Back contact solar cell, manufacturing process thereof and cell string thereof

Abstract

The invention relates to the field of solar cells, and discloses a back contact solar cell, a manufacturing process thereof and a cell string thereof. And the disconnected part of the first fine grid and the second fine grid of the battery piece is an insulating area. And an insulating layer is arranged on the insulating area. And a gap is formed between the insulating layer and the disconnection port of the first fine grid or the second fine grid. Wherein the width D of the insulating layer is larger than the width of the P region or the N region and completely covers the region on the width of the P region or the N region, the length L of the insulating layer is not smaller than two times of the width of the welding strip, and the height of the insulating layer is not larger than the heights of the first fine grid and the second fine grid. The upper end face of each insulating layer or part of the insulating layer is provided with a stop block used for preventing the solder strip from shifting. The battery string comprises a plurality of battery pieces and a welding strip. And the welding strip is positioned between the two stop blocks on the insulating layer and connects the plurality of battery pieces in a series welding manner. Short circuit of the battery piece can be avoided, the double-sided rate of the battery can be improved, the welding precision of a welding machine is reduced, and the cost is reduced.

Description

Technical Field

[0001] The invention relates to the field of solar cells, in particular to a back-contact solar cell sheet and a manufacturing process thereof, and a cell string thereof. Background Art

[0002] The design feature of the back contact battery is that the positive and negative electrodes are both on the back of the battery, so that the front of the battery is unobstructed and the photoelectric conversion efficiency is improved. Therefore, it is particularly important to do a good job of insulating the positive and negative electrodes of different polarities. The existing related technology for the insulation treatment of the positive and negative electrodes includes disconnection treatment at the connection between the fine grid and the main grid with different polarities. In order to prevent the welding strip from offsetting and overlapping the fine grids with different polarities during welding, an insulating layer is set at both ends of the disconnected fine grid, and the insulating area and the fine grids at both ends of the disconnection are covered with an insulating layer, such as Figure 3 Although this solution can avoid the short circuit effect to a certain extent, it increases the use area of ​​the insulating layer, which reduces the double-sidedness and also increases the production cost. Summary of the invention

[0003] The purpose of the present invention is to provide a back-contact solar cell and its manufacturing process, and a cell string, which can not only avoid the short circuit of the cell caused by the interconnection of the positive and negative pole grid lines of the cell, but also reduce the use area of ​​the insulation layer to improve the double-sidedness of the cell, reduce the welding accuracy of the welding machine and reduce costs.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] The present invention discloses a back-contact solar cell, which includes a battery substrate, and a plurality of P regions and N regions with opposite polarities are alternately distributed on the back of the battery substrate. The upper surface layer of the P region and the N region is a conductive film layer; a first fine grid is arranged on the P region, and a second fine grid is arranged on the N region. A plurality of first main grids and second main grids perpendicular to the first fine grids and the second fine grids are arranged on the back of the battery substrate. A plurality of first fine grids are respectively connected to the first main grid, and are disconnected at the intersection with the second main grid; and are used to separately collect the currents of a plurality of first fine grids to the first main grid. A plurality of second fine grids are respectively connected to the second main grid, and are disconnected at the intersection with the first main grid, and are used to separately collect the currents of a plurality of second fine grids to the second main grid. The disconnection between the first fine grid and the second fine grid is an insulating region, and an insulating layer is arranged on the insulating region.

[0006] A gap is provided between the insulating layer and the disconnection port of the first fine grid or the second fine grid, and the disconnection port of the first fine grid or the second fine grid is not covered by the insulating layer, so that the electrical isolation of the back contact battery is done well in a limited area, and the use area of ​​the insulating layer is greatly reduced, which can improve the bifaciality of the battery. At the same time, the insulating layer is only used for insulating the first main grid or the second main grid and the conductive film layer in the insulating area, and there is no need to cover the first fine grid line or the second fine grid line, which can avoid the risk of insulation failure caused by the grid line piercing the insulating layer.

[0007] The width D of the insulating layer is greater than the width of the P region or the N region, and completely covers the area within the width of the P region or the N region to ensure the effectiveness of the insulation. The length L of the insulating layer is not less than twice the width of the welding strip to ensure that the welding strip to be welded can be fully accommodated and the insulation effect between the welding strip and other grid lines is ensured. The height of the insulating layer is not higher than the height of the first and second fine grids to ensure that the welding strip can be placed flat, so that the main grid and the welding strip can be better contacted. A blocking block for preventing the welding strip from deviating is provided on the upper end surface of each insulating layer or part of the insulating layer to prevent the welding strip from deviating from the fine grids that contact different electrodes and causing a short circuit, which can reduce the welding accuracy of the welding machine and reduce costs.

