JPH0471276A - Deterioration reduced solar battery module - Google Patents

Abstract

PURPOSE:To reduce the optical deterioration by a method wherein the rear surface side of the photodetecting surface of an amorphous silicon solar battery element is provided with a heat insulating means. CONSTITUTION:n, i, p, i, p type amorphous silicon thin films are laminated on a stainless steel-made substrate in this order from the substrate side and then indium oxide tin is evaporated as a transparent electrode while 13 step silver paste impressed inseries is used as a grid electrode. Besides, as for the heat insulating material 2, the adhesive layer 3, the surface protective surface material 4 and the rear surface protective material 5, a sheet type glass fiber, a sheet type E, V, A, 'Tefzel' and aluminum foils held by white colored 'tedlar(R)' are respectively applicable. Next, said materials are laminated from the lower side in the order of the rear surface protective material 5, the adhesive layer 3, the heat insulating material 2, an amorphous silicon solar battery element 1, the adhesive layer 3 and the surface protective material 4. Next, the solar battery element 1 is arranged in a frame 6 to be set using an adhesive 7 and then a wiring and an output terminal are fixed. Through these procedures, the optical deterioration of the so lar battery element after long time use can be reduced by the annealing effect.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a solar cell module, and particularly to a solar cell module using an amorphous silicon solar cell element with little deterioration.

[Conventional technology] As a use of solar energy, solar power generation in particular has the characteristics of not being depleted and not polluting the environment, and is expected to be used on a large scale from the household level to the future as an alternative energy to fossil energy and nuclear energy. It is expected that it will be widely used for power generation.

Among these solar cells, those using silicon as a raw material include single crystal, polycrystal, and amorphous solar cell elements, and various types of modules are commercially available. In particular, amorphous silicon solar cells have advantages such as low manufacturing cost and the ability to manufacture large-area solar cells.

However, in this amorphous silicon solar cell, a decrease in performance caused by light irradiation, that is, so-called photodeterioration, occurs.
The conversion efficiency, which indicates the degree of conversion of light energy into electrical energy, is characterized in that it no longer satisfies the initial value as the cumulative light irradiation time increases. This is one of the drawbacks of amorphous silicon solar cells because it is generally said that photodeterioration does not occur in monocrystalline and polycrystalline silicon solar cells.

Until now, various studies have been conducted on this photodegradation, and it is known that the reduced conversion efficiency can be recovered to some extent by annealing (heat treatment) the solar cell element.

In addition, although the degree is lower than that of crystalline solar cells, even amorphous silicon solar cells show a slight decrease in conversion efficiency as the temperature of the solar cell element increases. The device has been manufactured with emphasis on its good heat dissipation effect.

[Problem B that the invention seeks to solve] As mentioned above, conventional amorphous silicon solar cells are manufactured to have good heat dissipation effects, and are manufactured to be as unaffected by temperature rise as possible. Therefore, it is difficult for the temperature of the solar cell element to reach a high temperature when receiving sunlight outdoors.

In other words, it is difficult to expect the above-mentioned annealing effect when receiving sunlight outdoors, and it is necessary to recover the reduced conversion efficiency and
In the long term, it is difficult to reduce photodeterioration.

That is, in conventional amorphous silicon solar cells, it has not been considered to prevent photodeterioration by effectively utilizing the annealing effect caused by the heat simultaneously received when sunlight is received.

[Object of the Invention] In view of the above-mentioned problems, the present invention reduces the heat dissipation of an amorphous silicon solar cell element, promotes the temperature increase of the solar cell element when receiving sunlight, and also reduces the temperature drop due to air temperature. By reducing the influence of the amorphous material, the temperature of the solar cell element can be maintained at a high temperature at all times, and the resulting annealing effect can be effectively used, and as a result, the photodeterioration of the solar cell element can be reduced after long-term use. Its purpose is to provide silicon solar cell modules.

[Means and effects for solving the problem] As a means for achieving the above-mentioned object, the present invention provides an amorphous silicon solar cell module, in which on the back side of the light receiving surface of the amorphous silicon solar cell element, The present invention provides a solar cell module with little deterioration characterized by being equipped with a heat insulating means.

By using an amorphous solar cell module having such a configuration, the heat dissipation of the solar cell element is reduced, and the temperature increase of the element when receiving sunlight is promoted,
It becomes less susceptible to the effects of temperature drops. Therefore, the temperature of the solar cell element is always kept high, the annealing effect is effectively utilized, and as a result, photodeterioration of the amorphous solar cell is reduced after long-term use.

