KR102165215B1 - Silicone adhesive sheet for sealing a solar cell and method for producing a solar cell module using the same - Google Patents

Abstract

The present invention is a silicone adhesive sheet for sealing a plurality of solar cells arranged between a light receiving surface panel and a rear panel having rigidity or flexibility, respectively, and the silicone adhesive sheet after curing is 180 degrees according to JIS K6256 with the light receiving surface panel. It provides a silicone adhesive sheet for sealing solar cells in an unvulcanized state, characterized in that the peel adhesive strength is 2.5 N / cm or more.
The adhesive sheet containing the silicone rubber composition of the present invention is a millable type adhesive sheet capable of extrusion molding, calender molding, etc., and a light-receiving surface panel, a first silicone adhesive sheet, a plurality of solar cells, and a second silicone The adhesive sheet and the back panel may be laminated to be modularized using a vacuum laminator. In addition, a module having good adhesion and high sealing property of the cell can be obtained simply without using conventional liquid silicone after lamination is completed.

Description

A silicon adhesive sheet for solar cell sealing and a method of manufacturing a solar cell module using the same TECHNICAL FIELD [0002] TECHNICAL FIELD The method for manufacturing a solar cell module using the same is a solar cell and a method of manufacturing a solar cell module using the same.

The present invention particularly relates to a silicon adhesive sheet useful for reliably sealing a solar cell formed using monocrystalline silicon or polycrystalline silicon, and a method of manufacturing a solar cell module using the same.

In recent years, interest in photovoltaic power generation has been increasing as an energy resource using sunlight. Here, the power generation element of a solar cell generally includes a semiconductor such as silicon, and the solar cell module is mounted on a light-receiving surface glass substrate or the like in a state in which individual solar cell cells are electrically interconnected.

At this time, the solar cell is protected from an external environment such as rain, wind, snow, dust, etc. by covering the surface or the back side of the solar cell to which the light is touched with a sealing material. As a sealing material, ethylene-vinyl acetate copolymer (EVA), which is a thermoplastic resin, is generally used in the form of a sheet, which is easy to handle, and from the viewpoint of low cost. To modularize a solar cell using EVA, a method of putting the laminated light-receiving surface/EVA sheet/solar cell/EVA/back panel (back sheet) into a vacuum laminator and pressing at 130 to 150°C for 15 to 30 minutes It is common.

However, when EVA is used as the sealing material, since acetic acid is generated in a high-temperature, high-humidity environment in particular, there is a problem that the generated acetic acid is the cause and the power generation performance is deteriorated due to influences such as corrosion of the solar cell electrode. In particular, since a solar cell is expected to be used for a long period of time in units of several decades, the deterioration over time is required to be resolved promptly from the viewpoint of a guarantee.

In addition, EVA is not limited to the above problems, and has low UV resistance, and discoloration occurs when exposed to outdoors for a long period of time, resulting in yellow or brown color, which also impairs the appearance.

Silicone is mentioned as a sealing material which does not generate these problems. For example, when silicone is used as a sealing material, not only the electrode corrosion is suppressed by generation of acetic acid, but also the problem of discoloration of yellow or brown color is solved. In addition, there is no such thing as an abrupt increase in the elastic modulus at a low temperature as in EVA, and the reliability of connection of electrodes is also increased. For example, in Non-Patent Literature 1, a re-evaluation of a silicon-encapsulated solar cell module exposed outdoors for 29 years is conducted, and a decrease in the maximum output is only -0.22%/year, which has very high reliability.

In order to obtain a silicon sealed solar cell, various sealing methods have been studied so far. In Japanese Patent Publication No. 2007-527109 (Patent Document 1), a connected solar cell is placed on a liquid silicone material or in a silicone material coated on a substrate by a multi-axis robot, and then the silicone material is cured to form air bubbles. It is proposed to enclose without putting. In addition, in Japanese Unexamined Patent Publication No. 2011-514680 (Patent Document 2), using a cell press having a movable plate, the solar cell is placed on a cured or semi-cured silicone under vacuum to enclose without air bubbles. Is proposed. On the other hand, in International Publication No. 2009/091068 (Patent Document 3), a sealant, a solar cell element, and a silicon liquid material are disposed on a glass substrate, and finally, a back surface protection substrate is stacked to form a temporary laminate, and pressurized and adhered under vacuum at room temperature. Although a method of making and sealing is proposed, it is considered that it is difficult to expand the solar cell module to a practical size in this method. However, any method includes a cumbersome process of applying or potting liquid silicon in the solar cell sealing process. This is a reality that cannot be easily accepted by manufacturers using EVA sheets for modularization of solar cells. In addition, cured products using low-viscosity silicone, which are optimal for coating and potting, have weaker physical strength and lower adhesive strength than EVA. Therefore, long-term outdoor exposure or accelerated deterioration test (85°C/85% RH) Securing the reliability of the sealing becomes a problem.

