JP5273860B2 - Solar cell module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solar cell module tolerant of heat shock or physical shock. <P>SOLUTION: The solar cell module is formed by sealing solar cells between a transparent insulating substrate and a rear insulating substrate with a resin sealing sheet. In the solar cell module, a gel fraction of the resin sealing sheet is &le;65 mass%. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a solar cell module.

  In recent years, the global warming phenomenon has heightened awareness of the environment, and a new energy system that does not generate greenhouse gases such as carbon dioxide is attracting attention. Since the energy generated by solar cell power generation does not emit carbon dioxide and other gases that cause global warming, research and development has been conducted as clean energy, and has attracted attention as industrial energy. Representative examples of solar cells include those using single crystal and polycrystalline silicon cells (crystalline silicon cells), those using amorphous silicon, and compound semiconductors (thin film cells). Solar cells are often used outdoors for a long period of time by being exposed to wind and rain, and the power generation part is modularized by laminating a glass plate or back sheet to prevent moisture from entering from outside. It was intended to protect and prevent leakage. The member that protects the power generation portion uses transparent glass or transparent resin on the light incident side in order to ensure light transmission necessary for power generation. For the member on the opposite side, an aluminum foil called a back sheet, a polyvinyl fluoride resin (PVF), polyethylene terephthalate (PET), or a laminated sheet of a barrier coating such as silica is used. The power generation element is sandwiched between resin sealing sheets, the outside is further covered with glass or a back sheet, heat treatment is performed to melt the resin sealing sheet, and the whole is integrally sealed (modularized).

  The following (1) to (3) are required as characteristics of the resin-encapsulated sheet described above. (1) Good adhesion to glass, power generation element and back sheet, (2) Flow prevention (creep resistance) of power generation element due to melting of resin-sealed sheet at high temperature, (3) Transparency that does not hinder the incidence of sunlight. From this point of view, the resin-encapsulated sheet is made of an ethylene-vinyl acetate copolymer (hereinafter also abbreviated as EVA), an ultraviolet absorber as a measure against ultraviolet deterioration, a coupling agent for improving adhesion to glass, For crosslinking, additives such as organic peroxides are blended, and the film is formed by calendar molding or T-die casting. In view of exposure to sunlight over a long period of time, various additives such as a light-resistant agent are blended in order to prevent deterioration of optical properties due to deterioration of the resin. Thereby, the transparency which does not inhibit the incidence of sunlight for a long time is maintained.

  As a form of modularizing solar cells with the resin-encapsulated sheet as described above, glass / resin encapsulated sheet / power generation element such as crystalline silicon cell / resin encapsulated sheet / back sheet are stacked in this order, and the glass surface is Using a dedicated solar cell vacuum laminator, the resin sealing sheet is melted and pasted through a step of preheating above the melting temperature of the resin (temperature condition of 150 ° C in the case of EVA) and a pressing step. There is. In this method, first, the resin of the resin sealing sheet is melted in the preheating process, and is in close contact with the member in contact with the melted resin in the pressing process and vacuum laminated. In this laminating step, (i) a crosslinking agent contained in the resin sealing sheet, for example, an organic peroxide, is thermally decomposed to promote EVA crosslinking. (Ii) It is covalently bonded to the member in contact with the coupling agent contained in the resin sealing sheet. Thereby, mutual adhesiveness improves more and the outstanding adhesiveness with glass, a power generation element, and a back sheet is implement | achieved.

Patent Document 1 discloses a solar cell filling adhesive sheet made of an ethylene copolymer resin containing a coupling agent and an organic peroxide.
Patent Document 2 discloses a sheet for sealing a solar cell, which is a sheet made of an ethylene vinyl acetate copolymer blended with a crosslinking agent and a silane coupling agent, and is radiation-crosslinked to a certain gel fraction. Is disclosed.
In the above document, after stacking each member such as glass, sealing sheet, cell, back sheet, etc., a solar cell module is manufactured by performing melt bonding and crosslinking with an organic peroxide using a vacuum laminator. ing.

JP 58-060579 A JP-A-8-283696

  However, when the solar cell module disclosed in the above document is subjected to a heat shock such as being repeatedly placed in a high temperature state and a low temperature state, the followability of the resin sealing sheet is insufficient, so that the resin sealing sheet is melted. Therefore, there is a problem that the power generation element flows or a gap is generated in the module.

  Moreover, when a solar cell module deform | transforms by the physical shock from the outside, since the followability of a resin sealing sheet is inadequate, there exists a problem that a cell crack generate | occur | produces in a solar cell module.

  In view of the above circumstances, the problem to be solved by the present invention is to provide a solar cell module that is resistant to heat shock and physical shock.

  As a result of earnest studies on the above problems, the present inventors have found that a solar cell module sealed with a resin sealing sheet whose gel fraction is adjusted to a specific range can solve the above problems. The headline and the present invention were completed.

That is, the present invention provides the following.
[1]
A solar cell module formed by sealing solar cells between a translucent insulating substrate and a back insulating substrate with a resin sealing sheet,
The solar cell module whose gel fraction of the said resin sealing sheet is 65 mass% or less.
[2]
[1] The solar cell module according to [1], wherein the resin encapsulating sheet has a decrease rate from a storage elastic modulus (E ′) at 80 ° C. to a storage elastic modulus (E ′) at 140 ° C. of 10% or more.
[3]
The solar cell module according to [1] or [2], wherein the resin sealing sheet is subjected to ionizing radiation treatment.
[4]
The resin-encapsulated sheet is an ethylene-vinyl acetate copolymer, an ethylene-aliphatic unsaturated carboxylic acid copolymer, an ethylene-aliphatic carboxylic acid ester copolymer, an ethylene-vinyl acetate copolymer saponified product, an ethylene- The solar cell module according to any one of [1] to [3], which is at least one resin selected from the group consisting of a saponified vinyl acetate-acrylic acid ester copolymer and a polyolefin resin.

  According to the present invention, a solar cell module resistant to heat shock and physical shock can be provided.

It is the figure which showed typically sectional drawing of the solar cell module in this Embodiment.

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

  The solar cell module in the present embodiment is a solar cell module formed by sealing solar cells between a translucent insulating substrate and a back insulating substrate with a resin sealing sheet, A solar cell module having a gel fraction of 65% by mass or less.

  FIG. 1 is a diagram schematically showing a cross-sectional view of the solar cell module in the present embodiment. As shown in FIG. 1, the solar cell module 1 in the present embodiment is formed by sandwiching and stacking solar cells 4 formed of polycrystalline silicon or the like between two or more resin-encapsulated sheets 5A and 5B. The translucent insulating substrate 2 has a structure in which the back surface is covered with the back insulating substrate 3. That is, it has the structure of translucent insulating substrate 2 / resin sealing sheet 5A / solar battery cell 4 / resin sealing sheet 5B / back surface insulating substrate 3. However, since the configuration shown in FIG. 1 is one of the preferred embodiments, the solar cell module of the present embodiment is not limited to the above-described configuration, and layers other than those described above are provided as long as the object of the present invention is not impaired. It can be provided as appropriate. Typically, an adhesive layer, a shock absorbing layer, a coating layer, an antireflection layer, a back surface rereflection layer, a light diffusion layer, and the like can be provided, but not limited thereto. The position where these layers are provided is not particularly limited, and can be provided at an appropriate position in consideration of the purpose of providing such layers and the characteristics of such layers.

