Novel welding strip for back contact solar cell and solar cell module

Abstract

The utility model provides a novel solder strip for a back contact solar cell and a solar cell module, the novel solder strip comprises a conductive base material, and first coatings and second coatings arranged on the conductive base material, the first coatings and the second coatings are alternately distributed along the length direction of the conductive base material; the thermal expansion coefficient of the material of the first coating is greater than that of the battery piece to be subjected to series welding; and the thermal expansion coefficient of the material of the second coating is smaller than that of the battery piece to be subjected to series welding. According to the utility model, the welding strip with the first coatings with larger thermal expansion coefficients and the second coatings with smaller thermal expansion coefficients distributed alternately at intervals is used for series welding of the back contact battery, so that the welding strip respectively forms upward and downward pulling forces on the battery piece at different parts of the battery piece, the upward and downward pulling forces offset each other, the warping and deformation of the battery piece are reduced, and the service life of the battery piece is prolonged. Therefore, the production yield and the outdoor reliability of the photovoltaic module are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of photovoltaic components, in particular to a novel welding strip for back contact solar cells and a solar cell component. Background Art

[0002] Crystalline silicon solar cells dominate the field of photovoltaic power generation. Compared with other types of commercial cells, crystalline silicon solar cells have higher conversion efficiency. High-conversion-efficiency back-contact cells and back-contact modules are the main development trend of crystalline silicon photovoltaic modules. Reducing the shading of the front grid lines of the cells and the welding of the front conductive ribbons is the direction to improve the conversion efficiency of cells and modules.

[0003] There is no grid line on the front of the back contact cell, and the proportion of metal grid lines on the back is doubled. Therefore, in the context of reducing costs and increasing efficiency of photovoltaics, its thickness continues to decrease. At present, when preparing back contact components, tin-lead solder strips are usually used to weld the back contact cells together so as to connect multiple back contact cells together; then, the front plate, the adhesive film, the connected back contact cells and the back plate are laminated to obtain a back contact component. However, high temperature operation is required to weld the back contact cells and the solder strips together. Since the thermal expansion coefficient of the cell itself is smaller than that of the tin-lead solder strip, after the cell string is cooled after welding, the contraction of the solder strip is greater than the contraction of the cell itself, causing the solder strip to produce a tensile stress on the cell toward the middle of the cell. For conventional cells, solder strips are set on both the front and back sides of the cell, and the tensile stresses on the front and back cancel each other out, so that the cell basically does not deform. The back-contact battery only has a solder strip on the back, and the tension of the solder strip cannot be offset, which will cause the back-contact battery to deform and warp with a warping rate of 3%-5%, and then cause hidden cracks during subsequent lamination, affecting the production yield of the components. Utility Model Content

[0004] In view of the above-mentioned defects of the prior art, the purpose of the present invention is to provide a new type of solder strip and solar cell module for back-contact solar cells, so as to solve the problem of deformation and warping of back-contact cell series welding.

[0005] The utility model provides the following technical solutions:

[0006] On the one hand, a new type of solder strip for back-contact solar cells is provided, comprising a conductive substrate and a first coating and a second coating arranged on the conductive substrate, wherein the first coating and the second coating are alternately distributed along the length direction of the conductive substrate; the thermal expansion coefficient of the material of the first coating is greater than the thermal expansion coefficient of the battery cell to be soldered in series; the thermal expansion coefficient of the material of the second coating is less than the thermal expansion coefficient of the battery cell to be soldered in series.

[0007] Furthermore, the thickness of the first coating layer is the same as that of the second coating layer.

[0008] Furthermore, the thickness of the first coating layer and the second coating layer are both 0.01-0.03 mm.

[0009] Furthermore, the lengths of adjacent first coating layers and second coating layers are equal.

[0010] Furthermore, the conductive substrate is a copper substrate, and the diameter of the copper substrate is 0.18-0.35 mm.

