JPH065781B2 - Solar cell module - Google Patents

Description

TECHNICAL FIELD The present invention relates to a solar cell module, and more particularly to a CdS / CdTe or CdS / CuInSe ₂ based solar cell module structure.

2. Description of the Related Art Recently, solar cells have attracted attention as a means of supplying energy. This is because electrical energy can be easily extracted directly from infinite clean solar energy. However, the reason why solar cells have not become widespread is that power costs are high, and the root cause is that solar cell elements and their module parts are expensive.

Needless to say, efforts are being made to reduce costs in the former case, but it is equally important to reduce costs in the latter case, and various efforts have been made to achieve this. In addition, as the solar cell element changes, a package suitable for it is required.

Many conventional solar cell modules have been developed on the assumption that crystalline solar cell elements such as single crystal or polycrystalline silicon solar cell elements are used. II-VI group compound semiconductor solar cell elements and II-VI group / When using a thin film solar cell element such as a group I-III-VI compound semiconductor solar cell element, there are many points left to be improved.

In particular, among CdS / CdTe solar cells of II-VI group compound semiconductor solar cells and CdS / CuInSe ₂ solar cells of II-VI group / I-III-VI group compound semiconductor solar cells, the solar cells are In order to exhibit the following unique behavior, it is necessary to have a special module structure.

A CdS / CdTe solar cell module will be described. For example, a solar cell module having a structure shown in FIG. 2 or 3 has been invented (Japanese Patent Application Laid-Open No. 62-132371, Japanese Patent Application No. 63-29226). . All of these are CdS / CdTe
This is a product in which an oxygen releasing substance is enclosed inside a solar cell module including a junction as a photovoltaic portion. FIG. 2 is a cross-sectional view of the main part of the solar cell module in the embodiment of the invention described above. The CdS / CdTe solar cell element 1 is directly formed on the glass substrate 6 (bottom in FIG. 2), leaving a peripheral margin 20. The thermoplastic resin layer 10 sandwiches the oxygen-releasing substance 50, and covers the portion where the CdS / CdTe solar cell element 1 is present and the margin 20 of the outer peripheral portion of the substrate 6. Furthermore, the facing protective film 7 covers the outside of the thermoplastic resin layer 10.
The thermoplastic resin layer 10 adheres the facing protection film 7 to the margin 20 or the like on the outer peripheral portion of the substrate 6. FIG. 3 is a sectional view of an essential part of a solar cell module according to an embodiment of the latter invention. The CdS / CdTe solar cell element 1 is directly formed on the substrate 6 (bottom in FIG. 3), leaving a peripheral margin 20. The thermoplastic resin layer 10 sandwiches zeolite, which is an oxygen-releasing material, and covers a portion where the CdS / CdTe solar cell element 1 is present and a margin 20 on the outer peripheral portion of the substrate 6. Furthermore, the facing protective film 7 covers the outside of the thermoplastic resin layer 10. The thermoplastic resin layer 10 adheres the facing protection film 7 to the margin 20 or the like on the outer peripheral portion of the substrate 6.

Problems to be Solved by the Invention In the previous CdS / CdTe-based or CdS / CuInSe-based solar cell modules, emphasis was placed on preventing the entry of moisture into the element, and regarding the effect of oxygen on the element when modularized, I was indifferent. But recently
For CdS / CdTe solar cell elements, it was discovered that oxygen existing around the elements has a significant effect particularly when irradiated with light and at high temperature. That is, as shown in Reference Example 2 in Table 1, it was found that the conversion efficiency was extremely low when oxygen was not present in the periphery of the element during irradiation with a weather meter, as compared with when oxygen was present. The present invention solves the problem of low conversion efficiency when oxygen is not present in the module.

As a means for solving this problem, the above-mentioned two inventions supply oxygen by arranging an oxygen-releasing substance such as peroxide or zeolite around the element,
This is intended to prevent rapid deterioration due to a decrease in oxygen concentration.

Means for Solving the Problems The present invention is a CdS / CdTe or CdS / CuInSe ₂ solar cell device element coating (passivation) resin from a conventional epoxy resin to a fluoroolefin and a hydrocarbon vinyl ether monomer alternating copolymer By changing to either a fluorine-based resin or a silicon-based resin that has a basic skeleton, it is possible to prevent a decrease in the oxygen concentration existing around the element caused by high temperature or light irradiation, and to improve the reliability of modules using these solar cell elements To suppress the decrease of

