JP2005101404A - Solar cell module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solar cell module, low in cost yet high in durability. <P>SOLUTION: In this solar cell module, solar cell elements 1 are sandwiched between a surface protective cover (glass) 3 and a rear surface protective cover 4, and sealed in an EVA resin 2. The rear surface protective cover 4 comprises a highly moisture-resistant film 41 which is on the side of the EVA resin 2, a water-resistant film 43 which is on the side of the air and is higher in water permeability than the highly moisture-resistant film 41, and a moisture absorbing/desorbing layer 42 which is sandwiched between the two films. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a solar cell module, and more particularly to a structure of a back surface side cover material of a solar cell module with improved moisture resistance and safety.

  Efforts are being made enthusiastically not only in Japan but around the world to spread solar cells that are expected to be clean energy friendly to the global environment. In order to promote the spread, in addition to low-cost supply, long-term durability that is economically balanced is required. In addition, since solar cells are often installed on the outer walls, rooftops, roofs, and the like of houses, high-quality technical measures are required in an extremely harsh natural environment outdoors.

  Under such circumstances, conventionally, a laminated sheet obtained by laminating both surfaces of an aluminum sheet with an insulating film has been used as a back cover material in order to ensure durability represented by moisture resistance.

  FIG. 3 is a diagram showing a configuration of an example of this solar cell module. As shown in FIG. 3, the solar cell module includes a plurality of solar cells 102, for example, EVA (ethylene-vinyl acetate) between a glass plate 100 and a back film 101 in which an aluminum sheet is sandwiched between plastic films. Polymer) It is configured to be sealed with a sealing layer 103 made of resin. Adjacent solar cells 102 are electrically connected by a connecting member 104 made of, for example, copper foil.

  However, although the aluminum sheet is a material excellent in moisture resistance and gas barrier properties, since it is a conductive material, it is necessary to ensure insulation between the solar cell element and an external member such as a frame.

  Since there is no plastic sheet showing high moisture resistance and equivalent or better moisture resistance that can be replaced with an aluminum sheet with excellent moisture and gas barrier properties, one means is to use PET (polyethylene terephthalate) film, etc. A material in which water vapor and gas barrier properties are improved by coating a film of an inorganic oxide such as silicon oxide or aluminum oxide on a base film using a vacuum deposition method or a plasma chemical vapor deposition method (for example, , See Patent Document 1). In addition, a material in which a plurality of the same materials are stacked and laminated to further improve the barrier property, or a material using a fluorine-based resin sheet such as a PCTFE film, which has a lower water vapor transmission rate, is proposed for the base film. (For example, refer to Patent Document 2). Furthermore, a material in which a coating film made of a composition comprising a polycondensate obtained by hydrolysis of a silicon compound is further provided on an inorganic oxide film has been proposed (see, for example, Patent Document 3).

As proposed in each of these patent documents, an ultra-high moisture-proof sheet having a water vapor permeability of 1 g / m ² · day (40 ° C. 90% RH) or less has been proposed as a back cover material.

However, the barrier properties are basically not sufficient with these materials as will be apparent from the experimental results to be described later, and a barrier property close to that of a conventional aluminum sheet is exhibited by laminating and laminating three layers and four layers. However, there was a new problem in terms of cost balance.
JP 2000-114565 A JP-A-5-283727 JP 2001-7368 A

  The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide a solar cell module that is inexpensive and has long-term durability.

  This invention is a solar cell module in which a solar cell element is sealed with a sealing resin between a front glass member and a back surface protective member, and the protective member has a hygroscopic member between the resin film. It is comprised by the laminated sheet arrange | positioned, It is characterized by the above-mentioned.

  In addition, the back surface protection member has a high moisture resistance film on the sealing resin side, a waterproof film having a water vapor transmission rate equal to or higher than the water vapor transmission rate of the high humidity resistance film on the outside air side, and a hygroscopic member between the two films. What is necessary is just to comprise so.

  As the hygroscopic member, one formed of a non-woven fabric containing a hygroscopic polymer can be used.

  Specifically, the present invention replaces the conventional laminated sheet using aluminum in the back cover material, and uses a laminated sheet in which a moisture absorbing member is provided between the moisture proof film and the waterproof film. It is possible to provide a solar cell module having high durability.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing the basic configuration of the solar cell module of the present invention.