  In the solar cell module in the present embodiment, the gel fraction of at least one of the resin sealing sheets 5A and 5B shown in FIG. 1 is 65% by mass or less. For example, although not illustrated, when the resin sealing sheet has a multilayer structure of three or more layers, the gel fraction of any one of the resin sheet layers may be 65% by mass or less. The present inventors can exhibit excellent followability as a solar cell module by setting the gel fraction of the resin encapsulating sheet to 65% by mass or less, and is resistant to heat shock and physical shock, and also has creep resistance. I discovered that I could do it with an excellent solar cell module.

  The upper limit of the gel fraction of the resin encapsulating sheet is preferably 70% by mass or less, more preferably 65% by mass or less, from the viewpoint of sealing the silicon cells of the power generation layer without gaps, and the lower limit is From the viewpoint of preventing flow of the silicon cell in a high temperature state such as summer, it is preferably 2% by mass or more, more preferably 3% by mass or more.

  In the solar cell module in the present embodiment, the gel fraction is an average gel of the entire resin-encapsulated sheet, regardless of whether the resin-encapsulated sheet has a single-layer structure or a multi-layer structure described later. It means the value of fraction (total layer gel fraction).

The gel fraction of the resin sealing sheet is a ratio of an insoluble part obtained by extracting the resin sealing sheet in boiling p-xylene for 12 hours, and can be obtained by the following formula.
Gel fraction (mass%) = (sample weight after extraction / sample weight before extraction) × 100

  Moreover, the solar cell module in this Embodiment is 10% or more especially in the fall rate from the storage elastic modulus (E ') of 80 degreeC of the resin sealing sheet to the storage elastic modulus (E') of 140 degreeC. Preferably there is. More preferably, it is 13% or more, More preferably, it is 15% or more. The decrease rate from the storage elastic modulus (E ′) at 80 ° C. to the storage elastic modulus (E ′) at 140 ° C. of the resin-encapsulated sheet 5A or 5B shown in FIG. For example, although not shown, when the resin sealing sheet has a multilayer structure of three or more layers, any one of the resin sheet layers is stored at a storage elastic modulus (E ′) of 80 ° C. to 140 ° C. The rate of decrease to the elastic modulus (E ′) may be 10% or more.

  When the rate of decrease from the storage elastic modulus (E ′) at 80 ° C. to the storage elastic modulus (E ′) at 140 ° C. is in the above range, heat shock resistance and physical shock resistance tend to be better. . In particular, even when repeatedly exposed to a high temperature environment and a low temperature environment, the followability of the resin-encapsulated sheet does not deteriorate.

In this Embodiment, the decreasing rate from the storage elastic modulus (E ') of 80 degreeC of the resin sealing sheet to the storage elastic modulus (E') of 140 degreeC can be calculated | required by a following formula.
Reduction ratio (%) from storage elastic modulus (E ′) at 80 ° C. to storage elastic modulus (E ′) at 140 ° C. = (Storage elastic modulus (E ′) at 80 ° C.) − Storage elastic modulus at 140 ° C. (E ′ )) / ((80 ° C. storage elastic modulus (E ′)) × 100

  The solar cell module in the present embodiment has a storage elastic modulus (E ′) at 80 ° C. of the resin-encapsulated sheet, regardless of whether the resin-encapsulated sheet has a single-layer structure or a multi-layer structure described later. The rate of decrease from 140 to 140 ° C. storage elastic modulus (E ′) means the average value of the entire resin-encapsulated sheet.

  As a means for adjusting the gel fraction of the resin-encapsulated sheet and the rate of decrease of the storage elastic modulus (E ′) to the above range, a suitable crosslinking treatment can be given to the sheet. As the crosslinking treatment method at that time, known methods can be used without limitation, and examples thereof include crosslinking treatment by irradiation with ionizing radiation (electron beam, γ-ray, ultraviolet ray, etc.), crosslinking treatment with organic peroxide, and the like. It is done.

  In the case of crosslinking by irradiation with ionizing radiation, a method of irradiating the resin encapsulating sheet with ionizing radiation such as α-ray, β-ray, γ-ray, neutron beam, electron beam, and the like can be used. The acceleration voltage of ionizing radiation such as an electron beam may be selected according to the thickness of the resin sealing sheet. For example, when the thickness is 500 μm, when the entire resin sealing sheet is crosslinked, the acceleration voltage is 300 kV or more. is necessary.

  The acceleration voltage of ionizing radiation such as an electron beam can be appropriately adjusted according to the resin layer subjected to the crosslinking treatment. The irradiation dose of ionizing radiation varies depending on the resin used, but is generally less than 3 kGy. It tends to be difficult to uniformly cross-link the entire resin-encapsulated sheet.

  The accelerating voltage and irradiation dose of ionizing radiation can be appropriately adjusted in order to obtain a desired gel fraction. The degree of crosslinking can be evaluated by measuring the gel fraction.

  In order to achieve the gel fraction in the above range, in addition to the irradiation amount of ionizing radiation, the difference in the degree of crosslinking depending on the type of resin, or the effect of crosslinking promotion or crosslinking inhibition by a transfer agent or the like may be utilized. .

  In the case of crosslinking with an organic peroxide, thermal crosslinking is performed by blending or impregnating the organic peroxide in the resin as a crosslinking agent. In this case, an organic peroxide having a half-life at 100 to 130 ° C. of 1 hour or less is preferable.

  Examples of organic peroxides that have good compatibility and have the above half-life include 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, 1,1 -Bis (t-butylperoxy) cyclohexane, n-butyl-4,4-bis (t-butylperoxy) valerate, 2,2-bis (t-butylperoxy) butane and the like. The resin-encapsulated sheet using these organic peroxides can reduce the crosslinking time relatively, and the curing process is an organic material having a half-life at 100 to 130 ° C., which is conventionally used, of 1 hour or more. Compared with the case of using a peroxide, it can be shortened to about half.

  The content of the organic peroxide is preferably 0 to 10% by mass and more preferably 0 to 5% by mass with respect to the resin constituting the resin sealing sheet.

  The resin-encapsulated sheet containing the organic peroxide is softened during lamination, and after the gap is filled, the decomposition and crosslinking of the organic peroxide are promoted, so the resin gel fraction increases. However, it has an advantage that the gap filling property is not hindered.

