阅读说明：本技术 一种提高焊接拉力不合格晶硅太阳能电池焊接拉力的方法 (Method for improving welding tension of crystalline silicon solar cell with unqualified welding tension ) 是由 吝占胜 李倩 陈晨 刘伟 孙晓娟 王静 张东升 史金超 张伟 于 2021-08-20 设计创作，主要内容包括：本发明涉及太阳能电池领域,尤其涉及一种提高焊接拉力不合格晶硅太阳能电池焊接拉力的方法,对不合格晶硅太阳能电池进行热处理；其中,热处理的温度为玻璃粉的软化温度,热处理的时间为20～35s。整个方法操作简便,对于浆料、硅片以及工艺方面等各因素所造成的晶硅太阳能电池的焊接拉力不够的现象均具有良好的适用性,避免因焊接拉力出现太阳能电池不合格的现象,在晶硅太阳能电池领域具有广泛的应用前景。(The invention relates to the field of solar cells, in particular to a method for improving welding tension of crystalline silicon solar cells with unqualified welding tension, which comprises the following steps of carrying out heat treatment on the unqualified crystalline silicon solar cells; wherein the heat treatment temperature is the softening temperature of the glass powder, and the heat treatment time is 20-35 s. The whole method is simple and convenient to operate, has good applicability to the phenomenon that the welding tension of the crystalline silicon solar cell is insufficient due to various factors such as slurry, a silicon wafer and the process, avoids the phenomenon that the solar cell is unqualified due to the welding tension, and has wide application prospect in the field of crystalline silicon solar cells.)

1. A method for improving welding tension of crystalline silicon solar cells with unqualified welding tension is characterized by comprising the following steps: carrying out heat treatment on the unqualified crystalline silicon solar cells; the heat treatment temperature is the softening temperature of the glass powder, and the heat treatment time is 20-35 s.

2. The method for improving the welding tension of the crystalline silicon solar cell with unqualified welding tension according to claim 1, wherein the lowest temperature of the heat treatment is 80-120 ℃ higher than the lowest temperature of the softening temperature of the glass powder.

3. The method for improving the welding tension of the crystalline silicon solar cell with unqualified welding tension according to claim 1, wherein the heat treatment time is 25-30 s.

4. The method for improving the welding tension of the crystalline silicon solar cell with unqualified welding tension according to claim 1, wherein the number of the heat treatments is 1-3.

5. The application of the method for improving the welding tension of the crystalline silicon solar cell with unqualified welding tension in claims 1-4 to the improvement of the qualified rate of the crystalline silicon solar cell.

6. The application of the method for improving the welding tension of the crystalline silicon solar cell with unqualified welding tension in the improvement of the qualification rate of the crystalline silicon solar cell as claimed in claim 5, wherein when the crystalline silicon solar cell with unqualified welding tension occurs in the production process of the solar cell, when the reason for unqualified welding tension can be eliminated, the crystalline silicon solar cell with unqualified welding tension is treated by the method for improving the welding tension of the crystalline silicon solar cell with unqualified welding tension, and the production is continued after the reason for unqualified welding tension is eliminated.

7. The application of the method for improving the welding tension of the crystalline silicon solar cell with unqualified welding tension in the improvement of the qualification rate of the crystalline silicon solar cell as claimed in claim 5, wherein when the crystalline silicon solar cell with unqualified welding tension occurs in the production process of the solar cell, when the reason for the unqualified welding tension cannot be eliminated, a retreating process is added in the production process, and the method for improving the welding tension of the crystalline silicon solar cell with unqualified welding tension is used for carrying out heat treatment on the sintered crystalline silicon solar cell.

Technical Field

The invention relates to the field of solar cells, in particular to a method for improving welding tension of crystalline silicon solar cells with unqualified welding tension.

