JP2000174298A - Solar cell, and cover material and seal film therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cover material and seal film for a solar cell and a lightweight solar cell which has high shock resistance and endurance using a cover material for the solar cell as a transparent protective material on the top/back of the solar cell. SOLUTION: A cover material 1 for a solar cell is formed by laminating a transparent film 2 of high moisture proof and a transparent film 3 of high lightfastness through a sheet 4 of EVA resin adhesive being composed of an ultraviolet absorbent and a cross-linking material (hereafter called ultraviolet absorbing EVA adhesive sheet) and integrally bonding them. The transparent film 2 of high moisture proof is preferably provided by forming a moisture- proofing film consisting of a coating film of inorganic oxide such as silica and alumina on a transparent base film such as a PET film by CVD(chemical vapor deposition) method, PVD(physical vapor deposition) method and others. Namely, the moisture-proof film provided by forming a metallic coating film such as aluminum on a base film is also well known. However, when a metal such as aluminum is used in a solar cell, current leakage may occur. Thus, the coating film of inorganic oxide is preferable as a moisture-proof film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cover material used as a transparent protective member for a solar cell, a sealing film using the cover material, and a solar cell. In particular, the present invention has both moisture resistance and light resistance. A solar cell cover material, a solar cell cover material / sealing film which is made of a transparent film and is effective for weight reduction, impact resistance and durability improvement of the solar cell, and the solar cell cover material on the front side and / or The present invention relates to a lightweight, high impact resistance, and high durability solar cell used as a backside transparent protective member.

[0002]

2. Description of the Related Art In recent years, solar cells which directly convert sunlight into electric energy have been attracting attention from the viewpoints of effective use of resources and prevention of environmental pollution, and their development has been promoted.

As shown in FIG. 6, a solar cell generally has an ethylene-vinyl acetate copolymer between a glass substrate 11 as a front-side transparent protective member on the light-receiving side and a back-side protective member (back cover) 12. (EVA) Films 13A, 13
The solar cell, that is, the power generation element 14 made of silicon or the like is sealed by the sealing film B.

[0004] Such a solar cell comprises a glass substrate 11,
EVA film 13A for sealing film, silicon power generation element 1
4. EVA film 13B for sealing film and back cover 1
2 are laminated in this order, and the EVA is heated and melted and cross-linked and cured to be bonded and integrated to be manufactured.

[0005] By the way, the surface side transparent protective member of the solar cell is required to be excellent in durability against ultraviolet rays at first. In addition, rust of internal conductors and electrodes due to permeation of moisture or water is required. It is an extremely important requirement that the film has excellent moisture proof properties in order to prevent the occurrence of moisture. For this reason, conventionally, a glass plate has been used as the front side transparent protective member.

[0006]

However, while the glass plate is excellent in light resistance and moisture proof, it has the disadvantage that it is heavy, and it is easily damaged by impact.

[0007] A transparent resin film is light and has no problem of breakage due to impact. However, at present, a resin film having both good light resistance and good moisture resistance has not been provided. That is, for example, a fluororesin film such as 2-ethylene-4-fluorinated ethylene copolymer (ETFE) is known as a transparent resin film having excellent light resistance. Cannot be applied as a transparent protective member on the front side.

The present invention solves the above-mentioned conventional problems, and is a cover material used as a transparent protective member of a solar cell, which is made of a transparent film having both moisture-proof and light-proof properties, and reduces the weight of the solar cell. , A solar cell cover material that is effective for improving impact resistance and durability, a solar cell cover material dual-purpose sealing film, and a light weight using the solar cell cover material as a front side and / or back side transparent protective member , High impact resistance,
An object is to provide a highly durable solar cell.

[0009]

A cover material for a solar cell according to the present invention is a cover material used as a transparent protective member for a cell for a solar cell. Containing a curing agent and a crosslinking agent
It is characterized by being laminated and integrated with an A resin adhesive.

In the cover material for a solar cell of the present invention, the moisture resistance required for the transparent protective member of the solar cell is provided by a transparent high moisture-proof film, and the light resistance is provided by the transparent high light-resistant film and the EVA resin adhesive. Can be secured by the ultraviolet absorber. In addition, if this EVA resin adhesive is used,
EVA resin-based adhesives having a high moisture-proof property and a cross-linking agent are also excellent in weather resistance, and thus are effective in improving the properties of the cover material. As a crosslinking agent to be mixed with the EVA resin-based adhesive, an organic peroxide may be used.

