JP2012253164A - Rear surface protection sheet for solar cells and solar cell module including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rear surface protection sheet for solar cells which improves adhesion with an EVA resin serving as a filler used for sealing solar cell elements and maintains weather resistance for a long period, and to provide a solar cell module including the rear surface protection sheet for solar cells.SOLUTION: A rear surface protection sheet 10 for solar cells, which is disposed on a rear surface side of a solar cell module, includes: a first resin layer 11, a second resin layer 12, and a third resin layer 13 that are laminated in this order, and the second resin layer 12 includes a non stretched polypropylene. The solar cell module includes: a filler disposed for sealing solar cell elements and the rear surface protection sheet 10 for the solar cells having the above described characteristics and fastened so that the first resin layer 11 is disposed on an outer surface of the filler on the rear surface side of the solar cell module.

Description

  TECHNICAL FIELD The present invention relates to a solar cell back surface protective sheet disposed on the back surface side of a solar cell module and a solar cell module including the solar cell module, and specifically, a solar cell back surface protective sheet having long-term weather resistance and the solar cell module. The present invention relates to a solar cell module.

  Since the solar cell module is disposed outdoors, a transparent glass plate is disposed on the front surface side and the back surface side is a resin as a solar cell back surface protection sheet for the purpose of protecting the solar cell elements, electrodes, wiring, and the like. A laminated sheet of film is placed. The solar cell element is sealed with a filler such as ethylene-vinyl acetate copolymer (EVA) resin, and is disposed so as to be sandwiched between the transparent glass plate on the front surface side and the laminated sheet on the back surface side. The back surface protection sheet for solar cells is bonded to the outer surface of the EVA resin by a hot press.

  Generally, the back surface protection sheet for solar cells is provided with an adhesive resin film (adhesive layer) on the side to be bonded to EVA and a weather resistant film (weather resistant layer) on the side exposed to the outside air. ing. Furthermore, in order to prevent vapor, moisture, etc. from the outside air from reaching the solar cell element, a moisture-permeable film (moisture-resistant layer) is disposed between the adhesive layer and the weather-resistant layer. For example, Japanese Laid-Open Patent Publication No. 2006-179557 (hereinafter referred to as Patent Document 1) proposes a back protective sheet for solar cells that includes a polyethylene terephthalate (PET) film as a moisture-permeable layer.

JP 2006-179557 A

  The back surface protection sheet for solar cells described in Patent Document 1 is such that PET as a moisture permeable layer is hydrolyzed by ultraviolet light and moisture in the atmosphere during use in the open air, and the adhesive layer and weather resistance are used over a long period of use. There was a problem that the adhesiveness with the adhesive layer was lowered.

  The object of the present invention has been made in view of the above-described problems, and a solar cell back surface protective sheet capable of improving long-term adhesion between layers constituting the solar cell back surface protective sheet and the same. It is providing the solar cell module provided.

  The back surface protection sheet for solar cells according to this invention is a back surface protection sheet for solar cells arrange | positioned at the back surface side of a solar cell module, Comprising: The 1st resin layer laminated | stacked in order, 2nd resin layer, and The third resin layer is provided, and the second resin layer contains unstretched polypropylene.

  In the back surface protection sheet for solar cells of the present invention, by using unstretched polypropylene that does not cause hydrolysis in the second resin layer, between the first resin layer and the second resin layer, and second High adhesiveness can be maintained for a long time between the resin layer and the third resin layer.

  In the back surface protection sheet for a solar cell of the present invention, the second resin layer is a first film made of an unstretched polypropylene film exhibiting white color or an unstretched polypropylene film exhibiting colorless transparency, and both surfaces of the first film. And a second film made of an unstretched polypropylene film exhibiting colorless and transparent.

  By configuring the second resin layer in this way, the second resin layer is formed between the first resin layer and the third resin layer so that the surface roughness or the like generated during the production of the unstretched polypropylene film is not noticeable. It can be laminated with a gap therebetween.

  Moreover, in the back surface protection sheet for solar cells of this invention, it is preferable that a 2nd resin layer contains a titanium oxide.

