JPH08222751A - Thin film solar battery - Google Patents

Abstract

PURPOSE: To obtain a thin film solar battery capable of even application causing no winding reform at all while enhancing the mechanical strength by a method wherein a weatherproofing resin layer is formed by coating and drying step with fluorine resin solution between a bonding layer used for covering the surface of a thin film solar battery with the weatherproofing layer is manufactured in the incident light side using a glass fiber. CONSTITUTION: A thin film solar battery has a photoelectric conversion semiconductor layer 3 held between the first electrode layer 2 and the second electrode layer 4 on a flexible substrate 1 and both surfaces thereof are covered with weatherproofing resin layers 7, 72 through the intermediary of a bonding agent layers 6, 62. Since the thin solar battery is mounted on the surface in the incident light side in the case of application, the incident side bonding agent 6 is reinforced by coating or mixing a glass fiber to enhance the mechanical strength. Otherwise, the weatherproofing resin layer 7 on the surface is thinly formed by coating and drying up with a solution of weatherproofing fluorine resin solution. Through these procedures, the weatherproofing resin layer 7 on the surface is evenly applied causing no winding reform at all even if this layer 7 is wound up in roll.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film solar cell using a flexible substrate, and more particularly to a thin film solar cell which can be installed on a roof of a house or the like to obtain electric power.

[0002]

2. Description of the Related Art Amorphous silicon (hereinafter referred to as a-Si) formed by glow discharge decomposition of a raw material gas or photo-CVD.
A solar cell made mainly of is a thin film and has the characteristics that it can be easily enlarged, and is expected to be a low-cost solar cell.
In particular, solar cells using flexible substrates such as stainless steel or plastic films with metal electrodes deposited are
It is considered promising because it can achieve high productivity by roll-to-roll method or stepping roll method during manufacturing. Further, since it is lightweight and flexible, it can be installed on a surface of any shape, and a long product can be obtained, which is advantageous for installation on a roof of a house or the like having a large area. Conventionally, the structure of such a solar cell has a cross-sectional structure as shown in FIG. 2, for example, and a first electrode layer 2 made of metal, a-Si, is formed on one surface of a flexible insulating substrate 1.
A photoelectric conversion semiconductor layer 3 and a transparent second electrode layer 4 made of ITO or the like are laminated, and on the other surface side, for example, a third electrode layer 5 described in Japanese Patent Application No. 5-67976.
Is formed and is connected to the first electrode layer 2 or the second electrode layer 4 through a through hole formed in the substrate 1. A solar cell having such a structure has a transparent weather resistant film 71 having a transparent adhesive layer 61 on a second electrode layer and a weather resistant film 72 having an adhesive layer 62 on a third electrode layer 5. It is sandwiched and protected by. The thickness of the weather resistant films 71 and 72 is, for example, 50 μm. Adhesive layer 6
1, 62 is ethylene vinyl acetate copolymer (EV
A) is used.

[0003]

By the way, such a conventional thin film solar cell has a problem that it is vulnerable to mechanical strength, particularly impact and compression. In other words, when installing on the roof, the construction worker puts his foot on the thin-film solar cell to work, so a tens of kilogram impact and compressive load is applied to the foot part, and this load is applied to the solar cell. This has a drawback that the output of the solar battery cell is reduced due to the influence.
In addition, the weather resistant films 71 and 72 are hard, and the laminated body which is a combination of materials having different hardness becomes hard due to the rigidity of the film, and when it is wound, it has a curl and is deformed after construction. When the curl is rewound, wrinkles occur and output decreases, which is a problem especially when installing on a roof. Further, the fluorine-based resin film mainly used for the weather resistant film has a drawback that it is expensive.

A first object of the present invention is to solve the above problems and provide a thin film solar cell having high mechanical strength. A second object is to provide a low-cost thin-film solar cell that has no weathering when wound in a roll and has weather resistance.

[0005]

In order to achieve the above object, the first invention according to claim 1 and others provides a flexible substrate with a first electrode layer and a second electrode layer. In a thin-film solar cell that has a sandwiched photoelectric conversion semiconductor layer and is covered on both sides with a weather-resistant resin layer with an adhesive layer in between, the adhesive layer on the light-incident side is made of a resin reinforced with glass fiber. Shall be done. The glass fiber may be deposited on the surface of the adhesive resin layer or may be mixed in the adhesive resin. The adhesive resin is preferably EVA.

In order to achieve the above-mentioned second object, the second invention according to claim 5 and others is sandwiched between a first electrode layer and a second electrode layer on a flexible substrate. In a thin-film solar cell having a photoelectric conversion semiconductor layer, both surfaces of which are covered with a weather resistant resin layer with an adhesive layer interposed therebetween, the weather resistant resin layer is formed by applying a fluororesin solution and drying. A general-purpose resin layer may be interposed on the adhesive layer side of the weather resistant resin layer.
The thickness of the resin layer on the adhesive layer is preferably 5 to 30 μm. Fluororesin is polytetrafluoroethylene (P
It may be TFE) or polyvinyl fluoride (PFV).

