TWI453922B - Back protection sheet for solar cell and method for manufacturing the same - Google Patents

Description

Solar cell back protective sheet and solar battery module therewith

The present invention relates to a solar cell back protective sheet which is disposed on the back side of a solar cell module in general, and a solar cell module including the same, and particularly relates to a solar cell back protective sheet having weather resistance and the same Solar battery module.

In the solar battery module, since it is mostly installed outdoors, for example, a transparent glass plate is disposed on the surface side for the purpose of protecting the solar cell element, the electrode, the wiring, and the like, and an aluminum foil and a resin film are disposed on the back side, for example. A laminated sheet, or a laminated sheet of a resin film or the like.

For example, Japanese Laid-Open Patent Publication No. Hei 11-261085 proposes to use a polyethylene-based resin having a density of 0.94 g/cm ³ or more and 0.97 g/cm ³ or less and having weather resistance and moisture resistance. A rear protective sheet for a solar cell.

Further, in Japanese Laid-Open Patent Publication No. 2000-294813, a solar cell coating in which an outer film and a moisture-proof film are laminated by an ethylene-vinyl acetate copolymer-based bonding agent has been proposed. A backing material in which a moisture-proof film has a film formed by forming a coating film of an inorganic oxide on a surface of a substrate film. Here, as the outer film, a fluororesin film such as a polyvinylidene fluoride (PVDF) or a polyvinyl fluoride (PVF) film is used, and the thickness of the outer film is 12 to 200 μm.

Among them, the back surface protective sheet for solar cells is joined by heat-pressing the outer surfaces of the ethylene-vinyl acetate copolymer (EVA) resin which is a filler for sealing the solar cell elements.

However, the back surface protective sheet for a solar cell proposed in Japanese Laid-Open Patent Publication No. Hei 11-261085 is an EVA resin which is used as a filler for sealing a solar cell element, although it has weather resistance at an initial stage of use. The poor adhesion is the problem. Therefore, the back surface protective sheet for a solar cell cannot maintain its adhesion over time, so that peeling occurs and the back surface of the solar cell module can no longer be protected, and there is a possibility that the weather resistance cannot be maintained for a long period of time.

In the coated backing material for a solar cell proposed in Japanese Laid-Open Patent Publication No. 2000-294813, a fluororesin film such as PVDF or PVF film is used as the outer film film, so that it has weather resistance, but processing of such a fluororesin film The thickness is poor, so it is difficult to form a thickness of 40 μm or less. Therefore, it is difficult to reduce the weight of the back surface protection sheet and the solar battery module as a whole. Moreover, since the fluororesin film has poor wettability, sufficient bonding strength cannot be obtained when laminating with other resin films, which is a problem.

In view of the above, it is an object of the present invention to provide a back surface protective sheet for a solar cell which can improve the adhesion of an EVA resin which is a filler for sealing a solar cell element, and which can maintain weather resistance for a long period of time, and can be reduced in weight. And provide a solar battery module with it.

The back surface protective sheet for a solar cell of the present invention is disposed on the back side of the solar cell module, and includes a linear low-density polyethylene having a density of 0.91 g/cm ³ or more and 0.93 g/cm ³ or less. A film comprising a second film comprising polyvinylidene fluoride and polymethyl methacrylate or a copolymer of ethylene and tetrafluoroethylene laminated on the first film.

The solar cell module of the present invention comprises a filler composed of an ethylene-vinyl acetate copolymer resin disposed to seal the solar cell element, and a filler adhered to the outer surface of the filler on the back side of the solar cell module. Back protection sheet for solar cells. The back surface protective sheet for a solar cell comprises: a first film which is adhered to the surface of the filler and has a linear low-density polyethylene having a density of 0.91 g/cm ³ or more and 0.93 g/cm ³ or less; The second film is laminated on the outermost layer of the back surface protective sheet for a solar cell, and contains a mixture of polyvinylidene fluoride and polymethyl methacrylate or a copolymer of ethylene and tetrafluoroethylene. film.