Japanese Patent Publication No. 2007-527109 Japanese Patent Publication No. 2011-514680 International Publication No. 2009/091068

Atsuo Ito, Hiroto Owada, Tomoyoshi Furihata, Hyangbae Kim, Naoki Yamakawa, Atsushi Yaginuma, Tomono Imataki, Momoki Watanabe, Sadao Sakamoto: The 9th Next Generation Solar Power System Symposium Preview, 2012 , p.54

The present invention has been made in view of the above circumstances, and in particular, by processing a silicone rubber composition having high adhesive strength with a light-receiving surface panel into a sheet, and sealing the solar cell through this sheet, handling is easy and sealing property is high. An object of the present invention is to provide a solar cell sealing silicone adhesive sheet and a method of manufacturing a solar cell module using the same.

The inventors of the present invention repeated intensive studies to achieve the above object, and as a result of processing a silicone rubber composition having an adhesive strength of 2.5 N/cm or more of a cured product to a light-receiving surface panel into a sheet to form a silicone adhesive sheet, , By laminating a first silicone adhesive sheet, a plurality of solar cell (solar cell strings), a second silicone adhesive sheet, and a back panel, and pressing under vacuum and heating, a solar cell module is obtained without using conventional liquid silicone. Found this and came to the present invention.

That is, the present invention provides the following silicone adhesive sheet for solar cell sealing and a method of manufacturing a solar cell module using the same.

(1) A silicone adhesive sheet for sealing a plurality of solar cells disposed between a light-receiving panel and a back panel having rigidity or flexibility, respectively, and 180 degrees according to JIS K6256 of the silicone adhesive sheet and the light-receiving panel after curing. A silicone adhesive sheet for sealing solar cells in an unvulcanized state, characterized in that the peel adhesive strength is 2.5 N/cm or more.

(2) (A)

(In the formula, R ¹ represents an unsubstituted or substituted monovalent hydrocarbon group of the same or different types, and a is a positive number of 1.95 to 2.05)

100 parts by mass of organopolysiloxane represented by and having a degree of polymerization of 100 or more,

(B) 10 to 150 parts by mass of reinforcing silica having a specific surface area of 50 m ² /g or more,

(C) 0.1 to 30 parts by mass of an organohydrogenpolysiloxane containing at least two hydrogen atoms bonded to a silicon atom in one molecule and not containing an alkoxy group, an epoxy group, or a (meth)acrylic group,

(D) catalyst amount of hydrosilylation reaction catalyst,

(E) 0 to 10 parts by mass of an adhesion imparting agent

The silicone adhesive sheet according to [1] containing a silicone rubber composition containing.

(3) The blending amount of the component (E) is 0.01 to 10 parts by mass per 100 parts by mass of the component (A), and the component (E) contains at least one of an alkoxy group, an epoxy group, and an acrylic (methacrylic) group. The solar cell sealing silicone adhesive sheet according to [2].

[4] The silicone adhesive sheet according to any one of [1] to [3] having a thickness of 0.3 to 2.5 mm.

[5] The silicone adhesive sheet according to any one of [1] to [4] formed by a calendar roll or extrusion processing.

[6] the light-receiving panel, the first silicone adhesive sheet according to any one of [1] to [5], a plurality of solar cells, the second silicone adhesive sheet according to any one of [1] to [5], and the back surface A method of manufacturing a silicone-encapsulated solar cell module in which a solar cell is sealed by a cured product of the first and second silicone adhesive sheets, characterized in that the panels are laminated and then subjected to modularization by heating and pressing under vacuum using a vacuum laminator.

[7] A silicon-sealed solar cell module obtained by the production method according to [6].

The adhesive sheet comprising the silicone rubber composition of the present invention is a millable adhesive sheet capable of extrusion molding, calender molding, etc., and a light-receiving surface panel, a first silicone adhesive sheet, a plurality of solar cells, and a second silicone The adhesive sheet and the back panel may be laminated to be modularized using a vacuum laminator. In addition, a module having good adhesion and high sealing property of the cell can be obtained simply without using conventional liquid silicone after lamination is completed.

1 is a cross-sectional view showing an example of a silicon-sealed solar cell module according to the present invention.
2 is a cross-sectional view showing an example of a laminate according to the present invention to be set in a vacuum laminator.
3 is a plan view showing an example in which a masking tape is applied to an adherend glass for an adhesion test.
4 is a cross-sectional view of an adhesion test piece.
5 is a cross-sectional view showing a state in the middle of an adhesion test.

The silicone adhesive sheet according to the present invention is for sealing a plurality of solar cells (solar cell strings formed by connecting the plurality of cells to each other). The silicon adhesive sheet sealing the solar cell is sandwiched between the light-receiving panel and the back panel to form a solar cell module.

