JP2013030584A - Sealing film for solar cell, and solar cell using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing film for a solar cell having improved designability by harmonizing colors with a solar battery cell.SOLUTION: The sealing film 13B for the solar cell arranged on a rear side of a solar battery cell 14 for sealing the solar battery cell 14 is characterized by containing an ethylene-polar monomer copolymer, a crosslinking agent, and a colorant, in which the colorant is a white pigment having an average grain diameter of 150 to 230 nm.

Description

  The present invention relates to a solar battery sealing film disposed on the back side of a solar battery cell, and particularly to a solar battery sealing film with improved design and a solar battery including the same.

  In recent years, solar cells that directly convert sunlight into electrical energy have been widely used from the viewpoints of effective use of resources and prevention of environmental pollution, and further development has been promoted in terms of power generation efficiency and weather resistance. As a solar cell, a crystalline silicon solar cell that has been widely manufactured conventionally, a thin film solar cell that can be manufactured at low cost, and the like are known.

  As shown in FIG. 1, the crystalline silicon solar cell generally has a surface side transparent protective member 11 made of a glass substrate or the like, a surface side sealing film 13A, a solar battery cell 14 made of single crystal or polycrystalline silicon, and a back surface side. The sealing film 13B and the back surface side protection member (back cover) 12 are laminated in this order, and after deaeration under reduced pressure, the surface side sealing film 13A and the back surface side sealing film 13B are crosslinked and cured by heating and pressurization. It is manufactured by bonding and integration.

  Moreover, as a thin film type solar cell, a thin film silicon type, a thin film amorphous silicon type solar cell, a copper indium selenide (CIS) type solar cell, etc. are known. For example, as shown in FIG. After the solar battery cell 24 including the thin film power generation element such as a semiconductor layer is formed on the surface of the front surface side transparent protective member 21 such as a substrate by chemical vapor deposition or the like, the sealing film 23 and the back surface side protective member 22 are formed thereon. Are laminated in this order and bonded and integrated.

  Conventionally, as a sealing film for solar cells, a film made of an ethylene-polar monomer copolymer such as an ethylene vinyl acetate copolymer (EVA) or an ethylene ethyl acrylate copolymer (EEA) has been used. In particular, an EVA film is preferably used because it is inexpensive and has high transparency. The ethylene-polar monomer copolymer film for the sealing film is crosslinked by using a crosslinking agent such as an organic peroxide in addition to the ethylene-polar monomer copolymer in order to improve the film strength and durability. The density is improved.

  In order to improve the power generation efficiency of the solar battery, it is necessary to make light enter the battery as efficiently as possible and concentrate it on the solar battery cell. Therefore, for the sealing film disposed on the back surface side of the solar battery cell, light at the interface between the front surface side sealing film and the back surface side sealing film inside the solar battery by blending titanium dioxide and coloring white. A sealing film has been developed in which light incident between solar cells is diffusely reflected by the reflection of light or the irregular reflection of light by the white pigment itself, and the reflected light is effectively used (Patent Document 1).

JP 2010-245391 A

  Since the external appearance of the sealing film disposed on the back surface side of the solar battery cells is visually recognized from the gaps between the solar battery cells, the harmony of the color tone with the solar battery cells whose surface is blue or black is required. However, the solar cell sealing film of Patent Document 1 may appear yellowish by blending with titanium dioxide, and may lack color harmony with the solar cells. In particular, since the number of solar cells installed on the roofs of ordinary houses has been increasing in recent years, there has been a strong demand for improving the design of solar cells.

  Accordingly, an object of the present invention is a solar cell sealing film disposed on the back surface side of a solar battery cell for sealing the solar battery cell, the solar battery sealing film having improved design properties. It is to provide. Moreover, it is providing the solar cell using this sealing film for solar cells.

  The above object is a solar cell sealing film that is disposed on the back side of a solar cell to seal the solar cell, and includes an ethylene-polar monomer copolymer, a crosslinking agent, and a colorant, and the coloring The agent is a white pigment having an average particle diameter of 150 to 230 nm, and is achieved by a sealing film for solar cells.