  As described above, “crosslinking” includes a method of irradiating with ionizing radiation and a method of using an organic peroxide, and a method of crosslinking by irradiation with ionizing radiation is particularly preferable. The crosslinking treatment by irradiation with ionizing radiation does not generate gas due to thermal decomposition of the organic peroxide, and therefore tends to further reduce the corrosion damage and oil contamination of the vacuum pump. In addition, the crosslinking method using an organic peroxide requires a long curing process for decomposing the organic peroxide in the lamination process and promoting the crosslinking of the resin sealing sheet. Although it is difficult to speed up production, the crosslinking method by irradiation with ionizing radiation is excellent in that it does not require a long-time curing step and can improve the productivity of the solar cell module.

  The resin constituting the resin encapsulating sheet is not particularly limited as long as it is a resin that is crosslinked by ionizing radiation or organic peroxide. However, it has good transparency, flexibility, adhesion and handling properties of an adherend. From the viewpoint of securing, ethylene-vinyl acetate copolymer, ethylene-aliphatic unsaturated carboxylic acid copolymer, ethylene-aliphatic carboxylic acid ester copolymer, saponified ethylene-vinyl acetate copolymer, ethylene-vinyl acetate -It is preferable to contain at least 1 sort (s) of resin selected from the group which consists of saponification thing of acrylic ester copolymer, ethylene copolymer containing glycidyl methacrylate, and polyolefin resin.

  The ethylene-vinyl acetate copolymer refers to a copolymer obtained by copolymerization of an ethylene monomer and vinyl acetate. The ethylene-aliphatic unsaturated carboxylic acid copolymer refers to a copolymer obtained by copolymerization of an ethylene monomer and at least one monomer selected from aliphatic unsaturated carboxylic acids. Furthermore, the ethylene-aliphatic unsaturated carboxylic acid ester copolymer refers to a copolymer obtained by copolymerization of an ethylene monomer and at least one monomer selected from aliphatic unsaturated carboxylic acid esters.

  The copolymerization can be performed by a known method such as a high pressure method or a melting method, and a multisite catalyst, a single site catalyst, or the like can be used as a catalyst for the polymerization reaction. Moreover, in the said copolymer, the bond shape of each monomer is not specifically limited, The polymer which has bond shapes, such as a random bond and a block bond, can be used. From the viewpoint of optical properties, the copolymer is preferably a copolymer polymerized by random bonding using a high-pressure method.

  In the ethylene-vinyl acetate copolymer, the ratio of vinyl acetate in all monomers constituting the copolymer is preferably 10 to 40% by mass from the viewpoint of optical properties, adhesiveness, and flexibility. More preferably, it is -35 mass%, and it is still more preferable that it is 15-30 mass%. Further, from the viewpoint of workability of the resin-encapsulated sheet, a melt flow rate value (hereinafter also abbreviated as “MFR”) (190 ° C., 2.16 kg) measured according to JIS-K-7210 is obtained. It is preferably 0.3 g / 10 min to 30 g / 10 min, more preferably 0.5 g / min to 30 g / min, and still more preferably 0.8 g / min to 25 g / min.

  Examples of the ethylene-aliphatic unsaturated carboxylic acid copolymer include an ethylene-acrylic acid copolymer (hereinafter also abbreviated as “EAA”) and an ethylene-methacrylic acid copolymer (hereinafter, “EMAA”). Abbreviated as well)). Examples of the ethylene-aliphatic unsaturated carboxylic acid ester copolymer include an ethylene-acrylic acid ester copolymer and an ethylene-methacrylic acid ester copolymer. Here, as acrylic acid ester and methacrylic acid ester, ester with C1-C8 alcohols, such as methanol and ethanol, is used suitably.

  These copolymers may be multi-component copolymers obtained by copolymerizing three or more monomers. Examples of the multi-component copolymer include a copolymer obtained by copolymerizing at least three types of monomers selected from ethylene, aliphatic unsaturated carboxylic acid, and aliphatic unsaturated carboxylic acid ester.

  In the ethylene-aliphatic unsaturated carboxylic acid copolymer, the proportion of the aliphatic unsaturated carboxylic acid in all monomers constituting the copolymer is preferably 3 to 35% by mass. Further, MFR (190 ° C., 2.16 kg) is preferably 0.3 g / 10 min to 30 g / 10 min, more preferably 0.5 g / 10 min to 30 g / 10 min, and 0.8 g / 10 min to More preferably, it is 25 g / 10 min.

  Examples of the saponified ethylene-vinyl acetate copolymer include a partially or completely saponified ethylene-vinyl acetate copolymer, and examples of the saponified ethylene-vinyl acetate-acrylic acid ester copolymer include ethylene- Examples thereof include a vinyl acetate-acrylic acid ester copolymer part or a completely saponified product.

  The ratio of the hydroxyl group in each saponified product is preferably 0.1% by mass to 15% by mass, more preferably 0.1% by mass to 10% by mass, in the resin constituting the resin sealing sheet. More preferably, it is 0.1 mass%-7 mass%. If the proportion of the hydroxyl group is 0.1% by mass or more, the adhesiveness tends to be good, and if it is 15% by mass or less, the compatibility tends to be good. The risk of clouding can be reduced.

  The ratio of the hydroxyl group was determined based on the olefin-based polymer resin of the saponified ethylene-vinyl acetate copolymer and the saponified ethylene-vinyl acetate-acrylic acid ester copolymer, and VA% of this resin (vinyl acetate copolymer by NMR measurement). (Polymerization ratio), its saponification degree, and the blending ratio in the resin.

  The content of vinyl acetate in the ethylene-vinyl acetate copolymer and the ethylene-vinyl acetate-acrylic acid ester copolymer before saponification is determined from the viewpoint of obtaining good optical properties, adhesiveness, and flexibility. It is preferable that it is 10-40 mass% with respect to the whole union, it is more preferable that it is 13-35 mass%, and it is still more preferable that it is 15-30 mass%. The saponification degree of the saponified ethylene-vinyl acetate copolymer and the saponified ethylene-vinyl acetate-acrylic acid ester copolymer is 10 to 70% from the viewpoint of obtaining good transparency and adhesiveness. Is more preferable, 15 to 65% is more preferable, and 20 to 60% is still more preferable.

  Examples of the saponification method include a method of saponifying an ethylene-vinyl acetate copolymer, an ethylene-vinyl acetate-acrylic ester copolymer pellet or powder using an alkali catalyst in a lower alcohol such as methanol, toluene, And a method of dissolving a copolymer in advance using a solvent such as xylene and hexane and then saponifying using a small amount of alcohol and an alkali catalyst. Moreover, you may graft-polymerize the monomer containing functional groups other than a hydroxyl group to the saponified copolymer.

  Since each saponified product has a hydroxyl group in the side chain, the adhesiveness is improved as compared with the copolymer before saponification. Moreover, transparency and adhesiveness can be controlled by adjusting the amount of hydroxyl groups (degree of saponification).