FIG. 1 is a diagram that best represents the features of the present invention, and is a cross-sectional view conceptually showing the structure of an amorphous silicon solar cell module. In FIG. 1, l is an amorphous silicon solar cell element, 2 is a heat insulating material, 3 is an adhesive layer, 4 is a surface protection material, 5 is a back surface protection material, 6 is a frame material, and 7 is an adhesive. Sunlight enters from above the figure. As described above, the solar cell of the present invention is configured to include, for example, a heat insulating material 2 as a heat insulating means on the back side of the light-receiving surface of the amorphous silicon solar cell element 1.

Further, in the figure, the wiring and output terminal of the solar cell element are omitted.

The heat insulating material 2 is preferably a material that has heat resistance, fire resistance, and water resistance, and that does not require an excessive volume when modularized. Examples include sheet-shaped glass fiber, but the material And the shape is not limited to this.

Further, the heat insulating means is not limited to the method of laminating the heat insulating material 2 and the amorphous solar cell element 1 with the surface protection material 4 and the back surface protection material 5 as shown in FIG. For example, a closed space may be formed on the back side of the light-receiving surface of the solar cell element, and air may be used as a heat insulating material. Further, the closed space described above can also be filled with a heat insulating material.

[Example] (Example 1) In this example, as shown in FIG. A trial experiment was conducted to examine the photodeterioration of the solar cell element by actually irradiating it with sunlight outdoors.

As the amorphous silicon solar cell element l used in this example, n is placed on a stainless steel substrate in order from the substrate side.
+Lp+n+l+Il type amorphous silicon thin film type Needle crystalline silicon thin film is laminated, then indium/tin oxide is vapor deposited as a transparent electrode, and finally silver paste is printed as a grid electrode to form a unit of approximately 30 x 9 cm.13
A series of stages was used.

Further, as the heat insulating material 2, a sheet of glass fiber having a thickness of approximately 2 mm is formed into the same dimensions as the solar cell element 1, and as the adhesive layer 3, a sheet of E, V, A, etc. is used as the adhesive layer 3.
As the surface protection material 4, Tefzel with a thickness of 100 μm was used, and as the back surface protection material 5, aluminum foil sandwiched between white tetras was used from both sides.

The above materials are laminated in the following order from the bottom: back protection layer 5, adhesive layer 3, heat insulating material 2, amorphous silicon solar cell element 1, adhesive layer 3, surface protection material 4, and using a vacuum laminator.
It was laminated at 00°C.

The laminated solar cell element was installed on an aluminum frame 6, fixed with a silicone rubber adhesive 7, and attached with wiring and output terminals to produce a module.

Apart from this, when laminating, the heat insulating material 2 is not used, that is, the same material as above is used, and from the bottom, the back protection material 5, the adhesive layer 3. amorphous silicon solar cell element l,
A module was also produced in which the adhesive layer 3 and the surface protection material 4 were laminated in this order and the laminated product was fixed to a frame material 6 with an adhesive 7.

However, the characteristics of the individual units of the solar cell elements used in the above modularization, especially the effective conversion efficiency, were selected to be approximately the same. The total output of the module is approximately 23 watts
Met.

Using the two modules described above, an experiment was conducted outdoors to compare the degree of photodeterioration. The steps are as follows.

First, the light-receiving surface of each module was surrounded with aluminum foil, and then installed outdoors on a pedestal prepared in advance so that the light-receiving surface of the module faced due south and was at an angle of 37 degrees with the horizontal plane. A global pyranometer and a thermocouple were installed on the mount at the same time, so that the solar radiation density and temperature could be measured.

The measurement system for the current/voltage curves of each module was composed of a commercially available bus computer, two digital multimeters, an electronic load device, and a block.

Using these measurement systems, first confirm that the solar radiation density is stable at 1.0 at noon on a clear day, remove the aluminum foil on the light-receiving surface of the module, and remove the solar cell element. The temperature seems to have stabilized 10
Minutes later, the current/voltage curve and solar radiation density of each module were measured to calculate the effective conversion efficiency.

As a result, the effective conversion efficiency was 5.3% for the module using insulation material and 5.5% for the module without insulation material, and by using insulation material, the temperature of the solar cell element became higher and the conversion efficiency was 5.3%. It was found that the efficiency was low.

After the measurements, the two modules were left outdoors for about 100 days with a resistor connected to them corresponding to the optimum load for each current/voltage curve. Thereafter, we selected a day at noon on a clear day with almost the same solar radiation density and temperature as the measurement described above, and measured the effective conversion efficiency of each module using the procedure described above.

Here, the degree of photodeterioration is defined as the difference between the effective conversion efficiency after about 100 days and the initial effective conversion efficiency divided by the initial effective conversion efficiency.