  By setting the average particle diameter of the colorant within the above range, it is possible to reflect more light in the short wavelength region (particularly, 400 to 700 nm) out of the wavelength of light reflected from the sealing film, and It becomes possible to increase the blueness of the entire stop film. Thereby, it is possible to prevent the sealing film from being yellowish and to match the color tone of the solar battery cell.

Preferred embodiments of the present invention are as follows.
(1) The white pigment is titanium dioxide.
(2) 0.1-10 mass parts of white pigment is included with respect to 100 mass parts of ethylene-polar monomer copolymer.
(3) The ethylene-polar monomer copolymer is an ethylene-vinyl acetate copolymer.

  The above object is also achieved by a solar cell using this solar cell sealing film.

  According to the solar cell sealing film according to the present invention, by reflecting more light in the short wavelength region of the solar spectrum, the yellowness of the solar cell sealing film decreases and the bluish color increases. It becomes possible to match the color tone with the solar battery cell. Therefore, a solar cell with improved design properties can be provided.

It is a schematic sectional drawing which shows an example of a crystalline silicon type solar cell. It is a schematic sectional drawing which shows an example of a thin film type solar cell.

  Hereinafter, the solar cell sealing film and solar cell of the present invention will be described in detail.

[White pigment]
In the present invention, the white pigment blended in the sealing film is one having an average particle diameter of 150 to 230 nm, preferably 200 to 220 nm. If it is smaller than 150 nm, it tends to aggregate during processing, and it may be difficult to uniformly disperse. If it is larger than 230 nm, yellowishness may occur and the designability may be lowered.

  In the present invention, the average particle diameter is determined by observing the solar cell sealing film with an electron microscope (preferably with a transmission electron microscope) at a magnification of about 1,000,000 times, and measuring at least 100 white pigment projected area equivalent circle diameters. The average value is taken.

  Examples of white pigments include inorganic pigments such as titanium dioxide, calcium carbonate, and aluminum oxide. These can be used alone or in combination of two or more. Among the white pigments, titanium dioxide is preferable because of good colorability and processability.

  Content of a white pigment is 0.1-20 mass parts with respect to 100 mass parts of ethylene-polar monomer copolymers, Preferably it is 1-10 mass parts. If it is this range, a white pigment can be disperse | distributed favorably and it can maintain, without reducing the adhesiveness of a sealing film.

[Ethylene-polar monomer copolymer]
In the present invention, examples of the polar monomer of the ethylene-polar monomer copolymer include an unsaturated carboxylic acid, a salt thereof, an ester thereof, an amide thereof, a vinyl ester, and carbon monoxide. More specifically, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, fumaric acid, itaconic acid, monomethyl maleate, monoethyl maleate, maleic anhydride, itaconic anhydride, lithium of these unsaturated carboxylic acids, sodium, Salts of monovalent metals such as potassium, salts of polyvalent metals such as magnesium, calcium and zinc, methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, n-butyl acrylate, isooctyl acrylate, methacrylic acid Examples include unsaturated carboxylic acid esters such as methyl, ethyl methacrylate, isobutyl methacrylate, and dimethyl maleate, vinyl esters such as vinyl acetate and vinyl propionate, carbon monoxide, sulfur dioxide, etc. be able to.

  More specifically, as the ethylene-polar monomer copolymer, ethylene-acrylic acid copolymer, ethylene-unsaturated carboxylic acid copolymer such as ethylene-methacrylic acid copolymer, the ethylene-unsaturated carboxylic acid Ionomer in which some or all of carboxyl groups of copolymer are neutralized with the above metal, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene- Isobutyl acrylate copolymer, ethylene-unsaturated carboxylic acid ester copolymer such as ethylene-n-butyl acrylate copolymer, ethylene-isobutyl acrylate-methacrylic acid copolymer, ethylene-n-butyl acrylate -Ethylene-unsaturated carboxylic acid ester-unsaturated carboxylic acid such as methacrylic acid copolymer Some or all of the copolymer and its carboxyl group ionomer neutralized with the metal, ethylene - can be exemplified vinyl ester copolymer as a typical example - ethylene such as vinyl acetate copolymer.