  The ethylene copolymer containing glycidyl methacrylate refers to an ethylene copolymer and an ethylene terpolymer with glycidyl methacrylate having an epoxy group as a reaction site. For example, ethylene-glycidyl methacrylate copolymer, ethylene-glycidyl methacrylate-vinyl acetate copolymer And an ethylene-glycidyl methacrylate-methyl acrylate copolymer. Since the above compounds have high reactivity of glycidyl methacrylate, they can exhibit stable adhesion, and have a low glass transition temperature and tend to have good flexibility.

  As the polyolefin resin, polyethylene resin, polypropylene resin, and polybutene resin are preferable. Here, the polyethylene resin refers to a homopolymer of ethylene or a copolymer of ethylene and one or more other monomers. The polypropylene resin refers to a homopolymer of propylene or a copolymer of propylene and one or more other monomers.

  Examples of the polyethylene resin include polyethylene and ethylene-α-olefin copolymers.

  Examples of the polyethylene include low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and linear very low density polyethylene (referred to as “VLDPE” and “ULDPE”).

  The ethylene-α-olefin copolymer is preferably a copolymer composed of ethylene and at least one selected from α-olefins having 3 to 20 carbon atoms, and includes ethylene and 3 to 12 carbon atoms. More preferred is a copolymer comprising at least one selected from α-olefins. Examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-decene, and 1-decene. Examples include dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosane and the like, and these can be used alone or in combination. Moreover, it is preferable that the ratio (based on preparation monomer) of the alpha olefin in all the monomers which comprise a copolymer is 6-30 mass%. Further, the ethylene-α-olefin copolymer is preferably a soft copolymer, and preferably has a crystallinity of 30% or less by an X-ray method.

  In addition, as the ethylene-α-olefin copolymer, a copolymer of ethylene and at least one comonomer selected from propylene comonomer, butene comonomer, hexene comonomer, and octene comonomer is generally easily available. It can be used suitably.

The polyethylene resin can be polymerized using a known catalyst such as a single site catalyst or a multisite catalyst, and is preferably polymerized using a single site catalyst. The above polyethylene-based resin, from the viewpoint of cushioning properties, it is preferable that a density of 0.860~0.920g / cm ^3, more preferably 0.870~0.915g / cm ^3, 0. More preferably, it is 870-0.910 g / cm < ³ >. When the density is 0.920 g / cm ³ or less, the cushioning property tends to be good. If the density exceeds 0.920 g / cm ³ , the transparency may be deteriorated. When a high-density polyethylene-based resin is used, the transparency can be improved by adding a low-density polyethylene-based resin at a ratio of about 30% by mass, for example.

  The polyethylene resin preferably has an MFR (190 ° C., 2.16 kg) of 0.5 g / 10 min to 30 g / 10 min, preferably 0.8 g / 10 min to 30 g / min, from the viewpoint of processability of the resin encapsulated sheet. 10 min is more preferable, and 1.0 g / 10 min to 25 g / 10 min is still more preferable.

  As said polyethylene-type resin, the polyethylene-type copolymer which controlled crystal / amorphous structure (morphology) by nano order can also be used.

  Examples of the polypropylene resin include polypropylene, propylene-α-olefin copolymer, and terpolymer of propylene, ethylene, and α-olefin.

  The propylene-α-olefin copolymer refers to a copolymer composed of at least one selected from propylene and α-olefin. The propylene-α-olefin copolymer is preferably a copolymer composed of propylene and at least one selected from ethylene and an α-olefin having 4 to 20 carbon atoms, and propylene, ethylene and 4 to 8 carbon atoms. A copolymer comprising at least one selected from α-olefins is more preferable. Examples of the α-olefin having 4 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, and 3-methyl-1-pentene. , 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosane and the like, and these can be used alone or in combination. Moreover, it is preferable that the content rate (charged monomer reference | standard) of ethylene and / or alpha-olefin in all the monomers which comprise the said propylene-alpha-olefin copolymer is 6-30 mass%. Furthermore, the propylene-α-olefin copolymer is preferably a soft copolymer, and preferably has a crystallinity of 30% or less by an X-ray method.

  As the propylene-α-olefin copolymer, a copolymer of propylene and at least one comonomer selected from ethylene comonomer, butene comonomer, hexene comonomer, and octene comonomer is generally easily available, and preferably Can be used.

The polypropylene resin can be polymerized using a known catalyst such as a single-site catalyst or a multi-site catalyst, and is preferably polymerized using a single-site catalyst. Also the polypropylene-based resin, from the viewpoint of cushioning properties, it is preferable that a density of 0.860~0.920g / cm ^3, more preferably 0.870~0.915g / cm ^3, 0. More preferably, it is 870-0.910 g / cm < ³ >. When the density is 0.920 g / cm ³ or less, the cushioning property tends to be good. If the density exceeds 0.920 g / cm ³ , the transparency may be deteriorated.

  The polypropylene resin preferably has an MFR (230 ° C., 2.16 kgf) of 0.3 g / 10 min to 15.0 g / 10 min from the viewpoint of processability of the resin-encapsulated sheet, preferably 0.5 g / 10 min. 12 g / 10 min is more preferable, and 0.8 g / 10 min to 10 g / 10 min is still more preferable.

  As the polypropylene resin, a polypropylene copolymer in which the crystal / amorphous structure (morphology) is controlled in nano order can also be used.

  Examples of the polypropylene resin include copolymers of propylene and α-olefins such as ethylene, butene, hexene, and octene, or ternary compounds of propylene, ethylene and α-olefins such as butene, hexene, and octene. A copolymer etc. can be used conveniently. These copolymers may be in any form such as a block copolymer, a random copolymer, etc., preferably a random copolymer of propylene and ethylene, or a random copolymer of propylene, ethylene and butene. is there.

  The polypropylene resin is not limited to a resin polymerized with a catalyst such as a Ziegler-Natta catalyst, but may be a resin polymerized with a metallocene catalyst, for example, syndiotactic polypropylene, isotactic polypropylene, etc. it can. Moreover, it is preferable that the ratio (based on preparation monomer) of the propylene in all the monomers which comprise a polypropylene resin is 60-80 mass%. Furthermore, from the viewpoint of excellent heat shrinkability, the propylene content ratio (based on the charged monomer) in all monomers constituting the polypropylene resin is 60 to 80% by mass, and the ethylene content ratio (based on the charged monomer) is 10 to 30. A ternary copolymer having a butene content ratio (based on charged monomers) of 5 to 20% by mass is preferable.

  As the polypropylene resin, a resin obtained by uniformly finely dispersing a rubber component having a high concentration of 50% by mass or less with respect to the total amount of the polypropylene resin can be used.

  When the resin constituting the resin sealing sheet contains the polypropylene resin, properties such as hardness and heat resistance tend to be further improved.