  In FIG. 1, 1 is a solar cell element, and a plurality of solar cell elements 1 are electrically connected in series or in parallel by a low resistance tab 1a. Reference numeral 2 denotes a thermoplastic EVA (ethylene-vinyl acetate copolymer), which is a sealing resin layer responsible for planarization by adhering solar cell elements and filling the gaps between the element surfaces and between the elements. 3 is white tempered glass used as a surface protective cover on the sunlight incident side. Reference numeral 4 denotes a back surface protective cover which is a basic configuration of the present invention, and includes a high moisture resistant film 41, a moisture absorbing / releasing layer 42, and a waterproof film 43. In the back protective cover 4, a high moisture resistant film 41 is disposed on the EVA 2 side, a waterproof film 43 is disposed on the outside air side, and a moisture absorbing / releasing layer 42 is disposed between the films 41 and 43.

The high moisture resistant film 41 is made of a polyolefin or fluorine resin having a water vapor permeability of 10 g / m ² · day (40 ° C. 90% RH) or less. The moisture absorption / release layer 42 is a non-woven fabric containing a polyacrylate polymer as a highly hygroscopic material. As the waterproof film 43, a film having a water vapor permeability equivalent to, preferably higher than, the high moisture resistance 41 film used is used.

  Moreover, each solar cell element 1 consists of a solar cell element of the HIT (Heterojunction with Intrinsic Thin-layer) structure which joined the crystalline semiconductor and the amorphous semiconductor, for example, and is comprised as shown in FIG.

  In this case, the semiconductor layer 10 of each element 1 includes an amorphous silicon (a-Si) p-layer 10a, an i-type a-Si i-layer 10b, an n-type crystalline silicon n-layer 10c, and an i-type a in order from the surface side. A transparent electrode 11 having a transparent conductive film made of an indium tin oxide (ITO) film on the front surface side and the back surface side of the semiconductor layer 10, comprising an i-layer 10 d of -Si and an n-type highly doped layer 10 e of n-type a-Si; 11 ′, and comb-shaped collector electrodes 12 and 12 ′ made of silver (Ag) are provided.

  Next, the moisture resistance and the like of the solar cell module of the present invention will be described in detail. It has been described so far that solar cell modules are required to have long-term weather resistance that can withstand harsh outdoor environments, that is, high-temperature conditions under hot weather and humid conditions typified by storms. How the back surface protection cover 4 of the present invention functions in this outdoor environment will be described.

  The outline of the function is that, under wet and humid conditions, the water vapor component that has passed through the waterproof film 43 is held by the moisture absorption layer 42, and the water vapor component that reaches the high moisture resistant film 41 replaced with the conventional aluminum sheet is reduced to a minimum. Thus, the weakness of the high moisture resistant film 41 compared to the aluminum sheet is complemented. In sunny weather, in addition to heat generated by incident infrared light, heat generated by the photovoltaic resistance loss of the solar cell element causes sunlight. The moisture absorbing layer 42 is heated from the incident side surface protective cover 3 side, and the moisture held in the moisture absorbing / releasing layer 42 becomes water vapor and diverges from the waterproof film 43.

  At this time, the moisture released from the hold is promoted by the waterproof film 43 that allows water vapor to pass through more easily than the high moisture resistant film 41 and is released toward the outside of the solar cell module. By this moisture absorbing / releasing function, in other words, the function of breathing, the back protective cover 4 of the present invention is always kept in a certain range of quality, and prevents water vapor from entering the solar cell element over a long period of time. . Further, all the materials constituting the back surface protection cover 4 of the present invention are insulating materials, and a highly reliable solar cell module is ensured by ensuring insulation between the solar cell element 1 and the metal frame of the outer frame. Can be provided.

  The tempered white glass used as the surface protective cover 3 on the sunlight incident side has disadvantages such as being heavy and not resistant to impact, but has excellent advantages such as high light transmittance, high moisture resistance, and long-term quality stability. It is suitable as a cage front side cover material and is used in many solar cell modules. On the surface protective cover 3 made of tempered white glass, a sheet-like EVA 2 molded to a thickness of 0.6 mm, for example, is stacked as an adhesive. In order to avoid a decrease in light transmittance due to yellowing from transparency due to long-term sunlight exposure, this EVA2 is added with an ultraviolet absorber.

  Subsequently, a plurality of solar cell elements 1 connected in series and parallel with the low resistance tab 1a are arranged so that the light incident side faces the glass surface. Further, a sheet-like EVA 2 molded to a thickness of, for example, 0.6 mm is stacked thereon as a sealing and adhesive material. EVA2 may be made of the same material as EVA in the preceding stage, or may be a material containing a white pigment to increase the light reflectance by increasing the photovoltaic power of the solar cell module. In this embodiment, the thickness of the front and rear EVA sheets is 0.6 mm, but it is not fixed. In the front EVA, it is advantageous to be thin in terms of light transmission, handling property, filling, adhesive Many are determined in consideration of the balance of function security and cost.

  Then, the back surface protection cover 4 of this invention mentioned later was placed on EVA2, and the solar cell module was manufactured through the process of vacuum drawing-crimping-crosslinking promotion with a vacuum laminating apparatus.