  As the ethylene-polar monomer copolymer, it is preferable to use a copolymer having a melt flow rate defined by JIS K7210 of 35 g / 10 min or less, particularly 3 to 6 g / 10 min. According to the sealing film for solar cells using the ethylene-polar monomer copolymer having such a melt flow rate, the sealing film is melted or positioned at the time of heating and pressing in the sealing process at the time of manufacturing the solar battery. It is possible to suppress the occurrence of deviation and the protrusion from the end of the substrate. In the present invention, the value of the melt flow rate (MFR) is measured based on conditions of 190 ° C. and a load of 21.18 N according to JIS K7210.

  As the ethylene-polar monomer copolymer, an ethylene-vinyl acetate copolymer (also referred to as EVA) is particularly preferable. Thereby, it is cheap and can form the sealing film for solar cells excellent in a softness | flexibility.

  The content of vinyl acetate in the ethylene-vinyl acetate copolymer is preferably 20 to 35% by mass, more preferably 22 to 30% by mass, and particularly preferably 24 to 28% by mass with respect to the ethylene-vinyl acetate copolymer. . When the content of vinyl acetate is less than 20% by mass, the fluidity of the composition for sealing film is lowered, and the workability of the sealing film for solar cell may be lowered, and when it exceeds 35% by mass. Further, carboxylic acid, alcohol, amine and the like are generated, and foaming may easily occur at the interface with the member in contact with the sealing film.

  In addition to the ethylene-polar monomer copolymer, the solar cell encapsulating film of the present invention further comprises a polyvinyl acetal resin (for example, polyvinyl formal, polyvinyl butyral (PVB resin), modified PVB), and a vinyl chloride resin. May be used for In that case, PVB is particularly preferable.

[Crosslinking agent]
In the present invention, the crosslinking agent is capable of forming a crosslinked structure of an ethylene-polar monomer copolymer. As the crosslinking agent, an organic peroxide or a photopolymerization initiator is preferably used. Among these, it is preferable to use an organic peroxide because a sealing film with improved temperature dependency of adhesive strength, moisture resistance, and penetration resistance can be obtained.

  Any organic peroxide may be used as long as it decomposes at a temperature of 100 ° C. or higher and generates radicals. The organic peroxide is generally selected in consideration of the film formation temperature, the adjustment conditions of the composition, the curing temperature, the heat resistance of the adherend, and the storage stability. In particular, those having a decomposition temperature of 70 hours or more with a half-life of 10 hours are preferred.

  Examples of the organic peroxide include, from the viewpoint of resin processing temperature and storage stability, for example, benzoyl peroxide curing agent, tert-hexyl peroxypivalate, tert-butyl peroxypivalate, 3, 5, 5- Trimethylhexanoyl peroxide, di-n-octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, succinic acid peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, 2,5-dimethyl-2,5-di (2-ethylhexanoylperoxy) hexane, 1-cyclohexyl-1-methylethyl Peroxy-2-ethylhexanoate, tert-hexyl par Xyl-2-ethylhexanoate, 4-methylbenzoyl peroxide, tert-butylperoxy-2-ethylhexanoate, m-toluoyl + benzoyl peroxide, benzoyl peroxide, 1,1-bis (tert-butyl Peroxy) -2-methylcyclohexanate, 1,1-bis (tert-hexylperoxy) -3,3,5-trimethylcyclohexanate, 1,1-bis (tert-hexylperoxy) cyclohexanate 1,1-bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (tert-butylperoxy) cyclohexane, 2,2-bis (4,4-di-tert) -Butylperoxycyclohexyl) propane, 1,1-bis (tert-butyl) -Oxy) cyclododecane, tert-hexylperoxyisopropyl monocarbonate, tert-butylperoxymaleic acid, tert-butylperoxy-3,3,5-trimethylhexane, tert-butylperoxylaurate, 2,5- Dimethyl-2,5-di (methylbenzoylperoxy) hexane, tert-butylperoxyisopropyl monocarbonate, tert-butylperoxy-2-ethylhexyl monocarbonate, tert-hexylperoxybenzoate, 2,5-di-methyl -2,5-di (benzoylperoxy) hexane, and the like.

