Back contact cells, cell assemblies and photovoltaic systems

Abstract

The application relates to the technical field of solar cells, and provides a back contact cell, a cell assembly and a photovoltaic system. In the back contact cell, a first collecting grid line is discontinuous at a first edge series connection area and continuous at a second series connection area, and a first busbar grid line is continuous at the first edge series connection area and the second series connection area. The first edge busbar is closer to the first edge than the first edge series connection area. A first insulating layer is arranged on a portion of the first busbar grid line corresponding to the first series connection area. A second auxiliary connecting layer is arranged on a portion of the first grid line located at a third edge series connection area. The height of a second insulating layer is flush with the height of the second auxiliary connecting layer, or the height of the second insulating layer is smaller than the height of the second auxiliary connecting layer, or the height of the second insulating layer is greater than the height of the second auxiliary connecting layer, and the height difference is less than or equal to 15 um. In this way, the influence caused by false welding can be reduced through the arrangement of the second auxiliary connecting layer, so that the efficiency of the back contact cell is ensured.

Description

Technical Field

[0001] This application relates to the field of solar cell technology, and more particularly to a back-contact cell, a cell module, and a photovoltaic system. Background Technology

[0002] A back-contact battery is a type of battery in which both P-type and N-type doped layers are placed on the back of a silicon wafer, with no metal electrodes obstructing the front. It has higher short-circuit current and conversion efficiency.

[0003] In related technologies, the back of a back-contact battery has alternating grid lines. To reduce paste usage and transmission losses, solder ribbons can be directly used to form an electrical connection with the grid lines in the battery assembly. However, in this technical solution, insulating adhesive needs to be placed at the grid lines of opposite polarity where they intersect with the solder ribbon to prevent leakage. However, the placement of the insulating adhesive can easily lead to incomplete soldering during the soldering process, resulting in the current of some grid lines not being collected and affecting the efficiency of the back-contact battery. Summary of the Invention

[0004] This application provides a back-contact battery, a battery module, and a photovoltaic system.

[0005] This application is implemented as follows: the back contact battery in the embodiments of this application includes:

[0006] A substrate having a front side and a back side, the back side having a first edge and a second edge in a first direction, the back side having a plurality of first serialization areas and a plurality of second serialization areas, the first serialization areas and the second serialization areas being arranged alternately in the first direction, the plurality of first serialization areas including a first edge serialization area closest to the first edge, and no second serialization area between the first edge serialization area and the first edge.

[0007] A plurality of first grid lines and a plurality of second grid lines are alternately arranged on the back side along a second direction, the second direction intersecting the first direction. The first grid lines and all the second grid lines are arranged to intersect the first serial connection area and the second serial connection area. The plurality of first grid lines include a plurality of first collection grid lines and at least one first bus grid line. The first collection grid lines are discontinuous at the first edge serial connection area and continuous at the second serial connection area. The first bus grid line is continuous at both the first edge serial connection area and the second serial connection area. The second grid lines are continuous at the first edge serial connection area.

[0008] A first edge bus line, which is closer to the first edge than the first edge concatenation region, is electrically connected to at least a portion of the first collection grid line and to the first bus grid line.

[0009] A first insulating layer is disposed in the first edge serialization region and located on the first busbar; and

[0010] A first auxiliary connection layer is disposed on the portion of the second gate line located in the first edge serial connection area. The first auxiliary connection layer is used for welding with the solder strip. In the thickness direction of the back contact battery, the height of the first insulating layer is flush with the height of the first auxiliary connection layer, or the height of the first insulating layer is less than the height of the first auxiliary connection layer, or the height of the first insulating layer is greater than the first auxiliary connection layer. The height difference between the first insulating layer and the first auxiliary connection layer is less than or equal to 15 μm.

[0011] Furthermore, the first gate line includes a first solder section located within the second serial connection area, and the second gate line includes a second solder section located within the first serial connection area;

[0012] The first auxiliary connection layer is stacked on the second welding segment located within the first edge serial connection area, and the height of the first insulating layer is greater than the height of the second welding segment in the thickness direction of the back contact battery.

[0013] Furthermore, the first gate line includes a first collection layer and a first solder layer, the first collection layer being continuous at the second serial connection area and discontinuous at the first serial connection area, and the first solder layer being disposed at the second serial connection area and located on the first collection layer; or

[0014] The first collecting layer is interrupted at both the second serial connection area and the first serial connection area, and the first welding layer is disposed at the second serial connection area and electrically connected to the two ends of the first collecting layer formed at the second serial connection area;

[0015] The width of the first welding layer is greater than the width of the first collection layer.

[0016] Furthermore, the second grid line includes a second collecting layer and a second soldering layer, wherein the second collecting layer is continuous at the first serial connection area and discontinuous at the second serial connection area, and the second soldering layer is disposed at the first serial connection area and located on the second collecting layer; or, the second collecting layer is discontinuous at both the first serial connection area and the second serial connection area, and the second soldering layer is disposed at the first serial connection area and electrically connected to the two ends of the second collecting layer formed at the first serial connection area;

[0017] The width of the second welding layer is greater than the width of the second collecting layer, and the first auxiliary connecting layer is disposed on the second welding layer.

[0018] Furthermore, the first auxiliary connection layer includes a solder paste layer.

[0019] Furthermore, the first edge busbar is electrically connected to all of the first collection grid lines; or

[0020] The first edge busbar is electrically connected to a portion of the first collection grid lines, and the number of the first collection grid lines not electrically connected to the first edge busbar is less than or equal to 4.

[0021] Furthermore, the number of the first busbars is multiple, and the substrate has a third edge and a fourth edge in the second direction;

[0022] Of the first grid line and the second grid line, the grid line closest to the third edge is the first bus grid line, and / or the grid line closest to the fourth edge is the first bus grid line.

[0023] Furthermore, the substrate has a third edge and a fourth edge in the second direction;

[0024] At the junction of the first gate line closest to the third edge and the first edge bus line, the first edge bus line has a first protrusion extending toward the third edge; and / or

[0025] At the junction of the first gate line closest to the fourth edge and the first edge bus line, the first edge bus line has a second protrusion that protrudes toward the fourth edge.

[0026] Furthermore, the width of the first busbar is greater than the width of the portion of the first collection busbar located outside the second serial area.

[0027] Furthermore, a plurality of the second concatenation regions include a second edge concatenation region closest to the first edge; the first busbar includes a first bus segment located between the second edge concatenation region and the first edge;

[0028] Wherein, the width of the first bus section is greater than the width of the remaining portion of the first bus gate line located outside the second serial connection area; and / or

[0029] The first busbar section is provided with a first busbar layer.

[0030] Furthermore, the width of the first busbar is greater than the width of the portion of the first collection grid line located outside the second serial connection area.

[0031] Furthermore, the width of the first edge busbar is greater than the width of the portion of the first collection grid line located outside the second serial area.

[0032] Furthermore, the distance between the first edge concatenation area and the first edge is greater than or equal to 2mm and less than or equal to 20mm.

[0033] Furthermore, a plurality of the second concatenation areas include a third edge concatenation area closest to the second edge, wherein the third edge concatenation area and the second edge do not have the first concatenation area between them;

[0034] The plurality of second grid lines include a plurality of second collection grid lines and at least one second bus grid line, wherein the second collection grid lines are discontinuous at the third edge concatenation region and continuous at the first concatenation region, the second bus grid line is continuous at both the third edge concatenation region and the first concatenation region, and the first grid line is continuous at the third edge concatenation region.

[0035] The back contact battery also includes:

[0036] The second edge bus is closer to the second edge than the third edge connection area, and the second edge bus is electrically connected to at least a portion of the second collection grid and to the second bus grid.

[0037] A second insulating layer is disposed in the third edge series region and located on the second busbar; and

[0038] The second auxiliary connection layer is disposed on the portion of the first grid line located in the third edge serial connection area. The second auxiliary connection layer is used for welding with the solder strip. In the thickness direction of the back contact battery, the height of the second insulating layer is flush with the height of the second auxiliary connection layer, or the height of the second insulating layer is less than the height of the second auxiliary connection layer, or the height of the second insulating layer is greater than the height of the second auxiliary connection layer. The height difference between the second insulating layer and the second auxiliary connection layer is less than or equal to 15 μm.

[0039] Furthermore, the first gate line includes a first solder section located within the second serial connection area, and the second gate line includes a second solder section located within the first serial connection area;

[0040] The second auxiliary connection layer is stacked on the first welding segment located in the third edge series connection area, and the height of the second insulating layer is greater than the height of the first welding segment in the thickness direction of the back contact battery.

[0041] Furthermore, the first gate line includes a first collection layer and a first solder layer, the first collection layer being continuous at the second serial connection area and discontinuous at the first serial connection area, and the first solder layer being disposed at the second serial connection area and located on the first collection layer; or

[0042] The first collecting layer is interrupted at both the second serial connection area and the first serial connection area, and the first welding layer is disposed at the second serial connection area and electrically connected to the two ends of the first collecting layer formed at the second serial connection area;

[0043] Wherein, the width of the first welding layer is greater than the width of the first collecting layer, and the second auxiliary connecting layer is disposed on the first welding layer.

[0044] Furthermore, the second auxiliary connection layer is a solder paste layer.

[0045] Furthermore, the second edge bus is electrically connected to all the second collection grid lines; or

[0046] The second edge bus is electrically connected to a portion of the second collection grid lines, and the number of second collection grid lines not electrically connected to the second edge bus is less than or equal to 4.

[0047] Furthermore, the substrate has a third edge and a fourth edge in the second direction, and the second edge bus line includes a middle bus segment, a first edge bus segment, and a second edge bus segment. The middle bus segment, the first edge bus segment, and the second edge bus segment all extend along the second direction. The middle bus segment is closer to the second edge than the first edge bus segment and the second edge bus segment. The first edge bus segment is located close to the third edge, and the second edge bus segment is located close to the fourth edge.

[0048] The second edge busbar further includes a first connecting segment and a second connecting segment, both of which extend along the first direction. The first connecting segment connects the intermediate busbar to the first edge busbar, and the second connecting segment connects the intermediate busbar to the second edge busbar.

[0049] Wherein, the first edge busbar connects the two second gate lines closest to the third edge; at the junction of the first edge busbar and the first connecting section, the first edge busbar has a third protrusion protruding towards the fourth edge, and the first connecting section has a fourth protrusion protruding towards the first edge; at the junction of the intermediate busbar and the first connecting section, the intermediate busbar has a fifth protrusion protruding towards the third edge, and the first connecting section has a sixth protrusion protruding towards the second edge; and / or

[0050] The second edge busbar connects the two second gate lines closest to the fourth edge. At the junction of the second edge busbar and the second connecting section, the second edge busbar has a seventh protrusion protruding toward the third edge, and the second connecting section has an eighth protrusion protruding toward the first edge. At the junction of the intermediate busbar and the second connecting section, the intermediate busbar has a ninth protrusion protruding toward the fourth edge, and the second connecting section has a tenth protrusion protruding toward the second edge.

[0051] Furthermore, the width of the second busbar is greater than the width of the portion of the second collection busbar located outside the first cascading area.

[0052] Furthermore, a plurality of the first concatenation regions include a fourth edge concatenation region closest to the second edge; the second busbar includes a second bus segment located between the fourth edge concatenation region and the second edge;

[0053] The width of the second bus segment is greater than the width of the remaining portion of the second bus gate outside the first cascading area; and / or

[0054] The second busbar section is provided with a second busbar layer.

[0055] Furthermore, the width of the second bus layer is greater than the width of the portion of the second collection grid line located outside the first cascading area.

[0056] Furthermore, the width of the second edge busbar is greater than the width of the portion of the second collection grid line located outside the first cascading area.

[0057] Furthermore, the distance between the second edge concatenation area and the second edge is greater than or equal to 2 mm and less than or equal to 20 mm.

[0058] Furthermore, the substrate has a third edge and a fourth edge in the second direction;

[0059] Within the first serial connection area, the X first gate lines closest to the third edge are discontinuous at the first serial connection area, the Y first gate lines closest to the fourth edge are discontinuous at the first serial connection area, the width of the discontinuity area formed by the X first gate lines closest to the third edge gradually increases in the direction towards the third edge, and the width of the discontinuity area formed by the Y first gate lines closest to the fourth edge gradually increases in the direction towards the fourth edge, wherein X and Y are both greater than or equal to 2;

[0060] Within the second serial connection region, the W second gate lines closest to the third edge are discontinuous at the second serial connection region, the Z second gate lines closest to the fourth edge are discontinuous at the second serial connection region, the width of the discontinuity region formed by the W second gate lines closest to the third edge gradually increases in the direction towards the third edge, and the width of the discontinuity region formed by the Z second gate lines closest to the fourth edge gradually increases in the direction towards the fourth edge, wherein both W and Z are greater than or equal to 2.

[0061] This application also provides a battery assembly comprising a plurality of back contact batteries as described in any of the preceding claims.

