JP2012049242A - Sealing material sheet for solar cell and solar cell module using it - Google Patents

Abstract

An object of the present invention is to provide an encapsulant sheet that can be taken out only from a photovoltaic module and can be recycled.
In a solar cell module comprising a laminate in which a surface protective member / encapsulant sheet / photoelectric conversion cell / encapsulant sheet / back surface protective member are laminated, the encapsulant sheet comprises an ethylene-vinyl acetate copolymer. A solar cell encapsulant sheet comprising two layers of united resin (EVA) and including a transparent filler in a layer in contact with a photoelectric conversion cell.
[Selection] Figure 4

Description

  The present invention relates to a sealing material sheet used for a solar cell module.

  In recent years, solar cells have attracted attention as a power generation technology for clean energy sources using sunlight. As shown in FIG. 1, a general solar cell module 8 is composed of a layer structure of a surface protection member 1, a sealing material layer 2, solar cells 6, and a back surface protection member 7.

  When manufacturing this solar cell module, as shown in FIG. 2, the surface protection member 1, the sealing material sheet 3, the solar battery cell 6, the sealing material sheet 3, and the back surface protection member 7 are used in this order. The laminated material is heated while being deaerated in vacuum, and then cured, and the sealing material sheet 3 is crosslinked and cured to be integrated. For example, as production conditions, atmospheric pressure pressing is performed at about 150 ° C. while degassing, and then curing is performed at 150 ° C. for 30 minutes, so that the solar cell module 8 is produced.

  As a material for the encapsulant sheet, ethylene vinyl acetate copolymer resin (hereinafter abbreviated as EVA resin) is often used. In addition, for the purpose of imparting durability, in the EVA resin, a crosslinking agent for increasing the resin strength, a crosslinking assistant, a silane coupling agent for increasing adhesion to glass and photoelectric conversion cells, and weather resistance. Additives such as light stabilizers and UV absorbers are often included at a certain ratio.

  As a manufacturing method of the sealing material sheet, a molten resin is extruded from a die having a linear slit, and a T-die method in which the resin is cooled and solidified with a cooling roll, or a film is gradually formed by passing the extruded resin through a calendar roll. There is a calendar method. Usually, a film forming thickness of about 50 μm to 2 mm is used. Moreover, the embossing which makes an unevenness | corrugation on the sealing material sheet surface may be made in these film forming processes.

  During the process of manufacturing the solar cell module, when the heat treatment is performed, the cell may be damaged when the swelling of the EVA resin is not uniform around the photoelectric conversion cell. It is difficult to take out such a defective cell. Since the sealing material sheet is firmly bonded to the photoelectric conversion cell, if only the photoelectric conversion cell sandwiched between the sealing materials is taken out, the photoelectric conversion cell is further cracked or broken. . In particular, a polycrystalline silicon photoelectric conversion cell is more likely to be damaged than a single crystal silicon photoelectric conversion cell because its mechanical strength at the crystal grain boundary is weak. From such a current situation, recycling of photoelectric conversion cells also has a difficult problem.

  As a countermeasure for such a problem, there is a proposal that a non-adhesive film that does not adhere to the photoelectric conversion cell is interposed between the photoelectric conversion cell and the sealing material sheet (Patent Document 1).

  However, in this method, firing or peeling may occur between the photoelectric conversion cell and the non-adhesive film at the time of heating and pressurization when producing the solar cell module or when installed outdoors. When firing or peeling occurs, moisture enters between the photoelectric conversion cell and the non-adhesive film, not only lowering the insulation but also impairing the water vapor barrier and gas barrier properties of the protective sheet. There is a problem that causes a decrease in power generation performance.

Japanese Patent No. 4051430

  It is possible to provide only a photoelectric conversion cell from a solar battery module and to provide a sealing material sheet that can be recycled.

  The invention according to claim 1 of the present invention is a solar cell module comprising a laminate in which a surface protective member / encapsulant sheet / photoelectric conversion cell / encapsulant sheet / back surface protective member are laminated, wherein the encapsulant sheet comprises: A solar cell encapsulant sheet comprising two layers of ethylene-vinyl acetate copolymer resin, wherein the layer in contact with the photoelectric conversion cell contains a transparent filler.

  The invention according to claim 2 of the present invention is the solar cell encapsulant sheet according to claim 1, characterized in that it contains 0.5 to 5.0 parts by weight of the transparent filler.

