Back contact solar cell, cell assembly and photovoltaic system

Abstract

The invention relates to the technical field of solar cells, and provides a back contact solar cell, a cell module and a photovoltaic system, and in the back contact solar cell, a first bus grid line is continuous at a first edge serial connection area and a second serial connection area. A first groove is formed in the substrate. The first edge bus line is closer to the first edge than the first edge serial connection area. And a first insulating layer is arranged on the part, corresponding to the first serial connection area, of the first bus grid line. The first insulating layer is at least partially disposed within the first recess. The height of the first insulating layer is flush with the height of the second welding section, or the height of the first insulating layer is smaller than the height of the second welding section, or the height of the first insulating layer is larger than the height of the second welding section, and the height difference between the first insulating layer and the second welding section is smaller than or equal to 15 micrometers. Thus, through the arrangement of the first groove, the influence caused by pseudo soldering can be reduced, and the efficiency of the back contact solar cell is ensured.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and in particular to a back-contact solar cell, a cell assembly and a photovoltaic system. Background Art

[0002] A back-contact solar cell is a cell in which both the P-type doped layer and the N-type doped layer are arranged on the back of a silicon wafer. There is no metal electrode blocking the front, and it has a higher short-circuit current and conversion efficiency.

[0003] In the related art, the back of the back-contact solar cell is provided with alternately arranged grid lines. In order to reduce the use of slurry and transmission loss, a welding strip can be directly used in the battery assembly to form an electrical connection with the grid lines of the battery to achieve the current convergence output. However, in such a technical solution, since it is necessary to set an insulating glue at the grid lines of opposite polarity that cross the welding strip to avoid leakage, the setting of the insulating glue easily causes the welding strip to have a cold solder joint during the welding process, affecting the performance of the back-contact solar cell. Summary of the invention The present application provides a back-contact solar cell, a cell module and a photovoltaic system.

[0004] The present application is implemented in this way. The back contact solar cell of the embodiment of the present application comprises: A substrate, wherein the substrate has a front side and a back side opposite to each other, the back side has a first edge and a second edge opposite to each other in a first direction, the back side has a plurality of first series connection areas and a plurality of second series connection areas, in the first direction, the first series connection areas and the second series connection areas are alternately arranged, the plurality of first series connection areas include a first edge series connection area closest to the first edge, there is no second series connection area between the first edge series connection area and the first edge, and a first groove is formed on the substrate in the first edge series connection area; A plurality of first grid lines and a plurality of second grid lines arranged on the back side are alternately arranged along a second direction, the second direction intersects with the first direction, the first grid lines and all the second grid lines are arranged to intersect with the first series connection area and the second series connection area, the first grid lines include a first welding section located in the second series connection area, and the second grid lines include a second welding section located in the first series connection area; the plurality of first grid lines include a plurality of first collecting grid lines and at least one first bus grid line, the first collecting grid line is discontinuous at the first edge series connection area and continuous at the second series connection area, the first bus grid line is continuous at the first edge series connection area and the first bus grid line is partially located in the first groove, and the second grid line is continuous at the first edge series connection area; a first edge bus line, the first edge bus line being closer to the first edge than the first edge series connection region, the first edge bus line being electrically connected to at least a portion of the first collector gate line and to the first bus gate line; and A first insulating layer, the first insulating layer is at least partially arranged in the first groove and located on the first bus line, wherein, in the direction from the front side to the back side, the height of the first insulating layer is flush with the height of the second welding section, or the height of the first insulating layer is less than the height of the second welding section, or the height of the first insulating layer is greater than the height of the second welding section and the height difference between the first insulating layer and the second welding section is less than or equal to 15um.

[0005] Furthermore, the depression depth of the first groove is less than half of the thickness of the substrate.

[0006] Furthermore, the first insulating layer is completely located in the first groove.