[0062] This application also provides a photovoltaic system, which includes the aforementioned battery components.

[0063] In the back-contact battery, battery module, and photovoltaic system of this application embodiment, the first collecting grid line is discontinuous at the first edge series connection area and continuous at the second series connection area, and the first bus grid line is continuous at the first edge series connection area and the second series connection area. The first edge bus line is closer to the first edge than the first edge series connection area. A first insulating layer is provided on the portion of the first bus grid line corresponding to the first series connection area. A second auxiliary connection layer is provided on the portion of the first grid line located at the third edge series connection area. The height of the second insulating layer is flush with the height of the second auxiliary connection layer, or the height of the second insulating layer is less than the height of the second auxiliary connection layer, or the height of the second insulating layer is greater than the second auxiliary connection layer and the height difference is less than or equal to 15 μm. Thus, by providing the second auxiliary connection layer, the impact caused by poor soldering can be reduced, thereby ensuring the efficiency of the back-contact battery.

[0064] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0065] Figure 1 This is a schematic diagram of the photovoltaic system provided in the embodiments of this application.

[0066] Figure 2This is a schematic diagram of a battery assembly provided in an embodiment of this application;

[0067] Figure 3 This is a schematic diagram of the planar structure of the back contact battery provided in an embodiment of this application;

[0068] Figure 4 yes Figure 3 A partially enlarged schematic diagram of the back contact battery;

[0069] Figure 5 yes Figure 4 A schematic diagram of the cross-sectional structure along line VV of the back contact battery in the diagram.

[0070] Figure 6 yes Figure 4 A schematic diagram of the cross-sectional structure along line VI-VI of the back contact battery in the diagram.

[0071] Figure 7 yes Figure 4 A partially enlarged schematic diagram of the back contact battery;

[0072] Figure 8 yes Figure 4 Another cross-sectional view of the back contact battery along line VI-VI.

[0073] Figure 9 yes Figure 4 Another cross-sectional structural diagram of the back contact battery along line VI-VI.

[0074] Figure 10 yes Figure 4 Another enlarged schematic diagram of the back contact battery in the diagram;

[0075] Figure 11 yes Figure 4 A further enlarged schematic diagram of the back contact battery in the diagram;

[0076] Figure 12 yes Figure 3 Another enlarged schematic diagram of the back contact battery in the diagram;

[0077] Figure 13 yes Figure 12 A schematic diagram of the cross-sectional structure of the back contact battery along line XIII-XIII.

[0078] Figure 14 yes Figure 12 A schematic diagram of the cross-sectional structure of the back contact battery along line XIV-XIV.

[0079] Figure 15 yes Figure 12 A partially enlarged schematic diagram of the back contact battery;

[0080] Figure 16 yes Figure 12 Another cross-sectional view of the back contact battery along line XIV-XIV.

[0081] Figure 17 yes Figure 12 Another cross-sectional structural diagram of the back contact battery along line XIV-XIV.

[0082] Figure 18 yes Figure 12 Another enlarged schematic diagram of the back contact battery in the diagram;

[0083] Figure 19 yes Figure 12 A further enlarged schematic diagram of the back contact battery in the diagram;

[0084] Figure 20 This is another planar structural schematic diagram of the back contact battery provided in the embodiments of this application.

[0085] Explanation of key component symbols:

[0086] Photovoltaic system 1000;

[0087] Battery assembly 200;

[0088] Back contact battery 100, substrate 10, front side 11, back side 12, first edge 121, second edge 122, third edge 123, fourth edge 124, first series connection area 13, first edge series connection area 131, fourth edge series connection area 132, second series connection area 14, second edge series connection area 141, third edge series connection area 142, first groove 15, second groove 16;

[0089] Silicon substrate 101, first surface 1011, second surface 1012, first doped layer 102, second doped layer 103, back passivation film layer 104;

[0090] First grid line 20, first collecting grid line 21, first busbar grid line 22, first busbar section 221, first welding section 201; first grid line protrusion 202.

[0091] Second grid line 30, second collecting grid line 31, second busbar grid line 32, second busbar section 321, second welding section 301; second grid line protrusion 302

[0092] First edge busbar 40, first protrusion 41, second protrusion 42, first insulating layer 50, first auxiliary connecting line 60, first busbar 70, first auxiliary connecting layer 80, second auxiliary connecting line 90;

[0093] Second edge bus 110, first edge bus segment 111, second edge bus segment 112, middle bus segment 113, first connecting segment 114, second connecting segment 115, third protrusion 1101, fourth protrusion 1102, fifth protrusion 1103, sixth protrusion 1104, seventh protrusion 1105, eighth protrusion 1106, ninth protrusion 1107, tenth protrusion 1108, second insulating layer 120, third auxiliary connecting line 130, second bus layer 140, second auxiliary connecting layer 150, fourth auxiliary connecting line 160; fifth auxiliary connecting line 170, sixth auxiliary connecting line 180, seventh auxiliary connecting line 190, eighth auxiliary connecting line 1100. Detailed Implementation

[0094] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. Examples of embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. It should be noted that the embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. Furthermore, it should be understood that the specific embodiments described herein are merely for explaining this application and are not intended to limit this application.

[0095] In the description of this application, it should be understood that the terms "upper", "lower", "left", "right", "lateral", "longitudinal", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0096] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "several" means two or more, unless otherwise explicitly specified.

[0097] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0098] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0099] Please see Figure 1 and Figure 2 The photovoltaic system 1000 in this application embodiment may include the battery module 200 in this application embodiment, and the battery module 200 in this application embodiment may include a plurality of back contact cells 100 in this application embodiment. In the embodiments of this application, the plurality of back contact cells 100 in the battery module 200 may be connected in series to form a plurality of battery strings. The battery strings may be connected in series, in parallel, or in a series-parallel combination to achieve current collection and output. For example, the connection between the individual cells may be achieved by welding solder strips, or the connection between the individual battery strings may be achieved by busbars. In some embodiments, the individual battery strings may form a cell array, and then be packaged together by a front plate, a front adhesive film, a rear adhesive film, and a back plate to form the battery module 200.

[0100] In the embodiments of this application, the back contact battery 100 is a gridless back contact battery. Please refer to [link / reference]. Figures 3-6 The back contact battery 100 in this embodiment may include a substrate 10, a plurality of first grid lines 20, a plurality of second grid lines 30, a first edge bus line 40, a first insulating layer 50 and a first auxiliary connection layer 80.

[0101] like Figures 3-9As shown, the substrate 10 has a front side 11 and a back side 12. The back side 12 of the substrate 10 has a first edge 121 and a second edge 122 in a first direction. The back side 12 has a plurality of first series connection areas 13 and a plurality of second series connection areas 14. The first series connection areas 13 and the second series connection areas 14 are respectively used to provide positive electrode solder strips and negative electrode solder strips. That is to say, one of the first series connection areas 13 and the second series connection area 14 is a positive electrode series connection area, and the other is a negative electrode soldering area.

[0102] like Figure 3 and Figure 4 As shown, in a first direction, first connecting areas 13 and second connecting areas 14 are arranged alternately. A plurality of first connecting areas 13 include a first edge connecting area 131 closest to the first edge 121, and there is no second connecting area 14 between the first edge connecting area 131 and the first edge 121. That is to say, as... Figure 3 As shown, in the first serialization area 13 and the second serialization area 14, the serialization area closest to the first edge 121 is the first serialization area 13, and the first serialization area 13 is referred to as the first edge serialization area 131. There are no other serialization areas between the first edge serialization area 131 and the first edge 121.

[0103] like Figure 3 As shown, a plurality of first grid lines 20 and a plurality of second grid lines 30 are alternately arranged on the back surface 12 along a second direction, which intersects with the first direction. All first grid lines 20 and all second grid lines 30 are intersected with the first serial connection area 13 and the second serial connection area 14, that is, the first serial connection area 13 and the second serial connection area 14 both extend along the second direction to intersect with the first grid lines 20 and the second grid lines 30.

[0104] In some embodiments, the first direction and the second direction may be the longitudinal direction and the lateral direction of the back contact battery 100, respectively, and the two are perpendicular to each other, for example, in Figure 3 In the example shown, the first direction is the lateral direction of the back contact battery 100, and the second direction is the longitudinal direction of the back contact battery 100. Of course, in other embodiments, the first and second directions may also be other directions, such as the two diagonal directions of the back contact battery 100, and there is no specific limitation here.

[0105] The plurality of first grid lines 20 may include a plurality of first collection grid lines 21 and at least one first bus grid line 22, wherein the first collection grid lines 21 are discontinuous at the first edge concatenation region 131 and continuous at the second concatenation region 14, the first bus grid line 22 is continuous at both the first edge concatenation region 131 and the second concatenation region 14, and the second grid line 30 is continuous at the first edge concatenation region 131.

[0106] That is, the first grid line 20 includes at least two types of grid lines: a first collecting grid line 21 and a first bus grid line 22. The first collecting grid line 21 is discontinuous at the first edge series connection area 131, while the first bus grid line 22 is continuous at the first edge series connection area 131. The second grid line 30 is also continuous at the first edge series connection area 131. In the battery assembly 200, the solder strip in the first series connection area 13 (including the first edge series connection area 131) is used to connect with the second grid line 30 to realize the bus output of the second grid line 30, and the solder strip in the second series connection area 14 is used to weld to the first grid line 20 to realize the bus output of the first grid line 20.

[0107] like Figure 3 As shown, the first edge bus 40 is closer to the first edge 121 than the first edge series region 131. The first edge bus 40 is electrically connected to at least a portion of the first collection grid line 21 and to the first bus grid line 22. Specifically, to avoid microcracks in the battery caused by welding at the edge of the first edge 121, the first edge bus 40 is not used for welding. It is used to collect the current in the portion of the first collection grid line 21 located between the first edge series region 131 and the first edge 121, and then the current flows through the first bus grid line 22 to the second series region 14 adjacent to the first edge series region 131 (i.e., Figure 3 and Figure 4 On the same polarity solder strip in the second series area 14 on the leftmost side, the current of the grid line segment in the edge region of the first grid line 20 located at the first edge 121 is collected, thereby improving the efficiency of the back contact battery 100. If the first edge bus line 40 and the first bus grid line 22 are not provided, the part of the first grid line 20 located between the first edge series area 131 and the first edge 121 will form an isolated grid line segment, and the current in this part cannot be collected.

[0108] like Figure 3 As shown, the first insulating layer 50 is disposed in the first edge serial connection area 131 and located on the first bus gate line 22. That is, the first insulating layer 50 is provided on the portion of the first bus gate line 22 corresponding to the first edge serial connection area 131. The first insulating layer 50 is provided to insulate and separate the opposite polarity solder strip in the first edge serial connection area 131 from the first bus gate line 22 to avoid short circuit.

[0109] At the first edge serial connection area 131, a first auxiliary connection layer 80 may be disposed on the second gate line 30. The first auxiliary connection layer 80 is disposed on the portion of the second gate line 30 corresponding to the first edge serial connection area 131. The first auxiliary connection layer 80 is used for welding with the solder strip. In the thickness direction of the back contact battery 100, the first insulating layer 50 is flush with the first auxiliary connection layer 80, or the height of the first insulating layer 50 is less than the height of the first auxiliary connection layer 80, or the height difference between the first insulating layer 50 and the first auxiliary connection layer 80 is less than or equal to 15 μm.

[0110] In the back contact battery 100, battery module 200, and photovoltaic system 1000 of the embodiments of this application, the first collecting grid line 21 is interrupted at the first edge series connection area 131 and continuous at the second series connection area 14; the first bus grid line 22 is continuous at both the first edge series connection area 131 and the second series connection area 14; and the second grid line 30 is continuous at the first edge series connection area 131. The first edge bus line 40 is closer to the first edge 121 than the first edge series connection area 131, and is electrically connected to at least a portion of the first collecting grid line 21 and to the first bus grid line 22. A first insulating layer 50 is provided on the portion of the first bus grid line 22 corresponding to the first series connection area 13. At the first edge series connection area 131, a first auxiliary connection layer 80 may be provided on the second grid line 30. The first auxiliary connection layer 80 is disposed on the portion of the second gate line 30 corresponding to the first edge series connection area 131. The first auxiliary connection layer 80 is used for welding with the solder strip. In the thickness direction of the back contact battery 100, the first insulating layer 50 is flush with the first auxiliary connection layer 80, or the height of the first insulating layer 50 is less than the height of the first auxiliary connection layer 80, or the height difference between the first insulating layer 50 and the first auxiliary connection is less than or equal to 15 μm. Thus, by providing the first edge bus line 40 and the first bus gate line 22, the current collected by at least a portion of the isolated segment of the first gate line 20 located between the first edge series connection area 131 and the first edge 121 can be channeled to the solder strip of the same polarity in the second series connection area 14 adjacent to the first edge series connection area 131. This can effectively avoid microcracks caused by welding at the first edge 121 of the back contact battery 100 while ensuring the efficiency of the back contact battery 100. Meanwhile, by setting a first auxiliary connection layer 80 on the portion corresponding to the second grid line 30 and the first edge serial connection area 131, the height of the first insulating layer 50 is less than the height of the first auxiliary connection layer 80, or the first insulating layer 50 is flush with the first auxiliary connection layer 80, or the height of the first insulating layer 50 is greater than the first auxiliary connection layer 80 and the height difference between the two is less than or equal to 15um, thereby reducing or even eliminating the impact of the setting of the first insulating layer 50 on the back contact battery 100, and improving the performance and efficiency of the back contact battery 100.