  In addition, since the polybutene resin is particularly excellent in compatibility with the polypropylene resin, the polybutene resin is preferably used in combination with the polypropylene resin for the purpose of adjusting the hardness and waist of the resin sealing sheet. The polybutene resin is crystalline and is a copolymer of butene and at least one selected from ethylene, propylene and an olefin compound having 5 to 8 carbon atoms, and constitutes a polybutene resin. A high molecular weight polybutene resin having a butene content of 70 mol% or more in all monomers can be suitably used.

  The polybutene resin preferably has an MFR (190 ° C., 2.16 kg) of 0.1 g / 10 min to 10 g / 10 min. Moreover, it is preferable that a Vicat softening point is 40-100 degreeC. Here, the Vicat softening point is a value measured according to JIS K7206-1982.

The resin sealing sheet of the present embodiment may have either a single layer structure or a multilayer structure. Hereinafter, each structure will be described.
[Single layer structure]
When the resin encapsulating sheet has a single layer structure, ethylene-vinyl acetate copolymer, ethylene-aliphatic unsaturated carboxylic acid is used from the viewpoint of ensuring good transparency, flexibility, adhesion of adherends and handleability. From the group consisting of acid copolymer, ethylene-aliphatic unsaturated carboxylic acid ester copolymer, saponified ethylene-vinyl acetate copolymer, saponified ethylene-vinyl acetate-acrylic acid ester copolymer, and polyolefin resin A layer made of at least one selected resin is preferable.

  When the resin layer constituting the resin encapsulating sheet contains an ethylene-vinyl acetate copolymer saponified product or an ethylene-vinyl acetate-acrylic acid ester copolymer saponified product as an adhesive resin, the degree of saponification And content can be adjusted suitably and, thereby, adhesiveness with a to-be-sealed thing can be controlled. From the viewpoint of adhesiveness and optical properties, the content of the saponified ethylene-vinyl acetate copolymer and saponified ethylene-vinyl acetate-acrylate copolymer in the resin layer is 3 to 60% by mass. Preferably, it is 3-55 mass%, More preferably, it is 5-50 mass%.

[Multilayer structure]
The resin sealing sheet in the present embodiment may have a multilayer structure of at least two layers including a surface layer and an inner layer laminated on the surface layer. Here, the two layers forming both surfaces of the resin sealing sheet are referred to as “surface layers”, and the other layers are referred to as “inner layers”.

  In the case of having a multilayer structure, a layer containing a saponified ethylene-vinyl acetate copolymer and a saponified ethylene-vinyl acetate-acrylic acid ester copolymer as an adhesive resin is a layer in contact with an object to be sealed ( It is preferably formed as at least one surface layer. The surface layer may be a layer composed only of the saponified product described above. However, from the viewpoint of ensuring good transparency, flexibility, adhesion of the adherend and handleability, the saponified product and ethylene-vinyl acetate are used. It consists of a mixed resin with at least one resin selected from the group consisting of a copolymer, an ethylene-aliphatic unsaturated carboxylic acid copolymer, an ethylene-aliphatic unsaturated carboxylic acid ester copolymer, and a polyolefin resin. A layer is preferred.

  The layer ratio of the surface layer in contact with the object to be sealed preferably has a thickness of at least 5% with respect to the total thickness of the resin sealing sheet from the viewpoint of ensuring good adhesiveness. When the thickness is 5% or more, the same adhesiveness as in the case of the single layer structure described above tends to be obtained.

  The resin constituting the inner layer is not particularly limited, and any other resin may be used in addition to the resin contained in the surface layer described above. For the purpose of imparting other functions to the inner layer, resin materials, mixtures, additives, and the like can be appropriately selected. For example, for the purpose of newly imparting cushioning properties, a layer containing a thermoplastic resin may be provided as the inner layer.

  Examples of the thermoplastic resin used as the inner layer include polyolefin resins, styrene resins, vinyl chloride resins, polyester resins, polyurethane resins, chlorinated ethylene polymer resins, polyamide resins, and the like. Those possessed and those derived from plant-derived materials are also included. Among the above, a hydrogenated block copolymer resin, a propylene copolymer resin, and an ethylene copolymer resin that have good compatibility with the crystalline polypropylene resin and good transparency are preferable, and a hydrogenated block copolymer. A resin and a propylene-based copolymer resin are more preferable.

  As the hydrogenated block copolymer resin, a block copolymer of vinyl aromatic hydrocarbon and conjugated diene is preferable. Examples of vinyl aromatic hydrocarbons include styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 1,3-dimethylstyrene, α-methylstyrene, vinylnaphthalene, vinylanthracene, and 1,1-diphenyl. Examples thereof include ethylene, N, N-dimethyl-p-aminoethylstyrene, N, N-diethyl-p-aminoethylstyrene, and styrene is particularly preferable. These may be used alone or in combination of two or more. The conjugated diene is a diolefin having a pair of conjugated double bonds, such as 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3- Examples include butadiene, 1,3-pentadiene, and 1,3-hexadiene. These may be used alone or in combination of two or more.

  As the propylene-based copolymer resin, a copolymer obtained from propylene and ethylene or an α-olefin having 4 to 20 carbon atoms is preferable. The content of the ethylene or α-olefin having 4 to 20 carbon atoms is preferably 6 to 30% by mass. Examples of the α-olefin having 4 to 20 carbon atoms include 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, 3-methyl-1-pentene and 1-decene. 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosane and the like.

  The propylene-based copolymer resin may be polymerized using a multi-site catalyst, a single-site catalyst, or any other catalyst. Further, a propylene-based copolymer in which the crystal / amorphous structure (morphology) of the polymer is controlled in nano order can be used.

  The ethylene copolymer resin may be polymerized with any of a multisite catalyst, a single site catalyst, and other catalysts. Further, an ethylene copolymer in which the crystal / amorphous structure (morphology) of the polymer is controlled in nano order can be used.

When a polyethylene resin is used as the material for the inner layer, the density of the polyethylene resin is preferably 0.860 to 0.920 g / cm ³ from the viewpoint of obtaining appropriate cushioning properties, and 0.870 to 0.915 g. / Cm ³ is more preferable, and 0.870 to 0.910 g / cm ³ is still more preferable. When a resin layer having a density of 0.920 g / cm ³ or more is formed as a layer (inner layer) that does not contact the object to be sealed, the transparency tends to deteriorate.

  Moreover, the resin sealing sheet may have a structure in which one or two or more layers of the same component are laminated on both surfaces of the center layer so as to be symmetrically arranged with respect to the center layer. As such a resin sealing sheet, for example, a resin sealing sheet composed of two surface layers (hereinafter sometimes referred to as “skin layer”) and three inner layers, Examples thereof include a resin-encapsulated sheet in which the surface layer is composed of the same component, and two inner layers adjacent to the surface layer (hereinafter sometimes referred to as “base layer”) are composed of the same component.

