Preparation method of photovoltaic welding strip, photovoltaic welding strip and photovoltaic cell

Abstract

The embodiment of the invention provides a preparation method of a photovoltaic welding strip, the photovoltaic welding strip and a photovoltaic cell, and the method comprises the steps: applying a first solder covering a welding strip substrate in a PAD point welding region, and applying a second solder covering the welding strip substrate in an auxiliary grid welding region, so that the PAD point welding region can correspond to the position of a PAD point on a cell piece, and the welding efficiency is improved. And the auxiliary grid welding area can correspond to the position of an auxiliary grid on the battery piece, so that when the photovoltaic welding strip is used for welding the battery piece, each PAD point is connected with the first welding flux, and each auxiliary grid is connected with the second welding flux, so that the welding tension on the PAD points can be improved, and the welding quality of the battery piece is improved. And the tin stacking degree when the auxiliary grid welding point is welded with the second welding flux can be reduced, so that the grid breaking risk in the welding process is reduced.

Description

Technical Field

[0001] The present invention mainly relates to the field of photovoltaic technology, and in particular to a method for preparing a photovoltaic welding ribbon, a photovoltaic welding ribbon and a photovoltaic cell. Background Art

[0002] When welding a busbar-less battery module, the welding ribbon is pressed tightly against the PAD point and the auxiliary grid, and a high-power lamp is used to continuously heat the welding. The thermal conductivity of the slurry used in the auxiliary grid is lower than that used in the PAD point, and the grid is prone to breakage during the welding process, making welding more difficult. Summary of the invention

[0003] The object of the present invention is to provide a method for preparing a photovoltaic welding strip, a photovoltaic welding strip and a photovoltaic cell, so as to reduce the risk of grid breakage during welding.

[0004] To achieve the above-mentioned objectives, in a first aspect, the present application provides a method for preparing a photovoltaic welding strip, comprising: preparing a welding strip substrate, setting a PAD point welding area and a sub-grid welding area on the welding strip substrate; applying a first solder covering the welding strip substrate to the PAD point welding area; and applying a second solder covering the welding strip substrate to the sub-grid welding area, wherein the melting point of the first solder is higher than the melting point of the second solder.

[0005] In some embodiments, the PAD spot welding area and the auxiliary grid welding area are arranged at intervals along the length direction of the welding ribbon substrate.

[0006] In some embodiments, the length of each secondary grid welding region is greater than the length of the adjacent PAD spot welding region.

[0007] In some embodiments, the first solder and the second solder are both tin-lead-bismuth alloys.

[0008] In some embodiments, the bismuth content of the first solder is less than the bismuth content of the second solder.

[0009] In a second aspect, the present application provides a photovoltaic welding strip, comprising: a welding strip substrate, on which a PAD point welding area and a secondary grid welding area are provided; the PAD point welding area comprises a first solder covering the welding strip substrate; the secondary grid welding area comprises a second solder covering the welding strip substrate, wherein the melting point of the first solder is higher than the melting point of the second solder.

[0010] In some embodiments, the PAD spot welding area and the auxiliary grid welding area are arranged at intervals along the length direction of the welding ribbon substrate.

[0011] In some embodiments, the length of each secondary grid welding region is greater than the length of the adjacent PAD spot welding region.

[0012] In some embodiments, the first solder and the second solder are both tin-lead-bismuth alloys.

[0013] In some embodiments, the bismuth content of the first solder is less than the bismuth content of the second solder.

[0014] In a third aspect, the present application provides a photovoltaic cell, comprising the photovoltaic welding ribbon as described in any one of the first aspects above.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] The embodiments of the present application provide a method for preparing a photovoltaic welding strip, a photovoltaic welding strip and a photovoltaic cell. By applying a first solder covering the welding strip substrate in the PAD point welding area and applying a second solder covering the welding strip substrate in the sub-grid welding area, the PAD point welding area can correspond to the position of the PAD point on the battery cell, and the sub-grid welding area can correspond to the position of the sub-grid on the battery cell. In this way, when the photovoltaic welding strip is welded to the battery cell, by connecting each PAD point to the first solder and each sub-grid to the second solder, the welding tension on the PAD point can be increased, and the degree of tin accumulation when the sub-grid welding point is welded to the second solder can be reduced, thereby reducing the risk of grid breakage during welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are included to provide a further understanding of the present application. They are included and constitute a part of the present application. The accompanying drawings illustrate embodiments of the present application and together with the present specification serve to explain the principles of the present application. In the accompanying drawings:

[0018] Figure 1 It is a flow chart of a method for preparing a photovoltaic welding ribbon provided in an embodiment of the present application;

[0019] Figure 2 is a schematic diagram of a photovoltaic welding ribbon provided in an embodiment of the present application;

[0020] Figure 3 is a schematic diagram of a battery cell provided in an embodiment of the present application;

[0021] Figure 4 It is a schematic diagram of welding between a photovoltaic welding ribbon and a solar cell provided in an embodiment of the present application;

[0022] Figure 5 It is a schematic diagram of a photovoltaic cell provided in an embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for the description of the embodiments. Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. Unless it is obvious from the language environment or otherwise explained, the same reference numerals in the figures represent the same structure or operation.

[0024] As shown in this application and claims, unless the context clearly indicates an exception, the words "a", "an", "an" and / or "the" do not refer to the singular and may also include the plural. Generally speaking, the terms "include" and "comprise" only indicate the inclusion of the steps and elements that have been clearly identified, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.

[0025] In addition, it should be noted that the use of words such as "first" and "second" to define components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above words have no special meaning and cannot be understood as limiting the scope of protection of this application. In addition, although the terms used in this application are selected from well-known and commonly used terms, some terms mentioned in the specification of this application may be selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant parts of the description of this article. In addition, it is required to understand this application not only by the actual terms used, but also by the meaning implied by each term.

[0026] Figure 1 A flow chart of a method for preparing a photovoltaic ribbon provided in an embodiment of the present application. Figure 1 , specifically including the following steps:

[0027] S1, prepare a solder strip substrate, and set a PAD spot welding area and a secondary grid welding area on the solder strip substrate.

[0028] S2, applying a first solder covering the solder strip base at the PAD spot soldering area.

[0029] S3, applying a second solder covering the solder strip base to the secondary grid soldering region, wherein the melting point of the first solder is higher than the melting point of the second solder.

[0030] In some embodiments, the solder ribbon substrate may be, for example, a copper wire.

[0031] In this embodiment, the PAD point welding area is used to correspond to the PAD point printed on the cell, and the secondary grid welding area of ​​the photovoltaic welding strip is used to correspond to the secondary grid printed on the cell. Generally speaking, the PAD of the cell can be printed by pure silver paste, and the secondary grid welding point is printed by silver-coated copper paste. The welding performance of pure silver paste is better than that of silver-coated copper paste, and the cost of silver-coated copper paste is lower than that of pure silver paste, which helps to meet the requirements of battery preparation.

[0032] When the photovoltaic welding ribbon is welded to the battery cell, each PAD point made of pure silver paste is connected to the first solder, and the sub-grid made of silver-clad copper paste is connected to the second solder. The melting point of the first solder is higher than that of the second solder. Therefore, compared with the welding ribbon prepared only with low-temperature solder, the tensile force of the welding point formed between the PAD point welding area and the PAD point is higher. Similarly, the melting point of the second solder is lower than that of the first solder. Therefore, compared with the welding ribbon prepared only with high-temperature solder, the degree of tin accumulation at the welding point formed between the sub-grid welding area and the sub-grid is reduced, thereby reducing the risk of grid breakage during welding.

[0033] In other words, the photovoltaic welding strip prepared by the above method can make the welding points formed between the PAD point welding area and each PAD point more tin-pile, thereby increasing the tension between the PAD point on the cell and the photovoltaic welding strip. Correspondingly, it can also reduce the degree of tin accumulation at the welding points formed between the auxiliary grid welding area and each auxiliary grid, thereby reducing the risk of grid breakage during welding.