[0007] Furthermore, the substrate includes a silicon substrate, a plurality of first doped layers, a plurality of second doped layers and a back passivation film layer, the silicon substrate has a first surface and a second surface opposite to each other, the first doped layers and the second doped layers are both arranged on the second surface, the plurality of first doped layers and the plurality of second doped layers are alternately arranged along a second direction, the back passivation film layer is at least stacked on the first doped layers and the second doped layers, the first gate line is arranged corresponding to the first doped layers and at least partially penetrates the back passivation film layer and is in conductive contact with the first doped layers, and the second gate line is arranged corresponding to the second doped layers and at least partially penetrates the back passivation film layer and is in conductive contact with the second doped layers; Wherein, the first groove penetrates the back passivation film layer and the first doping layer, so that the silicon substrate is exposed from the first groove, and the portion of the first busbar line located in the first groove is in contact with the silicon substrate; or A first recessed groove is formed on the silicon substrate at a position corresponding to the first busbar line in the first edge series region, and the first doping layer and the back passivation film layer are both recessed toward the front side at the first recessed groove to form the first groove on the substrate.

[0008] Furthermore, the first edge bus line is electrically connected to all the first collecting gate lines; or The first edge bus line is electrically connected to a portion of the first collecting gate lines, and the number of the first collecting gate lines that are not electrically connected to the first edge bus line is less than or equal to four.

[0009] Furthermore, the number of the first busbar lines is plural, and the substrate has a third edge and a fourth edge in the second direction; Among the first gate lines and the second gate lines, 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.

[0010] Furthermore, the substrate has a third edge and a fourth edge in the second direction; At the junction where the first gate line closest to the third edge is connected with the first edge bus line, the first edge bus line has a first protrusion protruding toward the third edge; and / or At a junction where the first gate line closest to the fourth edge is connected to the first edge bus line, the first edge bus line has a second protrusion protruding toward the fourth edge.

[0011] Furthermore, the width of the first bus gate line is greater than the width of a portion of the first collecting gate line located outside the second series connection region.

[0012] Furthermore, the plurality of second series connection regions include a second edge series connection region closest to the first edge; the first busbar line includes a first bus segment located between the second edge series connection region and the first edge; Wherein, the width of the first bus segment is greater than the width of the remaining portion of the first bus grid line located outside the second series connection area; and / or A first busbar layer is provided on the first busbar segment.

[0013] Furthermore, the width of the first bus layer is greater than the width of a portion of the first collecting gate line located outside the second series connection region.

[0014] Furthermore, the width of the first edge bus line is greater than the width of a portion of the first collecting gate line located outside the second series connection region.

[0015] Furthermore, a distance between the first edge series connection area and the first edge is greater than or equal to 2 mm and less than or equal to 20 mm.

[0016] Furthermore, the plurality of second series connection areas include a third edge series connection area closest to the second edge, there is no first series connection area between the third edge series connection area and the second edge, and a second groove is formed on the substrate in the third edge series connection area; The plurality of second gate lines include a plurality of second collecting gate lines and at least one second bus gate line, the second collecting gate lines are discontinuous at the third edge series connection area and continuous at the first series connection area, the second bus gate lines are continuous at the third edge series connection area and the first series connection area and the second bus gate lines are partially located in the second groove, and the first gate lines are continuous at the third edge series connection area; The back contact solar cell further comprises: a second edge bus line, the second edge bus line being closer to the second edge than the third edge series connection region, the second edge bus line being electrically connected to at least a portion of the second collecting grid line and to the second bus grid line; A second insulating layer, the second insulating layer is at least partially arranged in the second groove and located on the second bus bar, the number of the second insulating layers corresponds to the number of the second bus bar, wherein, in the thickness direction of the back contact solar cell, the height of the second insulating layer is flush with the height of the first welding section, or the height of the second insulating layer is less than the height of the first welding section, or the height of the second insulating layer is greater than the height of the first welding section and the height difference between the second insulating layer and the first welding section is less than or equal to 15um.

[0017] Furthermore, the depression depth of the second groove is less than half of the thickness of the substrate.

[0018] Furthermore, the second insulating layer is completely located in the second groove.