  In the resin sealing sheet having the above structure, the film thickness of the surface layer is preferably 5 to 40% with respect to the film thickness of the entire resin sealing sheet, and the film thickness of the base layer is the resin sealing sheet. The film thickness of the inner layer (hereinafter sometimes referred to as “core layer”) sandwiched between the base layers is preferably 50% to 90% with respect to the entire film pressure. It is preferable that it is 5 to 40% with respect to the film thickness.

  Next, the viewpoint of resin-encapsulated sheet processability is examined. The MFR (190 ° C., 2.16 kg) of the resin constituting the resin sealing sheet is preferably 0.5 to 30 g / 10 min from the viewpoint of ensuring good workability, and 0.8 to 30 g / 10 min. It is more preferable that it is 1.0 to 25 g / 10 min. When the resin sealing sheet has a multilayer structure of two or more layers, the MFR of the resin constituting the inner layer (base layer or core layer) is preferably lower than the MFR of the surface layer from the viewpoint of resin sealing sheet processability.

  In the resin-encapsulated sheet in the present embodiment, various additives such as a coupling agent, an antifogging agent, a plasticizer, an antioxidant, a surfactant, a colorant, and an ultraviolet absorber are provided as long as the characteristics are not impaired. Further, an antistatic agent, a crystal nucleating agent, a lubricant, an antiblocking agent, an inorganic filler, a crosslinking regulator, and the like may be added.

  A coupling agent may be added to the resin sealing sheet for the purpose of ensuring stable adhesion. The addition amount and type of the coupling agent can be appropriately selected depending on the desired degree of adhesion and the type of adherend. The addition amount of the coupling agent is preferably 0.01 to 5% by mass, more preferably 0.03 to 4% by mass, based on the total mass of the resin layer to which the coupling agent is added. More preferably, the content is 0.05 to 3% by mass. As the kind of the coupling agent, a substance that gives the resin layer good adhesion to a solar battery cell or glass is preferable, and examples thereof include organic silane compounds, organic silane peroxides, and organic titanate compounds. . These coupling agents may be added by a known addition method such as injection and mixing into a resin in an extruder, mixing and introducing into an extruder hopper, masterbatching, mixing and adding. it can. However, when passing through an extruder, the function of the coupling agent may be hindered by heat, pressure, etc. in the extruder, so the amount of addition needs to be adjusted appropriately depending on the type of coupling agent. In addition, the type of the coupling agent may be appropriately selected in consideration of the transparency of the resin-encapsulated sheet and the degree of dispersion, the corrosion on the extruder, and the viewpoint of extrusion stability. Preferred coupling agents include γ-chloropropylmethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyl-tris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, β- (3,4- Ethoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ- Examples thereof include those having an unsaturated group or an epoxy group such as aminopropyltrimethoxysilane glycidoxypropyltriethoxysilane.

  Moreover, an ultraviolet absorber, antioxidant, discoloration inhibitor, etc. can be added to a resin sealing sheet. In particular, when it is necessary to maintain transparency and adhesiveness over a long period of time, it is preferable to add an ultraviolet absorber, an antioxidant, a discoloration inhibitor and the like. When these additives are added to the resin, the amount added is preferably 10% by mass or less, more preferably 5% by mass or less, based on the total amount of the resin to be added.

  Examples of the ultraviolet absorber include 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-n-5-sulfobenzophenone, 2-hydroxy-4-methoxybenzophenone, and 2,2′-dihydroxy-4. , 4′-dimethoxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, 2,4-dihydroxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, and the like. Examples of the antioxidant include phenol-based, sulfur-based, phosphorus-based, amine-based, hindered phenol-based, hindered amine-based, and hydrazine-based antioxidants.

  These ultraviolet absorbers, antioxidants, discoloration inhibitors and the like are preferably added in an amount of 0 to 10% by mass, more preferably 0 to 5% by mass, in the resin constituting the resin sealing sheet. When added to an ethylene-based resin, adhesiveness can be further imparted by mixing a resin having a silanol group into a master batch. The addition method is not particularly limited, and examples thereof include a method of adding to a molten resin in a liquid state, directly kneading and adding to the target resin layer, and applying after sheeting.

  Next, the optical characteristics of the resin sealing sheet will be described. A haze value is used as an index of optical characteristics. When the haze value is 10.0% or less, the sealed object sealed with the resin sealing sheet can be confirmed in appearance, and at the same time, when the power generation element of the solar cell is sealed, a practically sufficient power generation efficiency Is preferable. From the above viewpoint, the haze value is preferably 9.5% or less, and more preferably 9.0% or less. Here, the haze value can be measured according to ASTM D-1003.

  The resin-encapsulated sheet preferably has a total light transmittance of 85% or more, more preferably 87% or more, and 88% or more in order to ensure practically sufficient power generation efficiency. Is more preferable. Here, the total light transmittance can be measured in accordance with ASTM D-1003.

  The resin sealing sheet preferably has a thickness of 50 to 1500 μm, more preferably 100 to 1000 μm, and still more preferably 150 to 800 μm. When the thickness is less than 50 μm, there is a tendency for problems in durability and strength from the viewpoint of structurally poor cushioning properties or workability. On the other hand, when the thickness exceeds 1500 μm, there is a tendency that a problem of reducing productivity and adhesion is caused.

[Method for producing resin-encapsulated sheet]
Although there is no restriction | limiting in particular as a manufacturing method of a resin sealing sheet, For example, the following methods are mentioned. First, the resin is melted by an extruder, the molten resin is extruded from a die, and rapidly cooled and solidified to obtain an original fabric. As the extruder, a T die, an annular die or the like is used. When the resin sealing sheet has a multilayer structure, an annular die is preferable.

  The surface of the original fabric may be embossed according to the final form of the resin sealing sheet. For example, when embossing treatment is performed on both sides, between the two heated embossing rolls, when performing single-sided embossing processing, the original fabric is passed between embossing rolls heated only on one side. Embossing treatment can be performed. When the resin sealing sheet has a multilayer structure, a multilayer T die method and a multilayer annular (circular) die method are suitable, and the multilayer structure may be formed by other known laminating methods.

  Further, as post-treatment, for example, heat setting for dimensional stabilization, corona treatment, plasma treatment, lamination with other types of resin sealing sheets, and the like may be performed.

  Depending on each case, it is selected whether the crosslinking treatment for the resin constituting the resin encapsulating sheet, that is, the heat treatment by the use of ionizing radiation irradiation or the use of organic peroxide is performed as a pre-process or a post-process of the embossing process. be able to.

[Translucent insulating substrate]
There are no particular restrictions on the light-transmitting insulating substrate, but because it is located on the outermost layer of the solar cell module, long-term reliability in outdoor exposure of the solar cell module, including weather resistance, water repellency, contamination resistance, mechanical strength, etc. It is preferable to provide performance for ensuring the performance. Moreover, in order to utilize sunlight effectively, it is preferable that it is a highly transparent sheet | seat with a small optical loss.