[0034] In some embodiments, the PAD spot welding area and the auxiliary grid welding area are arranged at intervals along the length direction of the welding strip substrate. There may be one or more PAD spot welding areas, and one or more auxiliary grid welding areas, which are not limited.

[0035] In some embodiments, the first solder and the second solder are tin-lead-bismuth alloys. The first solder may also be a tin-lead alloy. The bismuth content of the first solder may be less than the bismuth content of the second solder, so that the melting point of the first solder is higher than that of the second solder, and the fluidity is better.

[0036] For example, some solder components and their corresponding melting points are listed in Table 1. Referring to Table 1, the tin-lead-bismuth alloy may include but is not limited to: Sn60Pb40, Sn53Pb37Bi10, Sn43Pb43Bi14, Sn40Pb42Bi18, Sn37Pb42Bi21, Sn37Pb37Bi26, Sn28.5Pb43Bi28.5, Sn25Pb38Bi37, and the like.

[0037] In the embodiment of the present application, one of the solder components listed in Table 1 can be selected as the first solder covering the PAD point welding area. Correspondingly, one of the remaining solder components listed in Table 1 with a lower melting point can be selected as the second solder covering the auxiliary grid welding area.

[0038] Solder components Melting point(℃) Sn60Pb40 183 Sn53Pb37Bi10 161-173 Sn43Pb43Bi14 136-167 Sn40Pb42Bi18 136-163 Sn37Pb42Bi21 136-158 Sn37Pb37Bi26 136-143 Sn28.5Pb43Bi28.5 93-146 Sn25Pb38Bi37 93-132

[0039] Table 1

[0040] For example, in step S2, Sn53Pb37Bi10 is used as the first solder to cover the solder strip substrate at the PAD point welding area, and in step S3, Sn43Pb43Bi14 is used as the second solder to cover the solder strip substrate at the auxiliary grid welding area. In this case, the difference between the melting point of the first solder and the melting point of the second solder is approximately 16-25°C. Comparing it with the solder strips prepared using only Sn53Pb37Bi10 and Sn43Pb43Bi14, it is found that the tensile force of the soldering point formed between the PAD point welding area and the PAD point is higher, and the degree of tin accumulation of the soldering point formed between the auxiliary grid welding area and the auxiliary grid is less, which reduces the risk of grid breakage during welding.

[0041] Figure 2 A schematic diagram of a photovoltaic ribbon 100 provided in an embodiment of the present application. Figure 2 The photovoltaic welding strip 100 includes a welding strip substrate 10, a PAD spot welding area 20 and a secondary grid welding area 30. The PAD spot welding area 20 and the secondary grid welding area 30 may be one or more, and a plurality of them are used as an example for explanation below.

[0042] In some embodiments, a plurality of PAD spot welding regions 20 and a plurality of auxiliary grid welding regions 30 are arranged at intervals along the length direction of the welding ribbon substrate 10. The length of each auxiliary grid welding region 30 is greater than the length of the adjacent PAD spot welding region 20.

[0043] refer to Figure 2 , the PAD point welding area 20 and the auxiliary grid welding area 30 are arranged at intervals along the length direction (x direction) of the welding strip substrate 10. The PAD point welding area 20 is roughly arranged in the middle part and the left and right ends of the welding strip substrate 10, and the auxiliary grid welding area 30 is roughly arranged in the interval area between adjacent PAD point welding areas 20. The length of each auxiliary grid welding area 30 is longer than that of its adjacent PAD point welding area 20, so as to facilitate the connection of more auxiliary grids.

[0044] Continue to refer Figure 2 Each PAD spot welding area 20 includes a first solder covering the welding strip substrate 10, and each auxiliary grid welding area 30 includes a second solder covering the welding strip substrate 10, wherein the melting point of the first solder is higher than the melting point of the second solder.

[0045] Figure 3 2 is a schematic diagram of a battery cell 200 provided in an embodiment of the present application. Figure 3 , the cell 200 is provided with a PAD point 40 and a secondary grid 50. Among them, a plurality of secondary grids 50 are provided parallel to the length direction (x direction) of the cell, and the PAD points 40 are arranged at intervals along the height direction (y direction) of the cell 200. A plurality of secondary grids are provided between two adjacent PAD points 40. It should be understood that the photovoltaic welding ribbon should be welded to each PAD point 40 and to each secondary grid 50.