  The invention according to claim 3 of the present invention is characterized in that the layer in contact with the photoelectric conversion cell has a light transmittance of 90% or more and a haze value of 75% or more. It is a sealing material sheet.

  The invention according to claim 4 of the present invention is a solar cell module using the solar cell sealing material sheet according to any one of claims 1 to 3.

  In the present invention, the sealing material sheet has a two-layer structure, and the layer in contact with the photoelectric conversion cell contains a transparent filler, thereby reducing the adhesion area with the photoelectric conversion cell and reducing the adhesive strength. Therefore, the photoelectric conversion cell can be taken out from the solar cell module and recycled. Moreover, conversion efficiency can be raised from the optical characteristic of the filler which has transparency.

It is explanatory drawing which shows an example of the laminated constitution of a solar cell module. It is explanatory drawing which shows an example of the member structure at the time of manufacture of a solar cell module. It is explanatory drawing which shows an example of the member layer structure at the time of the solar cell module manufacture of this invention. It is explanatory drawing which shows an example of the solar cell module of this invention.

  Hereinafter, embodiments of the present invention will be described in detail.

  FIG. 3 is an explanatory diagram showing an example of a member layer configuration when manufacturing the solar cell module of the present invention. The sealing material sheet 3 of the present invention has a two-layer structure. The EVA resin layer 5 includes a filler having transparency, and the EVA resin layer 4 does not include the filler. The EVA resin layer 5 containing a transparent filler is disposed so as to be in contact with the photoelectric conversion cell.

  FIG. 4 is an explanatory view showing an example of the solar cell module 9 of the present invention. The member configuration shown in FIG. 3 is changed to the solar cell module 9 by deaeration and heating curing.

In order to improve the crosslinking density of the EVA resin, an organic peroxide is added to the encapsulant sheet 3 used in the present invention as a crosslinking agent for initiating the crosslinking reaction of the EVA resin. Examples of organic peroxides include 1,1-di (t-butylperoxy) cyclohexane, 1,1-di (t-hexylperoxy) cyclohexane, n-butyl 4,4-di- (t-butylperoxy). ) Valerate, t-butylperoxy-3,5,5-trimethylhexanoate, 2,5-
Examples include dimethyl-2,5-di (t-butylperoxy) hexane, t-butylcumyl peroxide, 2,2-di- (t-butylperoxy) butane.

  In addition to the crosslinking agent, an additive for promoting the crosslinking reaction may be added. Examples of the additive include triallyl isocyanurate, diallyl phthalate, triallyl cyanurate and the like.

  A silane coupling agent can be added to improve adhesion to the surface protective member and the photoelectric conversion cell. As silane coupling agent, γ-methacryloxypropyltrimethoxysilane, various silane coupling agents such as trimethoxypropylsilane, trimethoxymethylsilane, vinyltrimethoxysilane, vinyltriethoxysilane, trichloropropylsilane, triethoxyphenyl Although silane etc. are also mentioned, γ-methacryloxypropyltrimethoxysilane is used in almost all cases because of its high adhesion promoting performance and low cost.

  Moreover, you may add a ultraviolet absorber and antioxidant in order to improve a weather resistance.

  Examples of ultraviolet absorbers used for improving weather resistance include 2- (5-methyl-2-hydroxyphenyl) benzotriazole and 2- (3-t-butyl-5-methyl-2-hydroxyphenyl) -5. -Chlorobenzotriazole, 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol, 2,4-dihydroxybenzophenone, 2-hydroxy-4 -N-octyloxybenzophenone etc. are mentioned.

  Antioxidants used for improving thermal stability include 1,6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], pentaerythrityl- Tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], tris (2,4-di-tert-butylphenyl) phosphite, 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine and the like can be mentioned.

  Of the two layers of the sealing material sheet 3, the EVA resin layer 5 including a filler having transparency is disposed so as to be in contact with the photoelectric conversion cell 6. This is because the EVA resin layer in contact with the photoelectric conversion cell 6 includes a transparent filler, thereby reducing the adhesion area and reducing the adhesion strength, thereby taking out the photoelectric conversion cell 6 in which a defect has occurred in particular. It is possible to improve the recyclability of the photoelectric conversion cell. Further, the front surface protection member 1 and the back surface protection member 7 have conventional physical properties by contacting with an EVA resin layer that does not contain a transparent filler.

  Examples of the transparent filler include polycarbonate resin, acrylic resin, fluorine acrylic resin, silicon acrylic resin, epoxy acrylate resin, polystyrene resin, cycloolefin polymer, methylstyrene resin, fluorene resin, polyethylene terephthalate. (PET), polypropylene, melamine resin and the like can be used.