  Examples of the material of the translucent insulating substrate include a resin film made of polyester resin, fluororesin, acrylic resin, cyclic olefin (co) polymer, ethylene-vinyl acetate copolymer, and a glass substrate. A glass substrate is preferable from the viewpoint of a balance between weather resistance, impact resistance, and cost.

  Particularly suitable as the resin film is a polyester resin excellent in transparency, strength, cost and the like, particularly a polyethylene terephthalate resin.

  A fluororesin having particularly good weather resistance is also preferably used. Specifically, tetrafluoroethylene-ethylene copolymer (ETFE), polyvinyl fluoride resin (PVF), polyvinylidene fluoride resin (PVDF), polytetrafluoroethylene resin (TFE), tetrafluoroethylene-6 Examples thereof include a fluorinated propylene copolymer (FEP) and a poly (trifluorotrifluoroethylene resin) (CTFE). Polyvinylidene fluoride resin is preferable from the viewpoint of weather resistance, but tetrafluoroethylene-ethylene copolymer is preferable from the viewpoint of achieving both weather resistance and mechanical strength. Moreover, it is preferable to perform a corona treatment and a plasma treatment to a translucent insulated substrate for the improvement of adhesiveness with the material which comprises other layers, such as a resin sealing sheet. Moreover, in order to improve mechanical strength, it is also possible to use a sheet that has been subjected to a stretching treatment, for example, a biaxially stretched polypropylene sheet.

  When a glass substrate is used as the translucent insulating substrate, the total light transmittance of light having a wavelength of 350 to 1400 nm is preferably 80% or more, and more preferably 90% or more. As such a glass substrate, it is common to use white plate glass with little absorption in the infrared part, but even blue plate glass has little influence on the output characteristics of the solar cell module if the thickness is 3 mm or less. Further, tempered glass can be obtained by heat treatment to increase the mechanical strength of the glass substrate, but float plate glass without heat treatment may be used. Further, an antireflection coating may be applied to the light receiving surface side of the glass substrate in order to suppress reflection.

[Back insulating substrate]
Although there is no restriction | limiting in particular as a back surface insulating substrate, Since it is located in the outermost layer of a solar cell module, various characteristics, such as a weather resistance and mechanical strength, are calculated | required similarly to the above-mentioned translucent insulating substrate. Therefore, you may comprise a back surface insulating board | substrate with the material similar to a translucent insulating board | substrate. That is, the above-described various materials that can be used in the light-transmitting insulating substrate can also be used in the back insulating substrate. In particular, a polyester resin and a glass substrate can be preferably used, and among these, a polyethylene terephthalate resin (PET) is more preferable from the viewpoint of weather resistance and cost.

  Since the back insulating substrate does not assume the passage of sunlight, the transparency (translucency) required for the light transmitting insulating substrate is not necessarily required. Therefore, a reinforcing plate may be attached to increase the mechanical strength of the solar cell module or to prevent distortion and warpage due to temperature change. For example, a steel plate, a plastic plate, an FRP (glass fiber reinforced plastic) plate or the like can be preferably used.

  Further, the back insulating substrate may have a multilayer structure composed of two or more layers. Examples of the multilayer structure include a structure in which one or more layers of the same component are laminated on both sides of the central layer so as to be symmetrically arranged with respect to the central layer. As what has such a structure, PET / alumina vapor deposition PET / PET, PVF (brand name: Tedlar) / PET / PVF, PET / AL foil / PET etc. are mentioned, for example.

[Solar cells]
The solar battery cell is not particularly limited as long as it can generate power using the photovoltaic effect of the semiconductor. For example, silicon (single crystal system, polycrystalline system, amorphous system), compound semiconductor (3 -5, 2-6, etc.) can be used, and among these, polycrystalline silicon is preferred from the viewpoint of balance between power generation performance and cost.

[Method for manufacturing solar cell module]
There is no restriction | limiting in particular as a manufacturing method of the solar cell module in this Embodiment, For example, it laminates | stacks in order of a translucent insulated substrate / resin sealing sheet / solar cell / resin sealing sheet / back surface insulating substrate, and vacuum lamination It can manufacture by vacuum-laminating on conditions of 150 degreeC and 15 minutes using an apparatus.

  The thickness of each member in the solar cell module is not particularly limited, but the thickness of the translucent insulating substrate is preferably 3 mm or more from the viewpoint of weather resistance and impact resistance, and the thickness of the back insulating substrate is insulating. From the viewpoint of safety, preferably 75 μm or more, the thickness of the solar battery cell is preferably 140 to 250 μm from the viewpoint of balance between power generation performance and cost, and the thickness of the resin sealing sheet is from the viewpoint of cushioning and sealing properties. Preferably it is 250 micrometers or more.

  Hereinafter, although a specific Example and a comparative example are given and demonstrated, this Embodiment is not limited only to these Examples. In Examples and Comparative Examples, a resin-sealed sheet having a multilayer structure was produced by sandwiching a predetermined inner layer between surface layers.

The measuring method and evaluation method of each physical property in Examples and Comparative Examples are as follows.
<Gel fraction>
About the total-layer gel fraction of the resin sealing sheet, the resin sealing sheet was extracted in boiling p-xylene for 12 hours, and the proportion of the insoluble portion was determined by the following formula. Evaluation was made as a measure of the degree of crosslinking of the resin-encapsulated sheet.
Gel fraction (mass%) = (sample weight after extraction / sample weight before extraction) × 100

<Irradiation treatment>
The resin-encapsulated sheet was subjected to electron beam treatment at various acceleration voltages and irradiation densities using an EPS-300 or EPS-800 electron beam irradiation apparatus (manufactured by Nisshin High Voltage).

<Power generation partial gap evaluation>
Glass plate for solar cell (AGC white plate glass 5cm x 10cm square: thickness 3mm) / resin sealing sheet / power generation part (polycrystalline silicon cell, thickness 250μm, cut to size 2cm x 3cm) / Resin encapsulating sheet / back sheet (PET, thickness 180 μm) in this order, and using a LM50 type vacuum laminator (NPC), vacuum laminating under conditions of 150 ° C. for 15 minutes. The contact state of the crystalline silicon cell with the resin sealing sheet was visually observed.

<Measurement of storage elastic modulus (E ')>
The resin-encapsulated sheet was cut into strips, and set in a viscoelasticity measuring machine (viscoelasticity measuring machine PHYSICA MCR-301 manufactured by ANTON PAAR) and measured. And the storage elastic modulus (E ') in the temperature of 80 degreeC and 140 degreeC is measured, and the decreasing rate from the storage elastic modulus (E') of 80 degreeC to the storage elastic modulus (E ') of 140 degreeC is represented by the following formula. Asked.
Reduction ratio (%) from storage elastic modulus (E ′) at 80 ° C. to storage elastic modulus (E ′) at 140 ° C. = (Storage elastic modulus (E ′) at 80 ° C.) − Storage elastic modulus at 140 ° C. (E ′ )) / ((Storage modulus at 80 ° C. (E ′))

<Total light transmittance>
Measured according to ASTM D-1003.