[0111] Specifically, as shown above, it is easy to understand that in this application, the first edge bus 40 is not used for welding; it is only used for current transmission and merging. The function of the first bus gate 22 is to collect and transmit current. Figure 3 and Figure 4 It can be seen that, in Figure 3 and Figure 4 In the example shown, if the first edge bus 40 and the first bus gate 22 are not provided, the first gate 20 is disconnected at the first edge connection area 131. The current of the portion of the gate line segment located between the first edge connection area 131 and the first edge 121 in the first gate line 20 cannot be collected. Therefore, by providing the first edge bus 40 and the first bus gate 22, the current of at least a portion of the isolated gate line segment of the first gate line 20 located in the edge region can be connected and transmitted to the solder strip provided in the adjacent second connection area 14, thereby effectively avoiding efficiency loss.

[0112] Because the first busbar 22 is continuously arranged in the first edge serial connection area 131, a first insulating layer 50 (e.g., insulating adhesive) needs to be provided at the position corresponding to the first busbar 22 and the first edge serial connection area 131 to avoid short circuit caused by contact between the solder strip on the first edge serial connection area 131 and the first busbar 22. However, in this case, without the first auxiliary connection layer 80, the height of the first insulating layer 50 is higher than the height of the portion of the second busbar 30 located in the first edge serial connection area 131. That is, in the thickness direction, the protrusion height of the first insulating layer 50 is higher than the height of the second busbar 30. In this case, the solder strip in the first edge serial connection area 131 will short circuit during the welding process. In the process of welding, it is easy for cold solder joints to occur with the second grid line 30, which may result in the current on some of the second grid line 30 not being effectively collected (especially the second grid line 30 adjacent to the first bus grid line 22, which is most likely to have cold solder joints). Based on this, this application provides a first auxiliary connection layer 80 on the part of the second grid line 30 corresponding to the first edge series connection area 131, so that the height of the first insulating layer 50 is flush with or less than the height of the first auxiliary connection layer 80, or the height between the first insulating layer 50 and the first auxiliary connection layer 80 is less than 15um. This can reduce or even eliminate the risk of cold solder joints, thereby improving the reliability of welding and ensuring the performance of the back contact battery 100.

[0113] When the height of the first insulating layer 50 is greater than the height of the first auxiliary connecting layer 80, the height difference between the two can be any value between 1um, 2um, 3um, 4um, 5um, 9um, 7um, 8um, 9um, 10um, 11um, 12um, 13um, 14um, 15um or 0-15um.

[0114] In some embodiments, when the height of the first insulating layer 50 is greater than the height of the first auxiliary connection layer 80, the height difference between the first insulating layer 50 and the first auxiliary connection layer 80 is preferably less than 8 μm, for example, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 9 μm, 7 μm, or 8 μm. Specifically, through repeated research and verification by the inventors of this application, it has been found that by preferably setting the height difference between the two within the preferred range of less than 8 μm, the risk of poor soldering caused by the first insulating layer 50 can be essentially eliminated.

[0115] Furthermore, in the embodiments of this application, such as Figure 5 and Figure 6 As shown, the substrate 10 may include a silicon substrate 101, a plurality of first doped layers 102, a plurality of second doped layers 103, and a back passivation film layer 104. The silicon substrate 101 has opposing first surfaces 1011 and second surfaces 1012. The first doped layers 102 and second doped layers 103 are both disposed on the second surface 1012, and the plurality of first doped layers 102 and the plurality of second doped layers 103 are alternately arranged along a second direction. The back passivation film layer 104 is at least stacked on the first doped layers 102 and the second doped layers 103. In some embodiments, the back passivation film layer 104 may cover the entire second surface 1012, that is, the first doped layers 102 and the second doped layers 103, as well as the areas of the second surface 1012 where no doped layers are disposed, are all stacked with the back passivation film layer 104.

[0116] Therefore, in the substrate 10, the surface on the side where the first surface 1011 is located is the front side 11 of the substrate 10, and the side where the second surface 1012 is located is the back side of the substrate 10. Of course, in some embodiments, a first passivation layer (not shown) may also be provided between the first doped layer 102 and the silicon substrate 101 in the substrate 10. The first passivation layer may be, for example, a tunneling layer, an intrinsic amorphous silicon layer, or other film layer. A second passivation layer (not shown) may also be provided between the second doped layer 103 and the silicon substrate 101. The second passivation layer may be, for example, a tunneling layer, an intrinsic amorphous silicon layer, or other film layer.

[0117] In the back contact battery 100, the first gate line 20 corresponds one-to-one with the first doped layer 102, and the second gate line 30 corresponds one-to-one with the second doped layer 103. One of the first doped layer 102 and the second doped layer 103 can be a P-type doped layer, and the other can be an N-type doped layer. In some embodiments, the first gate line 20 can completely penetrate the back passivation film layer 104 to form a complete contact with the first doped layer 102, or the first gate line 20 can only partially penetrate the back passivation film layer 104 to form a localized metallized contact with the first doped layer 102. The specific method is not limited here.

[0118] That is to say, in the embodiments of this application, the first gate line 20 is correspondingly disposed with the first doped layer 102 and at least partially penetrates the back passivation film layer 104 and makes conductive contact with the first doped layer 102, and the second gate line 30 is correspondingly disposed with the second doped layer 103 and at least partially penetrates the back passivation film layer 104 and makes conductive contact with the second doped layer 103.

[0119] Please see Figure 3 In some embodiments, the back contact battery 100 is a gridless back contact battery. Among a plurality of first grid lines 20, the first collection grid line 21 is broken at the first series connection area 13 and continuous at the second series connection area 14, and the first bus grid line 22 is continuous at the first edge series connection area 131 and broken at the remaining first series connection areas 13, and continuous at the second series connection area 14.

[0120] like Figure 3 , Figure 4 as well as Figure 7 As shown, in some embodiments, the first grid line 20 (including the first collecting grid line 21 and the first bus grid line 22) includes a first welding segment 201 located within the second serial connection region 14, that is, the first grid line 20 is continuous at each of the second serial connection regions 14 and has a first welding segment 201 for welding with solder ribbon at the second serial connection region 14. The second grid line 30 (including the second collecting grid line 31 and the second bus grid line 32 hereinafter) includes a second welding segment 301 located within the first serial connection region 13 (including the first edge serial connection region 131), that is, the second grid line 30 is continuous at each of the first serial connection regions 13 and has a second welding segment 301 for welding with solder ribbon at the first serial connection region 13. A first auxiliary connection layer 80 is stacked on the second welding segment 301 located within the first edge serial connection region 131, and the height of the first insulating layer 50 is greater than the height of the second welding segment 301 in the thickness direction of the back contact battery 100. Thus, the first auxiliary connection layer 80 can enhance the welding performance between the second welding section 301 and the welding strip.

[0121] In some embodiments, in the first collecting grid line 21, the width (i.e., the length in the second direction) of the first welding segment 201 may be greater than the width of the remaining portion. This increases the contact area between the first collecting grid line 21 and the solder strip, improving welding stability.

[0122] In some embodiments, the first weld segment 201 may be a double-layer structure. Specifically, in some embodiments, the first gate line 20 may include a first collection layer that penetrates the back passivation film layer 104 and a first weld layer that is stacked on the first collection layer and does not penetrate the back passivation film layer 104.

[0123] In some embodiments, the first collection layer may be continuous at the second serial area 14 and discontinuous at the first serial area 13, and the first welding layer may be disposed at the second serial area 14 and located on the first collection layer. In such a case, the portion corresponding to the first welding layer in the first gate line 20 is the first welding segment 201.

[0124] Of course, in some other embodiments, the first welding segment 201 may be a single-layer structure. In this case, the first collecting layer is interrupted at both the second series connection area 14 and the first series connection area 13. The first welding layer is disposed at the second series connection area 14 and electrically connected to the two ends of the first collecting layer formed at the second series connection area 14. It is easy to understand that in these cases, the portion corresponding to the first welding layer is the first welding segment 201.

[0125] In some embodiments, the width of the first welding layer can be set to be greater than the width of the first collecting layer, where the width refers to the length of both in the second direction. This increases the welding area during welding and improves the reliability of the welding process.

[0126] In some embodiments, the second welding segment 301 may also be a double-layer structure. Specifically, in some embodiments, the second gate line 30 may include a second collection layer that penetrates the back passivation film layer 104 and a second welding layer that is stacked on the second collection layer but does not penetrate the back passivation film layer 104.

[0127] In some embodiments, the second collection layer may be continuous at the first serial area 13 and discontinuous at the second serial area 14, and the second welding layer may be disposed at the first serial area 13 and located on the second collection layer. In such a case, the portion corresponding to the second welding layer in the second gate line 30 is the second welding segment 301.

[0128] Of course, in other embodiments, the second collecting layer may also be interrupted at both the first series connection area 13 and the second series connection area 14, and the second welding layer is disposed at the first series connection area 13 and electrically connected to the two ends of the second collecting layer formed at the first series connection area 13. It is easy to understand that in these cases, the portion corresponding to the second welding layer is the second welding segment 301.

[0129] In some embodiments, the width of the second welding layer may also be set to be greater than the width of the second collecting layer, where the width refers to the length of both in the second direction. A first auxiliary connecting layer 80 is stacked on the second welding layer.

[0130] Please see Figures 3-6In some embodiments, the back contact battery 100 may further include a first auxiliary connection line 60, which may be disposed within the first edge serial connection area 131. In the second direction, at least one side of the first busbar 22 is provided with the first auxiliary connection line 60, and the first auxiliary connection line 60 connects at least two second grid lines 30 located on the same side of the first busbar 22. For example, Figure 4 and Figure 6 As shown, in some embodiments, preferably, at least two second gate lines 30 connected to the first auxiliary connection line 60 include a second gate line 30 adjacent to the first bus gate line 22 (i.e., Figure 3 and Figure 4 In some embodiments, the first auxiliary connection line 60 is preferably connected to the second gate line 30 closest to the first bus gate line 22, and the first auxiliary connection line 60 is also connected to at least one of the remaining second gate lines 30 located on the same side as the second gate line 30. That is, the first auxiliary connection line 60 is preferably connected to at least one of the second gate lines 30 adjacent to the first bus gate line 22 and at least one of the remaining second gate lines 30 on the same side.

[0131] Thus, by setting the first auxiliary connection line 60, the risk of poor soldering caused by the first insulating layer 50 can be further reduced. Even if poor soldering occurs between the second grid line 30 and the solder strip near the first insulating layer 50 due to the setting of the first insulating layer 50, the presence of the first auxiliary connection line 60 allows the poorly soldered second grid line 30 to still achieve current convergence output through the first auxiliary connection line 60, reducing the impact of poor soldering and thus ensuring the efficiency of the back contact battery 100.

[0132] like Figure 3 and Figure 4 As shown in the embodiments of this application, in order to minimize the impact of poor soldering, when there are second gate lines 30 on both sides of the first bus gate line 22, it is preferable to simultaneously provide a first auxiliary connection line 60 on both sides of the first bus gate line 22.

[0133] In some embodiments, the width of the first busbar 22 (i.e., its length in the second direction) may be greater than the width (i.e., its length in the second direction) of the portion of the first collection busbar 21 located outside the second serial area 14 (i.e., the portion of the first collection busbar 21 excluding the first welding segment 201).

[0134] Therefore, since the first bus gate 22 needs to undertake the function of bus transmission, setting the width of the first bus gate 22 to be wider can reduce transmission loss during the bus process and improve efficiency.

[0135] In addition, such as Figure 3 , Figure 4as well as Figure 7 As shown in the embodiments of this application, in the first busbar 22, it is continuous only at the first edge connection area 131, and broken at the other first connection areas 13. Simultaneously, the first busbar 22 is continuous at the second connection area 14 and has a first welded section 201 at the second connection area 14. Only the section of the first busbar 22 closest to the first edge 121 performs the busbar function. Therefore, in some embodiments, to save slurry and reduce costs, only this portion of the busbar segment can be made wider. In such cases, please refer to... Figure 3 , Figure 4 and Figure 7 The second concatenation areas 14 may include a second edge concatenation area 141 closest to the first edge 121. The first bus gate 22 may include a first bus segment 221 located between the second edge concatenation area 141 and the first edge 121. In some embodiments, the width (i.e., the length in the second direction) of the first bus segment 221 may be greater than the width of the remaining portion of the first bus gate 22 outside the second concatenation areas 14 (i.e., the portion other than the first weld segment 201 in the portion other than the first bus segment 221).