[0008] Furthermore, the insulating layer is an insulating ink layer.

[0009] Furthermore, two blocking blocks are provided on the insulating layer, respectively located on two sides of the welding strip to be laid, and the height of the blocking blocks is not less than 30 um.

[0010] Furthermore, the blocking block is an insulating ink blocking block or a polyimide blocking block.

[0011] Furthermore, the blocking block is a cube or a cuboid.

[0012] Furthermore, the first main gate and the second main gate are complete continuous gate lines, or are discontinuous gate lines formed by being disconnected at both ends of the insulating layer.

[0013] The present invention also discloses a back-contact solar cell string, which includes a plurality of cells and welding strips, wherein the cells are the above-mentioned back-contact solar cells; the adjacent cells are arranged in sequence along a specified direction with a safe gap maintained, the welding strip is welded to the first main grid and / or the second main grid on the cell, and is located between two blocking blocks on the insulating layer, so as to connect the plurality of cells in series by welding.

[0014] The present invention also discloses a manufacturing process of the above-mentioned back contact solar cell, which comprises the following steps:

[0015] Printing a first fine grid on the P region on the back side of the battery substrate, and printing a second fine grid on the N region, wherein the first fine grid or the second fine grid is disconnected in the insulating region;

[0016] Printing an insulating layer on the insulating area and UV curing it;

[0017] The first main grid and the second main grid are printed in the straight line direction where the insulating layer is located; wherein the first main grid or the second main grid can be printed on the insulating layer to form a complete continuous grid line; the first main grid or the second main grid can also be disconnected on the insulating layer without printing to form a discontinuous grid line;

[0018] Stop blocks are printed or injection-molded on the insulating layer, and the stop blocks are located on both sides of the first main grid or the second main grid.

[0019] Furthermore, when the blocking block is injection molded, a high-precision injection mold and an injection molding machine are used close to the insulating layer, and the molten polyimide is injected into the mold, and after cooling, a micron-level blocking block is obtained.

[0020] The benefits of the present invention are:

[0021] 1. A gap is provided between the insulating layer and the disconnection port of the first fine grid or the second fine grid of the present invention, and the disconnection port of the first fine grid or the second fine grid is not covered by the insulating layer, so that the electrical isolation of the back contact battery can be done well in a limited area, and the use area of ​​the insulating layer can be greatly reduced, which can improve the bifaciality of the battery. At the same time, the insulating layer is only used for insulating the first main grid or the second main grid and the conductive film layer in the insulating area, and there is no need to cover the first fine grid line or the second fine grid line, which can avoid the risk of insulation failure caused by the grid line piercing the insulating layer.

[0022] 2. A blocking block is set on the insulating layer to prevent the welding strip from deviating. It can not only prevent the welding strip from deviating and contacting the fine grids of different electrodes to cause short circuit, but also reduce the welding accuracy of the welding machine and reduce costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention, and the drawings of this embodiment only draw a pair of main grids and part of fine grids as schematic diagrams in order to intuitively illustrate the technical features of the present invention. Therefore, it should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 1 is a schematic top view of a battery cell according to the first embodiment.

[0025] Figure 2 It is a front view schematic diagram of the battery cell of the first embodiment.

[0026] Figure 3 2 is a top view schematic diagram of the battery cell of Example 1.

[0027] Figure 4 3 is a top view of the battery cell of Example 1.

[0028] Figure 5 Schematic diagram of a top view of a battery string in the second embodiment.

[0029] Figure 6 It is a front view schematic diagram of a battery cell in the prior art in the background technology.

[0030] Figure 7 A schematic top view of a prior art battery cell in the background art.

[0031] Main component symbols:

[0032] 1. Battery substrate; 2. Conductive film layer; 3. First fine grid; 4. Second fine grid; 5. First main grid; 6. Second main grid; 7. Insulation layer; 8. Blocking block; 9. Welding strip. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] In the present invention, unless otherwise specified, directional words such as "upper, lower, left, right" are generally understood in conjunction with the directions shown in the drawings and actual applications.

[0035] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0036] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0037] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article. Among them, the terms "optional" and "optional" all mean that they may be included or not included (or may be present or not).