  The basic embodiment of the back protective cover 4 will be described in detail.

  The high moisture-proof film 41 is bonded with a material in which a white pigment is kneaded into polyester on both sides of a highly moisture-proof material obtained by depositing AlOx and SiOx on a PET film as a base material, and a material having improved heat resistance and hydrolysis resistance. Used. For the moisture absorption layer 42, Kanebo synthetic fiber Beloasis was used, in which a polymer mainly composed of polyacrylic acid sodium salt was directly spun and formed into a fiber shape and woven into a nonwoven fabric at an arbitrary mixing rate. Moreover, the material which adhere | attached white PET on the transparent barrier film which vapor-deposited SiOx as the waterproofing film 43 was used, and the adhesive material among these three was created using the 0.3 mm EVA sheet | seat.

  The waterproof film 43 used this time belongs to a super moisture-proof sheet, although it exhibits a water vapor permeability 20 times that of the former high moisture-proof film 41.

  Next, the solar cell module having the structure of Example 1 described above and the solar cell modules of the conventional example and Reference Examples 1 and 2 were prepared, and a high temperature and high humidity test was performed. The results are shown in Table 1. The test was performed for 1000 hours under conditions of a temperature of 85 ° C. and a humidity of 85%.

  Here, the conventional example uses a back surface protection cover in which an aluminum sheet is sandwiched between plastic films, the reference example 1 uses a back surface protection cover composed of one layer of the highly moisture-proof film of Example 1, and the reference example 2 is A back protective cover comprising the high moisture-proof film of Example 1 composed of two layers was used. The configuration other than the back protective cover is the same as that of the first embodiment. The evaluation is standardized with the conventional example as 100.

  As is apparent from Table 1, Example 1 of the present invention is slightly inferior in moisture resistance compared to the back surface protective cover in which an aluminum sheet is sandwiched between plastic films, but is significantly more resistant to moisture than the other Reference Examples 1 and 2. It can be seen that the sex has improved. Thus, according to the present invention, it is possible to provide a solar cell module that is inexpensive and has long-term durability and high safety.

  Further, the EVA sheet is not essential for the present invention, but is adopted as a means for simply promoting the adhesion of the film. The polymer used for the highly absorbent material is 45-80 times its own weight and does not release moisture easily even when mechanical pressure is applied. A representative porous hygroscopic material is also a usable material.

  In addition, the back surface protection cover 4 in this invention is not restricted to said structure, The thing of the following modifications can also be used.

(Modification 1)
Although the structure of the high moisture-proof film 41 and the waterproof film 43 is the same, the moisture absorption / release layer 42 located in the middle was changed. A hygroscopic material, for example, the polymer is kneaded into EVA. There is an excellent point that a non-woven fabric is not required and it is inexpensive, can be made of a transparent material including a moisture proof and waterproof film, and can be applied to a front side protective material of a solar cell module. However, when the amount of the hygroscopic material to be kneaded increases, it is necessary to pay attention to the decrease in adhesion, and 10% is the limit mixing rate.

(Modification 2)
This complements the adhesiveness degradation that is a weak point of the first modification. A polymer having adhesion on the side surface of the solar cell element of the waterproof film 43 is printed uniformly in the film plane in the shape of a one-stroke spiral, stripe, lattice, honeycomb or the like. Although the pattern is not particularly specified, a blank portion that is not printed is similarly uniformly arranged in the surface to prevent a decrease in the adhesion between the EVA and the film, thereby increasing the limit of the amount of the hygroscopic material disposed.

It is a schematic sectional drawing which shows the basic composition of the solar cell module of this invention. It is a schematic sectional drawing which shows the solar cell element used for this invention. It is a schematic sectional drawing which shows the basic composition of the conventional solar cell module.

Explanation of symbols

1 Solar cell element 2 EVA (sealing resin)
3 Protective cover (white tempered glass)
4 Back protective cover 41 High moisture resistant film 42 Moisture absorption / release layer 43 Waterproof film

Claims (3)

A solar cell module in which a solar cell element is sealed with a sealing resin between a front glass member and a back surface protective member, wherein the back surface protective member is a laminate in which a hygroscopic member is disposed between the resin film A solar cell module comprising a sheet. The back surface protection member has a high moisture resistance film on the sealing resin side, a waterproof film showing a water vapor transmission rate equal to or higher than the water vapor transmission rate of the high humidity resistance film on the outside air side, and a hygroscopic member between the both films. The solar cell module according to claim 1, wherein: The solar cell module according to claim 1, wherein the hygroscopic member is formed of a nonwoven fabric containing a hygroscopic polymer.

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