JP2001044462A - Solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lead wire insertion opening, where the edge face of a galvanized steel sheet is not exposed to a back sealing film, a three-layered film composed of EVA (ethylene-vinyl acetate copolymer resin) film/galvanized steel sheet/EVA film is used as the back sealing film so as to turn a solar cell flame-retardant or noncombustible. SOLUTION: Sealing films 3A and 10 are interposed between a surface transparent protective member 1 and a rear protective member 2, to seal up solar cells 4 for the formation of a solar cell module, where the sealing film 10 of three-layered film composed of two EVA films 11A and 11B and a galvanized steel sheet interposed between them is used as a sealing film interposed between the solar cells 4 and the rear protective member 2. A lead wire insertion opening is provided to the sealing film 10, and the edge faces of the galvanized steel sheet 12 facing the opening 5 are covered with the fused solid of an EVA film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solar cell using an ethylene-vinyl acetate copolymer (EVA) film sealing film, and more particularly to a method for solving the problem of flammability of an EVA film. The present invention relates to a solar cell in which the flame retardancy of a film is significantly improved, wherein the sealing film has an opening for inserting a lead wire.

[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. 4, a solar cell generally has an EVA film sealing film 3A between a transparent substrate 1 such as a glass substrate as a front transparent protective member and a rear protective member (back cover) 2. , 3B, the solar cell such as the silicon power generation element 4 is sealed. In addition,
Hereinafter, the sealing film disposed on the light receiving surface side with respect to the cell is referred to as “front side sealing film”, and the sealing film disposed on the rear side of the cell is referred to as “back side sealing film”.

In a solar cell, a silicon power generation element 4
A lead wire 6 for conduction is attached to the
Must be brought out. When this lead wire is pulled out from the side end surface of the solar cell, a problem such as intrusion of moisture from this portion occurs. Therefore, usually, an opening 5 is provided in the back cover 2 and the back surface sealing film 3B. A lead wire 6 is inserted through the opening 5 and drawn out.

In such a solar cell, a transparent substrate 1, a front-side sealing film 3A and a silicon power generation element 4, a back-side sealing film 3B provided with an opening 5, and a back cover 2 are laminated in this order. It is manufactured by applying heat and pressure, cross-linking and curing the EVA of the sealing films 3A and 3B and bonding and integrating them.

However, since solar cells are expensive at present, arranging the solar cells further on the roofing material increases the cost. Therefore, in order to reduce the construction cost, the solar cell is replaced with the roofing material. It is considered that the solar cell itself is used as a roofing material, and the cost is suppressed by omitting the roofing material instead of disposing the solar cell on the roofing material.

[0007]

SUMMARY OF THE INVENTION However, EVA
Although the film has excellent adhesiveness, E
Since VA is heated and dripped and burned, it has a drawback that it cannot be directly used as a roofing material.

As a method for imparting flame retardancy or non-combustibility to a solar cell, as shown in FIG.
It is conceivable to use a sealing film (hereinafter, referred to as a “three-layer film”) 10 formed by laminating and integrating layers 1 and 11 via a zinc steel plate 12. With such a three-layer film, extremely good flame retardancy and nonflammability can be secured by the zinc steel plate inside.

When the three-layer film 10 is made of a zinc steel plate 12, the light transmittance is slightly inferior to that of a normal EVA film. The use of this three-layer film 10 and the use of a normal EVA film as the front-side sealing film does not impair the light transmittance. Therefore, it is possible to obtain good flame retardancy and non-combustibility while maintaining high power generation efficiency. It is preferable for obtaining.

However, such a three-layer film 1
When a lead wire insertion opening is formed in this three-layer film 10 in order to use 0 as a back surface side sealing film, the end surface of the zinc steel plate 12 is exposed on the inner surface of the opening, and the zinc steel plate and the lead wire are conducted. Leakage, galvanization of the zinc steel plate, and partial elution occur, causing problems such as a decrease in power generation efficiency, deterioration in appearance due to yellowing, and a decrease in durability.

The present invention solves such a problem, and uses a three-layer film of EVA film / zinc steel plate / EVA film as a backside sealing film in order to impart flame retardancy or nonflammability to the solar cell. It is an object of the present invention to provide a solar cell having an opening for inserting a lead wire in which an end surface of a zinc steel sheet is not exposed in the sealing film.