  As the benzoyl peroxide-based curing agent, any can be used as long as it decomposes at a temperature of 70 ° C. or higher to generate radicals, and those having a decomposition temperature of 50 hours or higher with a half-life of 10 hours are preferable, It can be appropriately selected in consideration of preparation conditions, film formation temperature, curing (bonding) temperature, heat resistance of the adherend, and storage stability. Usable benzoyl peroxide curing agents include, for example, benzoyl peroxide, 2,5-dimethylhexyl-2,5-bisperoxybenzoate, p-chlorobenzoyl peroxide, m-toluoyl peroxide, 2, Examples include 4-dichlorobenzoyl peroxide and t-butyl peroxybenzoate. The benzoyl peroxide curing agent may be used alone or in combination of two or more.

  As organic peroxides, in particular, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, 1,1-bis (tert-hexylperoxy) -3,3,5-trimethylcyclohexane preferable. Thereby, the sealing film for solar cells which has the outstanding insulating property is obtained.

  The content of the organic peroxide is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass with respect to 100 parts by mass of the ethylene-polar monomer copolymer. If the content of the organic peroxide is small, the insulating properties of the resulting sealing film may be lowered, and if it is increased, the compatibility with the copolymer may be deteriorated.

  As the photopolymerization initiator, any known photopolymerization initiator can be used, but a photopolymerization initiator having good storage stability after blending is desirable. Examples of such a photopolymerization initiator include 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, and 2-methyl-1- (4- (methylthio) phenyl). Acetophenones such as 2-morpholinopropane-1, benzoins such as benzyldimethylketal, benzophenones such as benzophenone, 4-phenylbenzophenone and hydroxybenzophenone, thioxanthones such as isopropylthioxanthone and 2-4-diethylthioxanthone, As other special ones, methylphenylglyoxylate can be used. Particularly preferably, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- (4- (methylthio) phenyl) -2-morpholinopropane-1, Examples include benzophenone. These photopolymerization initiators may contain one or two or more kinds of known and commonly used photopolymerization accelerators such as benzoic acid-based or tertiary amine-based compounds such as 4-dimethylaminobenzoic acid as required. Can be mixed and used. Moreover, it can be used individually by 1 type of only a photoinitiator, or 2 or more types of mixture.

  It is preferable that content of the said photoinitiator is 0.5-5.0 mass parts with respect to 100 mass parts of ethylene-polar monomer copolymers.

[Crosslinking aid]
The solar cell sealing film of the present invention may further contain a crosslinking aid, if necessary. The cross-linking aid can improve the gel fraction of the ethylene-polar monomer copolymer and improve the adhesion and durability of the sealing film.

  The content of the crosslinking aid is generally 10 parts by mass or less, preferably 0.1 to 5 parts by mass, more preferably 0.1 to 2.5 parts by mass with respect to 100 parts by mass of the ethylene-polar monomer copolymer. Used in the department. Thereby, the sealing film excellent in adhesiveness is obtained.

  Examples of the crosslinking aid (compound having a radical polymerizable group as a functional group) include trifunctional crosslinking aids such as triallyl cyanurate and triallyl isocyanurate, and (meth) acrylic esters (eg, NK ester) ) Monofunctional or bifunctional crosslinking aids. Of these, triallyl cyanurate and triallyl isocyanurate are preferable, and triallyl isocyanurate is particularly preferable.