[0136] Thus, by simply widening the width of the first busbar 221, the amount of slurry used can be reduced while minimizing busbar transmission losses, thereby reducing costs.

[0137] Specifically, as described above, in such an embodiment, the first bus gate line 22 is continuous at the second edge series region 141 and has a first solder section 201 at the second edge series region 141. The first bus section 221 can channel current to the solder strip disposed at the second edge series region 141, and making only a portion of the first bus section 221 wider can reduce the amount of paste used. In this case, the first bus section 221 penetrates the back passivation film layer 104 and contacts the first doped layer 102.

[0138] Please see Figure 7 In other embodiments, a first bus layer 70 may be provided on the first bus segment 221. Thus, by providing the first bus layer 70 on the first bus segment 221, the cross-sectional area of ​​the first bus segment 221 is increased, which can also reduce transmission loss. At the same time, the first bus layer 70 can be made using a paste that is less expensive than the first bus segment 221, thereby reducing costs.

[0139] Specifically, in this embodiment, the first bus layer 70 can be made of a non-burn-through paste. The first bus layer 70 does not penetrate the back passivation film layer 104 and contact the first doped layer 102. The paste cost of the first bus layer 70 is lower than that of the first bus segment 221. It is understood that since the first bus layer 70 is provided on the first bus segment 221, it is not necessary to widen the first bus segment 221, and the purpose of reducing transmission loss can still be achieved.

[0140] Furthermore, in such an embodiment, the width (length in the second direction) of the first bus layer 70 may be greater than the width (length in the second direction) of the portion of the first collection gate line 21 located outside the second serial area 14 (i.e., the portion of the first collection gate line 21 excluding the first solder section 201). Thus, by increasing the width of the first bus layer 70, the transmission capacity can be further improved and the transmission loss reduced.

[0141] Specifically, in such an embodiment, the width of the first busbar 70 may be the same as the width of the first weld segment 201. In this document, the width of the first weld segment 201 refers to its length in the second direction. As shown above, when the width of the first weld layer is greater than the width of the first collection layer, the width of the first weld segment 201 is the width of the first weld layer (i.e., its length in the second direction). Similar descriptions will appear below and can be understood by referring to this document.

[0142] This ensures that there will be no significant transmission loss during the convergence process. Simultaneously, during printing, the first convergence layer 70 can be printed simultaneously with the first welding layer at the first welding section 201. When using the same screen printing plate, there is no need to create screen slots of different sizes on the screen, saving manufacturing steps and reducing manufacturing difficulty.

[0143] Please see Figure 7 In some embodiments, the width (length in the first direction) of the first edge bus 40 is greater than the width (length in the second direction) of the portion of the first collection grid line 21 located outside the second serial area 14 (i.e., the portion of the first collection grid line 21 excluding the first welding segment 201).

[0144] Therefore, since the first edge bus line 40 needs to undertake the function of bus transmission, setting the width of the first edge bus line 40 to be wider can also reduce transmission loss during the bus process and improve efficiency.

[0145] Specifically, in such an embodiment, the width of the first edge busbar 40 can be the same as the width of the first welding segment 201. This ensures that there is no significant busbar loss during the busbar process. Furthermore, during printing, only screen slots of the same size need to be created on the screen to print all three components simultaneously, effectively saving manufacturing steps and reducing manufacturing difficulty.

[0146] In addition, please continue to refer to Figure 7 In some embodiments, the width (length in the first direction) of the first auxiliary connection line 60 is greater than the width (length in the second direction) of the portion of the first collection grid line 21 located outside the second serial area 14 (i.e., the portion of the first collection grid line 21 excluding the first welding segment 201).

[0147] Thus, since the first auxiliary connection line 60 serves to transmit and combine current when a cold solder joint occurs, setting the width of the first auxiliary connection line 60 to be wider can also reduce transmission loss during the current combining process and improve efficiency.

[0148] In some embodiments, the width of the first auxiliary connecting line 60 may be the same as the width of the first edge bus line 40.

[0149] Please see Figure 3 and Figure 4 In some embodiments, the first edge bus 40 is electrically connected to all the first collection grid lines 21.

[0150] In this way, the current collected by the isolated grid segments located between the first edge series region 131 and the first edge 121 in all the first collection grid lines 21 can be combined, thereby maximizing the efficiency of the back contact battery 100.

[0151] Of course, in some embodiments, the first edge bus 40 may only be electrically connected to a portion of the first collection grid lines 21. In such cases, the number of first collection grid lines 21 not electrically connected to the first edge bus 40 is less than or equal to four. Thus, even if some of the first collection grid lines 21 are not connected to the first edge bus 40, their number is very small and will not cause excessive efficiency loss or product defects.

[0152] In some embodiments, the first auxiliary connection line 60 connects 2 to 20 second gate lines 30. By setting the number of second gate lines 30 connected to the first auxiliary connection line 60 within this reasonable range, the impact of poor soldering can be minimized or even eliminated.

[0153] In embodiments of this application, the number of first bus gate lines 22 may be a single line. In such cases, the first auxiliary connecting line 60 may be provided only on one side of the first bus gate line 22, or the first auxiliary connecting line 60 may be provided on both sides of the first bus gate line 22; the specific method is not limited here. When the first bus gate line 22 has second gate lines 30 on both sides, it is preferable to provide the first auxiliary connecting line 60 on both sides.

[0154] Furthermore, it should be noted that in this application, when there are multiple first busbars 22, the first auxiliary connecting line 60 may only be provided on one or both sides of some of the first busbars 22, while the first auxiliary connecting line 60 may not be provided on both sides of the remaining first busbars 22. In this case, the problem of cold solder joints in some locations can still be solved. In this application, it is preferable that the first auxiliary connecting line 60 is provided on both sides of each first busbar 22. Of course, if the first busbar 22 is located at the third edge 123, then the first auxiliary connecting line 60 only needs to be provided on one side of the first busbar 22.

[0155] Of course, please see Figure 3 and Figure 4 In some embodiments, the number of first bus gate lines 22 can also be multiple. Setting multiple first bus gate lines 22 can shorten the current bus path, effectively reduce bus transmission loss, and improve efficiency.

[0156] In this case, a first auxiliary connecting line 60 is provided between each two adjacent first busbars 22, and the first auxiliary connecting line 60 located between two adjacent first busbars 22 connects all the second busbars 30 located between two adjacent first busbars 22.

[0157] In this way, by connecting the first auxiliary connection line 60 to all the second grid lines 30 between two adjacent first busbar lines 22, the influence of poor soldering can be basically completely eliminated, and the efficiency of the back contact battery 100 can be improved as much as possible.

[0158] Specifically, in such an embodiment, the number of first busbars 22 in the back contact battery 100 can be selected according to the actual situation such as the size of the battery cell and the loss during transmission, and is not limited here.

[0159] Please see Figure 3 and Figure 4 as well as Figure 10 and Figure 11In some embodiments, there are multiple first bus gate lines 22, and the substrate 10 has a third edge 123 and a fourth edge 124 in the second direction. Among the first gate line 20 and the second gate line 30, the gate line closest to the third edge 123 is the first bus gate line 22, and / or the gate line closest to the fourth edge 124 is the first bus gate line 22.

[0160] Thus, by setting the gate lines located at the third edge 123 and / or the fourth edge 124 as the first bus gate lines 22, current can be bused at the edge positions, and the range affected by poor soldering can also be reduced.

[0161] Specifically, such as Figure 3 and Figure 4 As shown, in such an embodiment, in addition to the first busbar 22 at the third edge 123 and / or the fourth edge 124, a plurality of first busbar 22 can be provided in the middle region. A first auxiliary connecting line 60 is provided between each two adjacent first busbar 22, and the first auxiliary connecting line 60 connects all the second grid lines 30 between the two adjacent first busbar 22. This can basically completely eliminate the influence caused by poor soldering and maximize the efficiency of the back contact battery 100.

[0162] Of course, it is understood that in some embodiments, among the first grid line 20 and the second grid line 30, the grid line closest to the third edge 123 can also be the first collecting grid line 21. In such a case, the first auxiliary connecting line 60 between the first bus grid line 22 closest to the third edge 123 and the third edge 123 and all the second grid lines 30 between the first bus grid line 22 closest to the third edge 123 and the third edge 123 are connected, that is, the first auxiliary connecting line 60 between the first bus grid line 22 closest to the third edge 123 and the third edge 123 is connected, that is, the first auxiliary connecting line 60 between the first bus grid line 22 closest to the third edge 123 and the third edge 123 is connected, that is, the first auxiliary connecting line 60 between the first bus grid line 22 closest to the third edge 123 and the third edge 123 is connected, that is, the first auxiliary connecting line 60 between the first bus grid line 22 closest to the third edge 123 and the third edge 123 is connected, that is, the first auxiliary connecting line 60 between the first auxiliary connecting line 2 ... Figure 3 and Figure 4 The first busbar 22, which is closest to the third edge 123, is changed to the first collection bar 21.

[0163] In some embodiments, among the first grid line 20 and the second grid line 30, the grid line closest to the fourth edge 124 may also be the first collecting grid line 21. The first auxiliary connecting line 60 between the first bus grid line 22 closest to the fourth edge 124 and the fourth edge 124 and all the second grid lines 30 between the first bus grid line 22 closest to the fourth edge 124 and the fourth edge 124 are connected, that is, the grid line 21 is connected to the first bus grid line 22 closest to the fourth edge 124 and the fourth edge 124. Figure 3 and Figure 4 The first busbar 22, which is closest to the third edge 123, is changed to the first collection bar 21.

[0164] Thus, by setting the grid line closest to the third edge 123 and / or the fourth edge 124 as the first collecting grid line 21, and setting the first bus grid line 22 only in the middle region, it is unnecessary to set the first insulating layer 50 at the positions of the third edge 123 and the fourth edge 124, reducing the use of insulating adhesive and lowering costs. At the same time, by making the above-described connection arrangement between the first bus grid line 22 closest to the third edge 123 and the first auxiliary connecting line 60, the effect of poor soldering caused by the first insulating layer 50 can also be almost completely eliminated.

[0165] Please see Figure 7 and 8 As described above, the first gate line 20 may include a first welding segment 201 corresponding to the second serial connection area 14, and the second gate line 30 may include a second welding segment 301 corresponding to the first edge serial connection area 131.

[0166] In some embodiments, a first groove 15 is formed on the substrate 10 within the first edge serialization region 131, a first busbar 22 is partially located within the first groove 15, and a first insulating layer 50 is at least partially disposed within the first groove 15.

[0167] Thus, by forming a first groove 15 on the substrate 10 and placing the first insulating layer 50 inside the groove, the height of the first insulating layer 50 can be reduced, thereby controlling the thickness of the first auxiliary connecting layer 80 within a smaller range, reducing the use of paste, and lowering costs.

[0168] In some embodiments, the first groove 15 may penetrate the back passivation film layer 104 and the first doped layer 102, so that the silicon substrate 101 is exposed from the first groove 15, and the portion of the first bus gate line 22 located in the first groove 15 contacts the silicon substrate 101. In this way, the first groove 15 can be directly formed on the substrate 10 by etching (e.g., laser etching) after the substrate 10 is fabricated, without the need to insert an etching and grooving process during the fabrication of the substrate 10.

[0169] Specifically, in this case, a complete substrate 10 can be provided first, and then a groove can be made directly on the substrate 10 at the position where the first insulating layer 50 needs to be placed. Then, the first grid line 20 and the second grid line 30 are printed, and the first insulating layer 50 is set at the first groove 15.

[0170] Of course, in other embodiments, a first recessed groove may be formed on the silicon substrate 101 at the position corresponding to the first edge serial area 131 and the first bus gate line 22. The first doped layer 102 and the back passivation film layer 104 are both recessed at the first recessed groove toward the side where the front side 11 is located, so as to form a first groove 15 on the substrate 10.

[0171] Specifically, in this case, during the fabrication process, before preparing the first doped layer 102, a first recessed groove can be formed in the silicon substrate 101 at the location where the first doped layer 102 needs to be prepared and the first insulating layer 50 needs to be placed. Then, the first doped layer 102 and the back passivation film layer 104 are prepared to form the substrate 10. Since the first recessed groove is provided on the silicon substrate 101, the first groove 15 mentioned above can be formed on the substrate 10. Then, the first gate line 20 and the second gate line 30 are printed, and the first insulating layer 50 is placed at the first groove 15.

[0172] Please see Figure 4 and Figure 10 In some embodiments, the substrate 10 has a third edge 123 and a fourth edge 124 in a second direction. At the junction of the first gate line 20 closest to the third edge 123 and the first edge bus line 40, the first edge bus line 40 has a first protrusion 41 protruding toward the third edge 123.

[0173] Please see Figure 4 and Figure 11 In some embodiments, at the junction of the first gate line 20 closest to the fourth edge 124 and the first edge bus line 40, the first edge bus line 40 has a second protrusion 42 that protrudes toward the fourth edge 124.

