Back contact cell assembly interconnection structure

Abstract

The application relates to the technical field of back contact battery assemblies, and particularly discloses a back contact battery assembly interconnection structure. The back contact battery assembly interconnection structure comprises a battery piece, a solder strip and a laminated package, the back surface of the battery piece is provided with a plurality of first main grids and first fine grids and second main grids and second fine grids, the two sides of the first main grids and the second main grids are provided with insulating adhesive layers, the insulating adhesive layers are respectively located at the two ends of the first fine grids and the second fine grids, the intersections of the first fine grids and the first main grids and the second main grids and the second fine grids are all printed with fine grid reinforcing layers, the first fine grids and the second fine grids which are not covered by the insulating adhesive layers are provided with tin paste layers, the tin paste layers are wrapped outside the fine grid reinforcing layers, one side of the solder strip close to the battery piece is provided with a positioning adhesive layer, and the solder strip is in contact with the tin paste layers through the positioning adhesive layer. The back contact battery assembly interconnection structure has the advantages that the stability of assembly welding is ensured, the warping problem is solved, the overwelding risk is reduced, and the finished product yield of the assembly is improved.

Description

Technical Field

[0001] This application relates to the technical field of back contact battery modules, and in particular to an interconnection structure for a back contact battery module. Background Technology

[0002] With the rapid development of photovoltaic technology, improving the photoelectric conversion efficiency of solar cells and reducing manufacturing costs have become core industry goals. Traditional crystalline silicon solar cells suffer from several drawbacks. The front electrode design involves metal grid lines that block incident light, reducing the effective light-receiving area. Furthermore, the contact area between the electrode and the silicon substrate is prone to carrier recombination, and the front and back electrodes require two printing / etching processes, increasing the number of steps. Back-contact solar cells, by moving both the positive and negative electrodes to the back of the cell, solve these problems and have become an important direction for high-efficiency photovoltaic technology.

[0003] Currently, back-contact battery module interconnection mainly employs thermal welding technology. When applied to back-contact batteries, traditional thermal welding technology is prone to over-welding during the welding process because both the positive and negative electrodes are located on the back of the cell, leading to a decrease in module yield. Furthermore, the excessively high instantaneous temperature caused by unilateral welding results in severe cell warping, affecting module reliability and lifespan.

[0004] In the prior art, CN119300523A discloses an interconnection method for a gridless back-contact battery assembly. This method includes printing insulating adhesive on the fine grid lines of the positive or negative electrode, drying it, printing conductive adhesive on the uninsulated grid lines, and then applying solder ribbons followed by curing and lamination. While this method simplifies the process, it still requires multiple drying processes, and the conductivity of the conductive adhesive is somewhat inferior to that of solder paste.

[0005] CN117995921A describes a gridless back-contact photovoltaic module that interconnects solar cells by interleaving solder paste dots and insulating adhesive dots on the fine grid lines of the positive and negative electrodes and laying interconnecting lines. While this method is applicable to gridless back-contact cells, it requires high precision in the placement and printing of the solder paste dots, making production difficult.

[0006] CN118073441A discloses a method for fabricating a gridless solar cell string, in which solder ribbons are directly laid without drying and curing after the solder paste layer is printed to avoid warping of the solar cells during the drying process. However, this method may result in uneven solder paste distribution, affecting the soldering quality.

[0007] The aforementioned technologies have the following shortcomings: the back-contact battery module interconnection structure of these technologies makes it difficult to guarantee the stability and warping of the module welding, which can easily lead to over-welding and reduce the yield of the finished module. Utility Model Content

[0008] In this application, the first main gate and the second main gate represent the positive main gate and the negative main gate, respectively. The first fine gate that intersects with the first main gate is the positive fine gate, and the second fine gate that intersects with the second main gate is the negative fine gate.

[0009] To ensure the stability of component welding, solve the warping problem, reduce the risk of over-welding, and improve the yield of finished components, this application provides a back contact battery module interconnection structure.

[0010] A back-contact battery module interconnection structure includes a battery cell, solder ribbon, and a laminated encapsulation body. The back of the battery cell has a first main grid and a first fine grid that are perpendicular and intersecting each other, as well as a second main grid and a second fine grid that are perpendicular and intersecting each other. The first main grid and the second main grid are parallel. Insulating adhesive layers are provided on both sides of the first main grid and the second main grid, and the insulating adhesive layers are respectively located at the two ends of the first fine grid and the second fine grid. Fine grid reinforcement layers are printed at the intersection of the first fine grid and the first main grid, as well as on the second main grid and the second fine grid. Solder paste layers are provided on the first fine grid and the second fine grid that are not covered by the insulating adhesive layers. The solder paste layers wrap around the outside of the fine grid reinforcement layers. The side of the solder ribbon closest to the battery cell has a positioning adhesive layer, and the positioning adhesive layer is located at both ends of the first main grid and the second main grid. The solder ribbon contacts the solder paste layer through the positioning adhesive layer.