1 shows an example of such a silicon-sealed solar cell module, in which (1) is a light-receiving panel, (2) is a back panel, (3) is a solar cell strings, and (10) is a silicone adhesive sheet. .

Here, the silicone adhesive sheet in the state in which the solar cell strings are sealed is vulcanized (cured) (cured sheet), and the silicone adhesive sheet according to the present invention is a silicone adhesive sheet (uncured sheet) comprising an unvulcanized silicone rubber composition. ), but the 180 degree peel adhesive strength between the cured silicone adhesive sheet (cured sheet) and the light-receiving surface panel is 2.5 N/cm or more, preferably 3.0 N/cm or more by the measurement method according to JIS K6256. The upper limit thereof is not particularly limited, but is usually 10 N/cm or less.

In this case, any curing type of the silicone rubber composition may be used, and an organic peroxide curing type, an ultraviolet curing type, a condensation reaction curing type, etc. are exemplified, but the addition reaction curing type is particularly preferable in that there is no fear of discoloration due to reaction by-products. .

As this addition curable silicone rubber composition,

(A)

(In the formula, R ¹ represents an unsubstituted or substituted monovalent hydrocarbon group of the same or different types, and a is a positive number of 1.95 to 2.05)

100 parts by mass of organopolysiloxane represented by and having a degree of polymerization of 100 or more,

(B) 10 to 150 parts by mass of reinforcing silica having a specific surface area of 50 m ² /g or more,

(C) 0.1 to 30 parts by mass of an organohydrogenpolysiloxane containing at least two hydrogen atoms bonded to a silicon atom in one molecule and not containing an alkoxy group, an epoxy group, or a (meth)acrylic group,

(D) catalyst amount of hydrosilylation reaction catalyst,

(E) 0 to 10 parts by mass of an adhesion imparting agent

It is preferable to contain.

In the silicone rubber composition, the component (A) is an organopolysiloxane having a degree of polymerization of 100 or more represented by the following average composition formula (I).

(In the formula, R ¹ represents an unsubstituted or substituted monovalent hydrocarbon group of the same or different types, and a is a positive number of 1.95 to 2.05)

In the above average composition formula (I), R ¹ represents an unsubstituted or substituted monovalent hydrocarbon group of the same or different types, and usually 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, specifically methyl group, ethyl group, propyl Alkyl groups such as groups, butyl groups, hexyl groups and octyl groups, cycloalkyl groups such as cyclopentyl groups and cyclohexyl groups, alkenyl groups such as vinyl groups, allyl groups, and propenyl groups, aryls such as cycloalkenyl groups, phenyl groups, and tolyl groups Group, an aralkyl group such as a benzyl group, a 2-phenylethyl group, or a group in which some or all of the hydrogen atoms of these groups are substituted with a halogen atom or a cyano group, and the like, methyl group, vinyl group, phenyl group, trifluoropropyl A group is preferable, and a methyl group and a vinyl group are particularly preferable. In addition, a (meth)acryl group is not included.

Specifically, the main chain of the organopolysiloxane includes repetition of dimethylsiloxane units, or a part of the dimethylpolysiloxane structure including repetition of dimethylsiloxane units constituting the main chain includes a phenyl group, a vinyl group, 3,3, A diphenylsiloxane unit having a 3-trifluoropropyl group or the like, a methylphenylsiloxane unit, a methylvinylsiloxane unit, a methyl-3,3,3-trifluoropropylsiloxane unit, or the like are introduced.

In particular, the organopolysiloxane preferably has two or more aliphatic unsaturated groups such as alkenyl groups and cycloalkenyl groups per molecule, and particularly preferably vinyl groups. In this case, it is preferable that 0.01 to 20 mol%, particularly 0.02 to 10 mol% of all R ¹ are aliphatic unsaturated groups. In addition, this aliphatic unsaturated group may be bonded to a silicon atom at the end of the molecular chain, may be bonded to a silicon atom in the middle of the molecular chain, or both, but at least bonded to the silicon atom at the end of the molecular chain. It is desirable. In addition, a is a positive number of 1.95 to 2.05, preferably 1.98 to 2.02, more preferably 1.99 to 2.01.

The organopolysiloxane of component (A) has triorganosiloxanes such as trimethylsiloxy group, dimethylphenylsiloxy group, dimethylhydroxysiloxy group, dimethylvinylsiloxy group, methyldivinylsiloxy group, trivinylsiloxy group, etc. What is blocked by time is preferably mentioned.

Particularly preferred examples include methylvinylpolysiloxane, methylphenylvinylpolysiloxane, and methyltrifluoropropylvinylpolysiloxane.