[0012]

Means for Solving the Problems The sealing film for a solar cell of the present invention is provided between a front side transparent protective member and a back side protective member.
In a solar cell in which a solar cell is sealed using a sealing film, a sealing film interposed between the solar cell and the back surface side protective member is made of a zinc steel sheet made of two EVA films. Film (three-layer film) formed by laminating and integrating through an opening, and an opening for lead wire insertion is provided in the sealing film, and the end face of the zinc steel sheet facing this opening is a molten and solidified product of the EVA film. Characterized by being coated with

In this solar cell, the zinc steel sheet facing the opening provided in the three-layer film of the backside sealing film is covered with the molten and solidified material of the EVA film, so that the end face of the zinc steel sheet appears on the inner surface of the opening. Problems such as electric leakage, rusting, and elution are eliminated.

[0014] The solar cell of the present invention is a solar cell in which, after perforating an opening in the three-layer film, the one EVA film is heated to melt one end of the EVA film to cover the end face of the zinc steel sheet. It is preferable that a perforation is made so as to protrude inward of the opening from the edge of the opening of the zinc steel sheet. In particular, an opening is provided so as to be continuous with the back side protective member and the three-layer film, and the zinc steel sheet facing this opening It is preferable that the end surface of the EVA film and the end surface of the back surface side protective member are covered with a molten and solidified product of the EVA film.

[0015]

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

FIG. 1 is a sectional view showing a method for coating an end face of a zinc steel sheet with a three-layer film used as a backside sealing film in the present invention. FIG. 2 is a sectional view showing an embodiment of the solar cell of the present invention. In FIGS. 1 and 2, members having the same functions as those shown in FIGS. 3 and 4 are denoted by the same reference numerals.

In the present invention, in order to perforate an opening for inserting lead wires in the three-layer film 10 used as the backside sealing film and cover the end face of the zinc steel sheet facing this opening with the molten and solidified EVA film, First, as shown in FIG.
It has a long cutting blade 20A on the inner circumference and a short cutting blade 20 on the outer circumference.
B using a Thomson blade 20 or the like
1 is pressed against the three-layer film 10 to cut out one of the EVA film 11A and the zinc steel plate 12, as shown in FIG. 1 (b), and the other EVA film 11B having a smaller opening area than the opening 5a. Opening 5 to cut out only
b is formed, and the opening 5A is perforated so that the edge of the opening 5b of the EVA film 11B protrudes inward from the opening edge of the zinc steel plate 12. When heated in this state, E
The VA film 11B melts and its overhanging edge 11d
Is melted and flows to the exposed end face side of the zinc steel sheet 12, and is solidified while covering the same, so that the exposed end face of the zinc steel sheet 12 is melt-solidified with the EVA film 11B as shown in FIG. Object 11M.

In the three-layer film 10 according to the present invention, when the opening 5 is formed, the overhang width W of the overhanging edge portion 11d is set to a value corresponding to the molten and solidified product 11 of the EVA film 11B.
It is necessary to perform perforation so that the end face of the zinc steel plate 12 can be sufficiently covered with M. The overhang width W varies depending on the thickness of the three-layer film EVA film 11B and the zinc steel plate 12, but generally ranges from 1 to 10 mm.
mm, and the end face of the zinc steel plate 12 has a thickness of 20 to 80 mm.
It is desirable to cover with a melt solidified product 11M of an EVA film of about 0 μm.

In order to manufacture a solar cell using such a three-layer film 10, as shown in FIG. 2A, a transparent substrate 1, a front-side sealing film (EVA film) 3A and a silicon power generation element 4 are formed. And an opening 5 for inserting a lead wire in advance.
A, 3A film provided with 2A and back cover 2
According to a conventional method, the laminate is heated and pressed 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 1 kg / cm ² , and a press time of 8 to 45 minutes. And integrate them.

As a result, the laminate is firmly integrated by EVA (part E in FIG. 2B). At this time, as shown in FIG. 2B, the EVA film 11B of the three-layer film 10 is formed. Is melted and flows along the inner surface of the opening 5, so that the molten and solidified material 1 of the EVA film
At 1M, the end face of the zinc steel plate 12 facing the opening 5 and the end face of the back cover 2 are covered.

