Solar cell interconnection sheet and connection method

Abstract

The present invention discloses an interconnection sheet and connection method for solar cells, which are suitable for working environments with large temperature differences and a large number of cycles, and belong to the technical field of solar cell circuit manufacturing for space use. More specifically, it relates to a high-reliability electrical interconnection structure with thermal stress matching, in which solar cells with welded interconnection sheets are respectively pasted on a substrate, with the interconnection sheets exposed upward, and two interconnection sheets are welded together by butt welding equipment to form a two-handed palm-shaped structure, which can be connected in series or in parallel according to the electrode polarity. The interconnection sheet design can form a directional stress-reducing arc during connection, and is easy to weld. This method can avoid the welding process on the surface of the solar cell when the solar cells are connected in series and parallel, reduce the process threshold and cost, and improve the efficiency of solar cell circuit manufacturing.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to an interconnection sheet and a connection method for a solar cell. Background Art

[0002] Solar cells can directly convert solar energy into electricity and are widely used in various spacecraft. A single solar cell is not very useful, so a large number of them are typically connected in series or parallel to form a circuit. Solar cells typically have a negative electrode on the front (N-type) and a positive electrode on the back (P-type). Connectors (interconnect tabs) are used to connect these electrodes in series and parallel via resistance welding, or in series via a shingled system, where the positive electrode of solar cell A is pressed onto the negative electrode of solar cell B using conductive adhesive.

[0003] As a space application, it is subjected to repeated fatigue of high and low temperature cycles in a vacuum environment for a long time. Resistance welding is a more reliable connection method. The traditional series connection method is to connect the front interconnection sheet of the solar cell directly to the back of the next solar cell through resistance welding to form a battery string. Figure 1 The advantage of this is that there are fewer solder joints, and the connection between the two solar cells only involves two states: the interconnection sheet and the positive electrode of the solar cell, and the interconnection sheet and the negative electrode of the solar cell. The disadvantages are: ① The interconnection sheet requires a pre-formed stress relief ring, which is difficult to process and has high cost; ② The cells must be connected in series first to form a battery string before subsequent assembly. In addition, the area of the solar cell continues to increase, the assembly process is complicated, and the process implementation is becoming more and more difficult; ② Parallel connection requires connection through dedicated wires or silver ribbons, the process is cumbersome, and the wires or silver ribbons occupy a certain area that can be laid out.

[0004] A search revealed a Chinese invention patent with publication number CN111900225, which discloses a space solar cell array interconnection structure. This series structure provides both planar and rotational stress reduction, improving the reliability of solar cell interconnections and possessing significant value for the application and promotion of solar cell arrays in space. However, the aforementioned solution also has the following shortcomings: it only forms a series connection, not a parallel connection; the solar cells are sequentially connected through the cell body and interconnection components, resulting in a large number of connection links; the spacing between solar cells is large; the interconnection components are complex, making installation difficult and costly; and the interconnection components have limited space for interaction, making the weldable area difficult to control and making the process difficult to implement. Summary of the Invention

[0005] The object of the present invention is to provide an interconnection sheet and a connection method for solar cells to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: An interconnection strip for a solar cell, comprising a strip body, the strip body is in a "zhi" - shaped planar structure and made of pure silver or kovar alloy plated with silver, the thickness of the strip body is 30μm ± 5μm, the strip body is divided into a butt - welding area, a bending area and a parallel - welding area, the bending area is located between the parallel - welding area and the butt - welding area, the parallel - welding area is used for welding with the solar cell, and the butt - welding area is used for welding the opposite strip bodies.

[0007] Preferably, the bending area and the parallel - welding area are formed by opening a plurality of notches extending from the side edge inward, the strip body is a left - right symmetric structure, and the direction of the notch in the bending area is perpendicular to the direction of the notch in the parallel - welding area.

[0008] The present invention also provides a connection method for a solar cell, using the above - mentioned interconnection strip for a solar cell. The interconnection strip is welded on the solar cell, and the solar cell after welding the interconnection strip is bonded to the substrate and the distance between adjacent two solar cells is maintained at 1 - 2mm. The interconnection strips on the opposite two sides of adjacent two solar cells are welded in the butt - welding area, and the two butt - welded interconnection strips are bent upward in the bending area and form a connection structure in the shape of two hands clasping.