[0174] Thus, the arrangement of the first protrusion 41 and the second protrusion 42 can provide redundancy for the first edge bus line 40 at the corner of the back contact battery 100 located at the first edge 121, avoiding the inaccuracy of printing during the printing process, which would cause the paste to fail to form a complete fill at the corner, resulting in poor contact between the first edge bus line 40 and the first grid line 20 closest to the third edge 123.

[0175] Specifically, in some embodiments, the first grid line 20 closest to the third edge 123 and the first grid line 22 closest to the fourth edge 124 can be the first bus grid line 22. In this case, when the first bus layer 70 is provided on the first bus grid line 22, the first edge bus line 40 and the first bus layer 70 can be directly printed integrally. The first protrusion 41 and the second protrusion 42 at the intersection of the two can ensure the integrity of the printing and filling and ensure that the two form good contact.

[0176] In addition, such as Figure 10 and Figure 11 As shown, in some embodiments, in the back contact battery 100, chamfers are formed at the intersections of the first edge 121, the third edge 123, and the fourth edge 124, and the first grid line 20 is provided at the corresponding chamfer locations. Therefore, as Figure 10 and Figure 11As shown, in order to connect the first edge busbar 40 to the first grid line 20, the first edge busbar 40 has bends at both chamfers. Of course, it is understood that in some embodiments, if the back contact battery 100 does not have chamfers, then there is no need to provide bends.

[0177] Please see Figure 10 and Figure 11 In some embodiments, at the junction of the first grid line 20 (including the first collection grid line 21 and the first bus grid line 22) and the first edge bus line 40, at least a portion of the first grid line 20 has a first grid line protrusion 202 that protrudes toward the first edge 121 relative to the first edge bus line 40.

[0178] Thus, by setting the first grid line protrusion 202, the stability of the electrical connection between the first grid line 20 and the first edge bus line 40 can be guaranteed, effectively avoiding the phenomenon that some of the first grid lines 20 cannot form a stable contact with the first edge bus line 40 due to printing accuracy issues during the printing process.

[0179] Please see Figure 3 , Figure 4 and Figure 7 In some embodiments, a plurality of second serial connection areas 14 include a second edge serial connection area 141 closest to the first edge 121 (i.e., a second serial connection area 14 adjacent to the first edge serial connection area 131), the first grid line 20 is continuous at the second edge serial connection area 141, the second grid line 30 is discontinuous at the second edge serial connection area 141, and the back contact battery 100 also includes a second auxiliary connection line 90 disposed within the second edge serial connection area 141. In a second direction, the second auxiliary connection line 90 connects the first bus grid line 22 and at least one first collection grid line 21 located on one side of the first bus grid line 22.

[0180] Thus, by setting a second auxiliary connection line 90 in the second edge series connection area 141, the phenomenon that the current transmitted from the first busbar 22 cannot be collected can be effectively avoided by the solder strip in the second edge series connection area 141 having poor soldering or contact at the first busbar 22.

[0181] Specifically, such as Figure 4 and Figure 7 As shown, in such an embodiment, the number of second auxiliary connecting lines 90 can be the same as the number of first busbars 22, and the two correspond one-to-one. When the first busbar 22 is in the middle position (i.e., there are first collection lines 21 on both sides of the first busbar 22), the second auxiliary connecting lines 90 connect the first busbar 22, and also connect the two first collection lines 21 adjacent to the first busbar 22 (i.e., the first collection lines 21 located on both sides of the first busbar 22 and adjacent to it).

[0182] When the grid line closest to the third edge 123 is the first bus grid line 22, this first bus grid line 22 has a first collection grid line 21 on only one side. In this case, the second auxiliary connecting line 90 connected to the first bus grid line 22 located at the third edge 123 connects to at least the first collection grid line 21 adjacent to the first bus grid line 22. The number of first collection grid lines 21 connected by the second auxiliary connecting line 90 is 1-6. For example, in Figure 3 and Figure 4 In this context, the second auxiliary connection line 90 connects to the six first collection grid lines 21 closest to the third edge 123, and the specific connection is not limited here.

[0183] Similarly, when the grid line closest to the fourth edge 124 is the first busbar 22, this first busbar 22 has a first collection grid line 21 on only one side. In this case, the second auxiliary connecting line 90 connected to the first busbar 22 located at the fourth edge 124 connects at least the first collection grid line 21 adjacent to the first busbar 22, and the number of first collection grid lines 21 connected by the second auxiliary connecting line 90 is 1-6. For example, in Figure 3 and Figure 4 In this context, the second auxiliary connection line 90 connects to the six first collection grid lines 21 closest to the fourth edge 124, and the specific connection is not limited here.

[0184] In some embodiments, the width (length in the first direction) of the second auxiliary connection line 90 may be greater than the width (length in the second direction) of the portion of the first collecting grid line 21 located outside the second serial connection area 14 (i.e., the portion of the first collecting grid line 21 excluding the first solder section 201). Thus, since the second auxiliary connection line 90 serves to transmit and combine current when a poor solder joint occurs at the first bus grid line 22, setting the width of the second auxiliary connection line 90 wider can also reduce transmission losses during the current combining process and improve efficiency.

[0185] In some embodiments, the distance between the first edge concatenation area 131 and the first edge 121 is greater than or equal to 2 mm and less than or equal to 20 mm.

[0186] This avoids the situation where the distance between the first edge serial connection area 131 and the first edge 121 is too small, causing the welding position to be too close to the first edge 121 and resulting in microcracks in the back contact battery 100, thus reducing the risk of microcracks. It also avoids the situation where the distance between the first edge serial connection area 131 and the first edge 121 is too large, resulting in excessively long isolated grid line segments between the first edge serial connection area 131 and the first edge 121, leading to excessive losses during the transmission path.

[0187] Specifically, in such an embodiment, the distance between the first edge connecting area 131 and the first edge 121 can be, for example, any value between 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm or 2mm-20mm, and is not limited here.

[0188] Please see Figure 3 as well as Figures 12-15 In some embodiments, a plurality of second concatenation areas 14 include a third edge concatenation area 142 closest to the second edge 122, wherein there is no first concatenation area 13 between the third edge concatenation area 142 and the second edge 122, that is, as Figure 3 and Figure 12 As shown, in the first serial connection area 13 and the second serial connection area 14, the serial connection area closest to the second edge 122 is the second serial connection area 14, and the second serial connection area 14 is referred to as the third edge serial connection area 142. There are no other serial connection areas between the third edge serial connection area 142 and the second edge 122.

[0189] The plurality of second grid lines 30 include a plurality of second collection grid lines 31 and at least one second bus grid line 32, wherein the second collection grid lines 31 are discontinuous at the third edge concatenation region 142 and continuous at the first concatenation region 13, the second bus grid line 32 is continuous at the third edge concatenation region 142, and the first grid line 20 is continuous at the second edge concatenation region 141.

[0190] That is, the second grid line 30 includes at least two types of grid lines: a second collection grid line 31 and a second bus grid line 32. The second collection grid line 31 is discontinuous at the third edge concatenation area 142, while the second bus grid line 32 is continuous at the third edge concatenation area 142. The first grid line 20 is also continuous at the third edge concatenation area 142.

[0191] The back contact battery 100 also includes a second edge bus 110, a second insulating layer 120, and a second auxiliary connection layer 150. The second edge bus 110 is closer to the second edge 122 than the third edge series region 142. The second edge bus 110 is electrically connected to at least a portion of the second collection grid line 31 and to the second bus grid line 32. Specifically, to avoid microcracks in the battery caused by welding at the edge of the second edge 122, the second edge bus 110 is not used for welding. It is used to collect the current in the portion of the second collection grid line 31 located between the third edge series region 142 and the second edge 122, and then converges through the second bus grid line 32 to the first series region 14 adjacent to the third edge series region 142 (i.e.,...). Figure 3 and Figure 12On the same polarity solder strip in the first series area 14) on the rightmost side, the current of the grid line segment in the edge region of the second grid line 30 located at the second edge 122 is collected, thereby improving the efficiency of the back contact battery 100. If the second edge bus line 110 and the second bus grid line 32 are not provided, the part of the second grid line 30 located between the third edge series area 142 and the second edge 122 will form an isolated grid line segment, and the current in this part cannot be collected.

[0192] The second insulating layer 120 is disposed in the third edge series region 142 and located on the second busbar 32. That is, the second insulating layer 120 is provided on the portion of the second busbar 32 corresponding to the third edge series region 142. The second insulating layer 120 is provided to insulate and separate the opposite polarity solder strip in the third edge series region 142 from the second busbar 32 to avoid short circuit.

[0193] At the third edge serial connection area 142, a second auxiliary connection layer 150 may be disposed on the first grid line 20. The second auxiliary connection layer 150 is disposed on the portion of the first grid line 20 corresponding to the third edge serial connection area 142. The second auxiliary connection layer 150 is used for welding with the solder strip. In the thickness direction of the back contact battery 100, the second insulating layer 120 is flush with the second auxiliary connection layer 150, or the height of the second insulating layer 120 is less than the height of the second auxiliary connection layer 150, or the height difference between the second insulating layer 120 and the second auxiliary connection layer 150 is less than or equal to 15 μm.

[0194] Thus, by setting the second edge bus line 110 and the second bus grid line 32, the current collected by at least a portion of the isolated segment of the second grid line 30 located between the third edge series region 142 and the second edge 122 can be channeled to the same polarity solder strip within the second series region 14 adjacent to the third edge series region 142. This effectively avoids microcracks caused by soldering at the second edge 122 of the back contact battery 100 while ensuring the efficiency of the back contact battery 100. Simultaneously, by setting the second auxiliary connection layer 150 on the portion corresponding to the second grid line 30 and the third edge series region 142, such that the height of the second insulating layer 120 is less than the height of the second auxiliary connection layer 150, or the second insulating layer 120 is flush with the second auxiliary connection layer 150, or the height of the second insulating layer 120 is greater than the second auxiliary connection layer 150 and the height difference between them is less than or equal to 15µm, the impact of the second insulating layer 120 on the back contact battery 100 is reduced or even eliminated, thereby improving the performance and efficiency of the back contact battery 100.

[0195] Specifically, as shown above, it is easy to understand that in this application, the second edge bus 110 is not used for welding; it is only used for current transmission and merging. The function of the second bus grid 32 is to collect and transmit current. Figure 3 and Figure 4 It can be seen that, in Figure 3 and Figure 4 In the example shown, if the second edge bus 110 and the second bus gate 32 are not provided, the second gate 30 is disconnected at the third edge cascading region 142. The current of the portion of the gate line segment of the second gate 30 located between the third edge cascading region 142 and the second edge 122 cannot be collected. Therefore, by providing the second edge bus 110 and the second bus gate 32, the current of at least a portion of the isolated gate line segment of the second gate 30 located in the edge region can be bused and transmitted to the solder strip provided in the adjacent first cascading region 13, thereby effectively avoiding efficiency loss.

[0196] Because the second busbar 32 is continuously arranged in the third edge serial connection area 142, a second insulating layer 120 (e.g., insulating adhesive) is required at the position corresponding to the second busbar 32 and the third edge serial connection area 142 to prevent short circuits caused by contact between the solder strip on the third edge serial connection area 142 and the second busbar 32. However, in this case, without the second auxiliary connection layer 150, the height of the second insulating layer 120 is greater than the height of the portion of the second busbar 30 located in the third edge serial connection area 142. That is, in the thickness direction, the protrusion height of the second insulating layer 120 is greater than the height of the second busbar 30. In this case, the solder strip in the third edge serial connection area 142 will short circuit during the soldering process. It is easy for cold solder joints to occur with the second grid line 30, resulting in the current on some of the second grid line 30 not being effectively collected (especially the second grid line 30 adjacent to the second bus grid line 32, which is most likely to have cold solder joints). Based on this, this application provides a second auxiliary connection layer 150 on the portion of the second grid line 30 corresponding to the third edge series connection area 142, so that the height of the second insulating layer 120 is flush with or less than the height of the second auxiliary connection layer 150, or the height between the second insulating layer 120 and the second auxiliary connection layer 150 is less than 15um. This can reduce or even eliminate the risk of cold solder joints, thereby improving the reliability of the welding and ensuring the performance of the back contact battery 100.

[0197] When the height of the second insulating layer 120 is greater than the height of the second auxiliary connecting layer 150, the height difference between the two can be any value between 1um, 2um, 3um, 4um, 5um, 9um, 7um, 8um, 9um, 10um, 11um, 12um, 13um, 14um, 15um or 0-15um.

[0198] In some embodiments, when the height of the second insulating layer 120 is greater than the height of the second auxiliary connection layer 150, the height difference between the second insulating layer 120 and the second auxiliary connection layer 150 is preferably less than 8 μm, for example, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 9 μm, 7 μm, or 8 μm. Specifically, through repeated research and verification by the inventors of this application, it has been found that by preferably setting the height difference between the two within the preferred range of less than 8 μm, the risk of poor soldering caused by the second insulating layer 120 can be substantially eliminated.

