DE102010021041A1 - Device for making electrical conductive connection between solar cells of solar cell strand, has cell connectors that are electrically connected with solar cell by thermal treatment of strand together with support frames - Google Patents

Abstract

The device has two support frames (1) on which solar cells (2) are positioned in a strand, where each frame comprises cell connectors (4). The cell connectors and the cells are electrically connected by thermal treatment of the strand together with the frames. Cell terminal stripes (3, 5) are inserted in recesses of the frames. The strand is continuously, evenly and slowly heated and cooled during the thermal treatment according to a fixed program. A pressure-spring element (6) locks the cell and/or the cell connector on the stripes and assembles over a pivot.

Description

The present invention relates to a device in which solar cells and solar cell connectors in the length of an entire string (string) are inserted into a support frame and both positioned and fixed and then introduced together with the support frame in a heating chamber, then in the temperature after a fixed program slowly and steadily increased to the necessary process temperature and lowered again after completion of the electrical connection and contacting slowly and steadily to ambient temperature.

Installations for the production of a solar cell string are generally known. They are z. B. in the patents DE 10 2006 034 492 A1 and DE 102 97 633 T5 described. The task is to concatenate the individual solar cells with solar cell connectors - usually narrow, thin metal strips - in electrical series connection with one another. The solar cell connectors are guided at the contact points of the solar cells with the ends alternately from the bottom of the preceding cells to the top of the following cells. As a joining technique, the soldering is used in most cases. The purpose of this strand formation is to achieve a technically usable electrical voltage. The voltage that a single cell generates when it is exposed to light is very low. The production of the solar cell strands takes place according to the current state of the art according to different clocking methods. However, the principle is always the same. Clock-by-cycle is supplied cell-by-cell and cell-connector cell-to-cell handling equipment by means of a transport system, and passed through a heating chamber to the same extent, usually as a tunnel solder oven, which divides into the preheat, solder and quench zones (multi-zone tunnel soldering oven). This is necessary because the solar cells made of silicon are very susceptible to sudden changes in temperature due to the resulting material stresses, so even at the soldering temperatures used, which start at about 250 ° C and can be up to 400 ° C.

For soldering and contact soldering is known. A heated soldering punch is pressed onto the contact point. Due to the resulting mechanical and the locally high temperature load, it is preferable to heat the entire cell via infrared radiators or halogen lamps. In the patent DE 42 41 439 A1 is described in great detail a soldering process, but whose claim is based on the composition of the solder used, with the between the metallic contact point of the solar cell and the metallic solar cell connector at a precisely maintained soldering temperature and temperature coefficient by diffusion, an alloy between the solder and the pad metal arises.

The advantage of this method is that the resulting melting temperature of the alloy is much higher than that of the solder itself and thus a higher thermal resistance is achieved.

The significant disadvantage of the described devices, which put the solar cell strand together in cycles and contact cell by cell in a multi-zone tunnel soldering or brazing is that despite zoning the high temperature jump occurs from zone to zone and relative to the ambient temperature and up to May be 200 ° C. This results in a relatively high breakage rate.

A further disadvantage of cyclic soldering is the fact that small twisting errors between two cells can occur during soldering of the cell connectors to the adjacent solar cells due to production-related tolerances and this with each cycle until the strand is complete. This results in part in a significant sum error, so that viewed on the strand on the plane an arcuate or serpentine outline can arise.

According to the invention, the disadvantages mentioned are avoided in that all the solar cells are embedded in a rigid support frame for a strand with the associated cell connectors and are therefore fixed and fixed to one another invariably for the soldering process. Furthermore, no multi-zone tunnel soldering oven is used in the method according to the invention, but a closed soldering chamber, in which the entire solar cell strand is introduced together with the support frame. After a fixed program, then the temperature, starting from the ambient temperature slowly and steadily, d. H. without temperature jumps, heated to the process temperature and cooled down to ambient temperature just as slowly and steadily after the process time. This avoids the dreaded material stresses and, as a result, the breakage of the cells. Compared to the clock method thereby the production time for a strand is not delayed because you have in the soldering chamber compared to the single clock n times more time available, according to the number of solar cells, for example, 10 pieces per strand. This achieves a much safer, more precise and almost jam-free production of the solar cell strings compared to the current state of the art with the same production times.

The features of claim 1 describe how, in accordance with the new method, a non-detachable electrical connection between cells and cell connectors is produced in one piece between the cells of a solar cell string.

With the features of claims 2 and 3, an embodiment is described in which the electrical contacting of the entire strand takes place in a single operation by a thermal treatment after a fixed heating and cooling program.

The features of claim 4 describe how the production process can be optimized for the new method.

Further details of the invention can be taken from the following description and the embodiment according to the drawings.

It shows

1 a partial longitudinal section through the support frame ( 1 ) into which the cells ( 2 ) and the cell connectors ( 4 ) and the cell connection strips ( 3 ) and ( 5 ) are inserted. The pressure spring elements ( 6 ) press on the cell connectors or cell connection strips and the intervening cells ( 2 ) and hold this unit together.

2 the partial top view of the support frame ( 1 ) with the inserted cells ( 2 ) and the longitudinally arranged cell connectors ( 4 ) and the cell connection strips ( 3 ) and ( 5 ) and the attached Andrückfederelementen ( 6 ).

3 a detailed view of how the cell ( 2 ) and the cell connector ( 4 ) with the Andrückfederelement ( 6 ) in the carrier frame ( 1 ).

In the 1 to 3 is shown how the solar cells ( 2 ) and the cell connectors ( 4 ) and the cell connection strips ( 3 ) and ( 5 ) in the support frame ( 1 ) and positioned. First, from right to left, below the space for the first cell ( 2 ) two or more cell connection strips ( 3 ) in the adjusted recesses of the support frame ( 1 ) and thus fixed and positioned. Then you put the first cell ( 2 ) and then the next cell connectors ( 4 ), with their free ends under the space for the second cell ( 2 ) in the recess of the support frame ( 1 ) come to rest. The free end of the cell connection strips ( 3 ) on the first cell ( 2 ) is then the connection for the cross-connection of solar cell strings. In this way, n cells ( 2 ) and n cell connectors ( 4 ) in the support frame ( 1 ). The last cell is replaced by the cranked cell connectors ( 4 ) planar cell connection strips ( 5 ), which with their free ends also in a recess of the support frame ( 1 ) are positioned and fixed. After fitting, you can use the swivel joint ( 6.1 ) the Andrückfederelemente ( 6 ) to the unit cell / cell connector or terminal strip with a snap-on function. Thus, the stocked carrier frame is ready for contacting the cells.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102006034492 A1 [0002]
• DE 10297633 T5 [0002]
• DE 4241439 A1 [0003]

Claims (4)

Device for producing an electrical conductive connection between the solar cells of a solar cell string, characterized in that all cells are positioned for a strand on a support frame and equipped with cell connectors and then in a process for all cells an indissoluble electrical connection between cells and cell connectors is made. Device according to claim 1, characterized in that an electrical connection between cells and cell connectors is brought about by a simultaneous thermal treatment for the entire strand together with the support frame. Device according to claim 1 and 2 characterized in that the thermal treatment during heating and cooling of the strand is carried out continuously uniformly and slowly and thus free of material stress according to a fixed program. Device according to claim 1, characterized in that at least two support frames are used, which serve alternately for the assembly with cells and cell connection or for electrical contacting.

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