  By configuring the second resin layer in this manner, the second resin layer can have a function of absorbing or reflecting ultraviolet rays.

  Furthermore, in the back surface protective sheet for solar cells of the present invention, the first resin layer contains linear low density polyethylene, and the third resin layer is made of polyvinylidene fluoride, polyvinyl fluoride, and ethylene tetrafluoroethylene. It is preferable to include at least one more selected.

  Thus, by comprising the 1st resin layer and the 3rd resin layer, between the 1st resin layer and the 2nd resin layer, and between the 2nd resin layer and the 3rd resin layer In the meantime, high adhesiveness can be maintained for a long time.

  In the solar cell back surface protective sheet of the present invention, the first resin layer and the second resin layer and / or the second resin layer and the third resin layer interpose a urethane adhesive layer. It is preferable that they are fixed.

  In the solar cell module according to the present invention, the first resin layer is disposed on the filler disposed for sealing the solar cell element and the outer surface of the charging material on the back surface side of the solar cell module. And a back surface protection sheet for solar cells having the above-described characteristics, which are fixed in such a manner.

  According to the present invention, by using unstretched polypropylene that does not cause hydrolysis in the second resin layer, the second resin layer and the third resin layer are provided between the first resin layer and the second resin layer. Since high adhesiveness can be maintained for a long time between the resin layers, the long-term weather resistance of the back surface protection sheet for solar cells and the solar cell module including the same can be improved.

It is a figure which shows schematic sectional structure of the solar cell module to which the back surface protection sheet for solar cells as one embodiment according to this invention is applied. It is sectional drawing which shows one embodiment of the back surface protection sheet for solar cells of this invention.

  As shown in FIG. 1, a large number of solar cell elements 1 are arranged in the solar cell module 100. These solar cell elements 1 are electrically connected to each other through connection wires 3 via electrodes 2, and the solar cell module 100 as a whole has a terminal 5 taken out on the back side by a lead wire 4, and the terminal 5 is a terminal box 6. It is stored in. A filler 7 made of an ethylene-vinyl acetate copolymer (EVA) resin or the like is arranged to seal a large number of solar cell elements 1. A transparent glass layer 8 is fixed to the outer surface of the filler 7 located on the light receiving surface side of the solar cell module 100. The back surface protection sheet 10 for solar cells of this invention is adhering to the outer surface of the filler 7 located in the installation surface side of a solar cell module. An aluminum frame member 9 is attached to the side surface of the solar cell module 100 via a sealing material.

  As shown in FIG. 2, the solar cell back surface protection sheet 10 includes a first resin layer 11, a second resin layer 2, and an outer layer disposed on the side (inside) relatively closer to the solar cell module 100 (FIG. 1). It is comprised from the laminated body laminated | stacked in order of the resin layer 12 and the 3rd resin layer 13. As shown in FIG. An adhesive layer 14 is disposed between the first resin layer 11 and the second resin layer 12 and between the second resin layer 12 and the third resin layer 13. In other words, as shown in FIG. 2, in the solar cell module back surface protective sheet 10 according to one embodiment of the present invention, the first resin layer 11 and the first resin layer 12 are formed on both surfaces of the second resin layer 12, respectively. Three resin layers 13 are laminated.

  As the material of the second resin layer 12, unstretched polypropylene is used. Since unstretched polypropylene does not undergo hydrolysis due to ultraviolet rays, moisture in the air, etc., it can have high adhesion with the first resin layer 11 in the long term. The second resin layer 12 may be an unstretched polypropylene film exhibiting colorless transparency or an unstretched polypropylene film exhibiting white. The second resin layer 12 may be configured by laminating an unstretched polypropylene film exhibiting colorless and transparent on both surfaces of an unstretched polypropylene film exhibiting white or an unstretched polypropylene film exhibiting colorless and transparent. preferable. In this case, the second resin layer 12 is laminated between the first resin layer 11 and the third resin layer 13 so that the surface roughness or the like generated during the production of the unstretched polypropylene film is not noticeable. Can do.