In the present invention, as the transparent high moisture-proof film, a transparent film obtained by coating a polyethylene terephthalate (PET) film or the like with an inorganic oxide such as silica or alumina, or two such transparent films with their coated surfaces adhered to each other A laminated film obtained by combining them is preferable.

Further, as the transparent high light-resistant film, polytetrafluoroethylene (PTFE), 4-fluoroethylene-perchloroalkoxy copolymer (PFA),
Fluoroethylene-6-fluoropropylene copolymer (FE
P), 2-ethylene-4-fluoroethylene copolymer (E
TFE), poly 3-fluorochloroethylene (PCTF)
E), a fluororesin film such as polyvinylidene fluoride (PVDF) and polyvinyl fluoride (PVF), or
What formed the resin composition which kneaded the ultraviolet absorber into resin, such as acrylic, polycarbonate, PET, and polyethylene naphthalate (PEN), is suitable.

The solar cell cover material / sealing film of the present invention is a sealing film which also serves as a transparent protective member of a solar cell, and is obtained by laminating the above solar cell cover material of the present invention and an EVA film. It is one that is integrated.

The solar cell according to the present invention is a solar cell in which a solar cell is sealed between a front-side protective member and a back-side protective member. Using the solar cell cover material.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings.

In the following, a case where the cover material for a solar cell of the present invention is used as a front side transparent protective member will be exemplified. However, the solar cell cover material of the present invention may be used as a back side transparent protective member. Also, it may be used as both front and back protective members.

FIG. 1 is a sectional view showing an embodiment of a cover material for a solar cell according to the present invention, FIGS. 2 and 3 are sectional views showing an embodiment of a transparent and highly moisture-proof film according to the present invention, and FIG. FIG. 5 is a cross-sectional view showing an embodiment of a solar cell cover material / sealing film, and FIG. 5 is a cross-sectional view showing an embodiment of a solar cell of the present invention.

A cover material 1 for a solar cell shown in FIG. 1 is a sheet of an EVA resin-based adhesive (hereinafter, referred to as "ultraviolet absorbing EVA") in which a transparent high moisture-proof film 2 and a transparent high lightproof film 3 are blended with an ultraviolet absorbent and a crosslinking agent. This is referred to as an “adhesive sheet”).

As shown in FIG. 2, a transparent base film 2A such as a PET film is coated with C.
It is preferable to form a moisture-proof film 2B made of a coating film of an inorganic oxide such as silica or alumina by VD (chemical vapor deposition), PVD (reactive vapor deposition), or the like. That is, as a moisture-proof film, a film obtained by forming a coating film of a metal such as aluminum on a base film is also known. However, when a metal such as aluminum is applied to a solar cell, current may leak. As the moisture-proof film, an inorganic oxide coating film is preferable.

As shown in FIG. 2, the moisture-proof film 2B made of an inorganic oxide such as silica or alumina formed on the surface of the base film 2A is easily peeled off during handling. Therefore, as shown in FIG. 3, the transparent high moisture-proof film 2 has a moisture-proof film 2B made of an inorganic oxide such as silica or alumina on the surface of a base film 2A such as a PET film.
Are used, and these are used as moisture-proof films 2B,
It is preferable to use a film in which the moisture-proof film 2B is not exposed on the surface by bonding with the adhesive sheet 2C with the 2B side inside. As the adhesive sheet 2C,
The same UV-absorbing EVA adhesive sheet 4 used for bonding the transparent high-moisture-proof film 2 and the transparent high-light-resistant film 3 described later can be used (however, the UV-absorbing agent may not be blended). What is necessary is just to perform the bonding process under the bonding conditions.

In the case of a laminated high moisture barrier film as shown in FIG. 3, a PET film having a thickness of 6 to 250 μm is suitable as the base film 2A, and a moisture barrier film 2B having a thickness of about 5 μm or less. It is preferable to form it. Further, the thickness of the adhesive sheet 2C is preferably about 5 to 50 μm.

