JPH06177412A - Sealing material film for solar battery - Google Patents

Abstract

PURPOSE:To prevent EVA from overhanging during thermocompression by using an ethylene-vinyl acetate copolymer sheet with a specified melt flow rate for a sealing material film. CONSTITUTION:A solar battery module is formed by thermally compressing glass 10, an ethylene-vinyl acetate copolymer (EVA) sheet layer 26, a silicon power generating element 12, an EVA sheet layer 28 as a solar battery sealing material film and a back cover 14 integrally. The EVA sheet has a melt flow rate of 14g/10min or less and contains organic peroxide whose half life at 130 deg. is at most one hour. The EVA sheet 28 contains coloring agent such as titanium white. Furthermore, a metallic layer of aluminum foil, etc., or a plastic film layer of Tedlar, etc., which is the back cover 14 and the EVA sheet layer are bonded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solar cell encapsulant film, and more particularly to a solar cell encapsulant film capable of providing a solar cell module at low cost and with high productivity.

[0002]

2. Description of the Related Art In recent years, sunlight has attracted widespread attention as a clean energy source due to environmental problems, and a device for directly converting this sunlight into electric power, that is, a solar cell has been actively developed. Solar cells are expected to play a major role in the conventional use of solar energy, and research and development are continuing with a focus on high efficiency and cost reduction.

Conventionally, a solar cell module used for photovoltaic power generation is usually glass as a substrate, an ethylene-vinyl acetate copolymer (EVA) sheet as a sealing material film, a silicon power generation element as a photoelectric conversion element, and a sealing material. EV as a membrane
A sheet and each layer of a back cover as a protective layer are laminated in this order to manufacture.

However, since this solar cell module is manufactured by the vacuum thermocompression bonding method, EVA, which is the encapsulant film, protrudes (burrs) from the edge of the glass during thermocompression bonding, and the burrs are cut off at the finishing stage. Since it was necessary to provide steps, the productivity could not be increased, and the cost of the originally expensive solar cell module could not be reduced.

[0005]

SUMMARY OF THE INVENTION In consideration of the above problems, the present invention uses a sealing film for a solar cell that eliminates the protrusion of EVA during thermocompression bonding, has a low cost, and has a high productivity, and uses the same. It is intended to provide a solar cell module.

[0006]

A solar cell encapsulating material film according to claim 1, wherein a silicon power generating element is arranged, and a sealing material film is interposed on both sides of the silicon power generating element, and they are integrally thermocompression bonded. The encapsulant film in the solar cell module consisting of
EV having a melt flow rate of 14 g / 10 min. Or less
It is characterized by being an A sheet.

The solar cell encapsulant film according to claim 2 is the solar cell encapsulant film according to claim 1, wherein at least one layer of the EVA sheet is
It is characterized by containing an organic peroxide having a half-life at 130 ° C. of 1 hour or less.

The solar cell encapsulant film according to claim 3 is characterized in that, in claim 1 or 2, the EVA sheet interposed on the back cover side of the silicon power generation element contains a colorant.

A solar cell encapsulant film according to claim 4 is characterized in that, in claim 1, 2 or 3, the EVA sheet is bonded to a metal layer and / or a plastic film layer.

The present inventors have paid attention to the molecular structure, physical properties and reactivity of the EVA sheet as a solar cell encapsulant film, and as a result of intensive studies, the molecular weight of EVA has been increased and the melt flow rate has been decreased. Also, in addition to this, EVA
The inventors have found that the object can be achieved by shortening the curing time of, and have completed the present invention.

The present invention will be described in detail below. A schematic cross-sectional view showing the state of the basic laminate of the solar cell module of the present invention is shown in FIG. 1 and will be described based on this.

This solar cell module laminate is usually composed of a glass 10 as a substrate and a silicon power generating element 12.
And the back cover 14 and the encapsulant film EVA sheet layers 16 and 18 used to bond the three members. The desired solar cell module is obtained by thermocompression-bonding this laminate. Here, the sunlight enters the glass 10 from the lower side of FIG.
And the silicon power generation element 1 through the EVA sheet layer 16
2 is irradiated.

EVA used in the EVA sheet layers 16 and 18 has a melt flow rate of 14 g / 10 min. Or less, preferably 6 g / min, as defined by JIS K7210.
The content of vinyl acetate in EVA is preferably 10% by weight or more, more preferably 10% by weight or more, and particularly preferably 15 to 30% by weight. Melt flow rate is 14g / 10
When it exceeds the min., it is not preferable because it is extruded from the glass 10 which is the substrate due to thermocompression bonding at the time of manufacturing the solar cell module. The vinyl acetate content is 1
If it is less than 0% by weight, EVA has a high melting point and is difficult to process into a sheet, which is not preferable.