[0019] Furthermore, the substrate includes a silicon substrate, a plurality of first doped layers, a plurality of second doped layers and a back passivation film layer, the silicon substrate has a first surface and a second surface opposite to each other, the first doped layers and the second doped layers are both arranged on the second surface, the plurality of first doped layers and the plurality of second doped layers are alternately arranged along a second direction, the back passivation film layer is at least stacked on the first doped layers and the second doped layers, the first gate line is arranged corresponding to the first doped layers and at least partially penetrates the back passivation film layer and is in conductive contact with the first doped layers, and the second gate line is arranged corresponding to the second doped layers and at least partially penetrates the back passivation film layer and is in conductive contact with the second doped layers; wherein the second groove penetrates the back passivation film layer and the second doping layer, so that the silicon substrate is exposed from the second groove, and a portion of the second busbar line located in the second groove is in contact with the silicon substrate; or A second recessed groove is formed on the silicon substrate at a position corresponding to the second edge series region and the second busbar line, and the second doping layer and the back passivation film layer are both recessed toward the front side at the second recessed groove to form the second groove on the substrate.

[0020] Furthermore, the second edge bus line is electrically connected to all the second collecting gate lines; or The second edge bus line is electrically connected to a portion of the second collecting gate lines, and the number of the second collecting gate lines that are not electrically connected to the second edge bus line is less than or equal to four.

[0021] Furthermore, the substrate has a third edge and a fourth edge in the second direction, the second edge bus line includes a middle bus section, a first edge bus section and a second edge bus section, the middle bus section, the first edge bus section and the second edge bus section all extend along the second direction, the middle bus section is closer to the second edge than the first edge bus section and the second edge bus section, the first edge bus section is arranged close to the third edge, and the second edge bus section is arranged close to the fourth edge; The second edge bus line further includes a first connecting section and a second connecting section, the first connecting section and the second connecting section both extend along the first direction, the first connecting section connects the middle bus section and the first edge bus section, and the second connecting section connects the middle bus section and the second edge bus section; Wherein, the first edge bus section connects two of the second grid lines closest to the third edge, and at the junction of the first edge bus section and the first connecting section, the first edge bus section has a third convex portion protruding toward the fourth edge, and the first connecting section has a fourth convex portion protruding toward the first edge, and at the junction of the middle bus section and the first connecting section, the middle bus section has a fifth convex portion protruding toward the third edge, and the first connecting section has a sixth convex portion protruding toward the second edge; and / or The second edge bus section connects the two second grid lines closest to the fourth edge. At the junction of the second edge bus section and the second connecting section, the second edge bus section 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 middle bus section and the second connecting section, the middle bus section has a ninth protrusion protruding toward the fourth edge, and the second connecting section has a tenth protrusion protruding toward the second edge.

[0022] Furthermore, the width of the second bus gate line is greater than the width of a portion of the second collecting gate line located outside the first series connection region.

[0023] Furthermore, the first series connection regions include a fourth edge series connection region closest to the second edge; the second busbar line includes a second bus segment located between the fourth edge series connection region and the second edge; The width of the second bus segment is greater than the width of the remaining portion of the second bus grid line located outside the first series connection region; and / or A second bus layer is provided on the second bus section.

[0024] Furthermore, the width of the second bus layer is greater than the width of a portion of the second collecting gate line located outside the first series connection region.

[0025] Furthermore, the width of the second edge bus line is greater than the width of a portion of the second collecting gate line located outside the first series connection region.

[0026] Furthermore, a distance between the third edge series connection area and the second edge is greater than or equal to 2 mm and less than or equal to 20 mm.

[0027] The present application also provides a battery assembly, which includes a plurality of back-contact solar cells as described in any one of the above items.

[0028] The present application also provides a photovoltaic system, which includes the above-mentioned battery assembly.