[0038] Embodiment 1:

[0039] like Figure 1 , Figure 2 As shown, the present invention discloses a back-contact solar cell, which includes a cell substrate 1. A plurality of P regions and N regions with opposite polarities are alternately distributed on the back of the cell substrate 1. Among them, the upper surface layer of the P region and the N region is a conductive film layer 2. A first fine grid 3 is arranged on the P region, and a second fine grid 4 is arranged on the N region. A plurality of first main grids 5 and second main grids 6 perpendicular to the first fine grids 3 and the second fine grids 4 are arranged on the back of the cell substrate 1. A plurality of first fine grids 3 are respectively connected to the first main grid 5, and are disconnected at the intersection with the second main grid 6; they are used to separately collect the currents of a plurality of first fine grids 3 to the first main grid 5. A plurality of second fine grids 4 are respectively connected to the second main grid 6, and are disconnected at the intersection with the first main grid 5, and are used to separately collect the currents of a plurality of second fine grids 4 to the second main grid 6. The disconnection between the first fine grid 3 and the second fine grid 4 is an insulating region, and an insulating layer 7 is arranged on the insulating region.

[0040] Among them, a gap is set between the insulating layer 7 and the disconnection port of the first fine grid 3 or the second fine grid 4, and the disconnection port of the first fine grid 3 or the second fine grid 4 is not covered by the insulating layer 7, so that the electrical isolation of the back contact battery is done well in a limited area, and the use area of ​​the insulating layer 7 is greatly reduced, which can improve the bifaciality of the battery. At the same time, the insulating layer 7 is only used for the insulation treatment of the first main grid 5 or the second main grid 6 and the conductive film layer 2 in the insulation area, and there is no need to cover the first fine grid 3 line or the second fine grid 4 line, which can avoid the risk of insulation failure caused by the insulation layer 7 being pierced by the grid line.

[0041] The width D of the insulating layer 7 is greater than the width of the P region or the N region, and completely covers the area within the width of the P region or the N region to ensure the effectiveness of insulation. The length L of the insulating layer 7 is not less than twice the width of the welding strip 9 to ensure that the welding strip 9 to be welded can be fully accommodated and the insulation effect between the welding strip 9 and other grid lines can be ensured. The height of the insulating layer 7 is not higher than the height of the first and second fine grids to ensure that the welding strip 9 can be placed flat, so that the main grid and the welding strip 9 can be better contacted. A blocking block 8 for preventing the welding strip 9 from deviating is provided on the upper end surface of each insulating layer 7 or part of the insulating layer 7 to prevent the welding strip 9 from deviating from the fine grids that contact different electrodes and cause a short circuit, which can reduce the welding accuracy of the welding machine and reduce costs.

[0042] The material of the insulating layer 7 needs to have good insulating properties, high temperature resistance, high plasticity and high stability in shaping. In this embodiment, an insulating ink layer is selected as the insulating layer 7.

[0043] There are two blocking blocks 8 on the insulating layer 7, which are respectively located on both sides of the welding tape 9 to be laid. The shape of the blocking block 8 is not limited, and can be a cube, a cuboid or other shapes. In this embodiment, a cuboid is preferred. The height of the blocking block 8 is not less than 30um, and the height of the blocking block 8 can be selected according to the thickness of the selected string welding tape 9.

[0044] Similarly, the material of the blocking block 8 needs to have good insulation performance, high temperature resistance, high plasticity and high stability shaping. In this embodiment, the material of the blocking block 8 can be selected from insulating ink and polyimide.

[0045] like Figure 1 , Figure 4 As shown, the blocking blocks 8 may be evenly spaced and distributed on the insulating layer 7 , or the blocking blocks 8 may be selectively arranged on a portion of the insulating layer 7 .

[0046] like Figure 1 , Figure 3 As shown, the first main grid 5 and the second main grid 6 are complete continuous grid lines, or discontinuous grid lines formed by disconnecting at both ends of the insulating layer 7. When the first main grid 5 or the second main grid 6 is a discontinuous grid line, a welding pad point can be appropriately set to enhance the welding effect of the welding strip 9 and the grid line.

[0047] Embodiment 2:

[0048] like Figure 5 As shown, this embodiment discloses a back-contact solar cell string, which includes a plurality of cells and a welding strip 9, and the cell is the back-contact solar cell of embodiment 1. Adjacent cells are arranged in sequence along a specified direction with a safety gap, and the welding strip 9 is welded to the first main grid 5 and / or the second main grid 6 on the cell, and is located between two blocking blocks 8 on the insulating layer 7, so as to connect the plurality of cells in series.