[0011] Furthermore, the material of the first coating is tin-lead alloy, tin-lead-bismuth alloy or tin-lead-silver alloy.

[0012] Furthermore, the material of the second coating layer is an antimony-containing alloy.

[0013] Furthermore, the antimony-containing alloy is any one of tin-antimony alloy, tin-lead-antimony alloy, tin-antimony-silver alloy, and tin-lead-antimony-bismuth alloy.

[0014] On the other hand, a solar cell assembly is provided, comprising the solar cell sheets to be serially welded and any one of the aforementioned welding strips, wherein the welding strips serially weld a plurality of the solar cells.

[0015] Furthermore, on the same cell sheet of the solar cell assembly, perpendicular to the extension direction of the welding strip, the first coating layer and the second coating layer of different welding strips are alternately distributed.

[0016] The beneficial effects of the utility model are:

[0017] The utility model arranges a first coating with a larger thermal expansion coefficient and a second coating with a smaller thermal expansion coefficient alternately and at intervals on a conductive substrate of a welding strip, and uses the welding strip to connect a plurality of battery cells in series, the welding strip is laid on the back of each battery cell in a straight line direction, and the first coating and the second coating of different welding strips on the same battery cell are alternately and at intervals, the welding strip forms an upward and downward pulling force on the battery cell at different parts of the battery cell, so that the two forces offset each other, reduce the warping and deformation of the battery cell, and thus improve the production yield and outdoor reliability of the solar cell module. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A top view of a welding strip in an embodiment of the utility model;

[0019] Figure 2 This is a cross-sectional view of the first coating layer of the welding strip in the embodiment of the utility model;

[0020] Figure 3 This is a cross-sectional view of the second coating layer of the welding strip in the embodiment of the utility model;

[0021] Figure 4 A schematic diagram of a solar cell assembly in an embodiment of the utility model;

[0022] Figure 5 A schematic diagram of welding stress of a series-welded battery cell from a top view according to an embodiment of the utility model;

[0023] Figure 6 In the embodiment of the utility model Figure 5 AA cross-section diagram of .

[0024] Explanation of the reference numerals: 1. Conductive substrate; 2. First coating layer; 3. Second coating layer; 4. Battery cell to be serially soldered. DETAILED DESCRIPTION

[0025] The following is a detailed description of the embodiments of the present invention. The following embodiments are implemented on the premise of the technical solution of the present invention, and provide detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to the following embodiments.

[0026] Example

[0027] Reference Figure 1 to Figure 3 In order to solve the shortcomings of the prior art, the embodiment of the utility model provides a new type of solder strip for back-contact solar cells, including a conductive substrate 1 and a first coating 2 and a second coating 3 arranged on the conductive substrate 1, the first coating 2 and the second coating 3 are alternately distributed along the substrate direction; the thermal expansion coefficient of the material of the first coating 2 is greater than the thermal expansion coefficient of the battery cell 4 to be soldered in series; the thermal expansion coefficient of the material of the second coating 3 is less than the thermal expansion coefficient of the battery cell 4 to be soldered in series.

[0028] By alternately distributing two coating materials with different thermal expansion coefficients on the conductive substrate of the welding strip, after the battery string is cooled after welding, the first coating 2 area will produce tensile stress on the battery cell 4 because its thermal expansion coefficient is greater than the thermal expansion coefficient of the battery cell 4 in series, while the second coating 3 area will produce tensile stress because its thermal expansion coefficient is less than the thermal expansion coefficient of the battery cell 4 in series. After welding, a single battery cell 4 is subjected to tensile stress and tensile stress at the same time, such as Figure 5 and 6 As shown, the two offset each other, greatly reducing the warping and deformation of the battery cell.

[0029] The thickness of the first coating 2 and the second coating 3 are the same; the thickness of the first coating 2 and the second coating 3 are both 0.01-0.03 mm.