  The material of the first resin layer 11 and the third resin layer 13 is not particularly limited. For example, polyethylene (PE) (high density polyethylene, low density polyethylene, linear low density polyethylene (LLDPE)), polypropylene (PP ), Polyolefin resins such as polybutene, (meth) acrylic resins, polyvinyl chloride resins, polystyrene resins, polyvinylidene chloride resins, saponified ethylene-vinyl acetate copolymers, polyvinyl alcohol, polycarbonate resins, fluorine Resin (polyvinylidene fluoride, polyvinyl fluoride, ethylene tetrafluoroethylene), polyvinyl acetate resin, acetal resin, polyester resin (polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate), polyamide A film or sheet of a resin or other various resins can be used. These resin films or sheets may be stretched uniaxially or biaxially. The first resin layer 11 includes linear low density polyethylene, and the third resin layer 13 includes one or two selected from polyvinylidene fluoride, polyvinyl fluoride (PVF), and ethylene tetrafluoroethylene. preferable. In this case, high adhesion between the first resin layer 11 and the second resin layer 12 and between the second resin layer 12 and the third resin layer 13 is maintained for a long time. Can do.

  The lamination method in each of the 1st resin layer 11 and the 2nd resin layer 12, and the 2nd resin layer 12 and the 3rd resin layer 13 should just use a well-known method, for example, 2 liquid curing type Uses dry lamination method, co-extrusion method, extrusion coating method, anchor coating agent using urethane adhesive, polyether urethane adhesive, polyester adhesive, polyester polyol adhesive, polyester polyurethane polyol adhesive, etc. It is possible to adopt a method such as a heat laminating method. In particular, a dry laminating method using a urethane-based adhesive containing at least one kind of aromatic isocyanate or aliphatic isocyanate can be suitably employed.

  For the purpose of absorbing or reflecting ultraviolet rays, the second resin layer 12 may be mixed with a white pigment such as titanium oxide or barium sulfate, or a black pigment such as carbon. Further, known additives such as known UV absorbers, moisture absorbers (drying agents), oxygen absorbers, antioxidants and the like other than the color pigments may be added to at least one of the first resin layer 11 and the third resin layer 13. It can also be mixed in crab.

  The first resin layer 11 is laminated on the surface on the solar cell module 100 (power generation cell) side. The thickness of the first resin layer 11 is preferably 50 μm or more and 300 μm or less, and more preferably 125 μm or more and 250 μm or less. If the thickness of the first resin layer 11 is less than 50 μm, the insulation between the solar cell module 100 (power generation cell) and the second resin layer 12 is not sufficient. Moreover, when the thickness of the 1st resin layer 11 exceeds 300 micrometers, insulation will be saturated, the weight of the back surface protection sheet 10 for solar cell modules will become heavy, or a softness | flexibility will be impaired. As the resin constituting the first resin layer 11, a linear low density polyethylene film is suitably used.

Moreover, the adhesiveness with the filler 7 (FIG. 1) which consists of ethylene-vinyl acetate copolymer (EVA) resin etc. on the surface by the side of the solar cell module 100 (power generation cell) of the 1st resin layer 11 is improved. In order to do so, a primer layer may be formed. As the primer agent, it is preferable to use an acrylic primer, a polyester primer or the like. The application amount of the primer agent may be about ² to 15 g / m ² .

  The second resin layer 12 is laminated on the surface of the first resin layer 11 opposite to the solar cell module 100 (power generation cell) side. The thickness of the second resin layer 12 is preferably 20 μm or more and 200 μm or less, and more preferably 20 μm or more and 50 μm or less. In addition, it is more preferable in terms of strength, heat resistance, durability, and the like that the second resin layer 12 includes at least one layer of colorless, transparent or white unstretched polypropylene. When the thickness of the second resin layer 12 is less than 20 μm, the weather resistance is not sufficient. Moreover, when the thickness of the 2nd resin layer 12 exceeds 200 micrometers, a weather resistance will be saturated, the weight of the back surface protection sheet 10 for solar cell modules will become heavy, or a softness | flexibility will be impaired. As the unstretched polypropylene exhibiting white, a white film colored with a titanium oxide pigment or a barium sulfate pigment is preferably used.

  The sample of the Example and comparative example of the back surface protection sheet 10 for solar cell modules was produced as follows.