[0011] By adopting the above technical solution, solder paste is directly printed on the fine gate reinforcement layer and forms an alloyed connection with the fine gate reinforcement layer, preventing over-soldering.

[0012] Optionally, the silver content of the fine grid reinforcement layer is ≥85%.

[0013] Optionally, the thickness of the insulating adhesive layer is ≥35μm, the width of the insulating adhesive layer is not less than the grid line width of the fine grid, and the resistivity of the insulating adhesive layer is ≥1×10¹³Ω·cm.

[0014] By adopting the above technical solution, the positive and negative grid lines are physically isolated by high-resistance insulating adhesive (≥10¹³Ω·cm), thus eliminating the risk of short circuits during the lamination process.

[0015] Optionally, the overlap area between the solder paste layer and the fine gate reinforcement area is 50%-90%, the thickness of the solder paste layer is not less than the thickness of the insulating adhesive layer, and the resistivity of the solder paste layer is ≤ .

[0016] By adopting the above technical solution, the solder paste layer is directly printed on the gate line reinforcement layer with a high silver content (≥85%) and the overlap area is 50-90%, which greatly reduces the series resistance and reduces the risk of over-soldering.

[0017] Optionally, the width of the positioning adhesive layer is 1.5-2 times the width of the solder strip, and the positioning adhesive layer completely covers the solder strip.

[0018] By adopting the above technical solution, the positioning adhesive can accurately control the position of the solder strip, avoid over-soldering or incomplete soldering caused by solder strip misalignment, and improve the yield.

[0019] Optionally, the centerline of the solder ribbon coincides with the centerline of the positioning adhesive layer, and the solder ribbon forms an alloyed connection with the solder paste layer through low-temperature lamination.

[0020] By adopting the above technical solution, the solder ribbon forms an alloyed connection with the solder paste layer through low-temperature lamination, which helps to reduce the warpage of the battery cell.

[0021] Optionally, the temperature of the low-temperature lamination is 125-150℃.

[0022] By adopting the above technical solution, the problem of warping during hot welding can be solved under the low-temperature lamination welding process of 125-150℃.

[0023] Optionally, the silver content of the paste for the first and second main gates is 80-85%, and the silver content of the paste for the first and second fine gates is ≥85%.

[0024] In summary, this application has the following beneficial effects:

[0025] 1. The positive and negative grid lines are physically isolated by a high-resistance insulating adhesive layer (≥10¹³Ω·cm), eliminating the risk of short circuits during the lamination process.

[0026] 2. Solder paste is directly printed on the gate reinforcement area with high silver content (≥85%), with an overlap area of ​​50-90%, which greatly reduces series resistance and reduces the risk of over-soldering.

[0027] 3. Solve the problem of warping during hot welding using a low-temperature lamination welding process. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the interconnection structure between the back contact cell and the solder ribbon in Embodiment 1 of this application.

[0029] Figure 2 This is a partially enlarged view of the back contact cell and solder strip in Embodiment 1 of this application.

[0030] Figure 3 This is a cross-sectional view of the battery cell and solder strip in Embodiment 1 of this application.

[0031] Figure 4 This is a cross-sectional view of the battery cell and solder ribbon of Comparative Example 1 of this application.

[0032] Figure 5 This is a cross-sectional view of the battery cell and solder strip of Comparative Example 2 of this application.

[0033] Figure 6This is a cross-sectional view of the battery cell and solder ribbon of Comparative Example 3 of this application.

[0034] Explanation of reference numerals in the attached diagram: 1. Solar cell; 2. Solder ribbon; 3. First main busbar; 4. Second main busbar; 5. First fine grid; 6. Second fine grid; 7. Insulating adhesive layer; 8. Fine grid reinforcement layer; 9. Solder paste layer; 10. Positioning adhesive layer; 11. PAD point. Detailed Implementation

[0035] The following is in conjunction with the appendix Figure 1-6 This application will be described in further detail.

[0036] This application discloses a back-contact battery assembly interconnection structure.

[0037] Example 1

[0038] Reference Figures 1-3 A back-contact battery module interconnection structure includes a battery cell 1, a solder ribbon 2, and a laminated encapsulation body (not shown in the figure). A plurality of first main grids 3 and second main grids 4 are alternately arranged on the back side of the battery cell 1. The first main grids 3 and the second main grids 4 are vertically arranged and parallel to each other. A plurality of first fine grids 5 are vertically fixed on each of the first main grids 3 at intervals. A plurality of second fine grids 6 are vertically fixed on each of the second main grids 4 at intervals. The first fine grids 5 and the second fine grids 6 are alternately arranged and parallel to each other.