[0029] In the back-contact solar cell, battery assembly and photovoltaic system of the embodiments of the present application, the first collecting grid line is discontinuous at the first edge series connection area and is continuous at the second series connection area, the first bus grid line is continuous at the first edge series connection area and the second series connection area, and the second grid line is continuous at the first edge series connection area. The first edge bus line is closer to the first edge than the first edge series connection area, and the first edge bus line is electrically connected to at least part of the first collecting grid line and to the first bus grid line. The first insulating layer is disposed at the first groove in the first edge series connection area, and the first insulating layer is at least partially disposed in the first groove and is located on the first bus grid line. The height of the first insulating layer is flush with the height of the second welding section, or the height of the first insulating layer is less than the height of the second welding section, or the height of the first insulating layer is greater than the height of the second welding section, and the height difference between the first insulating layer and the second welding section is less than or equal to 15um. In this way, by setting the first edge bus line and the first bus grid line, the current collected by at least part of the isolated section of the first grid line between the first edge series connection area and the first edge can be converged to the welding strip of the same polarity in the second series connection area adjacent to the first edge series connection area, which can effectively avoid welding at the first edge of the back contact solar cell to cause hidden cracks while ensuring the efficiency of the back contact solar cell. At the same time, by forming a first groove on the substrate, the first insulating layer is at least partially arranged in the first groove, so that the height of the first insulating layer is less than the height of the second welding section, or the first insulating layer is flush with the second welding section, or the height of the first insulating layer is greater than the second welding section and the height difference between the two is less than or equal to 15um, so that the insulation between the welding strip and the first bus grid line can be ensured, and the height difference between the first insulating layer and the grid line welding section can be reduced or even eliminated, thereby reducing the risk of cold welding caused by the first insulating layer, reducing the impact of cold welding on the back contact solar cell, and improving the performance of the back contact solar cell.

[0030] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a module schematic diagram of a photovoltaic system provided in an embodiment of the present application; Figure 2 is a module schematic diagram of a battery assembly provided in an embodiment of the present application; Figure 3 is a schematic diagram of the planar structure of a back-contact solar cell provided in an embodiment of the present application; Figure 4 yes Figure 3 A local enlarged schematic diagram of the back contact solar cell at IV; Figure 5 yes Figure 4 Schematic diagram of the cross-sectional structure of the back contact solar cell along line VV; Figure 6 yes Figure 4 A schematic diagram of the cross-sectional structure of a back-contact solar cell along line VI-VI; Figure 7 yes Figure 4 A partial enlarged schematic diagram of the back contact solar cell at position VII; Figure 8 yes Figure 4 A partial enlarged schematic diagram of the back contact solar cell at position VIII; Fig. 9 yes Figure 4 A local enlarged schematic diagram of the back contact solar cell at position IX; Fig.10 yes Figure 3 A local enlarged schematic diagram of a back contact solar cell at position X; Fig.11 yes Fig.10 Schematic diagram of the cross-sectional structure of the back contact solar cell along line XI-XI; Fig.12 yes Fig.10 A schematic diagram of a cross-sectional structure of a back contact solar cell along line XII-XII; Fig.13 yes Fig.10 A partial enlarged schematic diagram of the back contact solar cell at position XIII; Fig.14 yes Fig.10 A partial enlarged schematic diagram of the back contact solar cell at XIV; Fig.15 yes Fig.10 A local enlarged schematic diagram of the back contact solar cell at XV; Fig.16 It is another schematic diagram of the planar structure of the back-contact solar cell provided in an embodiment of the present application.