Action Conventionally, an epoxy resin has been used as the passivation resin, as described in the examples of the above application. One of the reasons is that the epoxy resin does not cause a dehydration reaction during curing, that is, it does not release water as a by-product. As often mentioned, CdS / CdTe-based or CdS / CuInSe ₂ -based solar cell elements are water-friendly, which is advantageous in this respect. Secondly, although it is related to the above reaction mechanism, since it does not produce a biproduct, it is advantageous that the volume shrinkage accompanying the progress of the reaction is small and no mechanical stress is applied to the element part. Besides, it has the advantage that the price is relatively low because it is popular. However, compared with epoxy resin and silicon resin, there is a drawback that thermal decomposition and photodecomposition are more likely to occur. When these decompositions occur, radicals are generated and react with oxygen, so that oxygen existing around the element is deprived, the oxygen concentration is lowered, and it is found that there is a serious drawback that the reliability of the solar cell module is lowered. .
It is generally known that it is more stable to heat and light than fluorine-based resins and silicon-based resins and epoxy-based resins, and is difficult to decompose, but when a light irradiation test with a weather meter was performed, As shown in Table 2, it was found that it was difficult to reduce the oxygen concentration. The fact that the oxygen concentration is not lowered makes it difficult to lower the reliability of the module.

EXAMPLES Next, the present invention will be described with reference to Examples and Reference Examples.

Example 1 FIG. 1 is a cross-sectional view of a main part of a solar cell module according to an example of the present invention. The CdS / CdTe solar cell element 1 is directly formed on the glass substrate 2 (bottom in FIG. 1), leaving a peripheral margin 20. The back sheet 15 formed by three layers of the thermoplastic resin layer 10 and the Al foil which is the main body and the protective resin layer 12 provided outside the Al foil is
The CdS / CdTe solar cell element 1 is surrounded, and its peripheral portion is bonded to the margin 20 on the outer peripheral portion of the glass substrate 2. The thermoplastic resin layer 10 functions to bond the Al foil 11 to the margin 20 on the outer peripheral portion of the glass 2.

The CdS / CdTe solar cell element 1 is a glass substrate 2 here.
On the 14 cm square non-alkali borosilicate glass used as a CdS film, leaving a 6.5 mm wide margin 20 in the periphery, and then Ag.
-CdTe film on the CdS film excluding the In electrode part, and C on it
The film and the Ag electrode are formed. In addition, an Ag-In electrode is formed in a portion without a CdTe film or the like. Finally, all of them were coated with a mixed cured product of a fluororesin and a diisocyanate having a basic skeleton of an alternating copolymer of fluoroolefin and a hydrocarbon vinyl ether monomer.

Polyethylene modified by copolymerization of acid anhydride was used for the thermoplastic resin layer 10, and polyethylene terephthalate resin (PET) was used for the Al foil protective resin layer 12. In the module thus manufactured, the back sheet 15 is
It was well adhered to the glass in the margin 20.

As the oxygen-releasing substance 50, 2 g of dehydrated product of synthetic zeolite was used and enclosed in the air layer 30.

An opaque silicone resin is used for the paint layer 40, and the margin 20
It was arranged that the thermoplastic resin layer 10 adhered to was protected from direct sunlight.

A reliability test result of the solar cell module produced as described above by a sunshine weather meter is shown together with the result (Reference Example 1) of the solar cell module produced by forming the element coating resin 3 with the conventional epoxy resin. Shown in the table. As shown in Table 1, the solar cell module using a fluorine-based resin as the element coating resin has a small decrease in conversion efficiency of 2%, whereas the solar cell module made using a conventional epoxy resin has a It was as high as%.

Example 2 A solar cell module similar to that of Example 1 was prepared except that the silicon-based resin 1 shown in Table 2 was used as the element coating resin. Silicon-based resin 1 shown in Table 2 is an addition reaction type silicone-based resin in which a vinyl group is bonded to Si atom (A material) and a hydrogen atom is bonded to Si atom (B material).
Is a type that reacts with a platinum compound catalyst.

The reliability test results are shown in Table 1. Silicone resin 1
The decrease in conversion efficiency of the module of this type in which the solar cell element was coated with was 3%, which was smaller than that of the conventional example.

Example 3 A solar cell module similar to that of Example 1 was prepared except that the silicon-based resin 2 shown in Table 2 was used as the element coating resin. Silicon-based resin 2 is a condensation reaction type silicone-based resin in which a silicon group has a hydroxy group bonded (C material).
And a Si atom to which an isopropeniooxyl group is bonded (material D) are of a type that reacts with an organic tin compound as a catalyst to cause a deacetone reaction.

The reliability test results are shown in Table 1. The conversion efficiency of the module prepared by using the silicon resin 2 as the element coating resin was 3.5%, which was smaller than that of the conventional example.