Background

After the battery piece is welded into the assembly, the welding strip is used for connection between the piece and the battery piece, the current of the whole assembly is led out by the welding strip, the whole performance of the assembly is affected by the looseness of the connection of the welding strip and the battery piece, the power of the assembly is reduced due to poor contact, or the local heat is gathered to form hot spots and the like. The parameter for evaluating the adhesion of the battery and the welding strip is welding tension, so that the welding tension is important for the performance of the assembly.

The welding quality and the performance of the battery piece can both influence the welding tension, wherein the main factor influencing the welding tension in the performance of the battery piece is that on the one hand, in the aspect of slurry, the welding tension can be influenced by the glass powder components in the silver paste formula and the proportion fluctuation in the batching process; secondly, in the aspect of silicon wafers, different cutting modes or texturing processes are adopted, and welding tension forces are different; thirdly, in terms of process, the size of the printing amount, the thickness of the printed main grid, the sintering process and the like, the welding tension is also influenced. Therefore, the welding tension of the cell is easily affected by various factors, so that the welding tension of the cell and the welding strip is insufficient, and the phenomenon of batch unqualified solar cells is caused. In the prior art, all the ways of improving the welding tension are measures taken for the unsintered battery after the battery tension is found to be low, but no proper treatment method is available for the battery with unqualified sintered welding tension, and the battery which does not meet the welding tension standard can not be applied to an assembly end, so the battery with unqualified sintered welding tension is usually treated as a waste product, and thus the waste of raw materials and the increase of cost are caused.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a method for improving the welding tension of the crystalline silicon solar cell with unqualified welding tension, which has the advantages of improved welding tension, simple and convenient operation and no influence on the use of the solar cell.

In order to achieve the purpose of the invention, the embodiment of the invention adopts the following technical scheme:

a method for improving welding tension of crystalline silicon solar cells with unqualified welding tension comprises the following steps: carrying out heat treatment on the unqualified crystalline silicon solar cells; the heat treatment temperature is the softening temperature of the glass powder, and the heat treatment time is 20-35 s.

Make glass can accomplish through thermal treatment and soften and flow and drive silver powder secondary distribution, make the crystallization layer and the network structure of glass more even fine and close, the pulling force obtains improving, and the softening temperature of glass powder is less than the temperature of silver-silicon alloy simultaneously, can not destroy the microcrystalline structure and the sculpture of silver-silicon and wear the silicon nitride film, consequently, can reach and promote the welding pulling force and do not influence the purpose of battery performance. The whole method is simple and convenient to operate, has good applicability to the phenomenon that the welding tension of the solar cell is insufficient due to various factors such as slurry, silicon wafers and the process, avoids the phenomenon that the solar cell is unqualified due to the welding tension, and has wide application prospect in the field of solar cells.

Preferably, the lowest temperature of the heat treatment is 80-120 ℃ higher than the lowest temperature of the softening temperature of the glass powder.

Preferably, the time of the heat treatment is 25-30 s.

Preferably, the number of times of the heat treatment is 1 to 3.

The optimal treatment times do not affect the performance of the battery, and the performance of the battery is reduced every time the heat treatment is added, so the treatment times are reduced as much as possible on the premise of meeting the welding tension, and if the welding tension can be met by one heat treatment, the heat treatment is not needed for two times.

Preferably, the heat treatment equipment is a sintering furnace.

And a sintering furnace is selected for heat treatment, so that the temperature stability in the treatment process is strong, and the method is environment-friendly.

The invention also provides application of the method for improving the welding tension of the crystalline silicon solar cell with unqualified welding tension in improving the qualified rate of the crystalline silicon solar cell.

Preferably, when the crystalline silicon solar cell with unqualified welding tension is produced in the production process of the solar cell, when the reason of unqualified welding tension can be eliminated, the crystalline silicon solar cell with unqualified welding tension is processed by the method for improving the welding tension of the crystalline silicon solar cell with unqualified welding tension, and the production is continued after the reason is eliminated.