As a result, the degree of photodegradation was 15% higher when no insulation material was used.
%, on the other hand, the one used was 12%, and the durability against deterioration was improved by 20%, confirming that the original purpose was achieved.

(Example 2) The difference between this example and Example 1 is that the heat insulating material was not laminated with the solar cell element, but instead, a closed space was provided on the back side of the light-receiving surface of the laminated solar cell element. , where the filled air is used as insulation. The advantage of this method lies in the simple structure in which the effect can be expected by simply attaching the lid to the frame.

FIG. 2 is a structural conceptual diagram showing the characteristics of this embodiment. In the figure, 1 is an amorphous silicon solar cell element, 3 is an adhesive layer, 4 is a surface protection material, and 5 is a back surface protection material. Material, 6
is a frame material, 7 is an adhesive, 8 is a frame lid, and 12 is air as a heat insulating material. However, in this figure as well, wiring and output terminals are not shown. Also used were amorphous silicon solar cell element 1, adhesive layer 3, surface protection material 4, back surface protection layer 5. The frame material 6 and the adhesive 7 are made of the same materials and have the same dimensions as those in Example 1.

The above materials are laminated in this order from the bottom: back protection material 5, adhesive layer 3, amorphous silicon solar cell element 1, adhesive layer 3, surface protection layer 4, and are laminated at 100°C using a vacuum laminator. It was fixed to the frame material 6 with adhesive 7.

Two of these were produced, and a frame lid 8 was fixed to one of the frame members 6 with an adhesive (not shown) so as to form a closed space on the opposite side of the light receiving surface. The frame lid 8 was not attached to the frame material 6 of the other module.

However, as in Example 1, the characteristics, particularly the effective conversion efficiency, of the individual units of the solar cell elements used for the modularization were selected to be approximately the same.

Using the two modules shown above, an experiment was conducted outdoors to compare the degree of photodeterioration. The procedure was the same as in Example 1, and the same pedestal for installing the module was used.

As a result, the degree of photodeterioration was 15% when the frame lid 8 was not used and 14% when it was used, and the durability against deterioration was improved by 7% as a percentage. It was confirmed that the objective was achieved.

(Example 3) In this example, a heat insulating material is not inserted during the lamination process described above, and a closed space is provided on the back side of the light receiving surface, but a heat insulating material is provided in the closed space. The difference is that it is filled with

This embodiment also has the advantage of a simple structure in that the effect can be expected only by attaching a frame lid and filling with a heat insulating material.

FIG. 3 is a structural conceptual diagram showing the features of this embodiment.
In the figure, the same components as in Example 2 are given the same numbers. Further, 22 is a heat insulating material that fills the closed space.

However, wiring and output terminals are not shown in this figure as well.

As the heat insulating material 22, instead of the sheet-like material used in Example 1, cotton-like glass fiber was used.

The above materials were laminated in the same manner as shown in Example 2 and fixed to the frame material 6 with adhesive 7.

Two modules were manufactured, the above-mentioned heat insulating material 22 was placed in the area surrounded by the frame material of one module, and the frame lid 8 was fixed to the frame 6 with an adhesive (not shown). The insulation material 22 and frame lid 8 were not attached to the other module.

However, as in Examples 1 and 2, the characteristics, particularly the effective conversion efficiency, of the individual units of the solar cell elements used for the above modularization were selected to be approximately the same.

Using the two modules shown above, an experiment was conducted outdoors to compare the degree of photodeterioration. The procedure is as in Example 1,
The same structure as in Example 2 was used, and the same mount on which the module was installed was used.

As a result, the degree of photodeterioration is the same as that of the heat insulating material 22 and the frame lid 8.
It is 15% better without using the heat insulating material 22 and 12.5% better with the frame lid 8.The durability against deterioration is improved by 17% in proportion, and the original purpose of this example is also achieved. I can confirm that this has been achieved.

In the embodiments described above, glass fiber or air was used as the heat insulating material, but the present invention is not limited to this.

[Effects of the Invention] As explained above, in an amorphous silicon solar cell module, by providing a heat insulating means on the back side of the light-receiving surface of the amorphous silicon solar cell element, heat dissipation from the solar cell element can be reduced. The annealing effect can be effectively utilized by increasing the temperature of the solar cell element when receiving sunlight and reducing the influence of a decrease in temperature. Therefore, this annealing effect results in the effect of reducing photodeterioration of the solar cell element after long-term use.

2...Sheet-like insulation material 4...Surface protection material 6...Frame material 8...Frame lid 22... cotton-like insulation material

Claims (1)

[Claims] 1. A low-deterioration solar cell module characterized in that the amorphous silicon solar cell module is provided with a heat insulating means on the back side of the light-receiving surface of the amorphous silicon solar cell element.