[0049] Embodiment three:

[0050] This embodiment discloses a process for manufacturing the solar cell according to the first embodiment, which comprises the following steps:

[0051] Printing a first fine grid 3 on the P region on the back side of the battery substrate 1, and printing a second fine grid 4 on the N region, wherein the first fine grid 3 or the second fine grid 4 is disconnected in the insulating region;

[0052] Printing an insulating layer 7 on the insulating area and UV curing it;

[0053] The first main grid 5 and the second main grid 6 are printed in the straight line direction where the insulating layer 7 is located; wherein the first main grid 5 or the second main grid 6 can be printed on the insulating layer 7 to form a complete continuous grid line; the first main grid 5 or the second main grid 6 can also be disconnected and not printed on the insulating layer 7 to form a discontinuous grid line;

[0054] The blocking blocks 8 are printed or injection molded on the insulating layer 7, and the blocking blocks 8 are located on both sides of the first main grid 5 or the second main grid 6. When the blocking blocks 8 are injection molded, a high-precision injection mold and an injection molding machine are used close to the insulating layer 7, and the molten polyimide is injected into the mold, and the micron-level blocking blocks 8 can be obtained after cooling.

[0055] In summary, the present invention can not only avoid short circuit of the battery cell caused by interconnection of the positive and negative grid lines of the battery cell, but also reduce the use area of ​​the insulation layer to improve the double-sidedness of the battery, reduce the welding accuracy of the welding machine and reduce costs.

[0056] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A back contact solar cell, characterized in that: It comprises a battery substrate (1), wherein a plurality of P regions and N regions with opposite polarities are alternately distributed on the back side of the battery substrate (1); A first fine grid (3) is arranged on the P region, and a second fine grid (4) is arranged on the N region; a plurality of first main grids (5) and second main grids (6) perpendicular to the first fine grids (3) and the second fine grids (4) are arranged on the back side of the battery substrate (1); A plurality of first fine grids (3) are respectively connected to the first main grid (5) and are disconnected at the intersection with the second main grid (6); A plurality of second fine grids (4) are respectively connected to the second main grid (6) and are disconnected at the intersection with the first main grid (5); The disconnection point between the first fine gate (3) and the second fine gate (4) is an insulating region, and an insulating layer (7) is provided on the insulating region; A gap is provided between the insulating layer (7) and the disconnection port of the first fine grid (3) or the second fine grid (4); wherein the width D of the insulating layer (7) is greater than the width of the P region or the N region, and completely covers the area on the width of the P region or the N region, the length L of the insulating layer (7) is not less than twice the width of the welding strip (9), and the height of the insulating layer (7) is not higher than the height of the first and second fine grids; and a blocking block (8) for preventing the welding strip (9) from deflecting is provided on the upper end surface of each insulating layer (7) or part of the insulating layer (7).

2. The back contact solar cell according to claim 1, characterized in that: The insulating layer (7) is an insulating ink layer.

3. The back contact solar cell according to claim 1, characterized in that: Two blocking blocks (8) are provided on the insulating layer (7), respectively located on two sides of the welding strip (9) to be laid, and the height of the blocking blocks (8) is not less than 30 um.

4. The back contact solar cell according to claim 1, characterized in that: The blocking block (8) is an insulating ink blocking block or a polyimide blocking block.

5. The back contact solar cell according to claim 1, characterized in that: The blocking block (8) is a cube or a cuboid.

6. The back contact solar cell according to claim 1, characterized in that: The first main grid (5) and the second main grid (6) are complete continuous grid lines, or discontinuous grid lines formed by being disconnected at both ends of the insulating layer (7).

7. A back contact solar cell string, characterized in that: The invention comprises a plurality of solar cells and welding strips (9), wherein the solar cells are back-contact solar cells according to any one of claims 1 to 6; the adjacent solar cells are arranged in sequence with a safety gap maintained along a specified direction, the welding strips (9) are welded to the first main grid (5) and / or the second main grid (6) on the solar cells, and are located between two blocking blocks (8) on the insulating layer (7), so as to connect the plurality of solar cells in series by welding.

8. A process for manufacturing a back contact solar cell according to any one of claims 1 to 6, characterized in that The following steps are involved: Printing a first fine grid (3) on the P region on the back side of the battery substrate (1), and printing a second fine grid (4) on the N region, wherein the first fine grid (3) or the second fine grid (4) is disconnected in the insulating region; Printing an insulating layer (7) on the insulating area and UV curing it; Printing a first main grid (5) and a second main grid (6) in the straight line direction where the insulating layer (7) is located; A blocking block (8) is printed or injection-molded on the insulating layer (7), and the blocking block (8) is located on both sides of the first main grid (5) or the second main grid (6).

9. The process for manufacturing a back contact solar cell according to claim 8, characterized in that: When injection molding the blocking block (8), a high-precision injection mold and an injection molding machine are used close to the insulating layer (7), and molten polyimide is injected into the mold. After cooling, a micron-level blocking block (8) is obtained.

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