The EVA sheet used in the present invention can also be thermally crosslinked by blending or impregnating an organic peroxide, which contains an organic peroxide having a half-life at 130 ° C. of 1 hour or less. Used. If the half-life exceeds 1 hour, it is not effective in preventing the EVA from squeezing out due to pressurization, which is not preferable. From the viewpoint of compatibility with EVA, such organic peroxides include, for example, 1,
1-bis (tert-butylperoxy) 3,3,5-trimethylcyclohexane, 1,1-bis (tert-butylperoxy) cyclohexane, n-butyl-4,4-bis (tert-butylperoxy) valerate , 2,2-bis (tert-butylperoxy) butane and the like, and particularly preferred is 1,1-bis (tert-butylperoxy) butane.
It is 3,3,5-trimethylcyclohexane. In particular,
1,1-bis (tert-butylperoxy) 3,3,5-
The solar cell encapsulant film using trimethylcyclohexane and 1,1-bis (tert-butylperoxy) cyclohexane has a particularly short crosslinking time, and the conventional solar cell encapsulant film is degassed with a laminator for 5 minutes, It is possible to significantly reduce the curing process of EVA, which was performed at 150 ° C. for about 30 minutes, to about half. On the other hand, as a method for manufacturing a solar cell module, there is also a method of performing atmospheric pressure pressing at 150 ° C. for about 5 minutes after deaeration, and cross-linking EVA through a heating furnace in a state where EVA is temporarily pressure-bonded, but the present invention is used. By doing so, it is possible to omit this curing step. These points are factors that reduce the manufacturing cost of the solar cell module. These organic peroxides are used in an amount of 0 to 10 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of EVA.

In order to increase the degree of crosslinking of EVA in the present invention, EVA can be blended or impregnated with a crosslinking aid. The cross-linking aid used here is at least one selected from the group consisting of an allyl group-containing compound, an acryloxy group-containing compound, and a methacryloxy group-containing compound. Allyl isocyanurate, triallyl cyanate,
Diallyl phthalate, diallyl fumarate, diallyl maleate and the like are preferably used. Further, as the acryloxy group-containing compound and the methacryloxy group-containing compound,
Acrylic acid derivatives or methacrylic acid derivatives, for example their esters, can be used. In this case, as the alcohol residue of the ester, a methyl group, an ethyl group, a dodecyl group, a stearyl group, an alkyl group such as a lauryl group, a cyclohexyl group, a tetrahydrofurfuryl group,
Aminoethyl group, 2-hydroxyethyl group, 3-hydroxypropyl group, 3-chloro-2-hydroxypropyl group and the like can be mentioned. Furthermore, esters with polyfunctional alcohols such as ethylene glycol, triethylene glycol, and polyethylene glycol can be similarly used. These crosslinking aids are used in an amount of 10 parts by weight or less based on 100 parts by weight of EVA.

In order to further improve the adhesive strength between the EVA and other substance materials in the present invention, a silane coupling agent may be blended or impregnated as an adhesion improver. In this case, the silane coupling agent used is, for example, γ-chloropropylmethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyl-tris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane. , Β- (3,4-ethoxycyclohexyl) ethyltrimethoxysilane, γ-
Glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N
Examples include -β- (aminoethyl) -γ-aminopropyltrimethoxysilane. The compounding amount of these silane coupling agents is preferably 5 parts by weight or less with respect to 100 parts by weight of EVA.

In addition to the above, an ultraviolet absorber, an antioxidant, a discoloration inhibitor, etc. may be added.

As the ultraviolet absorber used for imparting the ultraviolet absorbing performance, known ones, particularly benzophenone type ultraviolet absorbers are suitable. As the ultraviolet absorber, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-n-5-sulfobenzophenone, 2-hydroxy-4-methoxybenzophenone,
2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, 2,4-dihydroxybenzophenone,
2,2'-dihydroxy-4-methoxybenzophenone and the like can be mentioned.

Examples of antioxidants used for the purpose of further improving light stability and heat stability include phenols, sulfur compounds, phosphorus compounds, amine compounds, hindered phenol compounds, hindered amine compounds and hydrazine compounds. For example, bis (2,2,6,6-tetramethyl-
4-piperazyl) sebacate and the like can be mentioned.

Examples of the discoloration preventing agent include salts of metals such as cadmium and barium and higher fatty acids, that is, metal soaps.

