3-dioxolan-2-ylmethyl)]-1H-1,2,4-triazole (generic name: propiconazole) ), 1- (p-chlorophenyl) -4,4-dimethyl-3- (1,2,4-triazol-1-yl) methylpentan-3-ol (generic name: tebuconazole), 2- (4-chlorophenyl) ) -3-cyclopropyl-1- (1,2,4-triazol-1-yl) butane-2-diol (generic name: cyproconazole), 1-[{2- (2,4-dichloroph Nyl) -1,3-dioxysolan-2-yl} methyl] -1H-1,2,4-triazole and 1-[{2- (2,4-dichlorophenyl) -1,3-dioxysolan-2-yl} Methyl] -1H-1,3,4-triazole, a generic name such as azaconazole, and the like. 1- [bis (2-ethylhexyl) aminomethyl] -1H-1,2,4-triazole, N- (2H-1,2,4-triazol-5-yl) salicylamide is preferred. In addition, a triazole type compound may be used independently or 2 or more types may be used together.

  The benzotriazole-based compound is not particularly limited. For example, 1,2,3-benzotriazole, 2- (5-methyl-2-hydroxyphenyl) -2H-benzotriazole, 2- [2-hydroxy-3, 5-bis (α, αdimethylbenzyl) phenyl] -2H-benzotriazole, 2- (2′-hydroxy-5′-t-octylphenyl) benzotriazole, 2,2-methylenebis [4- (1,1,1, 3,3-tetramethylenebutyl) -6- (2H-benzotriazol-2-yl) phenol] and the like, and 1,2,3-benzotriazole is preferred. A benzotriazole type compound may be used independently, or 2 or more types may be used together.

  The hydrazine-based compound is not particularly limited, and may be any compound having a hydrazide group in the molecule, for example, dodecanedioic acid bis [N2- (2-hydroxybenzoyl) hydrazide], oxalic acid dihydrazide, malonic acid dihydrazide. Succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, itaconic acid dihydrazide and the like, and dodecanedioic acid bis [N2- (2-hydroxybenzoyl) hydrazide] is preferable. . A hydrazine compound may be used independently or 2 or more types may be used together.

  If the content of the metal deactivator in the solar cell sealing film is small, yellowing of the solar cell sealing film near the metal wiring of the solar cell element occurs, or the thin film electrode of the thin film solar cell element In many cases, the metal deactivator bleeds out to the surface of the solar cell sealing film, and the adhesive strength with the solar cell element, the back surface protective material or the transparent protective material may decrease. Therefore, 0.02-1 part by weight is preferable with respect to 100 parts by weight of the ethylene copolymer, 0.02-0.7 part by weight is more preferable, and 0.05-0.5 part by weight is particularly preferable.

  Among the adhesives and heat resistance particularly required for a sealing film for solar cells, an ethylene-based copolymer has a problem that heat resistance is low although it is excellent in adhesiveness. Therefore, an organic peroxide is contained in the ethylene copolymer constituting the solar cell sealing film, and the ethylene copolymer is crosslinked by heat applied during the production of the solar cell module. It is preferable to improve the heat resistance of the sealing film.

  Examples of the organic peroxide include dicumyl peroxide (136 ° C.), t-butyl peroxy-2-ethylhexyl monocarbonate (119 ° C.), t-butyl peroxybenzoate (125 ° C.), 1,1-di (T-butylperoxy) -2-methylcyclohexane (102 ° C.), 1,1-di (t-hexylperoxy) -3,3,5-trimethylcyclohexane (106 ° C.), 1,1-di (t -Hexylperoxy) cyclohexane (107 ° C.), 1,1-di (t-butylperoxy) cyclohexane (111 ° C.), 2,2-di (4,4-di (t-butylperoxy) cyclohexyl) propane (114 ° C.), t-hexyl peroxyisopropyl monocarbonate (115 ° C.), t-butyl peroxyisopropyl monocarbonate 118 ° C.), t-butyl peroxylaurate (118 ° C.), 2,5-dimethyl-2,5-di (benzoylperoxy) hexane (119 ° C.), t-hexyl peroxybenzoate (119 ° C.), t -Butylperoxymaleic acid (119 ° C), t-butylperoxy-3,5,5-trimethylhexanoate (119 ° C), t-butylperoxyacetate (121 ° C), 2,2-di (t -Butylperoxy) butane (122 ° C), n-butyl-4,4-di (t-butylperoxy) valerate (127 ° C), di-t-hexyl peroxide (136 ° C), t-butylcumylper Oxide (137 ° C), di (2-t-butylperoxyisopropyl) benzene (138 ° C), 2,5-dimethyl-2,5-di (t-butylperoxy) Hexane (138 ° C), di-t-butyl peroxide (144 ° C), 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3 (150 ° C), p-menthane hydroperoxide (151 ° C.) and the like, and may be used alone or in combination of two or more. The temperature in the parenthesis represents a 1 hour half-life temperature.