In the back protective sheet for a solar cell of the present invention, the first film comprising a linear low-density polyethylene having a density of 0.91 g/cm ³ or more and 0.93 g/cm ³ or less is disposed to seal the solar cell element. The filler composed of the ethylene-vinyl acetate copolymer resin is excellent in adhesion, and the adhesion can be maintained over time. Moreover, the second film containing polyvinylidene fluoride and polymethyl methacrylate or a copolymer of ethylene and tetrafluoroethylene is displayed on the outermost layer of the back surface protective sheet for solar cells to exhibit weather resistance. In addition, since it has a good workability as compared with the fluororesin film, it can be made thinner than 40 μm or less, and can be obtained by laminating the first film by a dry lamination method using a bonding agent for dry lamination, for example. Joining force.

Therefore, according to the present invention, the adhesion between the EVA resin as a filler for sealing the solar cell element and the back surface protective sheet can be improved, and the weather resistance of the back surface protective sheet can be maintained for a long period of time, and the back surface protective sheet for solar cells can be obtained. Lightweight with solar cell modules.

1 is a schematic cross-sectional structural view showing a solar battery module to which a back surface protective sheet for a solar battery according to an embodiment of the present invention is applied.

As shown in FIG. 1, a plurality of solar cell elements 1 are arranged in the solar cell module 100. The solar cell elements 1 are electrically connected to each other via the connection wires 3 via the electrodes 2, and the solar cell module 100 as a whole is taken out from the back side by the wires 4, and the terminals 5 are housed in the terminal box 6. The filler 7 composed of an ethylene-vinyl acetate copolymer (EVA) resin is used to seal a plurality of solar cell elements 1 and arrange them. The transparent glass layer 8 is adhered to the outer surface of the filler 7 on the light-receiving side of the solar cell module 100. The outer surface of the filler 7 on the side of the installation surface of the solar cell module 100 is fixed to the back surface protective sheet 10 for a solar cell of the present invention. Moreover, the aluminum frame member 9 is attached to the side surface of the solar cell module 100 through the sealing material.

Fig. 2 is a cross-sectional view showing an embodiment of a back protective sheet for a solar cell of the present invention.

As shown in FIG. 2, the solar cell back protective sheet 10 is sequentially laminated from the inner layer disposed on the side (inside) of the solar cell module 100: a density of 0.91 g/cm ³ or more and 0.93 g. a first film 11 of a linear low-density polyethylene (LLDPE) of at least ³ cm; composed of a mixed resin film containing polyvinylidene fluoride (PVDF) and polymethyl methacrylate (PMMA), or ethylene The second film 12 composed of a copolymer of tetrafluoroethylene. The bonding agent layer 13 is disposed between the first film 11 and the second film 12. The first film 11 is adhered to the surface of the filler 7 so as to be in contact with the surface of the filler 7. This solid adhesion can be carried out by heat pressing. The second film 12 is disposed on the outermost layer of the back surface protective sheet 10 for solar cells. The bonding agent layer 13 is composed of a dry lamination bonding agent. The thickness of the first film 11 is about 30 to 100 μm, and the thickness of the second film 12 is about 5 to 30 μm. The mixing ratio of polyvinylidene fluoride (PVDF) and polymethyl methacrylate (PMMA) constituting the mixed resin film of the second film 12 is preferably PVDF/PMMA = 1/9 to 9/1.

An anchor coat agent or the like may be applied to the respective surfaces of the first film 11 and the second film 12 as needed.

In the second film 12, a white pigment such as titanium oxide or barium sulfate may be mixed for the purpose of absorbing or reflecting ultraviolet rays.

A primer layer may be formed on the light-receiving surface side of the first film 11 in order to improve the adhesion to the filler 7. As the primer, an acrylic primer, a polyester primer, or the like is preferably used. The coating amount of the primer can be set to about 2 to 15 g/m ² .

The first film 11 and the second film 12 can be laminated by a known method. For example, a two-liquid-curing urethane-based bonding agent, a polyether urethane-based bonding agent, a polyester-based bonding agent, a polyester polyol-based bonding agent, or a polyester polyurethane can be used. In the dry lamination of an ester polyol-based bonding agent or the like, in addition to the method of laminating the first film 11 and the second film 12 via the bonding layer 13 as shown in FIG. 2, co-extrusion may be employed. A method of extrusion coating, thermal lamination using an anchor coating agent, or the like. It is preferable to laminate the first film 11 and the second film 12 by a dry lamination method, and it is particularly preferable to use a bonding agent containing a urethane resin and laminating by a dry lamination method.