[0030] Preferably, the thickness of the first coating 2 and the second coating 3 is 0.02 mm;

[0031] When performing battery cell string welding, insufficient coating thickness of the welding ribbon will lead to poor welding effect; while too thick coating thickness will cause the overall size of the battery assembly to be too large; using welding ribbon with a coating thickness of 0.01-0.03mm for battery cell string welding has good welding effect and the quality of the formed battery assembly is high.

[0032] The first coating layer 2 and the second coating layer 3 have the same length.

[0033] The lengths of the first coating 2 and the second coating 3 are designed according to the length of the battery cell 4 to be soldered in series and the spacing between two adjacent battery cells; specifically, the sum of the lengths of the first coating 2 and the second coating 3 is the same as the sum of the length of the battery cell 4 to be soldered in series along the main grid direction and the spacing between two adjacent battery cells.

[0034] The conductive substrate 1 is a copper substrate, and the diameter of the copper substrate is 0.18-0.35 mm.

[0035] Preferably, the diameter of the copper substrate is 0.26 mm.

[0036] During string welding, if the size of the conductive substrate 1 is too large, it will cause large shading losses; if the size of the conductive substrate 1 is too small, it will lead to large resistance losses; using a welding ribbon with a conductive substrate 1 diameter of 0.18-0.35mm for string welding of battery cells has a good welding effect and the resulting battery assembly has high performance.

[0037] The material of the first coating layer 2 is tin-lead alloy, tin-lead-bismuth alloy or tin-lead-silver alloy.

[0038] Preferably, the tin-lead alloy is composed of 60-90% tin and 10-40% lead; the tin-lead-bismuth alloy is composed of 50-80% tin, 15-35% lead and 5-20% bismuth; the tin-lead-silver alloy is composed of 60-75% tin, 20-40% lead and 1-5% silver.

[0039] The material of the second coating layer 3 is an antimony-containing alloy. Since antimony has a negative thermal expansion coefficient at low temperatures, the antimony-containing alloy is selected as the material of the second coating layer 3.

[0040] The antimony-containing alloy is any one of tin-antimony alloy, tin-lead-antimony alloy, tin-antimony-silver alloy, and tin-lead-antimony-bismuth alloy.

[0041] Preferably, the tin-antimony alloy is composed of 60-90% tin and 10-40% antimony; the tin-lead-antimony alloy is composed of 50-80% tin, 15-35% lead and 5-20% antimony; the tin-antimony-silver alloy is composed of 60-90% tin, 9-40% antimony and 1-5% silver; the tin-lead-antimony-bismuth alloy is composed of 50-80% tin, 14-40% lead, 5-10% antimony and 1-5% bismuth.

[0042] Specifically, in the embodiment of the utility model, the soldering tape uses a tin-lead-bismuth alloy with a composition ratio of Sn57%, Pb30%, and Bi13% as the material of the first coating 2, and a tin-lead-silver alloy with a composition ratio of Sn77%, Sb20%, and Ag3% as the material of the second coating 3, and a copper substrate is used as the conductive substrate 1; the first coating 2 and the second coating 3 are alternately distributed along the direction of the copper substrate 1; the diameter of the copper substrate is 0.26mm; the thickness of the first coating 2 and the second coating 3 are both 0.02mm; the sum of the length of the battery cell to be soldered in series along the main grid direction and the spacing between two adjacent battery cells is 182mm, and the length of the first coating 2 and the second coating 3 is 91mm. Using this soldering tape to solder multiple battery cells in series to form a battery string can greatly reduce the warping and deformation of the battery cells, and can improve production efficiency and product yield.