Example 1
A linear low density polyethylene resin composition is prepared by adding 25 kg of titanium oxide particles having an average particle diameter of 0.3 μm to 100 kg of polyethylene resin (manufactured by Tamapoly Co., Ltd.) having a density of 0.91 g / cm ³ and thoroughly kneading. Prepared. By extruding this linear low density polyethylene resin composition with an extruder, a first film having a thickness of 50 μm was produced as a film constituting the first resin layer 11. Next, non-stretched polypropylene (manufactured by Mitsubishi Plastics Co., Ltd.) that is colorless and transparent, white, and colorless and transparent is superposed in order, and coextruded with a T-die extruder so that the thickness ratio is 1: 8: 1. As a result, a second film having a thickness of 200 μm was produced as a film constituting the second resin layer 12. White unstretched polypropylene was obtained by mixing 25 kg of titanium oxide particles having an average particle diameter of 0.3 μm with 100 kg of colorless and transparent unstretched polypropylene. As a third film constituting the third resin layer 13, a polyvinyl fluoride film (manufactured by DuPont) having a thickness of 38 μm was prepared. With these films, the first film is placed on one side of the second film and the third film is placed on the other side, and a dry laminating adhesive is interposed between each film. And the back surface protection sheet 10 for solar cells was produced by making it adhere | attach by the dry laminating method. In addition, as an adhesive for dry lamination, a polyurethane-based adhesive in which a product name Takerak A315 (100 parts by weight) manufactured by Mitsui Chemicals, Inc. and a product name Takenate A50 (10 parts by weight) are mixed has a solid coating amount. It was prepared and used so that it might become 5 g / m < ² >.

(Example 2)
By superimposing unstretched polypropylene (manufactured by Mitsubishi Plastics Co., Ltd.) that are colorless and transparent, colorless and transparent, and colorless and transparent in order, and co-extruding with a T-die extruder so that the thickness ratio is 1: 8: 1 A solar cell back surface protective sheet 10 was produced in the same manner as in Example 1 except that a second film having a thickness of 200 μm was produced as a film constituting the second resin layer 12.

(Comparative Example 1)
A polyester film (made by Toyobo Co., Ltd.) having a thickness of 250 μm was prepared as the second film, and a polyvinyl fluoride film (made by DuPont) having a thickness of 38 μm was prepared as the first and third films. In the same manner as in Example 1, a solar cell back surface protective sheet 10 was produced by interposing a dry laminating adhesive between the respective films and adhering them by a dry laminating method.

(Comparative Example 2)
A solar cell back surface protective sheet 10 was produced in the same manner as in Comparative Example 1 except that the first film of Example 1 was used as the first film.

(Comparative Example 3)
As a third film, an adhesive for dry laminating is interposed between a silica-deposited polyester film having a thickness of 12 μm (manufactured by Mitsubishi Plastics) and a polyvinyl fluoride film having a thickness of 38 μm (manufactured by DuPont). A solar cell back surface protective sheet 10 was produced in the same manner as in Comparative Example 2, except that the second film and the third film were adhered to the silica-deposited polyester film side by adhering by a laminating method. .

(Measuring method)
About the back surface protection sheet 10 for solar cells produced in Examples 1-2 and Comparative Examples 1-3, according to the following method, total thickness, tensile strength retention, tensile elongation retention, change in moisture permeability, partial discharge voltage The reflectance was measured.

(Total thickness)
The actual thickness [μm] of the manufactured solar cell back surface protective sheet 10 was measured with a micro gauge.

(Tensile strength retention / tensile elongation retention)
A sample having a width of 10 mm was cut out from the manufactured back surface protective sheet 10 for solar cells, and the tensile strength and the tensile elongation were measured at a tensile speed of 200 mm / min using an autograph or a tester equivalent thereto.

  Measured after holding for 200 hours under conditions of tensile strength and tensile elongation measured immediately after sample preparation (initial stage) and pressure cooker test (test conditions: temperature 120 ° C., relative humidity 100% RH, 2 atm). From the values of tensile strength and tensile elongation, the initial value was taken as 100%, and the tensile strength retention [%] and tensile elongation retention [%] were calculated.

