JP2000174299A - Cover material for solar cell, sealing film, and solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cover material used as a transparent protective member for a solar cell, comprising a transparent film having both moisture proof and light resistance, to reduce the weight, impact resistance and durability of the solar cell. Cell material, a solar cell cover material and a sealing film which is effective for improving the performance, and a light weight, high impact resistance, which uses the solar cell cover material as a front side and / or back side transparent protective member. Provide highly durable solar cells. SOLUTION: A solar cell cover material 1A made of a transparent film having high light resistance and high moisture resistance in which an inorganic oxide coating film 3 is formed on the surface of a transparent substrate film 2 mixed with an ultraviolet absorber. A solar cell cover material / sealing film 6 formed by laminating and integrating the solar cell cover material 1A and the EVA film 7. The solar cell 9 is disposed between the front-side transparent protective member made of the solar cell cover material 1A and the back-side protective member.
A solar cell 20 obtained by sealing the above.

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]

Means for Solving the Problems The solar cell cover material of the present invention is a cover material used as a transparent protective member of a solar cell, and is provided on a surface of a transparent substrate film containing an ultraviolet absorber. It is characterized by comprising a highly light-resistant and highly moisture-proof transparent film coated with an inorganic oxide.

According to the cover material for a solar cell of the present invention, the moisture absorption required for a transparent protective member of the solar cell is coated with an inorganic oxide coating, and the light resistance is mixed with a transparent substrate film. Each can be secured by an agent.

In the present invention, the transparent film having high light resistance and high moisture resistance is preferably a film obtained by coating a polyethylene terephthalate (PET) film containing an ultraviolet absorber with an inorganic oxide such as silica or alumina. A laminated film obtained by laminating a transparent protective film on the substrate is preferable.

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.

[0014]

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

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

1 to 3 are cross-sectional views showing an embodiment of a solar cell cover material 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 the solar cell of the present invention.

The solar cell cover material 1 shown in FIG. 1 has a light-proof high-moisture-proof structure in which a moisture-proof film made of an inorganic oxide coating film 3 is formed on the surface of a transparent substrate film 2 containing an ultraviolet absorber. Consists of a transparent film.

The base resin of the transparent base film 2 includes
Acrylic, polycarbonate, polyethylene terephthalate (PET), polyethylene naphthalate (PEN)
And the like. Preferably, PET is mentioned, and as the ultraviolet absorber blended in the base resin, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-methoxy-
Benzophenones such as 5-sulfobenzophenone; 2
Benzotriazoles such as-(2'-hydroxy-5-methylphenyl) benzotriazole; hindered amine-based ultraviolet absorbers such as phenylsulfate and pt-butylphenylsulfate; ,
About 1 to 20% by weight of the base resin is blended.

The thickness of such a transparent substrate film 2 is 1
The thickness is preferably about 2 to 200 μm.

Examples of the inorganic oxide forming the moisture-proof film include silica and alumina. The coating film of such an inorganic oxide is formed by CVD (chemical vapor deposition), PVD, or the like.
It can be formed by a (reactive vapor deposition) method or the like, and its thickness is preferably about 5 to 50 μm.

As a moisture-proof film, a film in which a coating film of a metal such as aluminum is formed on a base film is also known. However, when a metal such as aluminum is applied to a solar cell, current may leak. Therefore, in the present invention, a coating film of an inorganic oxide is used as the moisture-proof film.

As shown in FIG. 1, the coating film 3 formed on the surface of the transparent substrate film 2 and formed of an inorganic oxide such as silica or alumina is easily peeled during handling. Therefore, as a cover material of the present invention, as shown in FIG. 2, a transparent protective film 5 is adhered to the transparent base film 2 on which the inorganic oxide coating film 3 is formed by an adhesive sheet 4 on the coating film 3 side. A cover material 1A made of a laminated film or a transparent base material film 2 such as the PET film described above, and two films each having a coating film 3 made of an inorganic oxide such as silica or alumina formed on the surface thereof are used. Cover material 1 in which coating film 3 is not exposed on the surface by bonding with adhesive sheet 4 with coating films 3 and 3 facing inside.
It is preferable to use B. As the adhesive sheet 4,
An EVA film described below, which is generally used for the manufacture of a solar cell, is preferable, and the bonding treatment may be performed under the bonding conditions.

As the transparent protective film 5, acrylic, polycarbonate, PET, PEN film, etc.
Preferably, a PET film can be used, and the transparent protective film 5 may also contain an ultraviolet absorber. The thickness of the transparent protective film 5 is 6 to 20.
The thickness is preferably about 0 μm.
Is preferably about 5 to 50 μm.

The cover material of the present invention is not a laminated type as shown in FIGS. 2 and 3, but when the coating film 3 is exposed, the transparent base film 2 is located on the front side. As shown in FIG. 2, when the transparent protective films 5 are laminated, it is preferable that the transparent protective films 5 are arranged on the front side.

In order to manufacture the solar cell of the present invention using such a solar cell cover material, sealing is performed 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 sealing material 6 for a solar cell cover material according to the present invention comprises a cover material 1A of the present invention (the cover material 1 and the cover material 1B may be used) and an EVA film 7. Are laminated and integrated.