[0032] Description of main component symbols: Photovoltaic system 1000; Battery assembly 200; Back-contact solar cell 100, substrate 10, front side 11, back side 12, first edge 121, second edge 122, third edge 123, fourth edge 124, first series connection region 13, first edge series connection region 131, fourth edge series connection region 132, second series connection region 14, second edge series connection region 141, third edge series connection region 142, first groove 15, second groove 16; Silicon substrate 101, first surface 1011, second surface 1012, first doping layer 102, second doping layer 103, back passivation film layer 104; First grid line 20, first collecting grid line 21, first bus grid line 22, first bus section 221, first welding section 201; first grid line protrusion 202, second grid line 30, second collecting grid line 31, second bus grid line 32, second bus section 321, second welding section 301, second grid line protrusion 302; The first edge bus line 40, the first protrusion 41, the second protrusion 42, the first insulating layer 50, the first auxiliary connection line 60, the first bus layer 70, and the second auxiliary connection line 90; The second edge bus line 110, the first edge bus section 111, the second edge bus section 112, the middle bus section 113, the first connecting section 114, the second connecting section 115, the third protrusion 1101, the fourth protrusion 1102, the fifth protrusion 1103, the sixth protrusion 1104, the seventh protrusion 1105, the eighth protrusion 1106, the ninth protrusion 1107, the tenth protrusion 1108, the second insulating layer 120, the third auxiliary connecting line 130, the second bus layer 140, the fourth auxiliary connecting line 160; the fifth auxiliary connecting line 170, the sixth auxiliary connecting line 180, the seventh auxiliary connecting line 190, and the eighth auxiliary connecting line 1100. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. Examples of embodiments are shown in the accompanying drawings, in which the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. It should be noted that the embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be construed as limiting the present application. In addition, it should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0034] In the description of the present application, it should be understood that the terms "up", "down", "left", "right", "horizontal", "vertical", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

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

[0036] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0037] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, and does not indicate the relationship between the various embodiments and / or settings discussed in itself. In addition, the various specific processes and examples of materials provided by the present application, but those of ordinary skill in the art can be aware of the application of other processes and / or the use scenarios of other materials.

[0038] See also Figure 1 and Figure 2 , the photovoltaic system 1000 in the embodiment of the present application may include the battery assembly 200 in the embodiment of the present application, and the battery assembly 200 in the embodiment of the present application may include several back-contact solar cells 100 in the embodiment of the present application. In the embodiment of the present application, multiple back-contact solar cells 100 in the battery assembly 200 can be connected in series to form multiple battery strings, and each battery string can be connected in series, in parallel, or in series and parallel combination to realize the current bus output. For example, the connection between each battery cell can be realized by welding a welding strip, and the connection between each battery string can be realized by a bus bar. In some embodiments, each battery string can form a battery 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 a battery assembly 200.

[0039] In the embodiment of the present application, the back contact solar cell 100 may be a busbar-free back contact solar cell. Figure 3-Figure 7The back-contact solar cell 100 in the embodiment of the present application 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 and a first insulating layer 50 .

[0040] like Figure 3-Figure 7 As shown, the substrate 10 has a front side 11 and a back side 12 opposite to each other. The back side 12 of the substrate 10 has a first edge 121 and a second edge 122 opposite to each other 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 used to set positive electrode welding strips and negative electrode welding strips, respectively, that is, one of the first series connection areas 13 and the second series connection areas 14 is a positive electrode series connection area, and the other is a negative electrode welding area.

[0041] like Figure 3 and Figure 4 As shown, in the first direction, the first serial connection areas 13 and the second serial connection areas 14 are arranged alternately, and the first serial connection areas 13 include a first edge serial connection area 131 closest to the first edge 121, and there is no second serial connection area 14 between the first edge serial connection area 131 and the first edge 121. In other words, Figure 3 and Figure 4 As shown, in the first series connection area 13 and the second series connection area 14, the series connection area closest to the first edge 121 is the first series connection area 13, and the first series connection area 13 is represented as the first edge series connection area 131, and there is no other series connection area between the first edge series connection area 131 and the first edge 121. Figure 6 As shown, in the first edge series connection area 131 , a first groove 15 is formed on the substrate 10 .

[0042] 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, and the second direction intersects with the first direction. All first grid lines 20 and all second grid lines 30 are intersected with the first series connection area 13 and the second series connection area 14, that is, the first series connection area 13 and the second series connection area 14 extend along the second direction to intersect with the first grid lines 20 and the second grid lines 30. In some embodiments, the first direction and the second direction may be the longitudinal direction and the lateral direction of the back contact solar cell 100, respectively, and the two directions 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 solar cell 100, and the second direction is the longitudinal direction of the back contact solar cell 100. Of course, in other embodiments, the first direction and the second direction may also be other directions, such as two diagonal directions of the back contact solar cell 100, which is not specifically limited here.