[Examples]

The examples of the back surface protective sheets for solar cells, the comparative examples, and the samples of the reference examples were produced as follows.

(Example 1)

The surface of the LLDPE film (product name: TUX-HC, manufactured by Tohcello Co., Ltd., density: 0.914 g/cm ³ ) having a thickness of 60 μm as the first film was joined as a second film by dry lamination using a bonding agent for dry lamination. A mixed resin film having a thickness of 20 μm (mixing ratio: 8 parts by weight of PVDF, 2 parts by weight of PMMA) (manufactured by Electric Chemical Industry Co., Ltd., product name Denka DX). As a binder for dry lamination, a urethane-based adhesive prepared by mixing a product name Takelac A315 (100 parts by weight) manufactured by Mitsui Chemicals Polyurethane Co., Ltd. and a product name Takenate A50 (10 parts by weight) is used. The coating amount of the solid portion was 3 g/m ² . Thus, a back protective sheet as an example of the present invention was produced.

(Example 2)

The surface of the LLDPE film (product name: TUX-HC, manufactured by Tohcello Co., Ltd., density: 0.914 g/cm ³ ) having a thickness of 60 μm as the first film was joined as a second film by dry lamination using a bonding agent for dry lamination. A tetrafluoroethylene-ethylene copolymer film having a thickness of 25 μm (manufactured by Asahi Glass Co., Ltd., product name: AFC). As a binder for dry lamination, an amine urethane-based adhesive prepared by mixing a product name Takelac A315 (100 parts by weight) manufactured by Mitsui Chemicals Polyurethane Co., Ltd. and a product name Takenate A50 (10 parts by weight) is used. The coating amount of the solid portion was 3 g/m ² . Thus, a back protective sheet as an example of the present invention was produced.

(Comparative Example 1)

A high-density polyethylene (HDPE) film (manufactured by Tamapoly Co., Ltd., product name HD, density: 0.945 g/cm ³ ) having a thickness of 80 μm was used as a comparative example of the back protective sheet of the present invention.

(Comparative Example 2)

A PVF film (manufactured by DuPont, product name Tedlar) having a thickness of 40 μm was bonded to the surface of a PVF film (product name: Tedlar, manufactured by DuPont) having a thickness of 40 μm by a dry lamination method. As a binder for dry lamination, a urethane-based adhesive prepared by mixing a product name Takelac A315 (100 parts by weight) manufactured by Mitsui Chemicals Polyurethane Co., Ltd. and a product name Takenate A50 (10 parts by weight) is used. The coating amount of the solid portion was 3 g/m ² . Thus, a back protective sheet as a comparative example was produced.

(Reference example)

The surface of the HDPE film (manufactured by Tamapoly Co., Ltd., product name HD, density: 0.945 g/cm ³ ) having a thickness of 80 μm as the first film was bonded as a second film by dry lamination using a bonding agent for dry lamination. A mixed resin film having a thickness of 20 μm (mixing ratio: 8 parts by weight of PVDF, 2 parts by weight of PMMA) (manufactured by Electric Chemical Industry Co., Ltd., product name Denka DX). As a binder for dry lamination, a urethane-based adhesive prepared by mixing a product name Takelac A315 (100 parts by weight) manufactured by Mitsui Chemicals Polyurethane Co., Ltd. and a product name Takenate A50 (10 parts by weight) is used. The coating amount of the solid portion was 3 g/m ² . Thus, a back protective sheet as a reference example of the present invention was produced.

A simulated solar cell module was produced using the obtained back protective sheet for solar cells. Specifically, the simulated solar cell module is attached to a glass plate having a thickness of 3 mm and an area of 15 cm ² × 18 cm ^{2 to} make an EVA resin having a thickness of 0.8 mm and an area of 15 cm ² × 18 cm ² (Mitsu Fabro). The back surface protective sheet of the product name: SOLAR EVA RC-01) and the area of 15 cm ² × 18 cm ² was laminated in this order by laminating three sides, and was produced by pressurization by heating under atmospheric pressure. The simulated solar cell module was fabricated under the following two conditions of heating atmospheric pressure.