Example 4 A solar cell module similar to that of Example 1 was prepared except that the silicon-based resin 3 shown in Table 2 was used as the element coating resin. The silicone resin 3 is an ultraviolet (UV) curable silicone resin in which a vinyl group is bonded to a Si atom (E
The agent) and the one in which a methyl group is bonded to a Si atom (F agent) are of a type that reacts with a free radical generated by irradiation of ultraviolet rays with the help of a sensitizer.

The reliability test results are shown in Table 1. The decrease in conversion efficiency of the module prepared by using the silicon resin 3 as the element coating resin was 4%, which was smaller than that of the epoxy resin.

Example 5 A solar cell module similar to that of Example 1 was prepared except that a CdS / CuInSe ₂ solar cell element was formed as the solar cell element. The CdS / CuInSe ₂ solar cell element is a CdS film on a 14 cm square non-alkali borosilicate glass with a 6.5 mm wide margin 20 around the periphery, and then C on the CdS film excluding the Ag-In electrode part.
The uInSe ₂ film, the C film, and the Ag electrode are formed on the uInSe ₂ film. The Ag-In the portion having no such CuInSe ₂ film
An electrode is formed. And finally, all of them are covered with fluorocarbon resin.

The solar cell module created as described above was subjected to a sunshine weather meter (due cycle) test.
After 00 hours, the decrease in conversion efficiency was as small as 1.8%, while the decrease in the solar cell module made using the conventional epoxy resin was as large as 19%.

Effects of the Invention As described above in the examples, the effect of forming the element coating resin of the CdS / CdTe or CdS / CuInSe ₂ solar cell element from the fluorine resin or the silicon resin is remarkable, and the weather meter light irradiation is performed. There was an effect of suppressing the performance deterioration of the solar cell module below.

As shown as Reference Example 2 in Table 1, when the oxygen concentration around the element is reduced without encapsulating the oxygen releasing agent, the change efficiency is lowered to 41%. As can be seen from the results of Reference Example 2, CdS / CdTe was placed in the closed space formed by the glass and the back sheet adhered to the periphery of the glass.
Alternatively, when there is a CdS / CuInSe ₂ system solar cell element, the reliability of the solar cell module decreases if the oxygen concentration in the enclosed space is low. The fluorine-based resin or silicon-based resin of the present invention is difficult to decompose even when directly exposed to light, and therefore does not consume oxygen, so that the effect of suppressing deterioration of reliability is finally exhibited.

When forming a solar cell module with one unit solar cell element, since the CdS film is formed on the front surface excluding the peripheral margins, the element coating resin is not directly exposed to the sunlight rays that have passed through the glass, When connecting two or more unit solar cell elements in order to obtain the required voltage, the element coating resin is always formed between the unit solar cell elements and the unit solar cell element, and that portion is not exposed to the sunlight that has passed through the glass. Exposed directly. Therefore, in the case of the high-voltage solar cell module, the resin area exposed to sunlight becomes wider, and the suitability of the resin in that portion has a great influence on the reliability of the solar cell module.

The effect of the present invention is more significant in a high voltage solar cell module.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view of a main part of a solar cell module according to a first embodiment of the present invention, and FIGS. 2 and 3 are enlarged cross-sectional views of a main part of a conventional solar cell module. 1 …… CdS / CdTe solar cell element, 2 …… glass, 3 ……
Element coating resin, 10 ... Thermoplastic resin, 11 ... Al
Foil, 12 ... Al foil protective resin layer, 15 ... Back sheet, 20 ... Margin, 30 ... Air layer, 40 ... Paint layer,
50 ... Oxygen release product.

Front page continuation (72) Inventor Sadaharu Shirai 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP 62-132371 (JP, A) JP 53-110492 (JP, A) JP-A-51-132972 (JP, A)

Claims (5)

[Claims] 1. A glass substrate and CdS / CdTe or CdS / Cu directly formed on one surface of the glass substrate.
A photovoltaic portion composed of InSe ₂ bonds, a fluorine-based resin or a silicon-based resin that covers the photovoltaic portion, a thermoplastic resin layer that surrounds the outside of the coated photovoltaic portion, and a metal foil-based material. A solar cell comprising a back sheet, wherein the photovoltaic portion and air are enclosed in an enclosed space formed by adhering the metal foil periphery to the outer peripheral portion of the glass substrate by the thermoplastic resin layer. module. 2. The solar cell module according to claim 1, wherein the fluorine-based resin has an alternating copolymer of fluoroolefin and a hydrocarbon-based vinyl ether monomer as a basic skeleton. 3. The solar cell module according to claim 1, wherein the silicone resin is an addition reaction type, a condensation reaction type, or an ultraviolet curing type. 4. The solar cell module according to any one of claims 1 to 3, wherein the oxygen-releasing substance is enclosed in a closed space. 5. The solar cell module according to claim 1, wherein the thermoplastic resin is polyethylene modified by co-polymerization with an acid anhydride.