Such organopolysiloxanes are, for example, by (co)hydrolysis condensation of one or two or more organohalogenosilanes, or cyclic polysiloxanes (such as siloxane trimers and tetramers) as alkaline or acidic catalysts. It can be obtained by ring-opening polymerization by using. These are basically linear diorganopolysiloxanes, but as the component (A), they may be a mixture of two or three or more different in molecular weight (degree of polymerization) and molecular structure.

Further, the degree of polymerization of the organopolysiloxane is 100 or more, preferably 100 to 100,000, and particularly preferably 3,000 to 20,000. In addition, this degree of polymerization can be measured as a weight average degree of polymerization in terms of polystyrene by gel permeation chromatography (GPC) analysis.

The reinforcing silica of the component (B) having a BET specific surface area of 50 m ² /g or more is added to obtain a rubber composition having excellent mechanical strength before and after vulcanization. In this case, in order to improve the transparency of the silicone rubber composition, the BET specific surface area is preferably 200 m ² /g or more, more preferably 250 m ² /g or more. If the BET specific surface area is less than 200 m ² /g, the transparency of the cured product may be inferior. In addition, the upper limit thereof is not particularly limited, but is usually 500 m ² /g or less. However, for the adhesive sheet on the back panel side, when transparency is not required, a BET specific surface area of 50 m ² /g or more is sufficient.

Examples of the reinforcing silica of the component (B) include fumed silica (dry silica or fumed silica), precipitated silica (wet silica), and the like. Further, those obtained by hydrophobizing these surfaces with chlorosilane, alkoxysilane, hexamethyldisilazane or the like are preferably used. In particular, treatment with hexamethyldisilazane is preferable because transparency is high. In order to increase transparency, it is preferable to use aerosol silica as the reinforcing silica. Reinforcing silica may be used alone or in combination of two or more.

As the reinforcing silica of the component (B), commercially available products can be used. For example, Aerosil 130, Aerosil 200, Aerosil 300, Aerosil R-812, Aerosil R-972, Aerosil R-974, etc. Seal series (manufactured by Nippon Aerosil Co., Ltd.), Cabosil MS-5, MS-7 (manufactured by Cabot), Rheolosil QS-102, 103, MT-10 (manufactured by Tokuyama), etc. Untreated or surface hydrophobicized (i.e., hydrophilic or hydrophobic) fumed silica, Tokusil US-F (manufactured by Tokuyama), NIPSIL-SS, Nipsil-LP (manufactured by Nippon Silica Co., Ltd.), etc. And precipitated silica subjected to untreated or surface hydrophobic treatment.

The blending amount of the reinforcing silica of the component (B) is 10 to 150 parts by mass, preferably 30 to 120 parts by mass, and more preferably 50 to 100 parts by mass per 100 parts by mass of the organopolysiloxane of the component (A). It is wealth. When the blending amount of the component (B) is too small, the reinforcing effect before and after vulcanization is not obtained, and the transparency of the silicone adhesive after curing decreases. In the case where there is too much, there is a fear that dispersion of silica in the silicone polymer becomes difficult, and the workability into a sheet is deteriorated.

The organohydrogenpolysiloxane of component (C) of the silicone rubber composition of the present invention contains at least two hydrogen atoms (SiH groups) bonded with silicon atoms in one molecule, and is represented by the following average composition formula (II). Known organohydrogenpolysiloxanes are applicable.

(Here, R ² is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 6 carbon atoms, and preferably does not have an aliphatic unsaturated bond. Specific examples include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group. Of the hydrogen atom of the monovalent hydrocarbon group such as an alkyl group such as an alkyl group, a cyclohexyl group, a cyclohexenyl group, and an unsubstituted monovalent hydrocarbon group such as a phenyl group, a 3,3,3-trifluoropropyl group, and a cyanomethyl group. At least a part is a substituted monovalent hydrocarbon group such as a substituted alkyl group substituted with a halogen atom or a cyano group, etc. Also, it does not contain an alkoxy group, an epoxy group, or a (meth)acryl group, b is 0.7 to 2.1, c is 0.01 to 1.0 , In addition, b+c is represented by a positive number satisfying 0.8 to 3.0, preferably b is 0.8 to 2.0, c is 0.2 to 1.0, and b+c is 1.0 to 2.5.)

In addition, the molecular structure of the organohydrogenpolysiloxane may be a linear, cyclic, branched, or three-dimensional mesh structure. In this case, the number of silicon atoms (or degree of polymerization) in one molecule is preferably in a liquid state at room temperature of 2 to 300, particularly 4 to 200. In addition, hydrogen atoms (SiH groups) bonded to the silicon atom may be at the end of the molecular chain, may be in the side chain, may be in both, and at least two per molecule (usually 2 to 300), Preferably, those containing 3 or more (for example, 3 to 200), more preferably 4 to 150, are used.