[0043] The first grid line 20 (including the first collecting grid line 21 and the first bus grid line 22 hereinafter) includes a first welding section 201 located in the second series connection area 14, that is, the first grid line 20 is continuous in each second series connection area 14 and has a first welding section 201 for welding with a welding strip at the second series connection area 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 section 301 located in the first series connection area 13 (including the first edge series connection area 131), that is, the second grid line 30 is continuous in each first series connection area 13 and has a second welding section 301 for welding with a welding strip at the first series connection area 13.

[0044] The first gate lines 20 may include a plurality of first collecting gate lines 21 and at least one first bus gate line 22, the first collecting gate lines 21 are discontinuous at the first edge series connection area 131 and continuous at the second series connection area 14, the first bus gate lines 22 are continuous at both the first edge series connection area 131 and the second series connection area 14, and the second gate lines 30 are continuous at the first edge series connection area 131. That is, the first gate lines 20 include at least two types of gate lines, one is the first collecting gate lines 21, and the other is the first bus gate lines 22, the first collecting gate lines 21 are discontinuous at the first edge series connection area 131, the first bus gate lines 22 are continuous at the first edge series connection area 131, and the second gate lines 30 are also continuous at the first edge series connection area 131. In the battery assembly 200 , the welding 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 welding strip in the second series connection area 14 is used to weld and connect with the first grid line 20 to realize the bus output of the first grid line 20 .

[0045] like Figure 6 As shown, the first bus bar line 22 is partially located in the first groove 15. In some embodiments, in the second direction, the first bus bar line 22 may extend along one sidewall of the first groove 15 to the bottom of the first groove 15 and extend out of the first groove 15 from the other sidewall of the first groove 15.

[0046] The portion of the first bus bar 22 corresponding to the first groove 15 does not fill the entire first groove 15 , that is, in the thickness direction of the back contact solar cell 100 , the height of the portion of the first bus bar 22 corresponding to the first groove 15 is less than the height of the opening of the first groove 15 .

[0047] like Figure 3 As shown, the first edge bus line 40 is closer to the first edge 121 than the first edge series region 131 , and the first edge bus line 40 is electrically connected to at least a portion of the first collecting grid lines 21 and to the first bus grid lines 22 .

[0048] Specifically, in order to avoid welding at the edge of the first edge 121 and causing hidden cracks in the battery, the first edge bus line 40 is not used for welding, but is used to collect the current in the first collecting grid line 21 between the first edge series connection area 131 and the first edge 121, and then converge to the second series connection area 14 (i.e., the second series connection area 14) adjacent to the first edge series connection area 131 through the first bus grid line 22. Figure 3 and Figure 4 The same polarity welding strip in the second series connection area 14 on the leftmost side is connected to collect the current of the grid line segment in the edge area of ​​the first grid line 20 located at the first edge 121, thereby improving the efficiency of the back contact solar cell 100. If the first edge bus line 40 and the first bus grid line 22 are not provided, the portion of the first grid line 20 located between the first edge series connection area 131 and the first edge 121 will form an isolated grid line segment, and the current of this portion cannot be collected.

[0049] like Figure 3 and Figure 6 As shown, the first insulating layer 50 is disposed at the first groove 15 in the first edge series connection area 131, and the first insulating layer 50 is at least partially disposed in the first groove 15 and located on the first bus bar line 22. That is, the first insulating layer 50 is disposed on the portion of the first bus bar line 22 located in the first groove 15, and the first insulating layer 50 is at least partially disposed in the first groove 15. The first insulating layer 50 is disposed to insulate and separate the opposite polarity welding strip in the first edge series connection area 131 from the first bus bar line 22 to avoid short circuit.

[0050] In which, in the thickness direction of the back-contact solar cell 100 (i.e., the direction from the front side 11 to the back side 12), the height of the first insulating layer 50 is flush with the height of the second welding section 301, or the height of the first insulating layer 50 is less than the height of the second welding section 301, or the height of the first insulating layer 50 is greater than the height of the second welding section 301, and the height difference between the first insulating layer 50 and the second welding section 301 is less than or equal to 15um.

