JP2013077622A - Sealant for solar battery, and solar battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealant for solar batteries which has a high durability after a solar battery module is formed by use of the sealant and which the increase in opaqueness owing to the coloring, foam formation and the like is suppressed.SOLUTION: The sealant for solar batteries is composed of a sheet which comprises: an ethylene-vinyl acetate copolymer; and 0.001-5 pts.mass of a triazole compound to 100 pts.mass of the ethylene-vinyl acetate copolymer. The solar battery module 10 of the invention has: solar battery cells 11; and a pair of sealants 12 for solar batteries which hold the solar battery cells 11 therebetween, provided that the sealants 12 are the above-described sealant for solar batteries.

Description

  The present invention relates to a solar cell sealing material for sealing solar cells and a solar cell module using the same.

In recent years, with the growing interest in environmental issues, the spread of solar power generation has been rapidly expanding. Usually, in solar power generation, a plurality of solar cells as power generation elements are sandwiched between a pair of sheet-like sealing materials in a state of being electrically connected, and these are further sandwiched between a transparent protective material and a back sheet. Power is generated by the solar cell module. As a sealing material, what has ethylene-vinyl acetate copolymer as a main component is used widely.
Since the solar cell module is installed outdoors, the sealing material is required to have high durability. Therefore, Patent Document 1 proposes a method in which benzotriazole is contained in a sealing material, deterioration of an ethylene-vinyl acetate copolymer that is a main component is suppressed, and durability is improved.

International Publication No. 2005/121227

However, even when solar cells are sealed using the sealing material described in Patent Document 1, the suppression of deterioration is insufficient, and the resulting solar cell module is colored, foamed, etc., and transmits light. As a result, the power generation amount per unit area (hereinafter referred to as “power generation efficiency”) and the appearance may be impaired.
An object of the present invention is to provide a solar cell encapsulant that has high durability when made into a solar cell module and is suppressed from becoming opaque due to coloring, foaming, and the like. Another object of the present invention is to provide a solar cell module having high durability and excellent power generation efficiency and appearance.

The solar cell encapsulant of the present invention is made from a sheet containing an ethylene-vinyl acetate copolymer and 0.001 to 5 parts by mass of a triazole compound with respect to 100 parts by mass of the ethylene-vinyl acetate copolymer. It is characterized by becoming.
In the sealing material for solar cells of this invention, it is preferable that the said sheet | seat contains 0.001-5 mass parts of compounds which have an epoxy group with respect to 100 mass parts of ethylene-vinyl acetate copolymers.
The solar cell module of the present invention includes a solar cell and a pair of solar cell encapsulants sandwiching the solar cell, and the solar cell encapsulant is the solar cell encapsulant. It is characterized by.

The solar cell encapsulant of the present invention has high durability when formed into a solar cell module, and is also inhibited from becoming opaque due to coloring and foaming.
The solar cell module of the present invention has high durability and is excellent in power generation efficiency and appearance.

It is sectional drawing which shows one embodiment of the solar cell module of this invention.

<Sealant for solar cell>
The solar cell encapsulant of the present invention (hereinafter abbreviated as “encapsulant”) comprises a sheet containing an ethylene-vinyl acetate copolymer (hereinafter referred to as “EVA”) and a triazole compound.

(EVA)
EVA has a vinyl acetate unit ratio of preferably 10 to 40% by mass, and more preferably 15 to 35% by mass. If the ratio of vinyl acetate units in EVA is not less than the lower limit, the transparency and adhesiveness of the encapsulant can be increased when the solar cell module is made, and if it is not more than the upper limit, the durability is further increased. it can.
The mass average molecular weight of EVA is preferably 10,000 to 300,000, and more preferably 30,000 to 100,000. If the EVA mass average molecular weight is equal to or higher than the lower limit, the mechanical properties of the encapsulant when the solar cell module is made can be improved, and if the EVA is equal to or lower than the upper limit, the processability of the encapsulant is improved. it can.

(Triazole compound)
The triazole compound is a derivative in which a hydrogen atom of a nitrogen-containing heterocyclic ring of triazole or triazole is substituted with a substituent. However, the triazole compound does not include benzotriazole.
Examples of the substituent include alkyl groups such as a methyl group, an ethyl group, and a propyl group. The alkyl group may be further substituted with an amino group, a halogen atom or the like.
In addition, as a triazole compound, trade name irgamet 30 (N, N-bis (2-ethylhexyl) -1,2,4-triazol-1-ylmethanamine) is a trade name from ADEKA Co., Ltd. from BASF Japan. Adekastab CDA-1 (3- (N-salicyloyl) amino-1,2,4-triazole) is commercially available.
Content of a triazole compound is 0.001-5 mass parts, and it is preferable that it is 0.2-1.0 mass part. When the content of the triazole compound is equal to or higher than the lower limit value, when the solar cell module is obtained, the solar cell module has higher durability, and the opacity is further suppressed. The mechanical properties of the sealing material at the time can be improved.