Therefore, according to the present invention, the problems of electric leakage, rusting and elution due to the end surface of the zinc steel plate 12 of the three-layer film 10 being exposed on the inner surface of the opening 5 are eliminated.

In the present invention, the zinc steel plate 12 constituting the three-layer film 10 is preferably a steel plate having a thickness of 10 to 50 μm and a zinc coating having a thickness of 0.1 to 5.0 μm formed on the front and back surfaces.

It is preferable to use the EVA film 11 having a thickness of 20 to 800 μm in order to secure the adhesiveness and to obtain the effect of improving the flame retardancy and nonflammability of the zinc steel sheet.

The sealing film 10 for a solar cell is coated or calendered to form an EVA film 11, 1
1 can be easily manufactured by laminating through a zinc steel plate 10 and bonding or temporarily bonding.

On the other hand, the thickness of the EVA film 3 as the front-side sealing film is preferably about 20 to 800 μm.

EVA films suitable as a raw material for forming an EVA film as a front-side sealing film and a three-layer EVA film used in the present invention are as follows.

The EVA used in the present invention has a vinyl acetate content of 10 to 50% by weight, particularly 15 to 40% by weight,
Melt flow rate is 0.7-20, especially 1.5-10
It is preferable that

It is preferable that the EVA used in the present invention has a crosslinked structure by adding a crosslinker for the purpose of improving the weather resistance. The crosslinker is generally an organic compound which generates radicals at 100 ° C. or higher. A peroxide is used, and in particular, in consideration of the stability at the time of blending, those having a decomposition temperature of 70 ° C. or more with a half-life of 10 hours are preferable. Examples of such an organic peroxide include 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) hexine; 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-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 5 parts by weight or less based on 100 parts by weight of EVA.
Preferably, it is 1 to 3 parts by weight.

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

Further, a crosslinking aid can be added to EVA in order to improve the gel fraction of EVA and improve durability. Examples of the crosslinking aid used for this purpose include trifunctional crosslinking aids such as triallyl isocyanurate and triallyl isocyanate as well as monofunctional crosslinking aids such as NK esters. it can. The amount of these crosslinking aids is generally 10 parts by weight or less, preferably 1 to 5 parts by weight, based on 100 parts by weight of EVA.

Further, for the purpose of improving the stability of EVA, hydroquinone; hydroquinone monomethyl ether;
-Benzoquinone; methylhydroquinone and the like can be added, and the blending amount thereof is generally 5 parts by weight or less based on 100 parts by weight of EVA.

Further, if necessary, a coloring agent, an ultraviolet absorber, an antioxidant, a discoloration inhibitor, a flame retardant and the like can be added in addition to the above. Examples of colorants include metal oxides,
There are inorganic pigments such as metal powder, and organic pigments such as azo-based, phthalocyanine-based, azo-based, acidic or basic dye-based lakes. Ultraviolet absorbers include benzophenones such as 2-hydroxy-4-octoxybenzophenone; 2-hydroxy-4-methoxy-5-sulfobenzophenone; 2- (2 ′
Benzotriazoles such as -hydroxy-5-methylphenyl) benzotriazole; phenyl salicylate;
There are hindered amines such as pt-butylphenyl salicylate. Antioxidants include amines; phenols; bisphenyls; and hindered amines.
For example, di-t-butyl-p-cresol; bis (2,
2,6,6-tetramethyl-4-piperazyl) sebacate and the like.

Examples of the flame retardant include organic flame retardants and inorganic flame retardants containing one or more halogen atoms, preferably chlorine atoms or bromine atoms, in the molecule.

Here, examples of the organic flame retardant include chlorinated paraffin, chlorinated polyethylene, hexachloroendmethylenetetrahydrophthalic acid, perchloropentacyclodecane, phthalic anhydride tetrachloride, and the like, and tris (2, 2).
A monomer or polymer having an aromatic ring such as (3-dibromopropyl) isocyanurate and having no halogen atom directly bonded to the aromatic ring, 1,1,2,2-tetrabromoethane, 1,4-dibromobutane , 1,3-dibromobutane, 1,5-dibromopentane, ethyl α-bromobutyrate, 1,2,5,6,9,10-hexabromocyclodecane and the like having no aromatic ring.