[0199] In some embodiments, a second auxiliary connection layer 150 is stacked on the first welding segment 201 located within the third edge serial connection area 142, and the height of the second insulating layer 120 is greater than the height of the first welding segment 201 in the thickness direction of the back contact battery 100. Thus, the provision of the second auxiliary connection layer 150 can enhance the welding performance between the first welding segment 201 and the solder strip.

[0200] Furthermore, in some embodiments, the specific structure of the first gate line 20 is as described above, which may include a second collection layer and a second welding layer, which will not be elaborated here. In such embodiments, the second auxiliary connection layer 150 may be stacked on the first welding layer.

[0201] Please see Figure 3 as well as Figures 12-15 In some embodiments, the back contact battery 100 may further include a third auxiliary connection line 130 disposed within the third edge serial connection area 142. In the second direction, at least one side of the second busbar 32 is provided with the third auxiliary connection line 130, and the third auxiliary connection line 130 connects at least two first grid lines 20 located on the same side of the second busbar 32. In some embodiments, preferably, the at least two first grid lines 20 connected to the third auxiliary connection line 130 include the first grid line 20 adjacent to the second busbar 32 (i.e.,...). Figure 3 and Figure 10 The first gate line 20 closest to the second bus gate 32. That is, in some embodiments, the third auxiliary connection line 130 is preferably connected to the first gate line 20 closest to the second bus gate 32, and the third auxiliary connection line 130 is also connected to at least one of the remaining first gate lines 20 located on the same side as the second gate line 30. That is, the third auxiliary connection line 130 is preferably connected to at least one of the first gate lines 20 adjacent to the second bus gate 32 and at least one of the remaining first gate lines 20 on the same side.

[0202] Thus, by setting the third auxiliary connection line 130, the risk of poor soldering caused by the second insulating layer 120 can be further reduced. Even if poor soldering occurs between the first grid line 20 and the solder strip near the second insulating layer 120 due to the setting of the second insulating layer 120, the presence of the third auxiliary connection line 130 allows the poorly soldered first grid line 20 to achieve current convergence output through the third auxiliary connection line 130, reducing the impact of poor soldering and thus ensuring the efficiency of the back contact battery 100.

[0203] Please see Figure 3 and Figure 12 In some embodiments, the back contact battery 100 is a gridless back contact battery. Among a plurality of second grid lines 30, the second collection grid line 31 is interrupted at the second series connection area 14 and continuous at the first series connection area 13, and the second bus grid line 32 is continuous at the third edge series connection area 142 and interrupted at the remaining second series connection areas 14, and continuous at the first series connection area 13.

[0204] like Figure 3 and Figure 12 As shown in the embodiments of this application, in order to minimize the impact of poor soldering, when the first grid line 20 is provided on both sides of the second bus grid line 32, it is preferable to simultaneously provide a third auxiliary connection line 130 on both sides of the second bus grid line 32.

[0205] In some embodiments, the second grid line 30 has a second welding segment 301, the structure of which has been described above and will not be repeated here. In some embodiments, in the second collecting grid line 31, the width (i.e., the length in the second direction) of the second welding segment 301 may be greater than the width of the remaining portion. In this way, the contact area between the second collecting grid line 31 and the solder strip can be increased, thereby improving the stability of the welding process.

[0206] In some embodiments, the width of the second busbar 32 (i.e., its length in the second direction) may be greater than the width (i.e., its length in the second direction) of the portion of the second collection busbar 31 located outside the first serial area 13 (i.e., the portion of the second collection busbar 31 excluding the second welding segment 301).

[0207] Therefore, since the second bus gate 32 needs to undertake the function of bus transmission, setting the width of the second bus gate 32 to be wider can reduce transmission loss during the bus process and improve efficiency.

[0208] Furthermore, in embodiments of this application, the second busbar 32 is continuous only at the third edge junction area 142, and broken at the other second junction areas 14. Simultaneously, the second busbar 32 is continuous at the first junction area 13 and has a second welded segment 301 at the first junction area 13. Only the segment of the second busbar 32 closest to the first edge 121 performs the busbar function. Therefore, in some embodiments, to save slurry and reduce costs, only this portion of the busbar segment can be made wider. In such cases, please refer to... Figure 3 , Figure 12 and Figure 15 The first cascading regions 13 may include a fourth edge cascading region 132 closest to the first edge 121. The second busbar 32 may include a second bus segment 321 located between the fourth edge cascading region 132 and the first edge 121, the width of the second bus segment 321 (i.e., its length in the second direction) being greater than the width of the remaining portion of the second busbar 32 outside the first cascading regions 13 (i.e., the portion of the second busbar 32 excluding the second bus segment 321 and the second welded segment 301).

[0209] Thus, by simply making the width of the second busbar 321 wider, the amount of slurry used can be reduced while reducing busbar transmission loss, thereby reducing costs.

[0210] Specifically, as described above, in such an embodiment, the second bus gate line 32 is continuous at the fourth edge series region 132 and has a second solder section 301 at the fourth edge series region 132. The second bus section 321 can channel current to the solder strip provided at the fourth edge series region 132, and making only a portion of the second bus section 321 wider can reduce the amount of paste used. In this case, the second bus section 321 penetrates the back passivation film layer 104 and contacts the second doped layer 103.

[0211] Please see Figure 15 In other embodiments, a second bus layer 140 may be provided on the second bus section 321. Thus, by providing a second bus layer 140 on the second bus section 321, the cross-sectional area of ​​the second bus section 321 is increased, which can also reduce transmission losses. At the same time, the second bus layer 140 can be made using a lower-cost paste than the second bus section 321, which can reduce costs.

[0212] Specifically, in this embodiment, the second bus layer 140 can be made of a non-burn-through paste. The second bus layer 140 does not penetrate the back passivation film layer 104 and contact the first doped layer 102. The paste cost of the second bus layer 140 is lower than that of the second bus segment 321. It is understood that since the second bus segment 321 is provided with the second bus layer 140, it is not necessary to widen the second bus segment 321, and the purpose of reducing transmission loss can still be achieved.

[0213] Furthermore, in such an embodiment, the width (length in the second direction) of the second bus layer 140 may be greater than the width (length in the second direction) of the portion of the second collection gate line 31 located outside the first serial area 13 (i.e., the portion of the second collection gate line 31 excluding the second solder section 301). Thus, by increasing the width of the second bus layer 140, the transmission capacity can be further improved and the transmission loss reduced.

[0214] Specifically, in such an embodiment, the width of the second busbar layer 140 may be the same as the width of the second weld segment 301. Hereinafter, the width of the second weld segment 301 refers to its length in the second direction. As shown above, when the width of the second weld layer is greater than the width of the second collection layer, the width of the second weld segment 301 is the width of the second weld layer (i.e., its length in the second direction). Similar descriptions will appear below and can be understood here. Hereinafter, the width of the second weld segment 301 may be the same as the width of the first weld segment 201.

[0215] This ensures that there will be no significant transmission loss during the busbar process. Furthermore, during printing, the second busbar layer 140 can be printed simultaneously with the first welding layer. When using the same screen printing plate, there is no need to create screen slots of different sizes on the screen, saving manufacturing steps and reducing manufacturing difficulty.

[0216] Please see Figure 15 In some embodiments, the width (length in the first direction) of the second edge bus 110 is greater than the width (length in the second direction) of the portion of the second collection grid 31 located outside the first serial area 13 (i.e., the portion of the second collection grid 31 excluding the second welded section 301).

[0217] Therefore, since the second edge bus line 110 needs to undertake the function of bus transmission, setting the width of the second edge bus line 110 to be wider can also reduce transmission loss during the bus process and improve efficiency.

[0218] Specifically, in such an embodiment, the width of the second edge busbar 110 can be the same as the width of the second welding section 301. This ensures that there is no significant busbar loss during the busbar process. Furthermore, during printing, only screen slots of the same size need to be created on the screen to print all three components simultaneously, effectively saving manufacturing steps and reducing manufacturing difficulty.

[0219] In addition, please continue to refer to Figure 15 In some embodiments, the width (length in the first direction) of the third auxiliary connection line 130 is greater than the width (length in the second direction) of the portion of the second collection grid line 31 located outside the first serial area 13 (i.e., the portion of the second collection grid line 31 excluding the second welding segment 301).

[0220] Thus, since the third auxiliary connection line 130 serves to transmit and combine current when a cold solder joint occurs, making the width of the third auxiliary connection line 130 wider can reduce transmission losses during the current combining process and improve efficiency.

[0221] In some embodiments, the width of the third auxiliary connection line 130 may be the same as the width of the second edge bus line 110.

[0222] Please see Figure 3 and Figure 12 In some embodiments, the second edge bus 110 is electrically connected to all the second collection grid lines 31. In this way, the current collected by the isolated grid line segments located between the third edge series region 142 and the second edge 122 in all the second collection grid lines 31 can be combined, maximizing the efficiency of the back contact battery 100.

[0223] Of course, in some embodiments, the second edge bus 110 may also be electrically connected to some of the second collection grid lines 31. In such cases, the number of second collection grid lines 31 not electrically connected to the second edge bus 110 is less than or equal to four. Thus, even if some of the second collection grid lines 31 are not connected to the second edge bus 110, their number is very small and will not cause excessive efficiency loss or product defects.

[0224] In some embodiments, the third auxiliary connection line 130 connects 2 to 20 first gate lines 20. Thus, by setting the number of first gate lines 20 connected to the third auxiliary connection line 130 within this reasonable range, the impact of poor soldering can be minimized or even eliminated.

[0225] In embodiments of this application, the number of second bus gate lines 32 may be a single line. In such cases, the third auxiliary connecting line 130 may be provided only on one side of the second bus gate line 32, or the third auxiliary connecting line 130 may be provided on both sides of the second bus gate line 32; the specific provision is not limited here. When the second bus gate line 32 has first gate lines 20 on both sides, it is preferable to provide the third auxiliary connecting line 130 on both sides.

[0226] Furthermore, it should be noted that in this application, when there are multiple second busbars 32, the third auxiliary connecting line 130 may be provided only on one or both sides of some of the second busbars 32, while the third auxiliary connecting line 130 may not be provided on both sides of the remaining second busbars 32. In this case, the problem of cold solder joints in some locations can still be solved. In this application, it is preferable that the third auxiliary connecting line 130 is provided on both sides of each second busbar 32.

[0227] Of course, please see Figure 3 and Figure 15 In some embodiments, the number of second bus gate lines 32 can also be multiple. Setting multiple second bus gate lines 32 can shorten the current bus path, effectively reduce bus transmission loss, and improve efficiency.

[0228] In this case, a third auxiliary connection line 130 is provided between each of the two adjacent second busbars 32, and the third auxiliary connection line 130 located between the two adjacent second busbars 32 connects all the first grid lines 20 located between the two adjacent second busbars 32.

[0229] In this way, by connecting the third auxiliary connection line 130 to all the first grid lines 20 between two adjacent second bus grid lines 32, the influence of poor soldering can be basically completely eliminated, and the efficiency of the back contact battery 100 can be improved as much as possible.

[0230] Of course, in some alternative embodiments, the third auxiliary connection line 130 may be provided only on one side of the second bus gate line 32, and there is no specific limitation here.

[0231] Specifically, in such an embodiment, the number of second busbars 32 in the back contact battery 100 can be selected according to the actual situation such as the size of the battery cell and the loss during transmission, and is not limited here.

[0232] Please refer to the figure. Figure 3 and Figure 12 as well as Figure 18 and Figure 19In some embodiments, there are multiple second bus gate lines 32, and the substrate 10 has a third edge 123 and a fourth edge 124 in the second direction. Among the second gate lines 30 and the first gate lines 20, the gate line closest to the third edge 123 may be the first gate line 20, and a third auxiliary connecting line 130 between the second bus gate line 32 closest to the third edge 123 and the third edge 123 connects all the first gate lines 20 between the second bus gate line 32 closest to the third edge 123 and the third edge 123.

[0233] In the second grid line 30 and the first grid line 20, the grid line closest to the fourth edge 124 can also be the first grid line 20. The third auxiliary connecting line 130 between the second bus grid line 32 closest to the fourth edge 124 and the fourth edge 124 connects all the first grid lines 20 between the second bus grid line 32 closest to the fourth edge 124 and the fourth edge 124.

[0234] Thus, by making the above-described connection arrangement between the second busbar 32 closest to the third edge 123 and the third auxiliary connection line 130 between the third edge 123, the effect of poor soldering caused by the second insulating layer 120 can be basically completely eliminated.

[0235] Please see Figure 15 and Figure 16 As described above, the first gate line 20 may include a first welding segment 201 corresponding to the second serial connection area 14, and the second gate line 30 may include a second welding segment 301 corresponding to the first edge serial connection area 131.