[0043] Reference Figures 4 to 6 In an embodiment of the utility model, a solar cell assembly is also provided, comprising the cell sheet 4 to be serially welded and any one of the aforementioned welding strips, wherein the welding strips serially weld and connect a plurality of the cell sheets 4; on the same cell sheet, perpendicular to the extension direction of the welding strips, the first coating 2 and the second coating 3 of different strips of the welding strips are alternately distributed at intervals, so that the welding strips can form an upward and downward pulling force on the cell sheet at different parts of the cell sheet, and the two offset each other, reducing the warping and deformation of the cell sheet, thereby improving the production yield and outdoor reliability of the solar cell assembly.

[0044] Specifically, in the embodiment of the utility model, the aforementioned welding strip with the first coating 2 and the second coating 3 alternately distributed at intervals is used for the string welding of the battery cells, and multiple battery cells are arranged in a straight line, and the welding strip is laid on the back of each battery cell in the straight line direction; at the joint formed by adjacent battery cells, along the extension direction of the joint, the first coating 2 and the second coating 3 of different welding strips are alternately distributed at intervals; on the same battery cell, perpendicular to the extension direction of the welding strip, the first coating 2 and the second coating 3 of different welding strips are alternately distributed at intervals. When the welding is completed, the welding strip is automatically cut off by the string welding machine, and each section of the welding strip cut off includes a first coating 2 and a second coating 3 of equal length. After the battery cells are string welded to form a battery pack, they are laminated with glass through a lamination process, and then fixed with the frame to form a solar cell module. With reference to the solar cell module manufactured in this embodiment, the warpage before lamination can be within 2%, and the hidden crack rate after lamination can be reduced to within 5%, and the production yield of the solar cell module can be improved, which helps to improve the production capacity and quality of the solar cell module.

[0045] The preferred specific embodiments of the utility model are described in detail above. It should be understood that ordinary technicians in this field can make many modifications and changes based on the concept of the utility model without creative work. Therefore, all technical solutions that can be obtained by technicians in this technical field based on the concept of the utility model through logical analysis, reasoning or limited experiments on the basis of the existing technology should be within the scope of protection determined by the claims.

Claims

1. A novel solder strip for back contact solar cells, characterized in that: It comprises a conductive substrate and a first coating and a second coating disposed on the conductive substrate, wherein the first coating and the second coating are alternately distributed along the length direction of the conductive substrate; The thermal expansion coefficient of the material of the first coating is greater than the thermal expansion coefficient of the battery cell to be serially soldered; the thermal expansion coefficient of the material of the second coating is less than the thermal expansion coefficient of the battery cell to be serially soldered.

2. A novel solder strip for back contact solar cells according to claim 1, characterized in that: The first coating layer and the second coating layer have the same thickness.

3. A novel solder strip for back contact solar cells according to claim 2, characterized in that: The thickness of the first coating layer and the second coating layer are both 0.01-0.03 mm.

4. A novel solder strip for back contact solar cells according to claim 1, characterized in that: The lengths of adjacent first coating layers and adjacent second coating layers are equal.

5. The novel solder strip for back contact solar cells according to claim 1, characterized in that: The conductive substrate is a copper substrate, and the diameter of the copper substrate is 0.18-0.35 mm.

6. A novel solder strip for back contact solar cells according to claim 1, characterized in that: The material of the first coating layer is tin-lead alloy, tin-lead-bismuth alloy or tin-lead-silver alloy.

7. A novel solder strip for back contact solar cells according to claim 1, characterized in that: The material of the second coating layer is an antimony-containing alloy.

8. A novel solder strip for back contact solar cells according to claim 7, characterized in that: The antimony-containing alloy is any one of tin-antimony alloy, tin-lead-antimony alloy, tin-antimony-silver alloy, and tin-lead-antimony-bismuth alloy.

9. A solar cell module, characterized in that: include: The battery cells to be serially welded and the welding strip as described in any one of claims 1 to 8, wherein the welding strip connects a plurality of the battery cells in series by welding.

10. The solar cell assembly according to claim 9, characterized in that: On the same battery cell, perpendicular to the extending direction of the welding strip, the first coating layer and the second coating layer of different welding strips are alternately distributed.

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