Preferably, when the crystalline silicon solar cell with unqualified welding tension is produced in the production process of the solar cell, and when the reason of unqualified welding tension cannot be eliminated, a reprocessing process is added in the production process, and the sintered crystalline silicon solar cell is subjected to heat treatment by the method for improving the welding tension of the crystalline silicon solar cell with unqualified welding tension.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

In the prior art, the welding tension is usually improved by increasing the sintering peak temperature or increasing the sintering time, but practice finds that the welding tension of the crystalline silicon solar cell can be improved by adopting the two methods, excessive sintering is easily caused, the passivation performance of the cell is damaged, the cell efficiency is reduced, or the situation of electric leakage caused by contact of silver paste with a PN junction occurs, so that the performance of the cell is adversely affected by adopting the two methods, and the probability of producing unqualified cells is greatly improved. Battery manufacturers are more demanding high battery conversion efficiency, so that the welding tension is not increased by changing the parameters of the sintering process, so as to avoid reducing the battery conversion efficiency or causing battery leakage. In addition, both methods are measures taken for the unsintered battery after the battery tension is found to be low, and cannot be applied to the battery with unqualified welding tension which is sintered. The applicant has conducted a great deal of research on crystalline silicon solar cells and found that the sintering process is a key factor for improving the unqualified welding tension. In view of the above, the applicant has creatively proposed a method for performing heat treatment on the unqualified crystalline silicon solar cell at the softening temperature of the glass powder through a great deal of research on unqualified product treatment modes, the method can improve the welding tension of the battery with unqualified welding tension, the unqualified battery caused by the welding tension is avoided, and the method is suitable for batteries with unqualified welding tension caused by different factors.

The type of the silver paste: DK93T-74 of Imperial department, and the softening temperature range of the obtained glass powder is 400-600 ℃ through detection;

the type of the sintering furnace: DESPATCH CDF, measuring the actual sintering temperature of the high-temperature sintering furnace to be 30 ℃ lower than the set sintering temperature by using a temperature measuring instrument, wherein the total length of the sintering temperature zone is 2.5 m.

Example 1:

during the production, the silver paste tension is lower than that of the normal test by routine sampling inspection at a certain time because the glass proportion has deviation in silver uniformity. At present, the unqualified batteries are subjected to heat treatment at different heat treatment temperatures, the number of the treated batteries is 198, the conveying speed is 5.58m/min, the treatment times are 1 time, and the following table 1 shows the performance parameters of the batteries before and after the heat treatment.

TABLE 1

From the test results in table 1, the unqualified solar cells are subjected to heat treatment at the actual temperatures of 520 ℃, 545 ℃, 570 ℃ and 595 ℃, and the performances of the solar cells, such as open-circuit voltage, short-circuit current, series resistance, filling factor, conversion efficiency and reverse leakage current, are measured after the heat treatment, so that the improvement of the welding tension of the cells can be realized by performing the heat treatment at the four temperatures, the influence of performance parameters is small, the use of the cells is not influenced, and the standard requirements of GB/T29195-2012 general Standard for ground crystalline silicon solar cells are completely met, wherein the effect is the best when the actual temperature is 570 ℃, which indicates that the method provided by the invention can improve the welding tension of the solar cells with unqualified welding tension.

Example 2:

the slurry is normally used in the mortar sheet, and the tension is lower after the black silicon sheet is used. At present, the unqualified batteries are subjected to heat treatment, the number of the treated batteries is 1195, the temperature of a sintering furnace is set to be 600 ℃, the transmission speed is 5.60m/min, the treatment times are 2 times, and the following table 2 shows the performance parameters of the batteries before and after the heat treatment.

TABLE 2

From the test results in table 2, the value of the average tension after the first heat treatment is still low, the tension after the second heat treatment is performed is obviously increased, the influence on the performance of the solar cell such as open-circuit voltage, short-circuit current, series resistance, filling factor, conversion efficiency and reverse leakage current is small, the standard requirements of the GB/T29195-2012 crystalline silicon solar cell general specification for the ground are completely met, and the method provided by the invention can improve the welding tension of the solar cell with unqualified welding tension and does not influence the use of the solar cell.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents or improvements made within the spirit and principle of the present invention should be included in the scope of the present invention.