The sealing film 6 also serves as a cover material for a solar cell.
In manufacturing the VA film 7, it can be easily manufactured by laminating and integrating the solar cell cover material 1A of the present invention. The laminating temperature in this case is 75
A temperature of about 90 ° C. is appropriate.

Incidentally, the thickness of the EVA film 7 is 0.1 mm.
It is preferably about 1 to 1 mm.

As shown in FIG. 5, a solar cell 20 according to the present invention uses the back cover 8, the EVA film 9, the silicon
The laminated body of the solar cell such as 0 and the solar cell cover material / sealing film 6 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, a press pressure of 0.5 to It can be easily manufactured by press-bonding under heat and pressure at 1 atm and a press time of 8 to 45 minutes.

The EV used in the solar cell of the present invention
An EVA resin composition suitable as a raw material for forming the A film will be described below.

The EVA resin according to the present invention preferably has a vinyl acetate content of 25% by weight or less. When the vinyl acetate content is less than 25% by weight, the water vapor transmission rate is too large, and it is difficult to obtain sufficient moisture proofness as a sealing film for a solar cell. However, an EVA resin having an excessively low vinyl acetate content has poor processability and an excessively high viscosity, so that the ability to follow a silicon power generation element during the production of a solar cell is poor. Therefore, the vinyl acetate content of the EVA resin is low. It is preferably at least 10% by weight. In addition, this EVA resin has a melt flow rate of 0.7 to 20, especially 1.5 to
It is preferably 10.

The EVA resin composition according to the present invention has a cross-linking structure by adding a cross-linking agent for improving weather resistance. The cross-linking agent generally generates radicals at 100 ° C. or higher. Organic peroxides are used, and those having a half-life of 10 hours and a decomposition temperature of 70 ° C. or more are particularly preferable in consideration of stability at the time of compounding. 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'-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 compounding amount of these organic peroxides is generally 5 parts by weight or less, preferably 1 to 3 parts by weight, based on 100 parts by weight of the EVA resin.

As a sealing film for a solar cell, a silane coupling agent can be added to the EVA resin for the purpose of improving the adhesion to the power generating element. Known silane coupling agents for this purpose, for example, γ-chloropropyltrimethoxysilane; vinyltrichlorosilane; vinyltriethoxysilane; vinyl-tris-
(Β-methoxyethoxy) silane; γ-methacryloxypropyltrimethoxysilane; β- (3,4-ethoxycyclohexyl) ethyltrimethoxysilane; γ-glycidoxypropyltrimethoxysilane; vinyltriacetoxysilane; γ-mercapto Propyltrimethoxysilane; γ-aminopropyltrimethoxysilane; N-β
-(Aminoethyl) -γ-aminopropyltrimethoxysilane and the like. The amount of the silane coupling agent is generally 5 parts by weight or less, preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the EVA resin.

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. The amount of these components is generally 100 parts by weight of the EVA resin. 5 parts by weight or less.

Further, if necessary, a coloring agent, an ultraviolet absorber, an antioxidant, a discoloration inhibitor and the like can be added in addition to the above. Examples of the coloring agent include inorganic pigments such as metal oxides and metal powders, and organic pigments such as azo-based, phthalocyanine-based, azo-based, acidic or basic dye-based lakes. UV absorbers include 2-hydroxy-4-octoxybenzophenone; benzophenones such as 2-hydroxy-4-methoxy-5-sulfobenzophenone; 2- (2'-hydroxy-5-methylphenyl) benzotriazole; Benzotriazoles; phenyl salicylate; pt-
There are hindered amines such as butylphenyl salicylate. As anti-aging agents, amines; phenols;
Bisphenyl type; hindered amine type, for example, di-t-butyl-p-cresol; bis (2,2,6,6
-Tetramethyl-4-piperazyl) sebacate.

[0037]

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.

[0038] 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. 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 cover material for a solar cell of the present invention as a transparent protective member on the front side and / or the rear side, 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 sectional view showing another embodiment of the solar cell cover material of the present invention.

FIG. 3 is a cross-sectional view showing another embodiment of the solar cell cover material of 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.

[Description of Signs] 1, 1A, 1B Solar cell cover material 2 Transparent base film 3 Coating film 4 Adhesive sheet 5 Transparent protective film 6 Solar cell cover material / sealing film 7 EVA film 8 Back cover 9 EVA film 10 Silicon power generation element 20 solar cell

Claims (5)

[Claims] 1. A highly light-resistant and highly moisture-proof transparent film obtained by coating an inorganic oxide on the surface of a transparent substrate film containing an ultraviolet absorber, which is a cover material used as a transparent protective member of a solar cell. A cover material for a solar cell, comprising: 2. The solar cell cover material according to claim 1, comprising a laminated film in which a transparent protective film is bonded to a coating surface of the high light-resistant and high-moisture-proof transparent film. 3. The cover material for a solar cell according to claim 1, wherein the transparent substrate film is a polyethylene terephthalate film containing an ultraviolet absorber, and the inorganic oxide is silica or alumina. . 4. A solar cell cover material and an ethylene-vinyl acetate copolymer film according to claim 1, which is a sealing film also serving as a transparent protective member of a solar cell. And a sealing film that also serves as a cover material for solar cells. 5. A solar cell comprising a solar cell sealed between a front side protection member and a back side protection member, wherein the front side and / or the back side protection member is any one of claims 1 to 3. A solar cell, which is the solar cell cover material according to claim 1.