A) After vacuum defoaming treatment at a temperature of 150 ° C for 15 minutes, pressurization was carried out at 150 ° C for 5 minutes under atmospheric pressure.

B) After vacuum defoaming treatment at a temperature of 120 ° C for 15 minutes, pressurization was carried out for 5 minutes at atmospheric temperature at a temperature of 120 ° C.

The initial physical properties and weather resistance of the simulated solar cell module produced as described above were evaluated as follows.

(initial physical property)

From the surface side of the back surface protective sheet, the EVA resin was cut into a depth of 15 mm in length and 18 cm in length (the thickness of the back surface protective sheet + 5 μm), thereby preparing a test piece having a width of 15 mm open at one end, and the test piece was prepared. Stretching at a stretching speed of 100 mm/min. The breaking stress value at this time was measured as the bonding force (N/15 mm) between the EVA resin and the back surface protective sheet. However, in the case where the fracture stress value exceeds 40 (N/15 mm), since the fracture occurs immediately before the peeling occurs between the EVA resin and the back protective sheet, the correct joining force cannot be evaluated, and the joint force is evaluated as 40 ( N/15mm) or more.

(weather resistance)

After the simulated solar cell module produced by the heating atmospheric pressure bonding condition A was kept in an environment of a temperature of 85 ° C and a relative humidity of 85% for 3,000 hours, the appearance of the back protective sheet was observed, and the gap between the EVA resin and the back protective sheet was measured. Bonding force (N/15mm). The measurement of the bonding strength was carried out in the same manner as described above (initial physical properties).

The above results are shown in Table 1.

As is apparent from the results of Table 1, according to the examples of the present invention, the adhesion between the EVA resin as the filler and the back surface protective sheet can be improved, and the weather resistance of the back surface protective sheet can be maintained for a long period of time.

The entire embodiments and examples disclosed herein are illustrative and not intended to be limiting. The scope of the present invention is not limited to the embodiments and examples described above, and various modifications and changes within the scope and scope of the invention are intended to be within the scope of the invention.

(industrial availability)

The back surface protective sheet for a solar cell of the present invention can be disposed on the back side of the solar cell module, and can improve the adhesion of the EVA resin and the back protective sheet as a filler for sealing the solar cell element, and can be used for a long period of time. The weather resistance of the back protective sheet is maintained, and the solar cell back protective sheet and the solar cell module can be made lighter.

1. . . Solar cell component

2. . . electrode

3. . . Connection wiring

4. . . wire

5. . . Terminal

6. . . Terminal box

7. . . Filler

8. . . Transparent glass layer

9. . . Aluminum frame member

10. . . Solar cell back protection sheet

11. . . First film

12. . . Second film

13. . . Adhesive layer

100. . . Solar battery module

1 is a schematic cross-sectional structural view showing a solar battery module to which a back surface protective sheet for a solar battery according to an embodiment of the present invention is applied.

Fig. 2 is a cross-sectional view showing an embodiment of a back protective sheet for a solar cell of the present invention.

10. . . Solar cell back protection sheet

11. . . First film

12. . . Second film

13. . . Adhesive layer

Claims (2)

A back surface protective sheet for a solar cell, which is disposed on the back side of the solar cell module, and includes a first film which has a linear low density of 0.91 g/cm ³ or more and 0.93 g/cm ³ or less. a density polyethylene; and a second film laminated on the first film, comprising polyvinylidene fluoride and polymethyl methacrylate, or a copolymer of ethylene and tetrafluoroethylene; and the first film and The second film is joined by a dry lamination bonding agent. A solar cell module comprising a filler made of an ethylene-vinyl acetate copolymer resin disposed to seal a solar cell element, and a filler which is adhered to the back side of the solar cell module The back surface protection sheet for solar cells of the surface; the back surface protection sheet for solar cells includes a first film which is adhered so as to be in contact with the surface of the filler, and has a density of 0.91 g/cm ³ or more. a linear low-density polyethylene of 0.93 g/cm ³ or less; and a second film laminated on the first film and disposed on the outermost layer of the back surface protective sheet for a solar cell, comprising polyvinylidene fluoride and poly Methyl methacrylate or a copolymer of ethylene and tetrafluoroethylene; and the first film and the second film are joined by a dry lamination bonding agent.