Examples of the transparent high light-resistant film 3 include a fluororesin film excellent in ultraviolet light resistance and a resin film kneaded with an ultraviolet absorbent.

Among them, the fluororesin film includes:
PTFE, PFA, FEP, ETFE, PCTFE, P
VDF, PVF film and the like can be mentioned.

As the resin film into which the ultraviolet absorbent is kneaded, acrylic, polycarbonate, PET,
PEN film and the like, and as the ultraviolet absorber, 2-hydroxy-4-octoxybenzophenone,
Benzophenones such as 2-hydroxy-methoxy-5-sulfobenzophenone; 2- (2′-hydroxy-5
Benzotriazoles such as-(methylphenyl) benzotriazole; hindered amine ultraviolet absorbers such as phenyl salicylate and pt-butylphenyl salicylate; ~ 20
It is blended in about weight%.

It is preferable that the thickness of such a transparent light-resistant film 3 is about 6 to 200 μm.

The UV-absorbing EVA adhesive sheet 4 includes:
A film obtained by forming a film of an EVA resin composition obtained by mixing an EVA resin with an ultraviolet absorber, a crosslinking agent, and other additives as necessary can be used.

An EVA resin composition suitable as a material for forming the ultraviolet absorbing EVA adhesive sheet 4 according to the present invention will be described below.

The EVA resin composition has a cross-linking structure by adding a cross-linking agent for improving weather resistance. The cross-linking agent is generally an organic peroxide which generates radicals at 100 ° C. or higher. The decomposition temperature with a half-life of 10 hours is 70 ° C.
Those described above are preferred. Such organic peroxides include, for example, 2,5-dimethylhexane; 2,5-dihydroperoxide; 2,5-dimethyl-2,5-
Di (t-butylperoxy) hexane; 3-di-t-butyl peroxide; t-dicumyl peroxide;
2,5-dimethyl-2,5-di (t-butylperoxy) hexyne; dicumyl peroxide; α, α′-bis (t-butylperoxyisopropyl) benzene; n
-Butyl-4,4-bis (t-butylperoxy) butane; 2,2-bis (t-butylperoxy) butane;
1,1-bis (t-butylperoxy) cyclohexane; 1,1-bis (t-butylperoxy) 3,3,5
-Trimethylcyclohexane; t-butylperoxybenzoate; benzoyl peroxide and the like can be used. The amount of these organic peroxides is generally E
It is 5 parts by weight or less, preferably 1 to 3 parts by weight, based on 100 parts by weight of the VA resin.

The EVA resin composition is blended with an ultraviolet absorber for imparting light resistance to the ultraviolet-absorbing EVA adhesive sheet 4. The ultraviolet absorber includes:
2-hydroxy-4-octoxybenzophenone, 2-
Benzophenones such as hydroxy-methoxy-5-sulfobenzophenone; benzotriazoles such as 2- (2'-hydroxy-5-methylphenyl) benzotriazole; phenyl salicylate, pt-butylphenyl salicylate And usually about 1 to 50 parts by weight based on 100 parts by weight of the EVA resin.

To the EVA resin composition, a silane coupling agent can be added to the EVA resin for the purpose of improving the adhesive strength between the transparent high moisture proof film 2 and the transparent high light fast film 3. Known silane coupling agents for this purpose include, for example, γ-chloropropyltrimethoxysilane; vinyltrichlorosilane; vinyltriethoxysilane; vinyl-tris- (β-methoxyethoxy) silane; γ-methacryloxy. Propyltrimethoxysilane; β- (3,4-ethoxycyclohexyl) ethyltrimethoxysilane; γ-glycidoxypropyltrimethoxysilane; vinyltriacetoxysilane; γ-mercaptopropyltrimethoxysilane; γ-aminopropyltrimethoxysilane N-β- (aminoethyl)-
γ-aminopropyltrimethoxysilane and the like can be mentioned. The amount of these silane coupling agents is
Generally, 5 parts by weight or less based on 100 parts by weight of the EVA resin,
Preferably it is 0.1 to 2 parts by weight.