The EVA sheet layer 18 in FIG. 1 may be colored with a coloring agent in order to improve efficiency as a solar cell. Examples of the coloring with a coloring agent include white with titanium white, calcium carbonate and the like, blue with ultramarine and the like, black with carbon black and the like, milky white with glass beads and a light diffusing agent and the like. Coloring to white with titanium white is preferable. The amount of these colorants added is 10 parts by weight or less based on 100 parts by weight of EVA,
It can be added preferably in an amount of 3 parts by weight or less, and can also be added by a masterbatch containing a high concentration of a colorant in advance.

Further, the back cover 14 according to the present invention.
Contains a metal layer and / or a plastic film layer and is adhered to an EVA sheet that is a sealing material film, is a support for the entire solar cell module, and also serves as a protective layer for the silicon power generation element 12. Moreover, the durability as a solar cell can be improved by inserting a metal layer such as aluminum. When the EVA sheet layer 18 used in the present invention is provided between the back cover 14 and the silicon power generation element 12, since the fluidity of the EVA is controlled, a metal layer is provided on the silicon power generation element side of the back cover 14. Even when the solar cell module is inserted, the solar cell module can maintain a sufficient withstand voltage without causing insulation failure due to contact between the silicon power generation element 12 and the metal layer during manufacturing of the solar cell module.

In the present invention, the metal that can be used for the metal layer of the back cover 14 is not limited as long as it is a metal that prevents the permeation of water vapor from the outside, such as aluminum, stainless steel, tin, etc., but aluminum is economically and weight-wise. preferable. The plastics that can be used for the plastic film layer of the back cover 14 include fluororesin and the like.

More specifically, the back cover 14 in the present invention can be constructed by adhering weather resistant plastic to one or both surfaces of the layer for preventing water vapor transmission. As a layer that prevents water vapor transmission,
Metal or plastic films can be used.
The metals used here include aluminum, stainless steel,
Examples of the plastic film include tin and the like, and examples of the plastic film include vinylidene chloride, polyester, polyethylene, and the like, but any layer may be used as long as it is a layer that prevents water vapor transmission.

As the plastic film having weather resistance, there are fluorine plastic films such as Tedlar film manufactured by DuPont, white polyester film and the like, but any plastic film having weather resistance may be used.

In the present invention, instead of adhering the weather resistant plastic to the water vapor permeation preventive layer, a weather resistant paint may be applied to the water vapor permeation preventive layer. The coating material may be any white coating material such as a urethane-based coating material as long as it has excellent weather resistance.

In the solar cell module using the solar cell encapsulant film of the present invention, the surface for absorbing sunlight is
The material is not limited to glass, and any material that can transmit light can be used, and, for example, transparent acrylic resin, polycarbonate resin or the like can be used.

Further, as the power generating element in the present invention,
Not limited to the silicon power generation element, any element that can convert light energy into electricity can be used.

[0029]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples as long as the gist of the present invention is not exceeded.

The parts and% in the examples are based on weight unless otherwise specified. Ethylene-acetic acid copolymer (E
VA) melt flow rate (MFR) value is JIS
According to K7210, it was measured based on the conditions of 190 ° C. and load 21.18N.

Example 1 FIG. 2 is a schematic sectional view showing the state of the solar cell module laminate according to Example 1.

EVA shown in Table 1 and each compound were blended according to Table 2 and embossed on one side to form a 1 mm thick 1
Ten kinds of EVA sheets of AS to 5BS were prepared. The back cover 14 is composed of two layers of plastic sheet layers 21 and a metal layer 23 sandwiched between them. For the plastic sheet layer 21, Tedlar (thickness: 38 μm, product name of DuPont) is used. Is aluminum foil (thickness:
30 μm) was used. Furthermore, colorless and transparent or colored EVA
Sheet layer 28, silicon power generation element 12, colorless transparent EVA
The sheet layer 26 and the glass plate 10 having a thickness of 3 mm were laminated as shown in FIG. EVA used in the colorless and transparent EVA sheet layer 26 and the colorless and transparent or colored EVA sheet layer 28 is a combination as shown in Table 3, and the 10 types of EVA described above are used.
Ten types (No. 1 to 10) of solar cell module laminates selected from the sheets were obtained. These laminates were degassed with a laminator at 150 ° C for 3 minutes and then 1
Ten kinds of module samples were prepared by performing atmospheric pressure pressing at 50 ° C. for 3 minutes, and the protrusion of EVA from the glass was visually confirmed. FIG. 3 is a schematic cross-sectional view of the solar cell module after laminating the laminate.

The results after pressing, as shown in FIG. 3, showed that no EVA squeeze out from the glass.

[Comparative Example 1] Ultrasen 750 (commercially available; having an MFR of 20 g / 10 min. And a vinyl acetate content of 20%).
The same procedure as in EVA sheet No. 1AS, 1BS (blending), and solar cell module Nos. 1 and 2 of Example 1 was performed, except that Tosoh Corporation trade name) was used for the EVA sheet.