  If the content of the organic peroxide contained in the solar cell sealing film is small, the crosslinking of the ethylene-based copolymer becomes insufficient during the production of the solar cell module, and the solar cell sealing The durability of the solar cell module obtained due to insufficient heat resistance of the film is lowered, and if it is large, the resin layer is crosslinked and stays in the T die when the solar cell sealing film is formed, and is uniform. It becomes impossible to obtain a sealing film for solar cells having a thickness, or the ethylene copolymer is solidified in the T-die and the sealing film for solar cells cannot be extruded. 0.05-3 weight part is preferable with respect to 100 weight part of coalescence.

  The sealing film for solar cells may contain a crosslinking aid. Examples of the crosslinking aid include polyfunctional monomers having two or more allyl groups, vinyl groups, acryloyl groups or methacryloyl groups, which stabilize polymer radicals to increase crosslinking efficiency and concentrate crosslinking points. Accelerates gel formation. Examples of the polyfunctional monomer include diallyl phthalate, diallyl itaconate, diallyl maleate, triallyl isocyanurate, triallyl cyanurate, triallyl phosphate, divinylbenzene; 1,6-hexanediol di (meth) acrylate (Meth) such as ethylene oxide modified bisphenol A di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ε-caprolactone modified dipentaerythritol Examples thereof include acrylates and (meth) acrylates of alkyl-modified dipentaerythritol, which may be used alone or in combination of two or more.

  If the amount of the crosslinking aid contained in the solar cell encapsulating film is small, the solar cell encapsulating film may be insufficiently crosslinked during the production of the solar cell module. Since the degree of cross-linking of the sealing film becomes too high and hard, it may be undesirable in protecting the solar cell element such as excessive stress applied to the solar cell element. The amount is preferably 0.01 to 1.5 parts by weight, more preferably 0.1 to 1.3 parts by weight, and particularly preferably 0.2 to 1.2 parts by weight.

  The solar cell sealing film may contain a silane coupling agent in order to improve the adhesion to the solar cell element, the back surface protective material or the transparent protective material. As the silane coupling agent, a silane coupling agent having one or two or more functional groups selected from the group consisting of an amino group, a glycidyl group, a methacryloxy group and a mercapto group is preferably used. Propyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane and the like, and a group consisting of amino group, glycidyl group, methacryloxy group and mercapto group A trialkoxysilane having one or more functional groups selected from the above is preferred, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane are more preferred, 3-aminop Pills triethoxysilane, 3-glycidoxypropyltrimethoxysilane is particularly preferred. In addition, a silane coupling agent may be used independently or 2 or more types may be used together.

  When the content of the silane coupling agent in the solar cell sealing film is small, the adhesion of the solar cell sealing film to the solar cell element, the back surface protective material or the transparent protective material is lowered, and when it is large, the solar cell sealing film is used for the solar cell. Since a weak adhesive layer is formed by discoloration of the adhesive sheet or a silane coupling agent and causes a reduction in adhesive strength, the amount is limited to 0.05 to 3 parts by weight with respect to 100 parts by weight of the ethylene copolymer, and 0 0.07 to 1 part by weight is preferred.

  In addition, the sealing film for solar cells of the present invention may contain additives such as an ultraviolet absorber, a light stabilizer, a scorch inhibitor, and an antioxidant as long as the physical properties are not impaired.

  Next, the manufacturing method of the sealing film for solar cells of this invention is demonstrated. The method for producing the solar cell sealing film is not particularly limited. For example, an ethylene copolymer, a pigment and a metal deactivator, and, if necessary, other additives are supplied to an extruder and melted. The method of manufacturing the sealing film for solar cells by kneading and extruding in sheet form from T-die attached to the front-end | tip of an extruder is mentioned.