  Originally, it is desirable to evaluate the tensile strength retention rate and the tensile elongation retention rate after 10 years or more have passed in a state where the back protective sheet for solar cell 10 is actually exposed outdoors. However, it is difficult to perform an actual outdoor exposure test over such a long time. Therefore, as an alternative to this evaluation, the tensile strength retention rate and the tensile elongation retention rate are evaluated by performing a pressure cooker test as an environmental promotion test in an atmosphere of a temperature of 120 ° C., a relative humidity of 100% RH, and 2 atmospheres. It is a thing.

(Change in moisture permeability)
About the produced solar cell back surface protection sheet 10, moisture permeability [g / m < ² > * day] was measured according to JISK7129A (moisture permeability test method-Lyssy degree method).

  Moisture permeability was measured immediately after sample preparation (initial stage) and after holding for 100 hours under pressure cooker test (PCT) conditions (test conditions: temperature 120 ° C., relative humidity 100% RH, 2 atm).

(Partial discharge voltage)
In accordance with the standard IEC606664-1, the partial discharge voltage of the solar cell back surface protective sheet 10 was measured.

(Reflectance)
Using a multi-purpose spectrophotometer manufactured by JASCO Corporation, the transmittance in the wavelength range of 200 to 2000 nm was measured, and the reflectance [%] at 550 nm was evaluated as the light reflectance.

  The above measurement results are shown in Table 1.

From Table 1, in Comparative Examples 1 to 3, after PCT, both the tensile strength and the tensile elongation were greatly reduced to 0% compared to before PCT (initial) (100%), but in Examples 1 and 2, It can be seen that both the tensile strength and the tensile elongation were maintained at 86% or more with respect to the pre-PCT (initial) (100%). That is, by using unstretched polyethylene for the second resin layer 12, it is between the first resin layer 11 and the second resin layer 12, and between the second resin layer 12 and the third resin layer 13. The adhesive strength of was maintained. Further, the moisture permeability after PCT increased by 0.3 [g / m ² · day] or more and increased in Comparative Examples 1 to 3 than before PCT, but in Examples 1 and 2, the moisture permeability was 0. 0 before PCT. It can be seen that it decreased by about 1 [g / m ² · day], decreased, and suppressed to a low value.

  It should be considered that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is shown not by the above embodiments and examples but by the scope of claims, and is intended to include all modifications and variations within the meaning and scope equivalent to the scope of claims. .

  The solar cell back surface protective sheet of the present invention is used by being disposed on the back surface side of the solar cell module, and can maintain the weather resistance over a long period of time.

10: Back surface protection sheet for solar cell, 11: 1st resin layer, 12: 2nd resin layer, 13: 3rd resin layer, 100: Solar cell module

Claims (6)

A solar cell back surface protection sheet disposed on the back surface side of the solar cell module,
A first resin layer, a second resin layer, and a third resin layer laminated in order,
The back surface protection sheet for solar cells in which a said 2nd resin layer contains unstretched polypropylene.   The second resin layer is colorless and transparent laminated on both sides of the first film made of an unstretched polypropylene film exhibiting white color or an unstretched polypropylene film exhibiting colorless and transparent, and the first film. The back surface protection sheet for solar cells of Claim 1 containing the 2nd film which consists of an unstretched polypropylene film.   The back surface protection sheet for solar cells of any one of Claim 1 or Claim 2 in which a said 2nd resin layer contains a titanium oxide.   The first resin layer includes linear low density polyethylene, and the third resin layer includes at least one selected from the group consisting of polyvinylidene fluoride, polyvinyl fluoride, and ethylene tetrafluoroethylene. The back surface protection sheet for solar cells of any one of Claim 1- Claim 3.   The first resin layer and the second resin layer and / or the second resin layer and the third resin layer are fixed to each other with a urethane adhesive layer interposed therebetween. The back surface protection sheet for solar cells of any one of Claims 1-4. A filler disposed to seal the solar cell element;
The sun according to any one of claims 1 to 5, which is fixed so that the first resin layer is disposed on an outer surface of the charging material on a back surface side of the solar cell module. The solar cell module provided with the back surface protection sheet for batteries.

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