<High temperature and high humidity test>
6-inch polycrystalline cells are arranged in 6 sheets (2 rows x 3 rows), white glass made by AGC (530 cm x 350 cm square: thickness 3 mm) / resin encapsulated sheet / power generation part (polycrystalline silicon cell, thickness 250 μm) / resin encapsulated sheet / back sheet (PET, thickness 180 μm) in this order, and laminated under vacuum conditions at 150 ° C. for 15 minutes using an LM50 type vacuum laminator (NPC). The created module was placed in a test tank, and maintained at a test temperature of 85 ° C. and a relative humidity of 85%, and the appearance of the module after each time was checked.

<Temperature cycle test>
6-inch polycrystalline cells are arranged in 6 sheets (2 rows x 3 rows), white glass made by AGC (530 cm x 350 cm square: thickness 3 mm) / resin encapsulated sheet / power generation part (polycrystalline silicon cell, thickness 250 μm) / resin encapsulated sheet / back sheet (PET, thickness 180 μm) in this order, and laminated under vacuum conditions at 150 ° C. for 15 minutes using an LM50 type vacuum laminator (NPC). The prepared module is installed in the test chamber, the test chamber is closed, the air around the module is circulated at a speed of 2 m / s or more, and the temperature in the test chamber is periodically between −40 ° C. and + 85 ° C. To change. One cycle was set to 4 hours, and the temperature was cycled by maintaining the minimum temperature and the maximum temperature for 30 minutes each. The appearance of the module after the predetermined number of times shown in the table was checked.

<1.2% twist result>
6-inch polycrystalline cells are arranged in 6 sheets (2 rows x 3 rows), white glass made by AGC (530 cm x 350 cm square: thickness 3 mm) / resin encapsulated sheet / power generation part (polycrystalline silicon cell, thickness 250 μm) / resin encapsulated sheet / back sheet (PET, thickness 180 μm) in this order, and laminated under vacuum conditions at 150 ° C. for 15 minutes using an LM50 type vacuum laminator (NPC). Three corners of the prepared module were fixed, and only one corner was lifted up to a height of 13 mm. The measurement was performed according to JIS-C-8990.

The materials used in the examples and comparative examples are as follows.
<Resin sealing sheet>
(1) Ethylene-vinyl acetate copolymer (EVA)
Tosoh Ultrasen 750 (VA = 32%, MFR = 10, melting point 63 ° C.)
(2) Saponified ethylene-vinyl acetate copolymer, Tosoh Corporation Mersen 6410 (VA = 28%, MFR = 5.7, saponification degree 10%, melting point 92 ° C.)
(3) Maleic anhydride modified polyethylene (PE)
Admer SE800 (MFR = 4.4, density = 0.900) manufactured by Mitsui Chemicals, Inc.
(4) Linear ultra-low density polyethylene (VL)
Affinity EG8100 (MFR = 1, density = 0.870) manufactured by Dow
(5) Ethylene-methacrylic acid copolymer (EMMA)
Nukurel N1207C manufactured by Mitsui DuPont Chemical
<Organic peroxide>
Lupelocks 101 made by Arkema Yoshitomi
<Translucent insulating substrate>
AGC glass for solar cells <Insulating substrate (back sheet)>
Mitsubishi Aluminum Packaging <Solar cell>
Crystalline silicon cell manufactured by E-TON

Hereinafter, it shows about the manufacturing method of the resin sealing sheet of Examples 1-13 and Comparative Example 1.
<Examples 1 to 13>
Using the resins shown in Tables 1 to 3, the resin was melted using two extruders (surface layer extruder, inner layer extruder), and the resin was formed into a tube from an annular die connected to the extruder. Resin-encapsulated sheets of Examples 1 to 13 were obtained by melt extrusion and rapidly cooling the tube formed by melt extrusion using a water-cooling ring. In the table, the thickness ratio indicates the ratio of the thickness of each layer when the thickness of the entire resin sealing sheet is 100.

Using the obtained resin sealing sheet, a solar cell module was produced as shown below.
6 inch polycrystalline cells are arranged in 6 sheets (2 rows x 3 sheets), AGC white plate glass (530 mm x 350 mm square: thickness 3 mm) / resin sealing sheet (A) / power generation part (polycrystalline silicon cell) By stacking in the order of (thickness 250 μm) / resin sealing sheet (B) / back sheet (PET 180 μm) and vacuum laminating using a LM50 type vacuum laminator (NPC) at 150 ° C. for 15 minutes. A solar cell module was manufactured and the above-described evaluation tests were performed, and the evaluation results are shown in Tables 1 to 3.

<Comparative Example 1>
Resin-encapsulated sheets were produced by the same methods as in the examples with the materials and composition ratios shown in Table 3. In introducing the organic peroxide, the resin to be introduced was kneaded in advance at a concentration of about 5% by mass to form a master batch, which was diluted to the desired amount.
Using the obtained resin-encapsulated sheet, a solar cell module was produced in the same manner as in the Examples according to the conditions shown in Table 3, and the above-described evaluation tests were performed. The evaluation results are shown in Table 3.

  As is clear from the results of the table, in the solar cell modules of the present embodiment (Examples 1 to 13), the gel fraction of the resin-encapsulated sheet is adjusted to a specific range, so heat shock and physical The solar cell module was strong against shock.

  The solar cell module of the present invention is a solar cell module that is strong against heat shock and physical shock.

1: Solar cell module 2: Translucent insulating substrate 3: Back insulating substrate 4: Solar cell 5A: Resin encapsulating sheet 5B: Resin encapsulating sheet

Claims (1)

A solar cell module formed by sealing solar cells between a translucent insulating substrate and a back insulating substrate with a resin sealing sheet,
The gel fraction of the resin sealing sheet is 65% by mass or less,
The rate of decrease from 80 ° C. storage elastic modulus (E ′) to 140 ° C. storage elastic modulus (E ′) of the resin-encapsulated sheet is 10% or more,
The resin sealing sheet has been subjected to ionizing radiation treatment,
The resin sealing sheet does not contain an organic peroxide,
The resin sealing sheet has a multilayer structure of at least two layers including a surface layer and an inner layer laminated on the surface layer,
At least one of the surface layers is
The adhesive resin includes at least one selected from the group consisting of an ethylene-vinyl acetate copolymer saponified product and an ethylene-vinyl acetate-acrylic ester copolymer saponified product, and
A solar cell module comprising at least one resin selected from the group consisting of an ethylene-vinyl acetate copolymer, an ethylene-aliphatic unsaturated carboxylic acid copolymer, and an ethylene-aliphatic carboxylic acid ester copolymer.

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