  And as a method of manufacturing a solar cell module using the solar cell sealing film A of the present invention, as shown in FIG. 1, a solar cell sealing film 2 is interposed on the upper surface of the solar cell element 1. A transparent protective material 3 such as a glass plate is laminated. Note that the solar cell sealing film 2 is not a solar cell sealing film of the present invention but a general-purpose solar cell sealing film having translucency. As the solar cell sealing film having translucency, a solar cell sealing film containing no pigment in the solar cell sealing film of the present invention may be used. The laminated body which laminated | stacked the back surface protection material 4 on the lower surface of the solar cell element 1 via the solar cell sealing film A of this invention is produced, and this laminated body is heat-pressed under pressure reduction. In addition, in the manufacturing process of the solar cell module, the laminated body may be formed in an upside down state, and the laminated body may be thermocompression bonded under reduced pressure.

  In addition, as the solar cell element 1, the solar cell element formed by connecting the cell for solar cells of the structure which uses a single crystal or a polycrystalline wafer with metal wiring is mentioned.

  Then, the solar cell sealing films A and 2 laminated on the upper and lower surfaces of the solar cell element 1 are melted, and the solar cell elements are sealed by the solar cell sealing films A and 2 by filling the gaps between the solar cell elements. Is done. Further, a transparent protective material 3 is laminated and integrated on the upper surface of the solar cell element 1 via a solar cell sealing film 2 and the lower surface of the solar cell element 1 via a solar cell sealing film A. The back surface protective material 4 is laminated and integrated to obtain the solar cell module B (see FIG. 1).

  In the above description, the solar cell module B having a structure in which the solar cell elements are sealed and integrated from the upper and lower surfaces using the solar cell adhesive sheet has been described, but the solar cell adhesive sheet A of the present invention is described below. It can also be used for the solar cell module B having a structure.

  A power generation element layer 6 such as a semiconductor layer made of silicon or a compound semiconductor is laminated and integrated in a thin film shape on the transparent substrate 5 by a chemical vapor deposition method or the like, and a thin film electrode (not shown) is formed on the power generation element layer 6. The adhesive sheet A for solar cells is laminated on the transparent substrate 5 so as to cover the power generating element layer 6 of the thin film solar cell element formed by forming the back protective material 4 on the adhesive sheet A for solar cells. A solar cell module B in which the transparent substrate 5, the power generation element layer 6, the solar cell adhesive sheet A and the back surface protective material 4 are laminated and integrated. Can be obtained (see FIG. 2). The power generating element layer 6 is sealed and integrated by the transparent substrate 5 and the solar cell adhesive sheet A.

  In the solar cell module B, since the solar cell sealing film A contains a metal deactivator, the solar cell module B is used for solar cells regardless of the presence of the metal wiring connecting the solar cell cells. The sealing film hardly yellows over a long period of time, and when the thin film solar cell element is used as the solar cell element, the thin film electrode is substantially prevented from being rusted due to the solar cell sealing film A. can do.

  Therefore, among the light incident on the solar cell module B, the light that reaches the solar cell sealing film A without being absorbed by the solar cell element 1 is favorably applied to the solar cell element 1 by the solar cell sealing film A. The power generation efficiency of the solar cell module B can be improved by reflecting the reflected light and the solar cell element 1 absorbing the reflected light.

  Furthermore, even when a thin film solar cell element is used as the solar cell element 1 of the solar cell module B, it is possible to satisfactorily prevent the thin film electrode from being rusted and to improve the power generation efficiency of the solar cell module B. be able to.

  Since the solar cell sealing film of the present invention has the above-described configuration, the solar cell sealing film has a long period of time despite the presence of the metal wiring connecting the solar battery cells. In the case where the thin film solar cell element is used as the solar cell element, it is possible to substantially prevent the thin film electrode from being rusted due to the solar cell sealing film A. And the fall of the power generation efficiency of a solar cell module can be suppressed.

It is a longitudinal cross-sectional view of the solar cell module using the sealing film for solar cells of this invention. It is the longitudinal cross-sectional view which showed another example of the solar cell module using the sealing film for solar cells of this invention.