Further, the gel fraction of the EVA resin is improved,
A crosslinking aid can be added to the EVA resin to improve durability. Examples of the crosslinking auxiliary used for this purpose include known triaryl isocyanurate; trifunctional crosslinking auxiliary such as triallyl isocyanate;
Monofunctional crosslinking assistants such as K ester can also be mentioned. The amount of these crosslinking aids is generally equal to the amount of EVA resin 1
10 parts by weight or less, preferably 1 to 5 parts by weight with respect to 00 parts by weight
Parts by weight.

Further, for the purpose of improving the stability of the EVA resin, hydroquinone; hydroquinone monomethyl ether; p-benzoquinone; methylhydroquinone and the like can be added, and the amount of these components is generally 100 parts by weight of the EVA resin. 5 parts by weight or less.

If necessary, a coloring agent, an antioxidant, a discoloration inhibitor and the like can be further added to the EVA resin composition. Examples of colorants include metal oxides, inorganic pigments such as metal powder, azo-based, phthalocyanine-based,
There are organic pigments such as ヂ -based, acidic or basic dye-based lakes. Antioxidants include amines; phenols; bisphenyls; and hindered amines.
t-butyl-p-cresol; bis (2,2,6,6-
Tetramethyl-4-piperazyl) sebacate and the like.

The thickness of the ultraviolet absorbing EVA adhesive sheet 4 made of such an EVA resin composition is preferably about 5 to 50 μm.

The solar cell cover material 1 of the present invention has an ultraviolet absorbing EVA adhesive sheet 4 interposed between the above-mentioned transparent and highly moisture-proof film 2 and the transparent and highly light-resistant film 3 so that the ultraviolet-absorbing EVA adhesive sheet 4 can be used. It can be easily manufactured by bonding and integrating by heating and pressing under bonding conditions.

In the cover material of the present invention, it is preferable that the transparent light-resistant film 3 is disposed on the front side and the transparent high moisture-proof film 2 is disposed on the inner side.

To manufacture the solar cell of the present invention using such a solar cell cover material, sealing is performed by using the cover material of the present invention instead of the conventional solar cell glass plate shown in FIG. At this time, it is preferable to use the cover material of the present invention by previously laminating and integrating it with the sealing EVA film.

As shown in FIG. 4, the encapsulating film 5 for a solar cell cover material according to the present invention comprises a transparent and highly moisture-proof film 2 and a transparent and highly light-resistant film 3 which are mixed with an ultraviolet absorber and a crosslinking agent.
Cover material 1 of the present invention adhered with VA resin adhesive
And the EVA film 6 are laminated and integrated.

The solar cell cover material / sealing film 5 is made of E
In manufacturing the VA film 6, the VA film 6 can be easily manufactured by laminating and integrating the solar cell cover material 1 of the present invention in which the transparent and highly moisture-proof film 2 and the transparent and highly light-resistant film 3 are bonded in advance. As the laminating temperature in this case, about 75 to 90 ° C. is appropriate.

As shown in FIG. 5, the solar cell 10 of the present invention uses the back cover 7, the EVA film 8,
The laminated body of the solar cell and the solar cell cover material / sealing film 5 is subjected to a conventional method by a vacuum laminator at a temperature of 120 to 150 ° C., a deaeration time of 2 to 15 minutes, and a press pressure of 0.5 to 1 atm. It can be easily manufactured by pressurizing under pressure for 8 to 45 minutes.

It should be noted that EV suitable as a material for forming an EVA film as a sealing film used in the solar cell of the present invention is preferably used.
The A resin composition is the same as the EVA resin composition suitable as a raw material for forming the above-mentioned ultraviolet absorbing EVA adhesive sheet 4.

This EVA resin composition for a sealing film also contains the same crosslinking agent as described above for improving the durability.
5 parts by weight or less, preferably 1 to 3 parts by weight, is added to 00 parts by weight to give a crosslinked structure.

Further, as a sealing film for a solar cell, the above-mentioned silane coupling agent is added to EVA resin in an amount of 5 parts by weight or less, preferably 0% by weight, based on 100 parts by weight of EVA resin for the purpose of improving the adhesion to the power generating element. .1 to 2 parts by weight.

Further, the gel fraction of the EVA resin is improved,
In order to improve the durability, the above-mentioned crosslinking aid can be added to the EVA resin in an amount of 10 parts by weight or less, preferably 1 to 5 parts by weight, based on 100 parts by weight of the EVA resin.