(Epoxy compound)
The sealing material of the present invention preferably contains a compound having an epoxy group (hereinafter referred to as “epoxy compound”). When an epoxy compound is contained in the sealing material, acetic acid generated by EVA deterioration can be reacted. Thereby, since acetic acid can be inactivated, the corrosion of the electrode of the photovoltaic cell and the tab string conducting wire due to acetic acid can be suppressed, and the reduction of the extracted electric energy can be prevented. And since an epoxy compound is a non-particulate organic substance, the transparency fall of a sealing material can be suppressed. Therefore, since most of the sunlight incident on the sealing material can be incident on the solar battery cell, sufficient power generation efficiency can be obtained.

The epoxy compound may have at least one epoxy group.
Examples of commercially available epoxy compounds include ADEKA Corporation's trade name Adeka Resin EP4100E (bisphenol A type epoxy compound), Nagase Chemtech's trade name Denacol EX-121 (2-ethylhexyl glycidyl ether), Denacol EX-141. (Phenyl glycidyl ether), Denacol EX-810 (ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether) and the like.
Of the epoxy compounds, chelate-modified epoxy compounds are not preferred because they may discolor the sealing material.
The molecular weight of the epoxy compound is preferably 100 or more because bleeding out from the sealing material can be suppressed. However, if the molecular weight is too large, the compatibility with EVA is lowered, and therefore it is preferably 30000 or less. Examples of the epoxy compound having a molecular weight of 100 to 30000 include an epoxy compound used for a monomer of an epoxy resin.

  The content of the epoxy compound is preferably 0.001 to 5 parts by mass, and more preferably 0.5 to 1.0 parts by mass. If the content of the epoxy compound is equal to or higher than the lower limit value, the solar cell module has higher durability and is superior in power generation efficiency. The mechanical properties of the sealing material can be improved.

(Additive)
The sealing material may contain additives such as an ultraviolet absorber, a light stabilizer, an antioxidant, a silane coupling agent, a crosslinking agent, and a crosslinking aid.

Examples of the ultraviolet absorber include benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, and salicylic acid ester-based ultraviolet absorbers.
Examples of the light stabilizer include hindered amine light stabilizers.
Examples of the antioxidant include hindered phenol antioxidants and phosphite antioxidants.

A silane coupling agent is a component which improves adhesiveness with the photovoltaic cell mentioned later, a transparent protective material, a back sheet, etc. As the silane coupling agent, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, N-2- (aminoethyl) -3 -Aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane and the like.
0-10 mass parts is preferable with respect to 100 mass parts of resin, and, as for the compounding quantity of a silane coupling agent, 0-5 mass parts is more preferable.

The crosslinking agent is a component that crosslinks EVA. Examples of the crosslinking agent include known organic peroxides (peroxyketals, dialkyl peroxides, peroxyesters, etc.), photosensitizers and the like.
0-5 mass parts is preferable with respect to 100 mass parts of EVA, and, as for the compounding quantity of a crosslinking agent, 0-2 mass parts is more preferable.

The crosslinking aid is a compound having one or more (preferably two or more) polymerizable unsaturated groups (vinyl group, allyl group, (meth) acryloxy group, etc.). Examples of the compound include triallyl isocyanurate, triallyl cyanurate, and trimethylolpropane trimethacrylate.
0-5 mass parts is preferable with respect to 100 mass parts of EVA, and, as for the compounding quantity of a crosslinking adjuvant, 0-2 mass parts is more preferable.

  In addition to the above additives, the encapsulant may contain a discoloration inhibitor (fatty acid metal salt or the like), a pigment, a dye, a filler, and the like.

(Thickness)
The thickness of the sheet-shaped sealing material is appropriately selected within the range of 0.05 to 1 mm according to the solar cell module to be produced. If the thickness of the sealing material is 0.05 mm or more, the solar battery cell can be sufficiently sealed, and if it is 1 mm or less, the solar battery cell can be thinned.

(Method for producing sealing material)
As a manufacturing method of a sealing material, the method of mixing EVA and a triazole compound and an additive as needed, preparing a mixture, shape | molding this mixture, and making it into a sheet | seat is mentioned.
Examples of the sheet forming method include an extrusion molding method using a T die, a press molding method, and the like. Moreover, it can also make into a sheet | seat by apply | coating the solution of a sealing material to a release sheet, and drying.

