JPH0563104B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to solar cell modules, particularly
CdS/CuInSe ₂ or (Cd _X Zn _1-X ) S/CuInSe ₂
This relates to the package structure of solar cells. BACKGROUND OF THE INVENTION Recently, solar cells have been attracting attention as a means of energy supply. This is because electrical energy can be easily extracted directly from the infinite amount of clean solar energy. However, solar cells have not become widespread on a large scale because of the high cost of electricity, and the root cause of this is that solar cell elements and their modules are expensive. It goes without saying that efforts are being made to reduce costs in the former, but it is equally important to reduce costs in the latter, and various efforts are being made to achieve this. In addition, as solar cell elements change, a package corresponding to the change is required. Most conventional solar cell modules were developed based on the premise of using crystalline solar cell elements such as single-crystal silicon solar cell elements or polycrystalline silicon solar cell elements, and thin-film solar cell elements such as compound semiconductor solar cell elements. There are many points that need to be improved when using . Among compound semiconductor solar cells, various modules have been proposed for CdS/CdTe-based solar cells depending on the unique properties of the solar cell element, but for CdS/CuInSe ₂ -based solar cells, etc. , remains largely unfinished. CdS/CuInSe ₂ -based solar cell elements are (1) relatively less resistant to water (humidity) than single-crystal or polycrystalline Si solar cells, and (2) corresponding to (1) above, they are resistant to moisture. Even if we create a module that strongly prevents the intrusion of oxygen, the oxygen present around the element at high temperatures has a serious effect. For example, at 80°C, the conversion efficiency will be lower if there is no oxygen around the element than when oxygen is present. It has the unique property of being extremely low.
However, I can't find any corresponding module. Problems to be Solved by the Invention By the way, as mentioned earlier, conventional solar cell modules were developed based on the use of single-crystalline or polycrystalline Si solar cell elements.
Even when applied to _two CdS/CuInSe elements, reliability is low. Therefore, there is a challenge to create a module with a structure that corresponds to the unique properties shown in (1) and (2) above, and to improve reliability. Means for Solving the Problems This invention aims to solve the above problems, and uses synthetic crystalline aluminosilicate (synthetic crystalline aluminosilicate ( M _2/o O・Al ₂ O ₃・
xSiO ₂ yH ₂ O, where M: metal cation, n:
The method is to use a crystal water-eliminated product (hereinafter abbreviated as synthetic zeolite) of atomic valence, x: coefficient, y: coefficient). Although all zeolites function as desiccants, not all of them act as oxygen release agents; only zeolites with pore diameters of 4 Å or more have oxygen adsorption and therefore oxygen release ability. In addition, even for materials that have oxygen adsorption ability, when cooling after heating to high temperatures to desorb crystal water, the amount of adsorbed oxygen is greater when cooled in a gas with a higher amount of oxygen than when cooled in air. Therefore, it is desirable to use zeolite cooled in an oxygen-rich atmosphere because it releases more oxygen. Effects To explain quantitatively, we will use diagrams.
As the zeolite, Zeostar (trademark) manufactured by Nihon Kagaku Kogyo Co., Ltd. will be used for explanation. Figure 2 shows the oxygen adsorption isotherms of various Zeostars at 25°C (personal communication from Mr. Kaname). According to Figure 2, Zeostar KA-112L (pore diameter 3 Å) does not adsorb O ₂ at all, while Zeostar NA-112L (4 Å) has a pore diameter of 760 mm.
When Hg is 1.2Nml/g, the same NX-112L (9Å) is
1.96Nml/g, CA-112L (5Å) 2.41Nml/g,
The same NM-112L (7 Å) adsorbs 4.76 Nml/g of O ₂ . Looking at the size of the pore diameter and the amount of O ₂ adsorption, there is a tendency that the larger the pore diameter, the larger the amount of O ₂ adsorption, except in the case of NX-112L (9 Å). “Zeolite Molecular” by DWBreck
Sieves” P633-641 (John Wiley & Sons, NY
((1974)), the minimum dynamic diameter (σ) of an O ₂ molecule is 3.46 Å, and that of H ₂ O is 2.65 Å. An O ₂ molecule with σ of 3.46 Å has a pore diameter of 3 Å.