[0009] Compared with the prior art, the beneficial effects of the present invention are as follows: The interconnection strip of the present invention is in a "zhi" shape, and the connection method can omit the series - welding, whole - string transfer and whole - string pasting of solar cells, and can also omit the parallel connection through bus bars, greatly simplifying the process of solar cell assembly, saving the available chip area, significantly improving the production efficiency and reducing the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is the connection mode of solar cells in the prior art;

[0011] Figure 2 is the front - view structural schematic diagram of the interconnection strip of the present invention;

[0012] Figure 3 is the three - dimensional structural schematic diagram of the interconnection strip of the present invention;

[0013] Figure 4 is the welding schematic diagram of the interconnection strip of the present invention on the solar cell;

[0014] Figure 5 is the schematic diagram of the interconnection strip of the present invention connecting solar cells. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0015] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0016] Please refer to Figure 2-5 , the present invention provides a technical solution: an interconnection strip for a solar cell, including a strip body. The strip body is a "zhi" - shaped planar structure and is made of pure silver or kovar alloy plated with silver. The thickness of the strip body is 30μm ± 5μm, the width is 6.5mm ± 5mm, and the length is 5mm to 10m. The strip body is divided into a butt - welding area 1, a bending area 2, and a parallel - welding area 3. The bending area 2 is located between the parallel - welding area 3 and the butt - welding area 1. The parallel - welding area 3 is used for welding with the positive or negative electrode of the solar cell, and the butt - welding area 1 is used for welding the opposite strip bodies. The bending area 2 and the parallel - welding area 3 are formed by opening a plurality of notches extending from the side edge inward. The strip body is a left - right symmetric structure, and the direction of the notches in the bending area 2 is perpendicular to the direction of the notches in the parallel - welding area 3.

[0017] The present invention also discloses a connection method for a solar cell. For the above - mentioned interconnection strip of a solar cell, the interconnection strip is welded on the solar cell using a tight - resistance butt - welding device. The solar cell uses a gallium arsenide solar cell or a silicon solar cell. After welding the interconnection strip, the solar cell is bonded to the substrate and the distance between adjacent two solar cells is maintained at 1 - 2mm. The interconnection strips on the opposite sides of adjacent two solar cells are welded in the butt - welding area 1. The two butt - welded interconnection strips are bent upward in the bending area 2 to form a connection structure in the shape of two hands clasping. After welding, a stress - reducing arc is formed at a specific position in the bending area 2, which can withstand a displacement of ±0.05mm for more than 100,000 cycles of fatigue, ensuring the long - term stable operation of the solar cell in the space environment. The tops of the two relatively - welded interconnection strips are horizontally aligned and form a tip. The distance from the top surface of the two relatively - welded interconnection strips to the solar cell does not exceed 5mm. After welding the interconnection strip, the solar cell is covered by bonding a glass cover plate on the front. The battery module formed by the above method only needs to lead out the positive and negative electrodes of the whole with a small amount of wires, greatly simplifying the assembly process of the solar cell and improving the production efficiency.

[0018] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A solar cell interconnection sheet, comprising a sheet body, characterized in that: The sheet body is a planar structure in the shape of "zhi" and is made of pure silver or kovar alloy plated with silver. The thickness of the sheet body is 30μm ± 5μm. The sheet body is divided into a butt-welding area (1), a bending area (2), and a parallel welding area (3). The bending area (2) is located between the parallel welding area (3) and the butt-welding area (1). The parallel welding area (3) is used for welding with the solar cell, and the butt-welding area (1) is used for welding the opposite sheet bodies. The bending area (2) and the parallel welding area (3) are formed by opening a plurality of notches extending from the side edge inward. The sheet body is a left-right symmetric structure, and the direction of the notch in the bending area (2) is perpendicular to the direction of the notch in the parallel welding area (3).

2. A method for connecting solar cells, using the solar cell interconnection sheet of claim 1, characterized in that: The interconnection strips are welded on the solar cells. After the interconnection strips are welded, the solar cells are bonded to the substrate and the distance between adjacent two solar cells is maintained at 1 - 2mm. The interconnection strips on the opposite sides of adjacent two solar cells are welded in the butt-welding area (1), so that adjacent two solar cells form a series-parallel connection. The two butt-welded interconnection strips are bent upward in the bending area (2) to form a connection structure in the shape of two hands clasping each other.

3. The solar cell connection method according to claim 2, wherein: After two opposite interconnection strips are welded, the distance from the top surface of the welded part to the solar cell does not exceed 5mm.

4. A solar cell connection method according to claim 3, characterized in that: After the interconnection strips are welded on the solar cells, the glass cover plate is adhesively bonded to the front surface to achieve coverage.

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