[0051] In the back-contact solar cell 100, the battery assembly 200 and the photovoltaic system 1000 of the embodiment of the present application, the first collector grid line 21 is discontinuous 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 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 the first edge bus line 40 is electrically connected to at least part of the first collector grid line 21 and the first bus grid line 22. The first insulating layer 50 is disposed at the first groove 15 in the first edge series connection area 131, and the first insulating layer 50 is at least partially disposed in the first groove 15 and located on the first bus grid line 22. The height of the first insulating layer 50 is flush with the height of the second welding section 301, or the height of the first insulating layer 50 is less than the height of the second welding section 301, or the height of the first insulating layer 50 is greater than the height of the second welding section 301, and the height difference between the first insulating layer 50 and the second welding section 301 is less than or equal to 15um. In this way, by providing the first edge bus line 40 and the first bus grid line 22, the current collected by at least part of the isolated section of the first grid line 20 located between the first edge series connection area 131 and the first edge 121 can be converged to the welding strip of the same polarity in the second series connection area 14 adjacent to the first edge series connection area 131, which can effectively avoid the hidden cracks caused by welding at the first edge 121 of the back contact solar cell 100 while ensuring the efficiency of the back contact solar cell 100. At the same time, by forming a first groove 15 on the substrate 10, the first insulating layer 50 is at least partially arranged in the first groove 15, so that the height of the first insulating layer 50 is less than the height of the second welding section 301, or the first insulating layer 50 is flush with the second welding section 301, or the height of the first insulating layer 50 is greater than the second welding section 301 and the height difference between the two is less than or equal to 15um. In this way, while achieving insulation between the welding strip and the first bus bar 22, the height difference between the first insulating layer 50 and the bus bar welding section can be reduced or even eliminated, thereby reducing the risk of cold solder joints caused by the first insulating layer 50, reducing the impact of cold solder joints on the back contact solar cell 100, and improving the performance of the back contact solar cell 100.

[0052] Specifically, as shown above, it is not difficult to understand that in the present application, the first edge busbar 40 is not used for welding, but is only used for current transmission and collection, and the function of the first busbar 22 is to collect and transmit. Figure 3 and Figure 4 It is known that in Figure 3 and Figure 4In the example shown, if the first edge bus line 40 and the first bus grid line 22 are not provided, the first grid line 20 is disconnected at the first edge series connection area 131, and the current of the partial grid line segment of the first grid line 20 located between the first edge series connection area 131 and the first edge 121 cannot be collected. Therefore, by providing the first edge bus line 40 and the first bus grid line 22, the current of at least a portion of the isolated grid line segment of the first grid line 20 located in the edge area can be transmitted to the welding strip provided in the adjacent second series connection area 14, thereby effectively avoiding efficiency loss.

[0053] Since the first bus grid line 22 is continuously arranged in the first edge series connection area 131, in order to avoid the welding strip on the first edge series connection area 131 from contacting with the first bus grid line 22 and causing a short circuit, a first insulating layer 50 (such as insulating glue) needs to be arranged at the position corresponding to the first bus grid line 22 and the first edge series connection area 131. However, in this case, when the first groove 15 is not provided, the height of the first insulating layer 50 is higher than the height of the second welding section 301 of the second grid line 30, that is, in the thickness direction, the protruding height of the first insulating layer 50 is higher than the height of the second welding section 301 of the second grid line 30. In this case, the welding strip in the first edge series connection area 131 is easy to be damaged during the welding process. It is easy for a cold solder joint to occur with the second grid line 30, resulting in the inability to effectively collect the current on part of the second grid line 30 (especially the second grid line 30 adjacent to the first bus grid line 22, which is most likely to have a cold solder joint). Based on this, the present application opens a first groove 15 on the substrate 10 and at least partially disposes the first insulating layer 50 in the first groove 15, so that the height of the first insulating layer 50 is flush with or less than the height of the second welding section 301, or the height between the first insulating layer 50 and the second welding section 301 is less than 15um, thereby reducing or even eliminating the risk of a cold solder joint, thereby improving the reliability of welding and ensuring the performance of the back-contact solar cell 100.