It is natural that it cannot be adsorbed to 112L, but it is adsorbed to those with a pore diameter of 4 Å or more. σ is 2.65Å
It is clear that H ₂ O is adsorbed by all Zeosters. From the above basic facts, all zeolites function as desiccants, and all zeolites with a pore diameter of 4 Å or more function as oxygen adsorbents.
Therefore, it can be seen that all zeolites with pore diameters of 4 Å or more that have adsorbed oxygen function as oxygen releasing agents. The present invention is intended to adsorb oxygen in advance to zeolite having a pore diameter of 4 Å or more, and to use it as an oxygen release agent and at the same time as a desiccant. By placing zeolite with a pore diameter of 4 Å or more that adsorbs oxygen near the formation area of the CdS/CuInSe ₂ -based solar cell element,
Oxygen is gradually supplied, making it possible to prevent a decrease in conversion efficiency caused by oxygen deficiency. At the same time, the element is kept dry, making it possible to prevent deterioration caused by moisture. Examples Next, the present invention will be explained 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 in Example 1 of the present invention. The solar cell element 1 is placed on the substrate 6 (bottom in FIG. 1) with a peripheral margin 20
It is directly formed leaving behind. A back sheet 50 made of a thermoplastic resin layer 10 and a metal foil 7 is thermocompression bonded to the margin 20 so as to cover the entire solar cell element 1. Solar cell element 1
An air layer 30 is created between the back sheet 50 and the back sheet 50, and a polyethylene bag 40 containing zeolite 9 having a pore diameter of 4 Å or more is interposed therein. The solar cell element 1 is made of a CdS film with a 6.5 mm wide margin 20 left around the periphery on a 14 cm square alkali-free borosilicate glass used as a substrate 6, and then a CdS film with the Ag-In electrode part removed. CuInSe ₂ film on the film,
Furthermore, a C film and an Ag electrode are formed on top of that. Also, in areas where there is no CuInSe ₂ film, etc.
An Ag-In electrode was formed. And finally they are all covered with epoxy resin. Polyolefin modified by multiple polymerization of acid anhydride was used for the resin layer 10, and Al foil was used for the metal foil 7. In the module created in this way, metal foil 7
The blank space 20 is bonded with glass. As zeolite, 2g of Zeostar-NA-
Use 112L and put it in a polyethylene pouch.
The unsealed package was folded in half and placed on top of the device (bottom in FIG. 1). Reliability test results at 80℃ and 95% RH for the solar cell module created as described above.Results for the solar cell module created without placing anything (Reference Example 1).2g Zeostar KA-112L. The results are shown in Table 1 together with the results obtained by placing 2 g of iron powder as an oxygen absorber (Reference Example 2) and the results obtained by placing 2 g of iron powder as an oxygen absorber (Reference Example 3). Zeostar NA-112L, which is an oxygen emitting product, as shown in Table 1
The reduction in conversion efficiency of the solar cell module encapsulated with the material was as small as 3.5%, while that of the solar cell module made without the encapsulation was as large as 12.5%.