[0046] In some embodiments, the PAD point 40 is made by printing a pure silver paste, and the secondary grid 50 is made by printing a silver-coated copper paste. The solder strip substrate 10 can be, for example, a copper wire. The soldering performance of the pure silver paste is better than that of the silver-coated copper paste, and the cost of the silver-coated copper paste is lower than that of the pure silver paste, which helps to meet the battery preparation requirements.

[0047] Figure 4 Schematic diagram of a photovoltaic ribbon 100 and a solar cell 200 provided in an embodiment of the present application. Figure 4 When the photovoltaic welding ribbon 100 is welded to the battery cell 200 , the battery cell 200 can be roughly located below the photovoltaic welding ribbon 100 (in the y direction).

[0048] Each PAD point welding area 20 is used to correspond to the PAD point 40 on the cell 200, and the auxiliary grid welding area 30 of the photovoltaic welding strip 100 is used to correspond to the auxiliary grid 50 on the cell 200. When the photovoltaic welding strip 100 is welded to the cell 200, each PAD point 40 is fixed to the corresponding PAD point welding area 20, and each auxiliary grid 50 is fixed to the corresponding auxiliary grid welding area 30. Since the melting point of the first solder covered on the PAD point welding area 20 is higher than the melting point of the second solder covered on the auxiliary grid welding area 30, the tensile force of the welding point formed between the PAD point welding area 20 and the PAD point 40 is higher than that of the welding strip prepared only with low temperature solder. Similarly, compared with the welding strip prepared only with high temperature solder, the degree of tin accumulation of the welding point formed between the auxiliary grid welding area 30 and the auxiliary grid 50 is reduced, thereby reducing the risk of grid breakage during welding.

[0049] In some embodiments, the first solder and the second solder are tin-lead-bismuth alloys. The first solder may also be a tin-lead alloy. The bismuth content of the first solder may be less than the bismuth content of the second solder, so that the melting point of the first solder is higher than that of the second solder, and the fluidity is better.

[0050] For example, the tin-lead-bismuth alloy may include, but is not limited to: Sn60Pb40, Sn53Pb37Bi10, Sn43Pb43Bi14, Sn40Pb42Bi18, Sn37Pb42Bi21, Sn37Pb37Bi26, Sn28.5Pb43Bi28.5, Sn25Pb38Bi37, etc. For details, please refer to Table 1, which will not be repeated here.

[0051] refer to Figure 5 The present application provides a photovoltaic cell 300, including the photovoltaic welding strip 100 mentioned above and a plurality of cells 200. Specifically, the photovoltaic welding strip 100 can be arranged along the width direction (y direction) of the photovoltaic cell 300. Wherein a plurality of cells 200 can be stacked together, and each cell 200 can include a plurality of PAD points 40 and a secondary grid 50. The photovoltaic welding strip 100 is arranged at intervals along the height direction (y direction) of the corresponding cell 200. Wherein, the photovoltaic welding strip 100 includes a PAD point welding area 20 and a secondary grid welding area 30. Each PAD point welding area 20 is welded to the PAD point 40 on the corresponding cell 200, and each secondary grid welding area 30 is welded to the secondary grid 50 on the corresponding cell 200.

[0052] Since the melting point of the first solder covering the PAD point welding area 20 is higher than the melting point of the second solder covering the auxiliary grid welding area 30, the tensile force of the welding point formed between the PAD point welding area 20 and the PAD point 40 is higher than that of the welding strip prepared only with low-temperature solder. Similarly, compared with the welding strip prepared only with high-temperature solder, the degree of tin accumulation at the welding point formed between the auxiliary grid welding area 30 and the auxiliary grid 50 is reduced, thereby reducing the risk of grid breakage during the welding process.