  The EVA layer resin 5 containing these transparent fillers needs to maintain adhesion to the photoelectric conversion cell 6. In the present invention, it is preferable to add 0.5 to 5 parts by weight of a transparent filler. Addition of 0.5 parts by weight or more makes it possible to take out the photoelectric conversion cell 6. However, when 5 parts by weight or more is added, floating occurs due to insufficient adhesive strength other than at the time of removal, resulting in a defect.

  Further, by providing a difference in refractive index between the transparent filler and the EVA resin, it is possible to provide a function of generating light scattering and increasing the conversion efficiency.

  At this time, the difference in refractive index between the EVA resin and the transparent filler is preferably 0.02 or more. If the difference in refractive index is smaller than this, sufficient light scattering performance cannot be obtained.

  In addition, since it is necessary to transmit incident light while being scattered, the average particle diameter of the transparent filler is preferably 0.5 to 10.0 μm. Preferably 1.0-5.0 micrometers is good.

  Higher diffusivity is desirable. Preferably, the haze value is 75% or more. However, if the diffusibility is excessively increased and the transmittance is lowered, the conversion efficiency is also lowered. Therefore, the transmittance is preferably 90% or more.

  As the EVA resin, it is preferable to use a resin having a melt flow rate (MFR) (JIS K 7210-1999) at 190 ° C. and a load of 2160 g of 0.1 to 200 g / 10 minutes, particularly 1 to 100 g / 10 minutes. MFR is an index indicating the fluidity of the resin. When using a material with a low MFR, there is an advantage that troubles due to the flow of the sealing material hardly occur even if a material with a slightly lower melting point is used. Deteriorate. On the other hand, if a material having an excessively high MFR is used, it protrudes from the end when the module is produced and adheres to the laminate, which takes time to remove the adhering material and extremely reduces the production efficiency.

  A mixed resin obtained by mixing an EVA resin and other additives and heat-melting them can be formed into two layers by a co-extrusion method using a T die or the like to form a sealing material sheet. What is necessary is just to produce the thickness of a sealing material sheet normally in the range of 50 micrometers-2 mm. As another method, a sheet can be formed by calendering (calendering).

  In addition, if these formed sheets are worried about blocking, a metal sheet having a concavo-convex pattern on the roll surface is used to prevent the blocking of the heat-melted resin sheet in the film forming process. It is possible to emboss the surface of the encapsulant sheet by passing it through a roll.

  Specific examples of the present invention will be described below.

  In order to prepare a sealing material sheet, an EVA resin having a vinyl acetate content of 30% by weight was used. The following additives were mixed in this EVA resin, and a sealing material sheet was prepared by a coextrusion method.

To 100 parts by weight of EVA resin, 0.6 parts by weight of t-butylperoxy-2-ethylhexyl monocarbonate as a crosslinking agent, 0.4 parts by weight of γ-methacryloxypropyltrimethoxysilane as a silane coupling agent, and crosslinking 0.6 parts by weight of triallyl isocyanurate as an auxiliary agent, 0.3 parts by weight of 2-hydroxy-4-n-octyloxybenzophenone as an ultraviolet absorber, bis (2,2,6,6, A resin material containing 0.1 part by weight of -tetramethyl-4-piperidyl) sebacate and 0.1 part by weight of tris (2,4-di-t-butylphenyl) phosphite as an antioxidant was used. Further, as a filler having transparency, 0.3 part by weight of melamine resin was added, and a two-layer encapsulant sheet resin sheet was prepared by co-extrusion by the T-die method. The thickness of the layer including the filler having transparency was 500 μm, the thickness of the layer not including the filler was 100 μm, and a sheet having a total thickness of 600 μm was prepared.

  A sealing material sheet was prepared in the same manner as in Example 1 except that 0.50 part by weight of the melamine resin as the filler of Example 1 was added.

  A sealing material sheet was prepared in the same manner as in Example 1 except that 0.75 part by weight of melamine resin, which is the filler of Example 1, was added.

  A sealing material sheet was prepared in the same manner as in Example 1 except that 1.00 part by weight of the melamine resin as the filler of Example 1 was added.

  A sealing material sheet was prepared in the same manner as in Example 1 except that 2.50 parts by weight of the melamine resin as the filler of Example 1 was added.

  A sealing material sheet was prepared in the same manner as in Example 1 except that 5.00 parts by weight of melamine resin as the filler of Example 1 was added.