  Hereinafter, embodiments of the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

(Examples 1-8, Comparative Examples 1-3)
A predetermined amount of ethylene-vinyl acetate copolymer shown in Table 1 (EVA, vinyl acetate content: 28% by weight, melt flow rate: 15 g / 10 min), titanium oxide as a pigment, and t-butylperoxy as a crosslinking agent 2-ethylhexyl monocarbonate (trade name “Perbutyl E” manufactured by NOF Corporation), triallyl isocyanurate as a crosslinking aid, 3-methacryloxypropyltrimethoxysilane (trade name “Syra Ace S710 manufactured by JNC Corporation) as a silane coupling agent 2) 2-hydroxy-4-n-octyloxybenzophenone (trade name “Adeka Stub 1413” manufactured by ADEKA), 2- (4,6-diphenyl-1,3,5-triazin-2-yl) as an ultraviolet absorber ) -5-[(Hexyl) oxy] -phenol) (trade name, manufactured by BASF Japan Ltd.) “Tinuvin 1577ED”), bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate as a light stabilizer (trade name “Adeka Stub LA-77Y” manufactured by ADEKA), N—as a metal deactivator (2H-1,2,4-triazol-5-yl) salicylamide (trade name “ADEKA STAB CDA-1M” manufactured by ADEKA), bis [N2- (2-hydroxybenzoyl) hydrazide] dodecanedioate (manufactured by ADEKA) Trade name “Adeka Stub CDA-6”), 1- [bis (2-ethylhexyl) aminomethyl] -1H-1,2,4-triazole (trade name “Irgamet 30” manufactured by BASF Japan Ltd.), 1,2,3 -Benzotriazole (trade name “Irgamet BTA” manufactured by BASF Japan Ltd.) is supplied to an extruder and melt-kneaded, and the tip of the extruder Thickness from a T-die attached extruded into a sheet to produce a solar cell sealing film of 0.6 mm.

  The yellowing resistance and power generation efficiency of the obtained solar cell sealing film were measured in the following manner, and the results are shown in Table 1.

(Yellowing resistance)
In each Example or Comparative Example, a transparent solar cell sealing film was obtained in the same manner as in each Example or Comparative Example except that titanium oxide was not supplied to the extruder.

  A transparent glass plate, a transparent solar cell sealing film, a copper wire, a solar cell sealing film obtained in each example or comparative example, and a polyester-based back surface protective material are laminated to produce a laminated sheet. The laminated sheet was heated to 150 ° C. for 3 minutes under vacuum and then heated under pressure at 150 ° C. for 3 minutes to produce a laminate.

The laminate was heated at 150 ° C. for 30 minutes to crosslink the solar cell sealing film of the laminate, and then the laminate was allowed to stand at 140 ° C. for 200 hours. The laminate was visually observed and yellowing resistance was evaluated based on the following criteria.
○: Almost no yellowing around the conductor is visible, or the part where yellowing is visible is the conductor
Within 0.5 mm.
Δ: The degree to which yellowing can be visually recognized slightly or the part where yellowing is visible is 0 from the lead wire.
. It was within 1 mm exceeding 5 mm.
X: Yellowing to the extent that it can be easily recognized visually, or the range where yellowing is visible is 1 from the lead wire
It expanded to the range exceeding mm.

(Power generation efficiency decrease rate)
α-Si thin film solar cell element, solar cell sealing film obtained in each example or comparative example, and polyester back surface protective material are laminated to produce a laminated sheet, and this laminated sheet is placed under vacuum And heated to 150 ° C. for 3 minutes and then heated under pressure at 150 ° C. for 3 minutes to produce a laminate. The laminate was heated at 150 ° C. for 30 minutes to crosslink the solar cell sealing film of the laminate.

The initial power generation amount W ₀ of the laminate was calculated using a solar simulator. Next, the laminate was allowed to stand for 300 hours in an environment of 85 ° C. and a relative humidity of 85%. After that. The amount of power generation W ₁ after the laminate was left was calculated using a solar simulator. The power generation efficiency reduction rate was calculated based on the following formula.
Reduction rate of power generation efficiency (%) = 100 × (initial power generation amount W ₀ −power generation amount W ₁ after being left) / initial power generation amount W ₀

DESCRIPTION OF SYMBOLS 1 Solar cell element 1 Solar cell element 2 Solar cell sealing film 3 Transparent protective material 4 Back surface protective material A Solar cell sealing film B Solar cell module

Claims (3)

A solar cell encapsulating film comprising an ethylene copolymer, a pigment and a metal deactivator, wherein the metal deactivator is at least selected from the group consisting of a triazole compound, a benzotriazole compound and a hydrazine compound. A sealing film for solar cells, comprising a kind of compound. The solar cell sealing film according to claim 1, wherein the metal deactivator is a benzotriazole-based compound. The solar cell sealing film according to claim 1, wherein the pigment is titanium oxide.

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