As the organohydrogenpolysiloxane of the component (C), specifically, 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, methylhydrogencyclopolysiloxane, methylhydro Rozensiloxane-dimethylsiloxane cyclic copolymer, tris(dimethylhydrogensiloxy)methylsilane, tris(dimethylhydrogensiloxy)phenylsilane, methylhydrogenpolysiloxane with blocking trimethylsiloxy groups at both ends, dimethylsiloxane with blocking trimethylsiloxy groups at both ends Methylhydrogensiloxane copolymer, both terminal dimethylhydrogensiloxy group-blocked dimethylpolysiloxane, both terminal dimethylhydrogensiloxy group-blocked dimethylsiloxane-methylhydrogensiloxane copolymer, both terminal trimethylsiloxy group-blocked methylhydrogensiloxane-diphenyl Siloxane copolymer, both terminal trimethylsiloxy group-blocked methylhydrogensiloxane·diphenylsiloxane·dimethylsiloxane copolymer, cyclic methylhydrogenpolysiloxane, cyclic methylhydrogensiloxane·dimethylsiloxane copolymer, cyclic methylhydrogensiloxane·diphenylsiloxane · dimethylsiloxane copolymer, (CH _{3) 2} copolymer comprising HSiO _1/2 units and SiO _{4/2 units, (CH 3) 2 HSiO 1} /2 units and SiO _4/2 units and (C ₆ H ₅ ) In the copolymer or the like containing SiO _{3 /2} units, or in each of the above exemplary compounds, some or all of the methyl groups are substituted with other alkyl groups such as ethyl groups and propyl groups, and those in which an aryl group such as phenyl groups is substituted.

The blending amount of this organohydrogenpolysiloxane is preferably 0.1 to 30 parts by mass, more preferably 0.1 to 10 parts by mass, and still more preferably 0.3 to 10 parts by mass based on 100 parts by mass of the organopolysiloxane of component (A). Do.

In addition, this organohydrogenpolysiloxane is the molar ratio of the hydrogen atom (i.e., SiH group) bonded to the silicon atom in the component (C) to the alkenyl group bonded to the silicon atom in the component (A) (hereinafter, the molar ratio of SiH/SiVi). Is 0.5 to 15 mol/mol, preferably 3 to 12 mol/mol, and more preferably 4 to 10 mol/mol.

Known hydrosilylation catalysts for component (D) can be applied. For example, platinum black, platinum chloride, chloroplatinic acid, a reaction product of chloroplatinic acid and monohydric alcohol, a complex of chloroplatinic acid and olefins, platinum bis Platinum catalysts such as acetoacetate, palladium catalysts, and rhodium catalysts may be mentioned. In addition, the amount of the hydrosilylation reaction catalyst to be blended can be a catalytic amount, and is usually in the range of 5 to 100 ppm with respect to the total of the components (A) and (C) in terms of the mass of the platinum group metal. If it is less than 1 ppm, there is a fear that the addition reaction does not proceed sufficiently and the curing may be insufficient, and it is uneconomical to add an amount exceeding 1,000 ppm.

The component (E) is added to improve adhesion to a solar panel, a solar cell, or a back sheet containing a fluororesin, and includes at least one of an alkoxy group, an epoxy group, and an acrylic (methacrylic) group. It is preferable that it is a containing compound, and in addition, it is more preferable to have a SiH group. The amount of the component (E) added is preferably 0 to 10 parts by mass based on 100 parts by mass of component (A), and when blended, 0.01 to 10 parts by mass, preferably 0.01 to 8 parts by mass, more preferably 0.2 to It is 5 parts by mass.

As for the component (E), what is shown below is illustrated specifically.

By adding a small amount of these adhesion-imparting agents, the adhesion to the surface of the solar cell (SiN film) or the back electrode (Al) of glass widely used as a light-receiving panel and the same ceramic is also improved, and accelerated deterioration test, eg For example, it is considered that the adhesiveness after leaving under 85°C/85% RH condition is also maintained. In addition, even when these adhesive components are added, the total amount of organohydrogenpolysiloxane in components (C) and (E) is the sum of alkenyl groups and (meth)acrylic groups bonded to silicon atoms in components (A) and (E). The total molar ratio (the molar ratio of SiH/SiVi) of the hydrogen atoms bonded to the silicon atoms in the components (C) and (E) (i.e., SiH groups) is 0.5 to 15 mol/mol, preferably 3 to 12 mol/mol, More preferably, it is preferable to blend in an amount of 4 to 10 mol/mol.

To the silicone adhesive composition (silicone rubber composition) of the present invention, in addition to the above reaction catalyst, an addition reaction control agent may be added for the purpose of adjusting the curing rate. Specifically, ethynylcyclohexanol and tetramethyltetravinylcyclotetrasiloxane are mentioned. Further, a flame retardant imparting agent, a UV absorber, a colorant, and the like can be added within a range that does not impair the object of the present invention.