  A sealing material sheet was prepared in the same manner as in Example 1 except that 5.50 parts by weight of the melamine resin as the filler of Example 1 was added.

<Comparative Example 1>
A sealing material sheet was prepared in the same manner as in Example 1 except that the melamine resin as the filler of Example 1 was not added.

  About the sealing material sheet obtained in Examples 1 to 7 and Comparative Example 1, recyclability (whether the photoelectric conversion cell sandwiched between the sealing materials can be taken out) and floating confirmation (to the photoelectric conversion cell due to a decrease in sealing performance) Evaluation was made on whether or not a floating portion was generated in the layer in contact. In addition, the optical properties and conversion efficiency of the obtained encapsulant sheet were also evaluated. Details of the evaluation criteria are shown below.

(Recyclability)
Each of the two sealing material sheets obtained in Examples 1 to 7 and Comparative Example 1 was overlapped with a surface protective member, a photoelectric conversion cell, and a back surface protective member as shown in FIG. A module was prepared by curing at 0 ° C. for 10 minutes. A polycrystalline cell was used as the photoelectric conversion cell, white plate glass (thickness: 3 mm) was used as the surface protection member, and vinyl fluoride polymer (thickness: 38 μm) was used as the back surface protection member.

  Each created module was stored at room temperature for 2 months, and it was confirmed whether or not the cell could be taken out. If the photoelectric conversion cell could be taken out, it was marked with “◯”, and if it could not be taken out, it was marked with “x”.

(Float check)
Each module using the sealing material sheets of Examples 1 to 7 and Comparative Example 1 was visually observed under a fluorescent lamp after being stored for 1000 h in an environment of 85 ° C. and 85% RH. When no gap of 5 mmφ or more was confirmed between the photoelectric conversion cell and the sealing material sheet in the A4 size, it was “◯”, and when one or more was confirmed, it was “X”.

(optical properties)
The optical properties (total light transmittance and haze value) of the sealing material sheets obtained in Examples 1 to 7 and Comparative Example 1 were measured according to JIS K7105. NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd. was used as the apparatus. The surface containing the filler of the sealing material sheet was measured.

(Conversion efficiency)
A sample in which the conversion efficiency was increased as compared with Comparative Example 1 was designated as “◯”, and a sample that was equivalent or lowered was designated as “X”. For the measurement method, the module was irradiated with simulated sunlight from a solar simulator manufactured by Yamashita Denso Co., Ltd., and the photovoltaic power was monitored with a digital multimeter to measure the conversion efficiency.

  Table 1 shows the evaluation results of recyclability, floating confirmation, optical characteristics, and conversion efficiency.

表１に示すように、実施例２〜６の構成では、リサイクル性及び浮きの発生がなく信頼性に優れる太陽電池モジュールを作成することができる。また実施例２〜４の構成では、光学特性から変換効率を更に上げることができた。本発明の封止材シートを用いることで、リサイクル性、信頼性を備え変換効率に優れる太陽電池モジュールを作成することができる。

As shown in Table 1, in the configurations of Examples 2 to 6, it is possible to create a solar cell module having no recyclability and no occurrence of floating and excellent in reliability. In the configurations of Examples 2 to 4, the conversion efficiency could be further increased from the optical characteristics. By using the sealing material sheet of the present invention, a solar cell module having recyclability and reliability and excellent conversion efficiency can be produced.

1 .. Surface protection member 2 .. Sealing material layer 3 .. Sealing material sheet 4.. EVA resin layer 5.. EVA resin layer 6 including a filler having transparency... Photoelectric conversion cell 7. Member 8 .. Conventional solar cell module 9 .. Solar cell module of the present invention

Claims (4)

  The solar cell module which consists of a laminated body which laminated | stacked surface protection member / encapsulant sheet / photoelectric conversion cell / encapsulant sheet / back surface protection member, and the encapsulant sheet is made of an ethylene-vinyl acetate copolymer resin. A solar cell encapsulant sheet comprising a layer and comprising a filler having transparency in a layer in contact with a photoelectric conversion cell.   The solar cell encapsulant sheet according to claim 1, comprising 0.5 to 5.0 parts by weight of the transparent filler.   The solar cell encapsulant sheet according to claim 1 or 2, wherein a light transmittance of a layer in contact with the photoelectric conversion cell is 90% or more and a haze value is 75% or more.   A solar cell module comprising the solar cell encapsulant sheet according to claim 1.

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