<Solar cell module>
Next, an embodiment of a solar cell module using the sealing material will be described.
In FIG. 1, sectional drawing of the solar cell module of this embodiment example is shown. The solar cell module 10 of the present embodiment includes a plurality of solar cells 11, 11..., A pair of sealing materials 12, 12, a transparent protective material 13, and a back sheet 14. The solar battery cell 11 is sandwiched and fixed between a pair of solar battery sealing materials 12 and 12. Further, the sealing materials 12 and 12 are disposed between the transparent protective material 13 and the back sheet 14.

(Solar cell)
Examples of the solar battery cell 11 include a pn junction solar battery element having a structure in which a p-type semiconductor and an n-type semiconductor are joined. Examples of the pn junction type solar cell element include silicon (single crystal silicon, polycrystalline silicon, amorphous silicon, etc.), compound (GaAs, CIS, CdTe-CdS) and the like.
In the present embodiment example, the plurality of solar cells 11 are electrically connected in series via a tab string 15 having a conductive wire and a solder joint.

(Transparent protective material)
Examples of the transparent protective material 13 include a glass plate and a resin plate. As a glass plate, the template glass which gave the surface unevenness | corrugation from the point of light transmittance is preferable. As the material of the template glass, white plate glass (high transmission glass) with less iron content is preferable.

(Back sheet)
Examples of the material of the back sheet 14 include polyvinyl fluoride, polyester (polyethylene terephthalate, etc.), polyolefin (polyethylene, etc.), glass, metal (aluminum, etc.) and the like. The backsheet 24 may be a single layer or a multilayer.

(Method for manufacturing solar cell module)
As a method for manufacturing a solar cell module, a plurality of solar cells 11, 11... Electrically connected using a tab string 15 are sandwiched between a pair of sealing materials 12, 12, and further the sealing materials 12, 12. Is sandwiched between the transparent protective material 13 and the back sheet 14 and then heated to bond the sealing materials 12 and 12, the sealing material 12 and the transparent protective material 13, and the sealing material 12 and the back sheet 14. Is mentioned.
When the sealing material 12 contains a crosslinking agent, it is preferable to heat it above the decomposition temperature of the crosslinking agent. When heated to a temperature equal to or higher than the decomposition temperature of the crosslinking agent, EVA contained in the sealing material 12 can be crosslinked, and the durability of the sealing material 11 can be further improved.

(Function and effect)
The conductive wires and solder joints included in the tab strings 15 that connect the solar cells 11 and 11 are deteriorated when used for a long time to generate copper ions, and EVA is decomposed and deteriorated by the copper ions. is there. In addition, since acetic acid generated by the decomposition of EVA further generates copper ions from the conductor and the solder joint, deterioration occurs at an accelerated rate.
However, in the sealing material of the present invention, since triazole can suppress the generation of copper ions from the conductive wire and the solder joint, it is possible to prevent EVA from being decomposed. Therefore, the sealing material is excellent in durability, coloring and foaming due to EVA decomposition are suppressed, and the solar cell module using the sealing material is excellent in power generation efficiency and appearance.

Example 1
Ethylene-vinyl acetate copolymer (SETETEC VE700 manufactured by Lotte Daesan Petrochemical Co., Ltd., proportion of vinyl acetate unit: 30% by mass) 100 parts by mass, UV absorber (TINUVIN P manufactured by BASF Japan) 0.5 Part by mass, 0.5 parts by mass of a light stabilizer (TINUVIN114 manufactured by BASF Japan), 0.5 parts by mass of a silane coupling agent (KBM-503 manufactured by Shin-Etsu Silicone), a cross-linking agent (Kayahexa AD manufactured by Kayaku Akzo) 0.5 parts by mass, 0.5 parts by mass of a crosslinking assistant (Nippon Kasei Co., Ltd.) and 1.0 parts by mass of triazole compound A (Irgamet 30 manufactured by BASF Japan) are mixed to obtain a composition for a sealing material. Obtained. Subsequently, the obtained composition for sealing materials was press-molded to obtain a sheet-shaped sealing material having a thickness of 500 μm.
Subsequently, a plurality of polycrystalline silicon solar cells electrically connected in series are sandwiched between the two sealing materials obtained as described above, and these are backed by a glass plate, polyvinyl fluoride and polyester. A laminate was obtained by sandwiching with a sheet. This laminate was put in a resin bag, the inside of the bag was evacuated and heated to 150 ° C. to obtain a solar cell module.