[0039] Insulating adhesive layers 7 are provided on both sides of the first main grid 3 and the second main grid 4, and the insulating adhesive layers 7 are printed at both ends of the first fine grid 5 and the second fine grid 6 respectively. The insulating adhesive layers 7 maintain a certain interval with the first main grid 3 and the second main grid 4, and the insulating adhesive layers 7 play a limiting role for the solder strip 2. Fine grid reinforcing layers 8 are printed on both the first fine grid 5 and the second fine grid 6. The fine grid reinforcing layers 8 are located at the intersection of the first fine grid 5 and the first main grid 3 and at the intersection of the second fine grid 6 and the second main grid 4, and the contact area between the fine grid reinforcing layers 8 and the first fine grid 5 and the second fine grid 4 is larger than the contact area between the fine grid reinforcing layers and the first main grid 3 and the second main grid 4.

[0040] The outer side of the fine grid reinforcement layer 8 is covered with a solder paste layer 9, which is located at the position where the insulating adhesive is not printed on the first fine grid 5 or the second fine grid 6. Positioning adhesive layers 10 are printed at both ends of the first main grid 3 and the second main grid 4, and the solder ribbon 2 is fixed to the solder paste layer 9 through the positioning adhesive layers 10. The overlap area between the solder paste layer 9 and the fine grid reinforcement area is 50%-90%, the size of the solder paste layer 9 is 0.6*1.2mm, the thickness of the solder paste layer 9 is not less than the thickness of the insulating adhesive layer 7, and the resistivity of the solder paste layer 9 is ≤ .

[0041] The silver content of the paste used for printing the first main grid 3 and the second main grid 4 is 80-85%, and the silver content of the paste used for printing the first fine grid 5 and the second fine grid 6 is ≥85%. The silver content of the fine grid reinforcing layer 8 is not less than 85%. The thickness of the insulating adhesive layer 7 is 35μm, the width of the insulating adhesive layer 7 is not less than the grid line width of the first fine grid 5 and the second fine grid 6, and the resistivity of the insulating adhesive layer 7 is 1×10¹³Ω·cm.

[0042] The positioning adhesive layer 10 is evenly distributed along the length of the solder strip 2, and its width is 1.5-2 times the width of the solder strip 2. The positioning adhesive layer 10 completely covers the solder strip 2. The centerline of the solder strip 2 coincides with the centerline of the positioning adhesive layer 10. The solder strip 2 forms an alloy bond with the solder paste layer 9 through low-temperature lamination. The lamination parameters are as follows: first, the solder strip is initially melted by lamination at 150°C for 10 minutes; then, a vacuum is applied, and lamination is performed at 150°C for 10 minutes to achieve curing.

[0043] The implementation principle of the back contact battery module interconnection structure in this application embodiment is as follows: By directly printing the solder paste layer 9 onto the fine grid reinforcement layer 8, the solder paste and the high silver content fine grid reinforcement layer 8 paste are in direct contact, and an alloy contact is formed by low temperature lamination. The solder ribbon 2 is in contact with the solder paste layer 9 through the positioning adhesive layer 10 to form an interconnection structure, which ensures the stability of module welding, solves the warping problem, reduces the risk of over-soldering, and improves the yield of module finished products.

[0044] Comparative Example 1

[0045] Reference Figure 4 A back-contact battery assembly interconnection structure differs from Embodiment 1 in that PAD points 11 are provided at the intersection of the first main grid 3 and the first fine grid 5, and at the intersection of the second main grid 4 and the second fine grid 6. A solder paste layer 9 is printed on the outside of the PAD points 11. The size of the solder paste layer 9 is 0.7*0.7mm. The solder strip 2 is directly soldered on the outside of the solder paste layer 9 by infrared thermal soldering at a temperature of 200-250℃. In this embodiment, the temperature is 200℃, thus forming an interconnection structure.

[0046] Comparative Example 2

[0047] Reference Figure 5A back-contact battery assembly interconnection structure differs from Embodiment 1 in that PAD points 11 are provided at the intersection of the first main gate 3 and the first fine gate 5, and at the intersection of the second main gate 4 and the second fine gate 6. A solder paste layer 9, measuring 0.7*0.7mm, is printed on the outside of the PAD points 11. A low-temperature solder ribbon 2 is provided on the outside of the solder paste layer 9, with its length parallel to the length directions of the first main gate 3 and the second main gate 4. A low-temperature lamination method is used, with lamination parameters as follows: first lamination at 125°C for 10 minutes, followed by vacuum lamination at 150°C for 10 minutes. The solder ribbon 2 is directly fixed to the outside of the solder paste layer 9 to form the interconnection structure.