The silicone adhesive composition of the present invention can be obtained by kneading a predetermined amount of the above-described components with a twin-screw roll, a kneader, a Benbury mixer, or the like.

The silicone adhesive composition thus prepared has a plasticity of 150 to 1,000, preferably 200 to 800, and more preferably 250 to 600. If the degree of plasticity is less than 150, it becomes difficult to maintain the shape of the uncured sheet, or the tack is strong and it becomes difficult to use. In addition, when it exceeds 1,000, it becomes crumbly and the sheet formation process becomes difficult. In addition, the plasticity is measured by the method according to JIS K6249.

In the case of molding the silicone adhesive composition of the present invention into a sheet, the molding method is not particularly limited, but extrusion molding, calender molding, and the like are used. At this time, the thickness of the silicone adhesive sheet is 0.3 to 2.5 mm, more preferably 0.3 to 1.0 mm. If it is thinner than 0.3 mm, it may be difficult to seal the unevenness of the take-out electrode or the busbar electrode without voids in the subsequent heat curing and solar cell sealing process.If it is thicker than 2.0 mm, the mass of the adhesive sheet increases, As a result, the mass of the module increases.

Since the silicone adhesive sheet according to the present invention is in an uncured state, the surface of the so-called EVA for solar cells is not smooth, but can be deformed by having a surface tag. Therefore, when forming a sheet, it is preferable to apply a laminate film to at least one surface, and to process so that sheets do not adhere to each other during winding. In addition, when modularizing, the laminate film is peeled off and used.

Hereinafter, a method for modularizing a solar cell according to the present invention will be described. Modularization mainly involves i) formation of a light-receiving panel laminate, ii) formation of a rear panel laminate, iii), bonding of the panel laminates of i) and ii), iv) encapsulation of solar cells using a vacuum laminator. It includes 4 processes.

Here, the light-receiving surface panel is a transparent member serving as a side to which sunlight is incident, but is required to be excellent in transparency, weather resistance, and impact resistance in terms of being exposed outdoors for a long period of time. Examples of the light-receiving surface panel include a white plate tempered glass, an acrylic resin, a fluorine resin, or a polycarbonate resin, and particularly, a white plate tempered glass having a thickness of about 3 to 5 mm is preferable.

In addition, in addition to the glass similar to the above-described surface panel, a back sheet such as TPT including a laminate of fluororesin or PET resin can be used for the rear panel, which is the side opposite to the incident sunlight. In addition, in order to mitigate the partial hot spot phenomenon that occurs in the solar cell module, a synthetic resin supporting materials having high thermal conductivity such as titanium oxide, alumina, and aluminum nitride, including metal sheets such as copper, aluminum, and iron, silica is used. May be.

[Step i]

As shown in Fig. 2, a first unvulcanized silicone adhesive sheet 10a is placed on the light-receiving surface panel 1, and cell strings 3 to which 2 to 60 solar cells are connected are placed below the light-receiving surface. Attach it to do it. This is referred to as a light-receiving surface panel laminate. Here, the solar cell is made of one or two types of silicon semiconductors selected from general monocrystalline silicon or polycrystalline silicon, and the solar cell strings (3) are used to connect the solar cell to the tab line (4). What made it a combination cell is mentioned.

[Step ii]

A second uncured silicone adhesive sheet 10b is affixed to the rear panel 2. This is referred to as a back panel laminate.

[Step iii]

The back surface of the cell of the light-receiving panel laminate and the silicone adhesive sheet 10b of the rear panel laminate are bonded to each other.

[Step iv]

The "light-receiving surface panel laminate/rear panel laminate" produced in step iii is set in a vacuum laminator, degassed for a certain period of time in a reduced pressure space, and then pressurized while heating to seal the solar cell.

Here, when the "light-receiving surface panel/rear panel laminate" is disposed in the decompression space, the degree of decompression thereof is not particularly limited, but it is preferably -0.08 to -0.10 MPa. In addition, although heating/pressurization conditions are appropriately selected, it is preferable to pressurize at atmospheric pressure for 5 to 30 minutes after vacuum decompression for 3 to 5 minutes under heating at 70 to 150°C, particularly 100 to 130°C. During this pressurization, the silicone adhesive sheets 10a and 10b are crosslinked, and the light-receiving surface panel, the first silicone adhesive sheet 10a, the solar cell strings 3, the second silicone adhesive sheet 10b, and the rear panel ( 2) It adheres. If the heating temperature is lower than 70°C, the curing speed is slow and there is a possibility that vulcanization may not be completely completed within the molding time. If the heating temperature is higher than 150°C, the curing speed increases and curing starts during the vacuum evacuation time, and thus the light-receiving surface or the rear panel There is a possibility that a void remains between the family. Here, in order to effectively vacuum decompression, it is effective to form irregularities of "zebra shape" or "rhombic shape" on the uncured silicone adhesive sheet.