(Example 2)
A solar cell module was obtained in the same manner as in Example 1 except that the amount of the triazole compound A was changed to 0.01 parts by mass.

(Example 3)
A solar cell module was obtained in the same manner as in Example 1 except that the amount of the triazole compound A was changed to 5.0 parts by mass.

Example 4
A solar cell module was obtained in the same manner as in Example 1 except that the triazole compound A was changed to the triazole compound B (ADEKA Corporation, ADK STAB CDA-1).

(Example 5)
A solar cell module was obtained in the same manner as in Example 1 except that epoxy compound A (ADEKA RESIN EP4100E manufactured by ADEKA Co., Ltd.) was further added to the composition for sealing material.

(Example 6)
A solar cell module was obtained in the same manner as in Example 1 except that epoxy compound B (Denacol EX-810 manufactured by Nagase Chemitex Co., Ltd.) was further added to the composition for sealing material.

(Comparative Example 1)
A sheet-shaped sealing material was obtained in the same manner as in Example 1 except that a benzotriazole compound (BASF Japan Irgamet BTA) was used instead of the triazole compound. And it carried out similarly to Example 1, and produced the solar cell module.

(Comparative Example 2)
A sheet-like sealing material was obtained in the same manner as in Example 1 except that the triazole compound was not mixed. And it carried out similarly to Example 1, and produced the solar cell module.

(Comparative Example 3)
A solar cell module was obtained in the same manner as in Example 1 except that the amount of the triazole compound A was changed to 7.0 parts by mass.

[Evaluation]
-Appearance of solar cell module The appearance of the obtained solar cell module was visually observed, and the appearance was evaluated according to the following criteria. The evaluation results are shown in Table 1.
○: No cloudiness, coloring, or foaming is observed.
Δ: Slightly cloudy, colored or foamed, but usable.
X: Cloudy, colored, or foaming is observed and cannot be used.
-Durability By using a solar simulator (PVS1114iD manufactured by Nisshinbo Mechatronics), the IV characteristics of the obtained solar cell module were measured, and the initial power generation performance (maximum power generation amount _Pmax ) was obtained.
Further, after the solar cell module was left in a humid heat environment at a temperature of 85 ° C. and a relative humidity of 85% for 1000 hours and 5000 hours, the power generation performance was evaluated according to the following criteria. The evaluation results are shown in Table 1.
○: The power generation amount after being left in a wet heat environment is within −5% with respect to the initial maximum power generation amount P _max .
X: The power generation amount after being left in a wet and heat environment is less than −5% with respect to the initial maximum power generation amount P _max
The durability is more excellent as the power generation amount after being left in the wet heat environment does not change with respect to the initial maximum power generation amount _Pmax .
-Appearance of tab string of solar cell module After the obtained solar cell module was left in a humid heat environment with a temperature of 85 ° C and a relative humidity of 85% for 1000 hours, the appearance of the tab string was visually observed, and the following criteria were used. evaluated. The evaluation results are shown in Table 1.
○: Rust, discoloration, and cloudiness are not observed.
Δ: Slightly rusted, discolored, or cloudy, but can be used.
X: Rust, discoloration, or cloudiness is seen and cannot be used.

The solar cell modules of Examples 1 to 6 in which the sealing material contains a triazole compound were excellent in durability and appearance. In particular, the solar cell modules of Examples 5 and 6 further containing an epoxy compound were excellent in the appearance of the tab string after being left in a wet heat environment.
The solar cell module of Comparative Example 1 in which the encapsulant contains a benzotriazole compound has an insufficient appearance.
The solar cell module of Comparative Example 2 in which the encapsulant did not contain any of the triazole compound and the benzotriazole compound had insufficient durability.
The solar cell module of Comparative Example 3 having a triazole compound content in the encapsulant of 7 parts by mass was insufficient in appearance and durability.

DESCRIPTION OF SYMBOLS 10 Solar cell module 11 Solar cell 12 Sealing material 13 Transparent protective material 14 Back sheet 15 Tab string

Claims (3)

  A sealing for solar cell comprising an ethylene-vinyl acetate copolymer and a sheet containing 0.001 to 5 parts by mass of a triazole compound with respect to 100 parts by mass of the ethylene-vinyl acetate copolymer. Wood.   The said sheet | seat contains 0.001-5 mass parts of compounds which have an epoxy group with respect to 100 mass parts of ethylene-vinyl acetate copolymers, The sealing for solar cells of Claim 1 characterized by the above-mentioned. Wood.   A solar battery cell and a pair of solar battery sealing materials sandwiching the solar battery cell, wherein the solar battery sealing material is the solar battery sealing material according to claim 1 or 2. A featured solar cell module.

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