[Table] The reduction in conversion efficiency of solar cell modules made by enclosing 2 g of KA-112L or 2 g of iron powder was 6.3% and 22.0%, respectively (Reference Examples 2 and 3). The reason why the deterioration rate is smaller when KA-112L is enclosed than when it is not included (Reference Example 1) is thought to be due to the effect of drying. The fact that the deterioration rate is as high as 22% when iron powder is encapsulated indicates that deterioration is greater in the absence of oxygen around the element. Example 2 Zeostar NX with a pore size of 9 Å as an oxygen release material
A solar cell module similar to that in Example 1 was created except that -112L was used. The reliability test results are shown in Table 1. The reduction in conversion efficiency of the module containing Zeostar NX-112L was as small as 3.2%. Example 3 Zeostar CA- with a pore size of 5 Å was used as an oxygen release material
A solar cell module similar to that in Example 1 was produced except that 112L was used. The reliability test results are shown in Table 1. The reduction in conversion efficiency of Zeostar CA-112L module containing oxygen emitting material is
It was 2.8%, which was smaller than that of Reference Example 1. Example 4 Zeostar-NM with a pore size of 7 Å as an oxygen release material
A solar cell module similar to Example 1 was created except that -112L was used. Zeostar NM-
The reduction in conversion efficiency of the module containing 112L is
It was 2.1%, which was smaller than that of Reference Example 1. Example 5 A solar cell module similar to Example 1 was produced except that a (Cd _0.9 Zn _0.1 )S film was formed instead of the CdS film. When conducting a reliability test at 80°C and 90% RH, a 3.1% decrease in performance was observed after 500 hours, which was smaller than the 11.9% when nothing was sealed. Effects of the Invention As explained above in detail, zeolite with a pore diameter of 4 Å or more adsorbs oxygen molecules, and the zeolite that has adsorbed oxygen molecules functions as an oxygen-releasing substance. The effect of encapsulating it in the module was remarkable, and it was effective in preventing the performance of the solar cell module from deteriorating in a high temperature and humidity environment. As shown in Reference Example 2 in Table 1, zeolite has no oxygen absorption ability and has a pore diameter of less than 3.46 Å,
For example, Zeostar KA-1121L, which has a pore diameter of 3 Å, does not have the ability to release oxygen, so even if it is enclosed in it, it has a drying effect, but its effectiveness in preventing performance deterioration is small, resulting in a reduction in conversion efficiency of 6.3%. Reference example 1
The results of the above and the results of the examples of the present invention are in good symmetry, clearly showing the effect of encapsulating zeolite with a pore diameter of 4 Å or more in the module. In addition, here, we have shown the data when Zeostar was heated to 400℃ or higher and then cooled in an air atmosphere as the oxygen release material. However, if it was cooled in an oxygen atmosphere, the Good results have been shown, and an even more reliable solar cell module has been obtained. Although zeolite has been described here as a substance that adsorbs and releases oxygen,
Since it naturally has the ability to adsorb moisture, it goes without saying that it is effective as a desiccant. Since zeolite with a pore diameter of less than 3.46 Å can of course be used as a desiccant, it is possible to use it in combination with a zeolite with a larger pore diameter. In addition, the oxygen in the air layer in the module is effective in preventing deterioration of the module in high temperature and high humidity environments.
It is obvious that a large amount is desirable, and this has been experimentally confirmed.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the main parts of Example 1 of the solar cell module of the present invention, and Figure 2 is a cross-sectional view of various zeolites.
It is an adsorption isotherm diagram at 25°C. DESCRIPTION OF SYMBOLS 1...Solar cell element, 6...Substrate, 7...Metal foil, 9...Oxygen emitting material, 10...Resin layer, 20...
...Margin, 30...Air layer, 40...Polyethylene bag, 50...Back sheet.

Claims (1)

[Claims] 1 CdS/CuInSe ₂ junction or (Cd _X Zn _1-X )
A solar cell module containing any of the S/CuInSe ₂ junctions as a photovoltaic part, comprising a synthetic crystalline aluminosilicate (M _2/o
O・Al ₂ O ₃・xSiO ₂・yH ₂ O, where M: metal cation, n: valence, x: coefficient, y: coefficient) separated from crystal water (hereinafter referred to as synthetic zeolite) is a desiccant and oxygen A solar cell module that is enclosed within the space of the module as a discharge. 2 CdS/CuInSe ₂ junction or (Cd _X Zn _1-X )
A solar cell module including one of S/CuInSe ₂ junctions as a photovoltaic part, wherein the zeolite is encapsulated in a space surrounded by a glass substrate, a metal foil, and a thermoplastic resin layer bonding both. A solar cell module according to claim 1. 3 CdS layer of photovoltaic part or (Cd _X Zn _1-X )
3. The solar cell module according to claim 1 or 2, wherein the S layer is formed between the glass substrate and CuInSe ₂ . 4. The solar cell module according to claim 1 or 2, wherein the zeolite is placed in a location where it does not interfere with light irradiation to the photovoltaic portion. 5 Claim 2 in which the thermoplastic resin layer is a polyolefin modified by copolymerizing acid anhydride.
The solar cell module described in Section 1. 6. The solar cell module according to claim 2, wherein the metal foil is Al. 7. The solar cell module according to claim 1 or 2, wherein the zeolite is enclosed together with air or a gas containing oxygen.