[Adhesion improver]
The sealing film for solar cell of the present invention preferably has excellent adhesive strength in consideration of the sealing performance inside the solar cell. Therefore, an adhesion improver may be further included. As the adhesion improver, a silane coupling agent can be used. Thereby, it becomes possible to form the sealing film for solar cells which has the outstanding adhesive force. Examples of the silane coupling agent include γ-chloropropylmethoxysilane, vinylethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, and γ-glycidoxypropyltrimethoxy. Silane, γ-glycidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, vinyltrichlorosilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β Mention may be made of-(aminoethyl) -γ-aminopropyltrimethoxysilane. These silane coupling agents may be used alone or in combination of two or more. Of these, γ-methacryloxypropyltrimethoxysilane is particularly preferred.

  The content of the silane coupling agent is 5 parts by mass or less, preferably 0.1 to 2 parts by mass with respect to 100 parts by mass of the ethylene-polar monomer copolymer.

[Others]
The sealing film for solar cells of the present invention is a plasticizer, if necessary, for improving or adjusting various physical properties (mechanical strength, optical characteristics, heat resistance, light resistance, crosslinking speed, etc.) of the film. Various additives such as an acryloxy group-containing compound, a methacryloxy group-containing compound and / or an epoxy group-containing compound may further be included.

  Although it does not specifically limit as a plasticizer, Generally the ester of a polybasic acid and the ester of a polyhydric alcohol are used. Examples thereof include dioctyl phthalate, dihexyl adipate, triethylene glycol-di-2-ethylbutyrate, butyl sebacate, tetraethylene glycol diheptanoate, and triethylene glycol dipelargonate. One type of plasticizer may be used, or two or more types may be used in combination. The content of the plasticizer is preferably in the range of 5 parts by mass or less with respect to 100 parts by mass of the ethylene-polar monomer copolymer.

  The acryloxy group-containing compound and the methacryloxy group-containing compound are generally acrylic acid or methacrylic acid derivatives, and examples thereof include acrylic acid or methacrylic acid esters and amides. Examples of ester residues include linear alkyl groups such as methyl, ethyl, dodecyl, stearyl, lauryl, cyclohexyl group, tetrahydrofurfuryl group, aminoethyl group, 2-hydroxyethyl group, 3-hydroxypropyl group. Group, 3-chloro-2-hydroxypropyl group. Examples of amides include diacetone acrylamide. In addition, polyhydric alcohols such as ethylene glycol, triethylene glycol, polypropylene glycol, polyethylene glycol, trimethylolpropane, and pentaerythritol, and esters of acrylic acid or methacrylic acid can also be used.

Examples of epoxy-containing compounds include triglycidyl tris (2-hydroxyethyl) isocyanurate, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, allyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, and phenol. (Ethyleneoxy) ₅ glycidyl ether, pt-butylphenyl glycidyl ether, adipic acid diglycidyl ester, phthalic acid diglycidyl ester, glycidyl methacrylate, butyl glycidyl ether can be mentioned.

  The acryloxy group-containing compound, the methacryloxy group-containing compound, or the epoxy group-containing compound is generally 0.5 to 5.0 parts by weight, particularly 1.0, respectively, with respect to 100 parts by weight of the ethylene-polar monomer copolymer. It is preferable that -4.0 mass part is contained.

  Furthermore, the solar cell sealing film of the present invention may contain an ultraviolet absorber, a light stabilizer and an anti-aging agent. By including the ultraviolet absorber, it is possible to suppress deterioration of the ethylene-polar monomer copolymer due to the influence of irradiated light and the like, and yellowing of the solar cell sealing film. The ultraviolet absorber is not particularly limited, but 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, 2,4-dihydroxybenzophenone, 2,2′-dihydroxy-4-methoxy. Preferred examples include benzophenone-based ultraviolet absorbers such as benzophenone and 2-hydroxy-4-n-octoxybenzophenone. In addition, it is preferable that the compounding quantity of the said benzophenone series ultraviolet absorber is 0.01-5 mass parts with respect to 100 mass parts of ethylene-polar monomer copolymers.