As a result after the pressing, the protrusion of EVA from the glass was recognized.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

[Table 3]

[Embodiment 2] The EVA sheets 3AS and 4BS obtained in the embodiment 1 are respectively colorless and transparent EVA sheet layer 2
6 and a transparent or colored EVA sheet layer 28, the back cover 14 comprises a metal layer 23 sandwiched between two plastic sheet layers 21.
Tedlar (thickness: 38 μm) is used for the metal layer 23.
An aluminum foil (thickness: 30 μm) was used for this. Furthermore, the colorless and transparent or colored sheet layer 28, the silicon power generation element 12,
A colorless transparent EVA sheet layer 26 and a glass plate 10 having a thickness of 3 mm were laminated as shown in FIG. These laminates were degassed with a laminator at 150 ° C. for 3 minutes and then 15
An atmospheric pressure press was performed at 0 ° C. for 4 minutes to prepare a solar cell module. The cross-linking of EVA was completed, EVA was well adhered to glass 10, silicon power generation element 12, and back cover 14, and EVA did not stick out from the glass.

[Embodiment 3] FIG. 4 is a schematic sectional view showing a state of a solar cell module laminate according to Embodiment 3.

2AS of EVA sheet obtained in Example 1
And 2BS are used for the colorless and transparent EVA sheet layer 26 and the colorless and transparent or colored EVA sheet layer 28, respectively, and in other examples, EBS.
VA sheets 3AS and 4BS are used in the same manner, and the back cover 14 is composed of two layers, a plastic sheet layer 21 and a metal layer 23, and a Tedlar (thickness: 38 μm) and an aluminum foil (thickness: 30 μm), respectively. Use, thickness 3mm
The glass plate 10 and the silicon power generation element 12 of No. 1 were laminated according to FIG. 4 to obtain two kinds of solar cell module laminates. These laminates were degassed by a laminator at 150 ° C. for 3 minutes, then atmospheric pressure pressed at 150 ° C. for 3 minutes, and then heat-treated at 150 ° C. for 15 minutes only for a combination of 2AS and 2BS, and then two kinds. The solar cell module of 1 was produced, and the protrusion of EVA from the glass was visually confirmed. FIG. 5 is a schematic cross-sectional view of the solar cell module after thermocompression bonding of the laminate.

The results after pressing, as shown in FIG. 5, showed that no EVA squeeze out from the glass was observed in any of the samples.

When the withstand voltage between the metal layer 23 of the back cover 14 and the silicon power generating element 12 was measured, it was found that the two types of solar cell modules each had a withstand voltage of DC 2000 V or more.

[0044]

EFFECT OF THE INVENTION Since the solar cell encapsulant film of the present invention has the above-mentioned constitution, it relates to the production of a solar cell module without impairing the high solar cell efficiency, while the EVA of glass from glass by thermocompression bonding during production is used. Since it does not protrude and can be manufactured in a short time, it has an excellent effect that it is possible to provide a low cost and high productivity encapsulating material film for a solar cell.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a state of a basic laminate of a solar cell module of the present invention.

FIG. 2 is a schematic cross-sectional view showing a state of a solar cell module laminate according to Example 1 of the present invention.

FIG. 3 is a schematic cross-sectional view of a solar cell module according to the first embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view showing a state of a solar cell module laminate according to Example 3 of the present invention.

FIG. 5 is a schematic sectional view of a solar cell module according to a third embodiment of the present invention.

[Explanation of symbols]

 10 Glass 12 Silicon Power Generation Element 14 Back Cover 16 EVA Sheet Layer 18 EVA Sheet Layer 21 Plastic Sheet Layer 23 Metal Layer 26 Colorless Transparent EVA Sheet Layer 28 Colorless Transparent or Colored EVA Sheet Layer

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location // C08L 23/08 KES 7107-4J

Claims (4)

[Claims] 1. A solar cell module in which a silicon power generation element is disposed and a sealing material film is interposed on both sides of the silicon power generation element and integrated and thermocompression bonded is 14 g / 10 min. A solar cell encapsulant film, which is an ethylene-vinyl acetate copolymer sheet having the following melt flow rate. 2. At least one layer of the ethylene-vinyl acetate copolymer sheet contains an organic peroxide having a half-life at 130 ° C. of 1 hour or less.
The solar cell encapsulant film described. 3. The solar cell encapsulant film according to claim 1, wherein the ethylene-vinyl acetate copolymer sheet interposed on the back cover side of the silicon power generation element contains a coloring agent. 4. The solar cell encapsulant film according to claim 1, 2 or 3, wherein the ethylene-vinyl acetate copolymer sheet is adhered to a metal layer and / or a plastic film layer.