[0236] In some embodiments, a second groove 16 is formed on the substrate 10 within the third edge serialization region 142, a second busbar 32 is partially located within the second groove 16, and a second insulating layer 120 is at least partially disposed within the second groove 16.

[0237] Thus, by forming a second groove 16 on the substrate 10 and placing the second insulating layer 120 inside the groove, the height of the second insulating layer 120 can be reduced, thereby controlling the thickness of the second auxiliary connecting layer 150 within a smaller range, reducing the amount of paste used, and lowering costs.

[0238] In some embodiments, the second groove 16 may penetrate the back passivation film layer 104 and the second doped layer 103, so that the silicon substrate 101 is exposed from the second groove 16, and the portion of the first bus gate line 22 located within the second groove 16 contacts the silicon substrate 101. Thus, after the substrate 10 is fabricated, the second groove 16 can be directly formed on the substrate 10 by etching (e.g., laser etching), without needing to insert an etching and grooving process during the fabrication of the substrate 10.

[0239] Specifically, in this case, a complete substrate 10 can be provided first, and then a groove can be made directly on the substrate 10 at the position where the second insulating layer 120 needs to be placed. Then, the first grid line 20 and the second grid line 30 are printed, and then the second insulating layer 120 is set at the second groove 16.

[0240] Of course, in other embodiments, a second recessed groove may be formed on the silicon substrate 101 at the position corresponding to the first edge serial area 131 and the first bus gate line 22. The second doped layer 103 and the back passivation film layer 104 are both recessed at the second recessed groove toward the side where the front side 11 is located, so as to form a second groove 16 on the substrate 10.

[0241] Specifically, in this case, during the fabrication process, before preparing the second doped layer 103, a second recessed trench can be formed in the silicon substrate 101 at the location where the second doped layer 103 needs to be prepared and the second insulating layer 120 needs to be placed. Then, the second doped layer 103 and the back passivation film layer 104 are prepared to form the substrate 10. Since the second recessed trench is formed on the silicon substrate 101, the aforementioned second groove 16 can be correspondingly formed on the substrate 10. Then, the first gate line 20 and the second gate line 30 are printed, and the second insulating layer 120 is placed at the second groove 16. Please refer to [link to previous text]. Figure 12 , Figure 18 and Figure 19 In some embodiments, the second edge bus line 110 may include an intermediate bus segment 113, a first edge bus segment 111, and a second edge bus segment 112, all of which extend along the second direction. Figure 12 As shown, the three can be arranged parallel to each other at intervals along the first direction. The middle merging segment 113 is closer to the second edge 122 than the first edge merging segment 111 and the second edge merging segment 112.

[0242] The first edge busbar 111 is disposed near the third edge 123, and the second edge busbar 112 is disposed near the fourth edge 124. The second edge busbar 110 also includes a first connecting segment 114 and a second connecting segment 115, both of which extend along a first direction. The first connecting segment 114 connects the intermediate busbar 113 and the first edge busbar 111, and the second connecting segment 115 connects the intermediate busbar 113 and the second edge busbar 112.

[0243] Wherein, the first edge merging segment 111 connects the two second gate lines 30 closest to the third edge 123; at the junction of the first edge merging segment 111 and the first connecting segment 114, the first edge merging segment 111 has a third protrusion 1101 protruding towards the fourth edge 124; the first connecting segment 114 has a fourth protrusion 1102 protruding towards the first edge 121; at the junction of the intermediate merging segment 113 and the first connecting segment 114, the intermediate merging segment 113 has a fifth protrusion 1103 protruding towards the third edge 123; and the first connecting segment 114 has a sixth protrusion 1104 protruding towards the second edge 122; and / or

[0244] The second edge merging segment 112 connects the two second grid lines 30 closest to the fourth edge 124. At the junction of the second edge merging segment 112 and the second connecting segment 115, the second edge merging segment 112 has a seventh protrusion 1105 protruding towards the third edge 123. The second connecting segment 115 has an eighth protrusion 1106 protruding towards the first edge 121. At the junction of the intermediate merging segment 113 and the second connecting segment 115, the intermediate merging segment 113 has a ninth protrusion 1107 protruding towards the fourth edge 124. The second connecting segment 115 has a tenth protrusion 1108 protruding towards the second edge 122.

[0245] Thus, when there is a chamfer at the connection between the second edge 122 and the third edge 123 and the fourth edge 124, the chamfer can be avoided by setting the second edge busbar 110 into a structure of 3 vertical segments + 2 horizontal segments, reducing printing difficulty. At the same time, setting corresponding protrusions at the junctions of each busbar segment can provide redundancy at the corners of the second edge 122, avoiding inaccurate printing during the printing process that would prevent the paste from forming a complete fill at the corners and cause poor contact between the busbar segments.

[0246] Of course, it is understood that in some embodiments, when a chamfer is formed at the intersection of the second edge 122, the third edge 123, and the fourth edge 124, the second edge busbar 110 can also be configured in the same way as the first edge busbar 40 (e.g., with a bend), and no specific limitation is made here. Of course, it is understood that in some embodiments, if the back contact battery 100 does not have a chamfer, then only one second edge busbar 110 extending vertically continuously along the second direction needs to be provided.

[0247] Please see Figure 18 and Figure 19In some embodiments, at the junction of the second grid line 30 (including the second collection grid line 31 and the second bus grid line 32) and the second edge bus line 110, at least a portion of the second grid line 30 has a second grid line protrusion 302 that protrudes toward the first edge 121 relative to the second edge bus line 110.

[0248] Thus, by setting the second grid line protrusion 302, the stability of the electrical connection between the second grid line 30 and the second edge bus line 110 can be guaranteed, effectively avoiding the phenomenon that some of the second grid lines 30 cannot form a stable contact with the second edge bus line 110 due to printing accuracy issues during the printing process.

[0249] Please see Figure 3 , Figure 12 as well as Figure 15 In some embodiments, the plurality of first serial connection areas 13 may further include a fourth edge serial connection area 132 closest to the second edge 122 (i.e., the first serial connection area 13 adjacent to the third edge serial connection area 142), the second grid line 30 is continuous at the fourth edge serial connection area 132, the first grid line 20 is discontinuous at the fourth edge serial connection area 132, and the back contact battery 100 may further include a fourth auxiliary connection line 160, the fourth auxiliary connection line 160 is disposed in the fourth edge serial connection area 132, and in the second direction, the fourth auxiliary connection line 160 connects the second bus grid line 32 and at least one second collection grid line 31 located on one side of the second bus grid line 32.

[0250] Thus, by setting the fourth auxiliary connection line 160 in the fourth edge series connection area 132, the phenomenon that the current transmitted from the second bus grid 32 cannot be collected can be effectively avoided by the solder strip in the fourth edge series connection area 132 having poor soldering or contact at the second bus grid 32.

[0251] Specifically, such as Figure 12 and Figure 15 As shown, in such an embodiment, the number of fourth auxiliary connecting lines 160 can be the same as the number of second busbars 32, and the two correspond one-to-one. When the second busbar 32 is in the middle position (i.e., there are second collection lines 31 on both sides of the second busbar 32), the fourth auxiliary connecting line connects the second busbar 32 and connects the two second collection lines 31 adjacent to the second busbar 32 (i.e., the second collection lines 31 located on both sides of the second busbar 32 and adjacent to it).

[0252] In some embodiments, the width (length in the first direction) of the fourth auxiliary connection line 160 is greater than the width (length in the second direction) of the portion of the second collection grid line 31 located outside the first serial connection area 13 (i.e., the portion of the second collection grid line 31 excluding the second solder section 301). Thus, since the fourth auxiliary connection line 160 functions to transmit and combine current when a poor solder joint occurs at the second bus grid line 32, setting the width of the fourth auxiliary connection line 160 wider can also reduce transmission losses during the current combining process and improve efficiency.

[0253] In some embodiments, the distance between the third edge concatenation area 142 and the second edge 122 is greater than or equal to 2 mm and less than or equal to 20 mm.

[0254] This avoids the situation where the distance between the third edge series connection area 142 and the second edge 122 is too small, causing the welding position to be too close to the second edge 122 and resulting in microcracks in the back contact battery 100, thus reducing the risk of microcracks. It also avoids the situation where the distance between the third edge series connection area 142 and the second edge 122 is too large, resulting in excessively long isolated grid line segments between the third edge series connection area 142 and the second edge 122, leading to excessive losses during the transmission path.

[0255] Specifically, in such an embodiment, the distance between the third edge connecting area 142 and the second edge 122 can be, for example, any value between 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm or 2mm-20mm, and is not limited here.

[0256] In the above embodiments, the polarity of the third edge series connection area 142 is opposite to that of the first edge series connection area 131, and the structures of the two edges of the back contact battery 100 in the first direction are different and asymmetrical. It is understood that in some possible embodiments, the polarity of the third edge series connection area 142 and the first edge series connection area 131 may also be the same. In this case, the structures of the two edges of the back contact battery 100 in the first direction are the same and symmetrical. That is to say, in this case, in the back contact battery 100, the two series connection areas closest to the second edge 122 are symmetrical to the first edge series connection area 131 and the second edge series connection area 141. A bus line, auxiliary connection line and other structures are also provided on one side of the second edge 122, which are completely stacked with one side of the first edge 121. To avoid being verbose, the specific structure will not be described in detail here.

[0257] Please see Figure 3In some embodiments, the substrate 10 has a third edge 123 and a fourth edge 124 in the second direction. The first serial connection area 13 is further provided with a fifth auxiliary connection line 170 and a sixth auxiliary connection line 180. The fifth auxiliary connection line 170 connects the N second gate lines 30 closest to the third edge 123, and the sixth auxiliary connection line 180 connects the M second gate lines 30 closest to the fourth edge 124, wherein N and M are both greater than or equal to 2 and less than or equal to 8.

[0258] In some embodiments, the second serial connection area 14 is provided with a seventh auxiliary connection line 190 and an eighth auxiliary connection line 1100. The seventh auxiliary connection line 190 is connected to the P first gate lines closest to the third edge, and the eighth auxiliary connection line 1100 is connected to the Q first gate lines closest to the fourth edge, wherein P and Q are both greater than or equal to 2 and less than or equal to 8.

[0259] Thus, by setting the fifth auxiliary connection line 170 and the sixth auxiliary connection line 180 at the positions near the third edge 123 and the fourth edge 124 of the first series connection area 13, that is, by setting the fifth auxiliary connection line 170 and the sixth auxiliary connection line 180 at the beginning and end of the solder strip in the first series connection area 13, the problem of some grid lines' current not being collected can be effectively avoided due to poor soldering at the starting and ending points of the solder strip on the first series connection area 13. Similarly, by setting the seventh auxiliary connection line 190 and the eighth auxiliary connection line 1100 at the positions near the third edge 123 and the fourth edge 124 of the second series connection area 14, that is, by setting the seventh auxiliary connection line 190 and the eighth auxiliary connection line 1100 at the beginning and end of the solder strip in the second series connection area 14, the problem of some grid lines' current not being collected can be effectively avoided due to poor soldering at some positions of the starting and ending points of the solder strip on the second series connection area 14.

[0260] Specifically, such as Figure 3 As shown, in some embodiments, the fifth auxiliary connecting line 170 in the first edge concatenation area 131 can be integrated with the first auxiliary connecting line 60 closest to the third edge 123 in the first edge concatenation area 131, and the sixth auxiliary connecting line 180 in the first edge concatenation area 131 can be integrated with the first auxiliary connecting line 60 closest to the fourth edge 124 in the first edge concatenation area 131.

[0261] The seventh auxiliary connecting line 190 in the second edge serialization area 141 can be integrated with the second auxiliary connecting line 90, which is closest to the third edge 123 in the second edge serialization area 141, and the eighth auxiliary connecting line 1100 in the second edge serialization area 141 can be integrated with the second auxiliary connecting line 90, which is closest to the fourth edge 124 in the second edge serialization area 141,.

[0262] The seventh auxiliary connecting line 190 in the third edge serialization area 142 can share a structure with the third auxiliary connecting line 130, which is closest to the third edge 123 in the third edge serialization area 142. The eighth auxiliary connecting line 1100 in the third edge serialization area 142 can share a structure with the third auxiliary connecting line 130, which is closest to the fourth edge 124 in the third edge serialization area 142.

[0263] The fifth auxiliary connection line 170 in the fourth edge serialization area 132 can be integrated with the fourth auxiliary connection line 160, which is closest to the third edge 123 in the fourth edge serialization area 132, and the sixth auxiliary connection line 180 in the fourth edge serialization area 132 can be integrated with the fourth auxiliary connection line 160, which is closest to the fourth edge 124 in the fourth edge serialization area 132,.

[0264] As for the first serial connection area 13 and the second serial connection area 14 located between the second edge serial connection area 141 and the fourth edge serial connection area 132, it is only necessary to set the corresponding auxiliary connection lines at the corresponding positions of the edges.