  Moreover, it can suppress that an ethylene-polar monomer copolymer deteriorates and the solar cell sealing film yellows by influence of the irradiated light etc. also by including a light stabilizer. As the light stabilizer, a light stabilizer called a hindered amine type is preferably used. For example, LA-52, LA-57, LA-62, LA-63, LA-63p, LA-67, LA-68 (all (Manufactured by ADEKA Corporation), Tinuvin 744, Tinuvin 770, Tinuvin 765, Tinuvin 144, Tinuvin 622LD, CHIMASSORB 944LD (all manufactured by Ciba Specialty Chemicals Co., Ltd.), UV-3034 (BF Goodrich) Etc. In addition, the said light stabilizer may be used individually or may be used in combination of 2 or more types, and the compounding quantity is 0.01-5 mass parts with respect to 100 mass parts of ethylene-polar monomer copolymers. It is preferable that

  Examples of the antioxidant include hindered phenolic antioxidants such as N, N′-hexane-1,6-diylbis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionamide], Examples thereof include phosphorus heat stabilizers, lactone heat stabilizers, vitamin E heat stabilizers, and sulfur heat stabilizers.

[Seal film for solar cell]
What is necessary is just to perform according to a well-known method in order to form the sealing film for solar cells of this invention mentioned above. For example, the composition containing each of the above-described components can be produced by a method of obtaining a sheet-like material by molding by ordinary extrusion molding, calendar molding (calendering) or the like. Alternatively, a sheet-like material can be obtained by dissolving the composition in a solvent and coating the solution on a suitable support with a suitable coating machine (coater) and drying to form a coating film. The heating temperature during film formation is preferably a temperature at which the crosslinking agent does not react or hardly reacts. For example, it is preferably 50 to 90 ° C, particularly 40 to 80 ° C. Although the thickness in particular of the sealing film for solar cells of this invention is not restrict | limited, It is 0.05-2 mm.

[Solar cell]
The structure of the solar cell of the present invention is not particularly limited as long as the solar cell sealing film of the present invention is disposed on the back side of the solar cell and has a structure for sealing the solar cell. In the solar battery, in order to sufficiently seal the solar battery cell, for example, in the crystalline silicon solar battery shown in FIG. 1, the surface side transparent protective member 11, the surface side sealing film 13A, the solar battery cell 14, the present invention. The back side sealing film 13B and the back side protection member 12 may be laminated, and the sealing films 13A and 13B may be cross-linked and cured according to a conventional method such as heating and pressing. The surface side sealing film 13A is not particularly limited as long as it is a transparent sealing film capable of transmitting sunlight.

  Moreover, it can also be used as a sealing film used for thin-film solar cells such as thin-film silicon-based, thin-film amorphous silicon-based solar cells, and copper indium selenide (CIS) -based solar cells. For example, as shown in FIG. 2, the thin film solar cell is a thin film solar cell formed by chemical vapor deposition or the like on the surface of a surface side transparent protective member 21 such as a glass substrate, a polyimide substrate, or a fluororesin transparent substrate. It can be manufactured by laminating the solar cell sealing film 23 and the back surface side protective member 22 of the present invention on the battery cell 24 and crosslinking and curing the sealing film by heating and pressing.

In order to heat and pressurize, for example, the laminate is heated with a vacuum laminator at a temperature of 135 to 180 ° C., further 140 to 180 ° C., particularly 155 to 180 ° C., a degassing time of 0.1 to 5 minutes, and a press pressure of 0.1. What is necessary is just to heat-press in about 1.5 kg / cm < ² > and press time 5-15 minutes.

  In addition, in this invention, the side (light-receiving surface side) by which the light of a photovoltaic cell is irradiated is called "front surface side", and the surface opposite to the light-receiving surface of a photovoltaic cell is called "back surface side."