[0007]

[Operation] A construction worker works by riding on the surface of the solar cell on the light incident side. Therefore, if the adhesive layer on that side is reinforced by adhering or mixing glass fibers, the influence on the photoelectric conversion semiconductor layer is weakened even if the impact or compression due to the ride of the worker is applied, and the characteristics change. There is no. EVA similar to the conventional one can be used for the adhesive resin.
In addition, by applying a solution of a weather-resistant fluororesin without using a highly rigid film as the weather-resistant resin layer on the surface and forming a thin film by drying, it does not curl even when wound in a roll shape, and is uniform. Can be constructed. The manufacturing process can be simplified because the construction can be performed only by coating and drying. If the thickness of the formed weather-resistant resin layer is less than 5 μm, a uniform film cannot be formed, and if it exceeds 30 μm, rigidity becomes a problem, and it is not possible to reduce the cost by suppressing the amount of expensive fluororesin used. It will be possible.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawing in which the same reference numerals are given to the same parts as in FIG. Example 1 This thin-film solar cell is an example of the first and second inventions and has a cross-sectional structure shown in FIG. 1, and a polyimide film (trade name: Kapton, Toray DuPont Co., Ltd.) is used as the insulating film substrate 1. The first electrode layer 2 is an Ag film, the photoelectric conversion semiconductor layer 3 is an a-Si film having a pin junction,
The transparent second electrode layer 4 was an ITO film, and an Ag film was formed as a third electrode layer 5 on the back side of the insulating substrate 1 by a predetermined device to form a solar cell.

On the back surface side of this solar cell, an EVA film (trade name: VS sheet) having a thickness of 100 μm was used as an adhesive layer 62, and an aluminum foil was sandwiched with polyvinyl fluoride (PVF) to have a thickness of 120 μm. Sano White Film (Trade name: DuPont: Tedra-PV
F) was coated as a weather resistant film 72. The light-incident side on the back side is a product manufactured by Springborn Co., Ltd. having a glass fiber 8 attached to one side of the EVA film 6 and having a thickness of 250 μm.
Temporary adhesion was performed under the condition of a pressure of kg / cm ² . Further, a fluororesin polytetrafluoroethylene (PTFE) solution (Toa Paint Co., Ltd .: Neugermet) was applied on the EVA film 6 having the glass fibers 8 adhered thereto by a doctor blade method so that the film thickness after drying was 50 μm. And apply
After preliminary drying at 80 ° C. for 30 minutes, main crosslinking of EVA and curing of the fluororesin were simultaneously performed under the conditions of 160 ° C. for 60 minutes to form a weather resistant thin film 7 to obtain a solar cell module.

As the flexible substrate 1, a metal film can be used in addition to the insulating film. The film-shaped insulating substrate is required to have heat resistance because the electrode layer and the thin film semiconductor layer are formed thereon at about 200 ° C. Therefore, as the plastic film having heat resistance, in addition to the polyimide film, polyetherimide, polysulfone, polyether sulfone, polyphenylene sulfide, para-based aramid, polyether ketone, fluorine-based film, but especially polyimide , Para-aramid, and fluorine-based films are suitable. Metal films are made of stainless steel, nickel,
If a copper foil or the like is used, there is no problem in heat resistance, and it can be used as it is as a conductive substrate that also serves as the first electrode layer, or can be used as an insulating substrate by coating a heat resistant insulating film on the surface.

Example 2 In another example of the first and second inventions, instead of the EVA film 6 having the cross-sectional structure of FIG. 3 and the glass fiber 8 of Example 1 attached to one side, Example 1 is the same as Example 1 except that the EVA film 63 containing glass fiber was used to bond the weather-resistant thin film 7 onto the solar cell.

Example 3 This thin-film solar cell is an embodiment of the second invention and has the cross-sectional structure shown in FIG. 4, and is formed on the EVA cell 6 having a thickness of 100 μm on the solar cell of Example 1. A fluororesin solution prepared by dissolving PVF in a solvent was applied so that the film thickness after drying was 20 μm, and the weather resistant thin film 7 was formed.
Is formed.

Embodiment 4: In another embodiment of the second invention,
In Example 3, the weather resistant thin film 7 having the cross-sectional structure of FIG. 5 was formed by directly applying the PVF solution on the EVA film 6.
It is formed so that the film thickness after drying is 10 μm through a polyvinylidene chloride resin (PVDC) layer 9 which is a general-purpose resin applied so that the film thickness after drying is 10 μm.