Through the above process, the silicon encapsulated solar cell is modularized. A frame made of an aluminum alloy or stainless steel is attached around the module and fixed with screws or the like, thereby completing a module with impact resistance.

Example

Hereinafter, the present invention is specifically described by showing examples and comparative examples, but the present invention is not limited to the following examples.

[Example 1]

100 parts by mass of organopolysiloxane containing 99.825 mol% of dimethylsiloxane units, 0.15 mol% of methylvinylsiloxane units and 0.025 mol% of dimethylvinylsiloxane units, and having an average polymerization degree of about 8,000, dry silica aro with a BET specific surface area of 300 m ² /g 70 parts by mass of Arosil 300 (manufactured by Nippon Aerosil Co., Ltd.), 16 parts by mass of hexamethyldisilazane and 4 parts by mass of water were added as a dispersant, kneaded with a kneader, and heated at 170° C. for 2 hours to form a compound. Was prepared. C-25A (platinum catalyst)/C-25B (organohydrogenpolysiloxane) (all manufactured by Shin-Etsu Chemical Co., Ltd.) as an addition crosslinking curing agent per 100 parts of the compound is 0.5 parts by mass/2.0 parts by mass, respectively. After kneading with a screw roll, it was added and mixed uniformly to obtain an uncured silicone adhesive composition (silicone rubber composition). In addition, the molar ratio of SiH/SiVi was 5.4.

[Preparation of adhesion measurement sample]

As shown in Fig. 3, a masking tape 6 was attached to the surface of the blue plate float glass 5 having a thickness of 125 mm × 25 mm × 5 mm in a size of 70 mm × 25 mm (the remaining 55 mm × 25 mm is the adhesive surface). This glass was put in a mold frame, and the uniformly mixed silicone adhesive composition (7) was heated and cured for 20 minutes under conditions of 120° C. and 70 kgf/cm ² so that the thickness was 1 mm, thereby obtaining a sample for measuring adhesion shown in FIG. 4. .

[Measurement of adhesion]

Using STROGRAPH VE10 (manufactured by Toyo Seiki Co., Ltd.), a 180 degree peel test was performed by pulling rubber and glass at a rate of 50 mm/min as shown in FIG. 5.

[Test production of solar cell module]

The uncured silicone adhesive composition was sheeted to a thickness of 0.7 mm with a biaxial roll. On both sides of the obtained silicone adhesive sheet, an embossing roll surface of a diamond embossing film (embossed NEF type; thickness 0.15 mm) manufactured by Ishijima Chemical Co., Ltd. is pressed with a rubber roll, and embossing is performed on both sides of the two silicone adhesive sheets. Implemented.

Next, after peeling the embossing film on one side of the silicone adhesive sheet subjected to the embossing process on one side, a white plate tempered glass substrate manufactured by Asahi Glass Co., Ltd. as a light-receiving surface panel of 340 mm x 360 mm (hereinafter, referred to as glass substrate) It was attached with a rubber roll. On the other hand, as the back panel, a single-layer PET film having a thickness of 250 μm was used in the same manner as described above, and the embossed film on one side of the silicone adhesive sheet subjected to the embossing process on the other side was peeled off on one side thereof, and then with a rubber roll. Attached.

Next, after peeling the embossing film on the other side of the one silicon adhesive sheet affixed on the glass substrate, the solar cell elements are connected in two rows and two rows in the vertical and horizontal direction on the single crystal silicon solar cell of a total of 4 Cell strings were loaded, and the embossing film on the other side of the other silicone adhesive sheet affixed to the rear panel was peeled off, and then the peeling surface was placed on the solar cell strings with the peeling side down. Thereby, an integral laminate of the light-receiving surface glass/silicon adhesive sheet/solar cell/silicone adhesive sheet/transparent PET was obtained.

This integrated laminate was put in a vacuum laminator device, heated at 110° C., reduced pressure for 3 minutes, and then compressed at atmospheric pressure for 15 minutes to obtain a solar cell module. The following evaluation was performed about this solar cell module.

[Appearance evaluation of solar cell module (void/cell crack)]

In order to evaluate the adhesion between the light-receiving surface glass and the cured silicone adhesive sheet, a peel test was performed by putting a cutter blade at the adhesive interface. At this time, the thing which had good adhesion was set to ○, and what was peeled from the light-receiving surface glass was set to x.

The solar cell module was subjected to an endurance test of 85°C/85% for 500 hours to evaluate the appearance and adhesion. On the light-receiving surface and the surface opposite to the light-receiving surface, the state of being sealed without a gap was referred to as "good", and the case where the gap remained was referred to as "defective".