  As the surface side transparent protective members 11 and 21 used in the solar cell of the present invention, a glass substrate such as silicate glass or a transparent resin substrate such as a polyimide substrate can be used. The thickness of the surface side transparent protective member is generally 0.1 to 10 mm, and preferably 0.3 to 5 mm. Generally, the surface side transparent protective member may be chemically or thermally strengthened.

  For the back side protection members 12 and 22 used in the present invention, plastic films such as polyethylene terephthalate (PET) and polyamide are preferably used. Further, a film obtained by laminating a fluorinated polyethylene film, particularly a fluorinated polyethylene film / Al / fluorinated polyethylene film in this order in consideration of heat resistance and wet heat resistance may be used.

  In addition, the solar cell of this invention has the characteristics in the sealing film which arrange | positions on the back surface side of a photovoltaic cell and seals a photovoltaic cell. Therefore, the members such as the front surface side transparent protective member, the back surface side protective member, and the solar battery cell are not particularly limited as long as they have the same configuration as a conventionally known solar battery.

  Hereinafter, the present invention will be described with reference to examples.

[Examples 1 to 3, Comparative Examples 1 to 5]
The materials shown in Table 1 were supplied to a roll mill and kneaded at 70 ° C. to prepare a solar cell sealing film composition. The solar cell sealing film composition was calendered at 70 ° C., allowed to cool, and then a solar cell sealing film (thickness 0.6 mm) was produced.

<Evaluation method>
1. Light reflectance Glass layer (3.2 mm) / Release PET (0.1 mm) / Sealing film for solar cell / Shielding sheet (0.6 mm: VT-50 black, manufactured by Nichiban) Then, using a vacuum laminator, thermocompression bonding was performed at 145 ° C., a vacuum time of 5 minutes, and a press time of 15 minutes, and then the release PET and glass were removed. The surface of the solar cell sealing film to which the release PET was adhered was measured for a light reflection spectrum using a spectrophotometer (manufactured by Hitachi, Ltd .: U-4100) according to JIS K7105, and was 400 to 700 nm. The average value of the light reflectance was taken as the light reflectance (%).

2. After being laminated so as to be a yellowness glass plate (3.2 mm) / the solar cell sealing film / glass plate (3.2 mm), and pressure-bonded at 100 ° C. for 10 minutes under vacuum with a vacuum laminator, 155 The sealing film for solar cells was cross-linked by pressure bonding for 45 minutes in an oven at ° C. The yellowness (YI) of this laminate was measured using a color difference meter (SH color computer; manufactured by Suga Test Instruments Co., Ltd.) in accordance with JIS-K-7105-6 (1981).

<Evaluation results>
As can be seen from Table 1, the light reflectance at 400 to 700 nm of the sealing films of Examples 1 to 3 is higher than that of the sealing film of the comparative example in which titanium dioxide having other particle sizes is blended. It was done. Moreover, it was shown also about the yellowness that the sealing film of Examples 1-3 is low compared with the sealing film of a comparative example.

  According to the solar cell sealing film of the present invention, light in the short wavelength region of the solar spectrum can be reflected more. Therefore, when the sealing film is bluish, it becomes a hue, and a solar battery harmonized with the color tone of the solar battery cell can be provided.

11, 21 Front side transparent protective member 12, 22 Back side protective member 13A, 13B, 23 Solar cell sealing film 14, 24 Solar cell

Claims (5)

A solar cell sealing film disposed on the back side of the solar cell to seal the solar cell,
An ethylene-polar monomer copolymer, a crosslinker and a colorant;
The sealing film for solar cells, wherein the colorant is a white pigment having an average particle diameter of 150 to 230 nm.   The solar cell sealing film according to claim 1, wherein the white pigment is titanium dioxide.   The solar cell sealing film according to claim 1, wherein the white pigment is contained in an amount of 0.1 to 10 parts by mass with respect to 100 parts by mass of the ethylene-polar monomer copolymer.   The solar cell sealing film according to claim 1, wherein the ethylene-polar monomer copolymer is an ethylene-vinyl acetate copolymer.   The solar cell using the sealing film for solar cells of any one of Claims 1-4.

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