Examples of inorganic flame retardants include inorganic hydroxides such as aluminum hydroxide and magnesium hydroxide;
Phosphorus oxides such as ammonium phosphate and zinc phosphate, and red phosphorus are exemplified.

The amounts of these flame retardants are EVA100
The amount is preferably 70 parts by weight or less, particularly preferably 1 to 50 parts by weight based on parts by weight.

In the present invention, if necessary, antimony trioxide and / or expanded graphite can be added to EVA as a flame retardant aid. In this case, the compounding amount of the expanded graphite is E
It is preferably 20% by weight or less, especially 1 to 15% by weight of the whole VA film, and the compounding amount of antimony trioxide is 10% by weight or less, particularly 2 to 8% of the whole EVA film.
% By weight.

In the present invention, the three-layer film can provide extremely good flame retardancy and non-flammability, so that the front side transparent substrate 1 and the like do not need to have high fire resistance. Therefore, since the three-layer film has an increase in the weight of the zinc steel sheet as compared with the normal EVA film, from the viewpoint of preventing the increase in the weight of the entire solar cell, the front transparent substrate 1 is made of a glass plate. Instead, it is preferable to use a transparent resin plate made of lightweight polycarbonate, acrylic, or the like.

The back cover may be made of a fluorinated polyethylene film such as polyethylene monofluoride, polyethylene difluoride, or polyethylene trifluoride, a polyester film, or an aluminum foil, such as polyethylene monofluoride, on both sides or one side. A laminate of films having high weather resistance can be used, but a transparent resin plate such as polyester or polycarbonate may be used. In the present invention, since the three-layer film can secure a certain degree of rigidity, rigidity is not required for the back cover on the back side, and therefore, the back cover is provided on the back side of the three-layer film, acrylic, polyester, epoxy Alternatively, it may be a coating film of a fluorine-based paint.

[0040]

As described in detail above, since the solar cell of the present invention uses a three-layer film of EVA film / zinc steel plate / EVA film as the back side sealing film, it has extremely good flame retardancy or non-combustibility. Yes, it can be used alternately as a roofing material, and construction costs can be reduced.

Further, in the solar cell according to the present invention, the end face of the zinc steel sheet facing the lead wire insertion opening of the three-layer film is EV
A is covered with the melted solidified A film,
It is free from problems such as rusting and elution and can maintain a high heat generation power and appearance of a solar cell for a long period of time, and is extremely excellent in durability.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a method of coating a zinc steel sheet end face with a three-layer film used as a backside sealing film in the present invention.

FIG. 2 is a sectional view showing an embodiment of the solar cell of the present invention.

FIG. 3 is a cross-sectional view showing a configuration of a three-layer film used as a back-side sealing film in the present invention.

FIG. 4 is a cross-sectional view showing a general solar cell.

[Explanation of symbols]

 Reference Signs List 1 transparent substrate 2 back cover 2A opening 3A, 3B sealing film (EVA film) 4 silicon power generation element 5, 5A, 5a, 5b opening 6 lead wire 10 three-layer film 11, 11A, 11B EVA film 11M EVA film solidification Thing 12 Zinc steel plate 20 Thomson blade

Claims (3)

[Claims] 1. A solar cell comprising a solar cell sealed with a sealing film between a front transparent protective member and a rear protective member, wherein the solar cell and the rear protective member are sealed. Is a sealing film formed by laminating and integrating two ethylene-vinyl acetate copolymer resin films via a zinc steel sheet, and for inserting lead wires into the sealing film. A solar cell, wherein an end face of a zinc steel sheet facing the opening is covered with a molten and solidified product of the ethylene-vinyl acetate copolymer resin film. 2. The zinc-steel sheet according to claim 1, wherein an opening is formed in the sealing film, and then one of the ethylene-vinyl acetate copolymer resin films is melted by heating to cover the opening-side end surface of the zinc steel sheet. A solar cell, wherein the one ethylene-vinyl acetate copolymer resin film is perforated so as to protrude inward of the opening from the opening edge of the zinc steel sheet. 3. The opening according to claim 1, wherein the opening is provided so as to be continuous with the back side protection member and the sealing film, and the end face of the zinc steel plate facing the opening and the end face of the back side protection member. Is coated with a melt-solidified product of an ethylene-vinyl acetate copolymer resin film.