Further, for the purpose of improving the stability of the EVA resin, hydroquinone; hydroquinone monomethyl ether; p-benzoquinone;
5 parts by weight or less can be added to 100 parts by weight of the VA resin.

Further, if necessary, other than the above, the same coloring agents, ultraviolet absorbers, antioxidants, discoloration inhibitors and the like as described above can be added.

[0047]

As described in detail above, the cover material for a solar cell of the present invention is a transparent resin film having good moisture resistance and light resistance. By using such a solar cell, it is possible to provide a solar cell that is lightweight, has excellent impact resistance, and has excellent durability without problems of ultraviolet deterioration and rusting.

Since the solar cell cover material / sealing film of the present invention is formed by integrating the solar cell cover material of the present invention and the EVA film, the solar cell cover material / sealing film is also used. By using the blocking film, a lightweight solar cell having excellent impact resistance and durability can be efficiently manufactured based on good workability.

The solar cell of the present invention uses the solar cell cover material of the present invention as a front side and / or back side transparent protective member, and is lightweight and excellent in impact resistance and durability.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a solar cell cover material of the present invention.

FIG. 2 is a cross-sectional view showing an embodiment of a transparent high moisture-proof film according to the present invention.

FIG. 3 is a cross-sectional view showing an embodiment of a transparent high moisture-proof film according to the present invention.

FIG. 4 is a cross-sectional view showing an embodiment of a solar cell cover material / sealing film according to the present invention.

FIG. 5 is a sectional view showing an embodiment of a solar cell of the present invention.

FIG. 6 is a cross-sectional view showing a conventional solar cell.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cover material for solar cells 2 Transparent high moisture-proof film 3 Transparent high light-resistant film 4 Ultraviolet-absorbing EVA adhesive sheet 5 Sealing film also used as cover material for solar cells 6 EVA film 7 Back cover 8 EVA film 9 Silicon power generation element 10 Solar cell

Claims (10)

[Claims] 1. A cover material used as a transparent protective member of a solar cell, comprising: a transparent and highly light-resistant film and a transparent and highly moisture-proof film, wherein an ethylene-vinyl acetate copolymer is prepared by blending an ultraviolet absorber and a crosslinking agent. A solar cell cover material which is laminated and integrated with a resin-based adhesive. 2. The solar cell cover material according to claim 1, wherein the crosslinking agent is an organic peroxide. 3. The cover material for a solar cell according to claim 1, wherein the transparent high-moisture-proof film comprises a transparent film coated with an inorganic oxide. 4. The solar cell cover material according to claim 3, wherein the transparent high-moisture-proof film comprises a laminated film in which two coated surfaces of the transparent film are adhered to each other. 5. The solar cell cover material according to claim 3, wherein said transparent film is a polyethylene terephthalate film, and said inorganic oxide is silica or alumina. 6. The solar cell cover material according to claim 1, wherein the transparent light-resistant film is a fluororesin film. 7. The method according to claim 6, wherein the fluororesin is polytetrafluoroethylene, 4-fluoroethylene-perchloroalkoxy copolymer, 4-fluoroethylene-6-propylenepropylene copolymer, 2-ethylene A solar cell cover material comprising one or more members selected from the group consisting of -4-fluoroethylene copolymer, poly (3-fluoroethylene chloride), polyvinylidene fluoride and polyvinyl fluoride. 8. The transparent light-resistant film according to claim 1, wherein an ultraviolet absorbent is kneaded into one or more resins composed of acrylic, polycarbonate, polyethylene terephthalate and polyethylene naphthalate. A cover material for a solar cell, comprising a resin composition formed into a film. 9. A solar cell cover material and an ethylene-vinyl acetate copolymer film according to any one of claims 1 to 8, which is a sealing film also serving as a transparent protective member of the solar cell. And a sealing film that also serves as a cover material for solar cells. 10. A solar cell comprising a solar cell sealed between a front side protection member and a back side protection member,
9. The protection member according to claim 1, wherein the front side and / or the back side protection member is provided.
A solar cell, comprising the solar cell cover material according to any one of the above.