Example 5: In still another example of the first and second aspects of the present invention, the structure is the same as that of Example 1 shown in FIG. 1, but the weather resistant thin film 7 is dried with a PVF solution. Film thickness is 2
It is formed by coating so as to have a thickness of 0 μm. The following solar cell was produced for a comparative test.

Comparative Example: The structure shown in FIG.
Adhesive layers 61 and 62 are formed from EVA film of m, and polyphenylene sulfide film (trade name: Torenina) is used for the weather resistant films 71 and 72.
Lamination was carried out under crosslinking conditions of 50 ° C. for 20 minutes.

The thin-film solar cells of these five types of Examples and Comparative Examples have a structure in which lead wires can be drawn from the electrodes to the outside to evaluate the characteristics. For the characteristic evaluation, a weather meter test of 500H is performed as an outdoor exposure acceleration test.
(Outdoor exposure equivalent to about 2.5 years) As a result, no change in appearance was observed in any of the Examples and Comparative Examples,
It showed good characteristics.

Subsequently, these solar cells are assembled in an amount of 10 to 100.
As a result of performing a bending test of winding on a core of mm and then rewinding in the opposite direction, the solar cells of all the examples were easily deformed and recovered, but the solar cells of the comparative examples were
A large amount of force was required to deform it, and wrinkles occurred when it was returned to its original state, and the characteristics were reduced by 60%. Further, when the operator installed the solar cell with an inclination of 35 °, worked on the solar cell module, and observed the appearance, the appearances of the solar cells of Examples 1, 2 and 5 changed. However, in Comparative Example, footprints remained. As a result of removing these solar cells and performing characteristic evaluation again, the solar cells of the examples maintained the initial characteristics, but the characteristics of the solar cells of the comparative example were reduced by 20%.

In each of the above-mentioned embodiments, the third electrode layer for connecting the solar cells is provided on the back surface side of the flexible insulating substrate, but the third electrode layer is not provided on the substrate front surface side. It can also be implemented in a thin-film solar cell for connecting solar cells. Moreover, in that case, it can implement also in the thin-film solar cell which makes light inject through a solar cell through a board | substrate.

[0019]

According to the present invention, the adhesive layer used for coating the surface of the thin film solar cell with the weather resistant resin layer is reinforced by the glass fiber on the light incident side,
No more damaging the solar cells when riding on top. Also, the weather resistant resin layer is coated with a fluororesin solution,
By forming it by drying, it is possible to make it thin so that rigidity does not matter, and even when it is wound, it is possible to perform uniform construction without winding curl, and also the manufacturing process is simplified. As a result, it was possible to obtain a long-life thin-film solar cell that was easy to construct and had excellent weather resistance.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the structure of thin-film solar cells of Examples 1 and 5 of the present invention.

FIG. 2 is a sectional view showing the structure of a conventional thin-film solar cell.

FIG. 3 is a sectional view showing the structure of a thin-film solar cell according to a second embodiment of the present invention.

FIG. 4 is a sectional view showing the structure of a thin-film solar cell according to Example 3 of the present invention.

FIG. 5 is a sectional view showing the structure of a thin-film solar cell according to Example 4 of the present invention.

[Explanation of symbols]

 1 flexible substrate 2 first electrode layer 3 a-Si film 4 transparent second electrode layer 5 third electrode layer 6 EVA film 63 glass fiber-containing EVA film 7 weatherproof thin film 8 glass fiber 9 PVDC layer

Claims (9)

[Claims] 1. A flexible substrate having a photoelectric conversion semiconductor layer sandwiched between a first electrode layer and a second electrode layer, both surfaces of which are covered with a weather resistant resin layer with an adhesive layer interposed therebetween. A thin-film solar cell, wherein the light-incident-side adhesive layer comprises a resin reinforced with glass fiber. 2. The thin-film solar cell according to claim 1, wherein glass fibers are deposited on the surface of the adhesive resin layer. 3. The thin film solar cell according to claim 1, wherein glass fibers are mixed in the adhesive resin. 4. The thin film solar cell according to claim 1, wherein the adhesive resin is an ethylene vinyl acetate copolymer. 5. A flexible substrate having a photoelectric conversion semiconductor layer sandwiched between a first electrode layer and a second electrode layer, both surfaces of which are covered with a weather resistant resin layer with an adhesive layer interposed therebetween. A thin film solar cell, wherein the weather resistant resin layer is formed by applying a fluororesin solution and drying. 6. The thin film solar cell according to claim 5, wherein a general-purpose resin layer is provided on the adhesive layer side of the weather resistant resin layer. 7. The thickness of the resin layer on the adhesive layer is 5 to 30 μm.
The thin film solar cell according to claim 5 or 6. 8. The thin film solar cell according to claim 5, wherein the fluororesin is polytetrafluoroethylene. 9. The thin-film solar cell according to claim 5, wherein the fluororesin is polyvinyl fluoride.