[0265] Please see Figure 20 In some embodiments, within the first serial connection region 13, the X first gate lines 20 closest to the third edge 123 are interrupted at the first serial connection region 13, and the Y first gate lines 20 closest to the fourth edge 124 are interrupted at the first serial connection region 13. The width of the interrupted region formed by the X first gate lines 20 closest to the third edge 123 gradually increases in the direction towards the third edge 123, and the width of the interrupted region formed by the Y first gate lines 20 closest to the fourth edge 124 gradually increases in the direction towards the fourth edge 124, wherein both X and Y are greater than or equal to 2. That is, in such an embodiment, in the first serial connection region 13, among the at least two second gate lines 30 closest to the third edge 123, the second weld segment 301 on the second gate line 30 closest to the third edge 123 is wider in the second direction. In the at least two second gate lines 30 closest to the fourth edge 124, the second weld segment 301 on the second gate line 30 closest to the fourth edge 124 is wider in the second direction.

[0266] Within the second serial connection region 14, the W second gate lines 30 closest to the third edge 123 are interrupted at the second serial connection region 14, and the Z second gate lines 30 closest to the fourth edge 124 are interrupted at the second serial connection region 14. The width of the interrupted region formed by the W second gate lines 30 closest to the third edge 123 gradually increases in the direction towards the third edge 123, and the width of the interrupted region formed by the Z second gate lines 30 closest to the fourth edge 124 gradually increases in the direction towards the fourth edge 124, wherein both W and Z are greater than or equal to 2. That is to say, in this embodiment, in the second serial connection region 14, among the at least two first gate lines 20 closest to the third edge 123, the first weld segment 201 on the first gate line 20 closest to the third edge 123 is wider in the second direction. In the at least two first gate lines 20 closest to the fourth edge 124, the first weld segment 201 on the first gate line 20 closest to the fourth edge 124 is wider in the second direction.

[0267] In this way, by setting the discontinuity of the grid lines at both ends of the solder strip to gradually increase towards the edge, it is possible to effectively prevent the solder strip from easily shifting at both ends during the welding process, causing it to come into contact with grid lines of opposite polarity, thus ensuring the reliability and stability of the welding.

[0268] In the description of this specification, the references to terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0269] Furthermore, the above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A back contact cell, characterized in that, The back contact battery comprises: a substrate having opposite front and back surfaces, the back surface having opposite first and second edges in a first direction, the back surface having a plurality of first and second stringing areas arranged alternately in the first direction, the plurality of first stringing areas including a first edge stringing area closest to the first edge without the second stringing area between the first edge stringing area and the first edge; a plurality of first and second gate lines arranged alternately on the back surface in a second direction intersecting the first direction, the first gate lines and all the second gate lines intersecting the first and second stringing areas, the plurality of first gate lines including a plurality of first collection gate lines and at least one first bus gate line, the first collection gate lines being discontinuous at the first edge stringing area and continuous at the second stringing area, the first bus gate line being continuous at both the first edge stringing area and the second stringing area, the second gate lines being continuous at the first edge stringing area; a first edge bus line closer to the first edge than the first edge stringing area, the first edge bus line being electrically connected to at least part of the first collection gate lines and to the first bus gate line; a first insulating layer arranged on the first bus gate line in the first edge stringing area; and a first auxiliary connection layer arranged on part of the second gate lines in the first edge stringing area, the first auxiliary connection layer being used for soldering with a solder strip, the height of the first insulating layer being flush with, less than, or greater than the height of the first auxiliary connection layer in the thickness direction of the back contact battery, the height difference between the first insulating layer and the first auxiliary connection layer being less than or equal to 15 um.

2. The back contact cell of claim 1, wherein, The first gate lines include first soldering sections in the second stringing areas, and the second gate lines include second soldering sections in the first stringing areas; The first auxiliary connection layer is arranged on the second soldering sections in the first edge stringing area in a stacked manner, and the height of the first insulating layer is greater than the height of the second soldering sections in the thickness direction of the back contact battery.

3. The back contact cell of claim 1, wherein, The first gate lines include a first collection layer and a first soldering layer, the first collection layer being continuous at the second stringing areas and discontinuous at the first stringing areas, and the first soldering layer being arranged on the first collection layer at the second stringing areas; or The first collection layer is discontinuous at both the second stringing areas and the first stringing areas, and the first soldering layer is arranged on the second stringing areas and electrically connected to both ends of the first collection layer at the second stringing areas; wherein the width of the first soldering layer is greater than the width of the first collection layer. ​ 4. The back contact cell of claim 1, wherein, The second gate line comprises a second collection layer and a second welding layer, the second collection layer is continuous at the first stringing area and discontinuous at the second stringing area, and the second welding layer is arranged at the first stringing area and located on the second collection layer; or the second collection layer is discontinuous at the first stringing area and the second stringing area, and the second welding layer is arranged at the first stringing area and electrically connected with two end portions of the second collection layer formed at the first stringing area; The width of the second welding layer is greater than the width of the second collection layer, and the first auxiliary connection layer is arranged on the second welding layer.

5. The back contact cell of claim 1, wherein, The first auxiliary connection layer comprises a tin paste layer.

6. The back contact cell of claim 1, wherein, The first edge bus line is electrically connected with all the first collection gate lines; or The first edge bus line is electrically connected with part of the first collection gate lines, and the number of the first collection gate lines not electrically connected with the first edge bus line is less than or equal to 4.

7. The back contact cell of claim 1, wherein, The number of the first bus gate lines is multiple, and the substrate has a third edge and a fourth edge in the second direction; In the first gate line and the second gate line, the gate line closest to the third edge is the first bus gate line, and / or the gate line closest to the fourth edge is the first bus gate line.

8. The back contact cell of claim 1, wherein, The substrate has a third edge and a fourth edge in the second direction; At the junction of the first edge bus line and the first gate line closest to the third edge, the first edge bus line has a first protruding portion protruding to one side of the third edge; and / or At the junction of the first edge bus line and the first gate line closest to the fourth edge, the first edge bus line has a second protruding portion protruding to one side of the fourth edge.

9. The back contact cell of claim 1, wherein, The width of the first bus gate line is greater than the width of the part of the first collection gate line located outside the second stringing area.

10. The back contact cell of claim 7, wherein, The second stringing area closest to the first edge is the second edge stringing area; the first bus gate line comprises a first bus section located between the second edge stringing area and the first edge; The width of the first bus section is greater than the width of the part of the remaining part of the first bus gate line located outside the second stringing area; and / or The first bus layer is arranged on the first bus section.

11. The back contact cell of claim 10, wherein, The width of the first bus layer is greater than the width of the part of the first collection gate line located outside the second stringing area.

12. The back contact cell of claim 1, wherein, The width of the first edge bus line is greater than the width of the part of the first collection gate line located outside the second stringing area.

13. The back contact cell of claim 1 wherein, The distance between the first edge stringing area and the first edge is greater than or equal to 2 mm and less than or equal to 20 mm.

14. The back contact cell of claim 1 wherein, The second stringing area closest to the second edge is the third edge stringing area, and the third edge stringing area does not have the first stringing area with the second edge; The second grid lines include second collection grid lines and at least one second bus grid line, the second collection grid lines are discontinuous at the third edge stringing area and continuous at the first stringing area, and the second bus grid line is continuous at the third edge stringing area and the first stringing area, and the first grid line is continuous at the third edge stringing area; The back contact battery further comprises: a second edge bus line, the second edge bus line is closer to the second edge than the third edge stringing area, the second edge bus line is electrically connected to at least part of the second collection grid lines and the second bus grid line; a second insulation layer, the second insulation layer is arranged at the third edge stringing area and on the second bus grid line; and a second auxiliary connection layer, the second auxiliary connection layer is arranged on the part of the first grid line at the third edge stringing area, the second auxiliary connection layer is used for welding with a solder strip, the height of the second insulation layer is flush with the height of the second auxiliary connection layer, or the height of the second insulation layer is less than the height of the second auxiliary connection layer, or the height of the second insulation layer is greater than the second auxiliary connection layer, and the height difference between the second insulation layer and the second auxiliary connection layer is less than or equal to 15 um.

15. The back contact cell of claim 14, wherein, The first grid line includes a first welding section in the second stringing area, and the second grid line includes a second welding section in the first stringing area; The second auxiliary connection layer is arranged on the first welding section at the third edge stringing area in a stacking manner, and the height of the second insulation layer is greater than the height of the first welding section in the thickness direction of the back contact battery.

16. The back contact cell of claim 14, wherein, The first grid line includes a first collection layer and a first welding layer, the first collection layer is continuous at the second stringing area and discontinuous at the first stringing area, and the first welding layer is arranged at the second stringing area and on the first collection layer; Or The first collection layer is discontinuous at the second stringing area and the first stringing area, and the first welding layer is arranged at the second stringing area and electrically connected to two ends of the first collection layer at the second stringing area; The width of the first welding layer is greater than the width of the first collection layer, and the second auxiliary connection layer is arranged on the first welding layer.

17. The back contact cell of claim 14, wherein, The second auxiliary connection layer is a tin paste layer.

18. The back contact cell of claim 14, wherein, The second edge bus line is electrically connected to all the second collection grid lines; or The second edge bus line is electrically connected to part of the second collection grid lines, and the number of the second collection grid lines not electrically connected to the second edge bus line is less than or equal to 4.

19. The back contact cell of claim 14, wherein, The substrate has a third edge and a fourth edge in the second direction, the second edge bus line comprises a middle bus segment, a first edge bus segment and a second edge bus segment, the middle bus segment, the first edge bus segment and the second edge bus segment all extend along the second direction, the middle bus segment is closer to the second edge than the first edge bus segment and the second edge bus segment, the first edge bus segment is arranged close to the third edge, and the second edge bus segment is arranged close to the fourth edge; The second edge bus line further comprises a first connecting segment and a second connecting segment, the first connecting segment and the second connecting segment both extend along the first direction, the first connecting segment connects the middle bus segment and the first edge bus segment, and the second connecting segment connects the middle bus segment and the second edge bus segment; The first edge bus segment connects two second grid lines closest to the third edge, at the junction of the first edge bus segment and the first connecting segment, the first edge bus segment has a third protrusion protruding to the side of the fourth edge, the first connecting segment has a fourth protrusion protruding to the side of the first edge, at the junction of the middle bus segment and the first connecting segment, the middle bus segment has a fifth protrusion protruding to the side of the third edge, and the first connecting segment has a sixth protrusion protruding to the side of the second edge; and / or The second edge bus segment connects two second grid lines closest to the fourth edge, at the junction of the second edge bus segment and the second connecting segment, the second edge bus segment has a seventh protrusion protruding to the side of the third edge, the second connecting segment has an eighth protrusion protruding to the side of the first edge, at the junction of the middle bus segment and the second connecting segment, the middle bus segment has a ninth protrusion protruding to the side of the fourth edge, and the second connecting segment has a tenth protrusion protruding to the side of the second edge.

20. The back contact cell of claim 14, wherein, The width of the second bus grid line is greater than the width of the part of the second collection grid line located outside the first stringing area.

21. The back contact cell of claim 14, wherein, The first stringing area closest to the second edge comprises a fourth edge stringing area, and the second bus grid line comprises a second bus segment located between the fourth edge stringing area and the second edge; The width of the second bus segment is greater than the width of the part of the second bus grid line located outside the first stringing area; and / or The second bus segment is provided with a second bus layer.

22. The back contact cell of claim 21, wherein, The width of the second bus layer is greater than the width of the part of the second collection grid line located outside the first stringing area.

23. The back contact cell of claim 14, wherein, The width of the second edge bus line is greater than the width of the part of the second collection grid line located outside the first stringing area.

24. The back contact cell of claim 14, wherein, The distance between the second edge stringing area and the second edge is greater than or equal to 2 mm and less than or equal to 20 mm.

25. The back contact cell of claim 1 wherein, The substrate has a third edge and a fourth edge in the second direction; In the first stringing area, X roots of the first gate lines closest to the third edge are interrupted at the first stringing area, Y roots of the first gate lines closest to the fourth edge are interrupted at the first stringing area, the width of the interrupted area formed by the X roots of the first gate lines closest to the third edge gradually increases in the direction towards the third edge, and the width of the interrupted area formed by the Y roots of the first gate lines closest to the fourth edge gradually increases in the direction towards the fourth edge, wherein X and Y are both greater than or equal to 2; In the second stringing area, W roots of the second gate lines closest to the third edge are interrupted at the second stringing area, Z roots of the second gate lines closest to the fourth edge are interrupted at the second stringing area, the width of the interrupted area formed by the W roots of the second gate lines closest to the third edge gradually increases in the direction towards the third edge, and the width of the interrupted area formed by the Z roots of the second gate lines closest to the fourth edge gradually increases in the direction towards the fourth edge, wherein W and Z are both greater than or equal to 2.

26. A battery assembly comprising: A back contact cell comprising a plurality of the back contact cell of any one of claims 1-25.

27. A photovoltaic system characterized by, A battery assembly comprising the battery assembly of claim 26.

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