[0048] Comparative Example 3

[0049] Reference Figure 6 A back-contact battery assembly interconnection structure differs from Embodiment 1 in that PAD points 11 are provided at the intersection of the first main gate 3 and the first fine gate 5, and at the intersection of the second main gate 4 and the second fine gate 6. A fine gate reinforcement layer 8 is printed on the outside of the PAD points 11. The fine gate reinforcement layer 8 only covers the outside of the first main gate 3 and the second main gate 4, and does not overlap with the first fine gate 5 and the second fine gate 6. A solder paste layer 9 is printed on the outside of the fine gate reinforcement layer 8. The size of the solder paste layer 9 is 0.7*0.7mm. A low-temperature solder ribbon 2 is provided on the outside of the solder paste layer 9. The solder ribbon 2 is fixed to the outside of the solder paste layer 9 by low-temperature soldering. The lamination parameters are: first lamination at 125°C for 10 minutes, then vacuum lamination at 150°C for 10 minutes to form an interconnection structure.

[0050] Performance testing experiment

[0051] 1. Testing of weld strip tension, over-welding ratio, and alloy condition.

[0052] Eight groups of interconnect structures from Example 1 and Comparative Examples 1-3 were tested in parallel, and the solder strip tension, over-soldering ratio, and alloy condition were tested respectively. The test results are shown in Table 1.

[0053] Table 1. Test results of the cell interconnection structure in Example 1 and Comparative Examples 1-3

[0054]

[0055] Combining Example 1 and Comparative Examples 1-3 with Table 1, it can be seen that the tensile test results, over-soldering ratio, and alloy condition ratio of the cell interconnect structure in Example 1 can all achieve better levels. However, Comparative Examples 1-3 cannot simultaneously meet the above parameters to achieve better levels. Therefore, Example 1 of this application can simultaneously meet the welding stability of the cell interconnect structure, solve the warping problem, reduce the risk of over-soldering, and improve the yield of the finished module.

[0056] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A back-contact battery module interconnection structure, comprising battery cells (1), solder ribbons (2), and a laminated encapsulation body, characterized in that: The back of the battery cell (1) has several mutually perpendicular and intersecting first main grids (3) and first fine grids (5), as well as mutually perpendicular and intersecting second main grids (4) and second fine grids (6). The first main grids (3) and second main grids (4) are parallel. Insulating adhesive layers (7) are provided on both sides of the first main grids (3) and second main grids (4), and the insulating adhesive layers (7) are located at the two ends of the first fine grids (5) and second fine grids (6), respectively. The intersection of the first fine grids (5) and the first main grids (3) and the second main grids (6) are also located at the intersection of the first fine grids (5) and the first main grids (3). A fine grid reinforcement layer (8) is printed on both the grid (4) and the second fine grid (6). A solder paste layer (9) is provided on both the first fine grid (5) and the second fine grid (6) which are not covered by the insulating adhesive layer (7). The solder paste layer (9) is wrapped around the outside of the fine grid reinforcement layer (8). A positioning adhesive layer (10) is provided on the side of the solder ribbon (2) near the battery cell (1). The positioning adhesive layer (10) is located at both ends of the first main grid (3) and the second main grid (4). The solder ribbon (2) contacts the solder paste layer (9) through the positioning adhesive layer (10).

2. The back-contact battery assembly interconnection structure according to claim 1, characterized in that: The thickness of the insulating adhesive layer (7) is ≥35μm, the width of the insulating adhesive layer (7) is not less than the grid line width of the first fine grid (5) or the second fine grid (6), and the resistivity of the insulating adhesive layer (7) is ≥1×10¹³Ω·cm.

3. The back contact battery assembly interconnection structure according to claim 1, characterized in that: The overlap area between the solder paste layer (9) and the fine grid reinforcement area is 50%-90%, the thickness of the solder paste layer (9) is not less than the thickness of the insulating adhesive layer (7), and the resistivity of the solder paste layer (9) is ≤11.4×10⁻¹. 0 Ω·m.

4. The back-contact battery assembly interconnection structure according to claim 1, characterized in that: The width of the positioning adhesive layer (10) is 1.5-2 times the width of the solder strip (2), and the positioning adhesive layer (10) completely covers the solder strip (2).

5. The back-contact battery assembly interconnection structure according to claim 1, characterized in that: The centerline of the solder strip (2) coincides with the center of the positioning adhesive layer (10), and the solder strip (2) forms an alloyed connection with the solder paste layer (9) by low-temperature lamination.

6. The back-contact battery assembly interconnection structure according to claim 5, characterized in that: The temperature of the low-temperature lamination is 125-150℃.

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