[Example 2]

In 100 parts by mass of the compound prepared as in Example 1, 10 mass of organopolysiloxanes containing 99.825 mol% of dimethylsiloxane units, 0.15 mol% of methylvinylsiloxane units and 0.025 mol% of dimethylvinylsiloxane units and having an average polymerization degree of about 8,000 After adding the part, a compound was obtained. This was made into a composition in the same manner as in Example 1, and an adhesion test and a solar cell were formed. In addition, the SiH/SiVi molar ratio was 4.6.

[Example 3]

To 100 parts by mass of the compound prepared as in Example 1, 0.3 parts by mass of the compound of formula (i) was added to obtain a compound. This was made into a composition in the same manner as in Example 1, and an adhesion test and a solar cell were molded. In addition, the SiH/SiVi molar ratio was 7.0.

[Example 4]

To 100 parts by mass of the compound prepared as in Example 1, 1 part by mass of C-153A (organohydrogensiloxane) (manufactured by Shin-Etsu Chemical Co., Ltd.) was added to obtain a compound. This was made into a composition in the same manner as in Example 1, and an adhesion test and a solar cell were molded. In addition, the SiH/SiVi molar ratio was 8.6.

[Comparative Example 1]

100 parts by mass of organopolysiloxane having an average polymerization degree of about 8,000, including 99.825 mol% of dimethylsiloxane units, 0.15 mol% of methylvinylsiloxane units, and 0.025 mol% of dimethylvinylsiloxane units, and dry silica aro with a BET specific surface area of 200 m ² /g 70 parts by mass of yarn 200 (manufactured by Nippon Aerosil Co., Ltd.), 20 parts by mass of dimethyl-dimethoxysilane as a dispersant, 0.6 parts by mass of vinyltrimethoxysilane, and 6 parts by mass of pH 3.5 hydrochloric acid water were added, and kneaded with a kneader. , A compound was prepared by heat treatment at 170° C. for 2 hours. With respect to 100 parts by mass of the compound, 0.5 parts by mass/2.0 parts by mass of C-25A (platinum catalyst)/C-25B (organohydrogenpolysiloxane) (all manufactured by Shin-Etsu Chemical Co., Ltd.) as an addition crosslinking agent The mixture was added after kneading with a twin-screw roll, and uniformly mixed to obtain an uncured silicone adhesive composition. The SiH/SiVi molar ratio at this time was 1.2. Using this, the same adhesion test and solar cell molding as in Example 1 were performed.

[Comparative Example 2]

100 parts by mass of organopolysiloxane having an average polymerization degree of about 8,000, including 99.825 mol% of dimethylsiloxane units, 0.15 mol% of methylvinylsiloxane units, and 0.025 mol% of dimethylvinylsiloxane units, and dry silica aro with a BET specific surface area of 200 m ² /g 60 parts by mass of yarn 200 (manufactured by Nippon Aerosil Co., Ltd.), 10 parts by mass of dimethyl-dimethoxysilane as a dispersant, 0.3 parts by mass of vinyltrimethoxysilane, and 6 parts by mass of pH 3.5 hydrochloric acid water were added, and kneaded with a kneader. , A compound was prepared by heat treatment at 170° C. for 2 hours. This composition was carried out in the same manner as in Comparative Example 1 to obtain an uncured silicone adhesive composition. The SiH/SiVi molar ratio at this time was 2.2. Using this, the same adhesion test and solar cell molding as in Example 1 were performed.

By using the silicone adhesive sheet of the present invention, it has become possible to reliably and effectively seal a solar cell without using liquid silicone that is difficult to handle as in the prior art. In addition, the productivity of the silicone sealing module could be significantly improved.

1: light-receiving panel
2: back panel
3: solar cell strings
10: silicone adhesive sheet after curing
10a, 10b: uncured silicone adhesive sheet

Claims (7)

It is a manufacturing method of a silicone encapsulated solar cell module by laminating a light-receiving surface panel, a first silicone adhesive sheet, a plurality of solar cells, a second silicone adhesive sheet, and a back panel, and then heating and pressing under vacuum using a vacuum laminator. ,
The first silicone adhesive sheet and the second silicone adhesive sheet are silicone adhesive sheets for sealing a plurality of solar cells disposed between a light-receiving surface panel and a rear panel having rigidity or flexibility, respectively, and the cured silicone adhesive sheet and It is characterized in that it is a silicone adhesive sheet for sealing solar cells in an unvulcanized state having a 180 degree peel adhesion strength of 2.5 N/cm or more according to JIS K6256 of the light-receiving panel,
A method of manufacturing a silicone-encapsulated solar cell module in which the solar cell is sealed by a cured product of the first and second silicone adhesive sheets. A silicon encapsulated solar cell module obtained by the manufacturing method according to claim 1. delete delete delete delete delete

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