[0053] In summary, the embodiments of the present application provide a method for preparing a photovoltaic welding strip, a photovoltaic welding strip, and a photovoltaic cell. By applying a first solder covering the welding strip substrate in the PAD point welding area, and applying a second solder covering the welding strip substrate in the sub-grid welding area, the PAD point welding area can correspond to the position of the PAD point on the battery cell, and the sub-grid welding area can correspond to the position of the sub-grid on the battery cell. In this way, when the photovoltaic welding strip is welded to the battery cell, by connecting each PAD point to the first solder and each sub-grid to the second solder, the welding tension on the PAD point can be increased, and the degree of tin stacking when the sub-grid welding point is welded with the second solder can be reduced, thereby reducing the risk of grid breakage during welding.

[0054] The basic concepts have been described above. Obviously, for those skilled in the art, the above invention disclosure is only used as an example and does not constitute a limitation of the present application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements and amendments to the present application. Such modifications, improvements and amendments are suggested in the present application, so such modifications, improvements and amendments still belong to the spirit and scope of the exemplary embodiments of the present application.

[0055] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0056] Similarly, it should be noted that in order to simplify the description of the disclosure of this application and thus help understand one or more embodiments of the invention, in the above description of the embodiments of this application, multiple features are sometimes combined into one embodiment, figure or description thereof. However, this disclosure method does not mean that the features required by the object of this application are more than the features mentioned in the claims. In fact, the features of the embodiments are less than all the features of the single embodiment disclosed above.

[0057] In some embodiments, numbers describing the number of components and attributes are used. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise specified, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may change according to the required features of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of the present application are approximate values, in specific embodiments, the setting of such numerical values ​​is as accurate as possible within the feasible range.

[0058] Although the present application has been described with reference to the current specific embodiments, ordinary technicians in this technical field should recognize that the above embodiments are only used to illustrate the present application, and various equivalent changes or substitutions may be made without departing from the spirit of the present application. Therefore, as long as the changes and modifications to the above embodiments are within the essential spirit of the present application, they will fall within the scope of the claims of the present application.

Claims

1. A method for preparing a photovoltaic welding ribbon, characterized in that: include: Prepare a solder strip substrate, and set a PAD spot welding area and a secondary grid welding area on the solder strip substrate; Applying a first solder covering the solder strip substrate at the PAD spot welding area; as well as, A second solder is applied to the auxiliary grid welding area to cover the solder strip base, wherein the melting point of the first solder is higher than the melting point of the second solder.

2. The method for preparing a photovoltaic ribbon according to claim 1, characterized in that: The PAD spot welding area and the auxiliary grid welding area are arranged at intervals along the length direction of the welding strip substrate.

3. The method for preparing a photovoltaic ribbon according to claim 2, characterized in that: The length of each auxiliary grid welding area is greater than the length of the adjacent PAD point welding area.

4. The method for preparing a photovoltaic ribbon according to claim 1, characterized in that: The first solder and the second solder are both tin-lead-bismuth alloys.

5. The method for preparing a photovoltaic welding ribbon according to claim 4, characterized in that: The bismuth content of the first solder is less than the bismuth content of the second solder.

6. A photovoltaic welding ribbon, characterized in that: include: A solder strip substrate, on which a PAD spot welding area and a secondary grid welding area are provided; the PAD spot welding area comprises a first solder covering the solder strip substrate; The secondary grid welding area includes a second solder covering the solder strip base, wherein the melting point of the first solder is higher than the melting point of the second solder.

7. The photovoltaic welding strip according to claim 6, characterized in that: The PAD spot welding area and the auxiliary grid welding area are arranged at intervals along the length direction of the welding strip substrate.

8. The photovoltaic welding strip according to claim 7, characterized in that: The length of each auxiliary grid welding area is greater than the length of the adjacent PAD point welding area.

9. The photovoltaic welding strip according to claim 6, characterized in that: The first solder and the second solder are both tin-lead-bismuth alloys.

10. The photovoltaic welding strip according to claim 9, characterized in that: The bismuth content of the first solder is less than the bismuth content of the second solder.

11. A photovoltaic cell, characterized in that: Comprising the photovoltaic welding strip as described in any one of claims 6-10.

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