[0054] Furthermore, in some embodiments, there may be a plurality of first bus bars 22, the number of first insulating layers 50 may correspond to the number of first bus bars 22, and the number of first grooves 15 may correspond to the number of first insulating layers 50. In this way, the risk of cold solder joints caused by all first insulating layers 50 may be reduced or even eliminated.

[0055] Of course, in some possible embodiments, the first groove 15 may be provided only at a portion of the first busbar lines 22, that is, the first groove 15 is opened only under a portion of the first insulating layer 50, and the first groove 15 is not opened at other positions. In this case, it can solve the problem of cold soldering caused by a portion of the first insulating layer 50.

[0056] When the height of the first insulating layer 50 is greater than the height of the second welding section 301, the height difference between the two may be 1um, 2um, 3um, 4um, 5um, 9um, 7um, 8um, 9um, 10um, 11um, 12um, 13um, 14um, 15um or any value between 0-15um.

[0057] In some embodiments, when the height of the first insulating layer 50 is greater than the height of the second welding section 301, the height difference between the first insulating layer 50 and the second welding section 301 may be preferably less than 8um, such as 0.5um, 1um, 2um, 3um, 4um, 5um, 9um, 7um, 8um. Specifically, after repeated research and verification by the inventors of the present application, it is found that by setting the height difference between the two preferably within the preferred range of less than 8um, the risk of cold solder joints caused by the first insulating layer 50 can be substantially eliminated.

[0058] Further, in the embodiments of the present application, 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 a first surface 1011 and a second surface 1012 opposite to each other, the first doped layers 102 and the second doped layers 103 are both arranged 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 the second direction. The back passivation film layer 104 is at least stacked on the first doped layer 102 and the second doped layer 103. In some embodiments, the back passivation film layer 104 may cover the entire second surface 1012, that is, the first doped layer 102 and the second doped layer 103 and the area of ​​the second surface 1012 where no doping layer is arranged are stacked with the back passivation film layer 104.

[0059] It can be seen that 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, in the substrate 10, a first passivation layer (not shown in the figure) may be further provided between the first doped layer 102 and the silicon substrate 101, and the first passivation layer may be, for example, a tunneling layer, an intrinsic amorphous silicon layer, or other film layers. A second passivation layer (not shown in the figure) may also be further provided between the second doped layer 103 and the silicon substrate 101, and the second passivation layer may be, for example, a tunneling layer, an intrinsic amorphous silicon layer, or other film layers.

[0060] In the back contact solar cell 100, the first gate line 20 corresponds to the first doped layer 102 one by one, and the second gate line 30 corresponds to the second doped layer 103 one by one. One of the first doped layer 102 and the second doped layer 103 may be a P-type doped layer, and the other may be an N-type doped layer. In some embodiments, the first gate line 20 may completely penetrate the back passivation film layer 104 to form a full contact with the first doped layer 102, or the first gate line 20 may only partially penetrate the back passivation film layer 104 to form a localized metallization contact with the first doped layer 102, and the specific details are not limited here.

[0061] That is to say, in the embodiment of the present application, the first gate line 20 is arranged corresponding to the first doped layer 102 and at least partially penetrates the back passivation film layer 104 and is in conductive contact with the first doped layer 102, and the second gate line 30 is arranged corresponding to the second doped layer 103 and at least partially penetrates the back passivation film layer 104 and is in conductive contact with the second doped layer 103.

[0062] See also Figure 3 and Figure 4 In some embodiments, the back-contact solar cell 100 is a busbar-free back-contact solar cell. Among the first grid lines 20, the first collection grid line 21 is disconnected at the first series connection area 13 and is 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 is disconnected at the remaining first series connection areas 13, and is continuous at the second series connection area 14.

[0063] like Figure 3 , Figure 4 as well as Figure 7 As shown, in such a case, as described above, the first grid line 20 (including the first collecting grid line 21 and the first bus grid line 22) includes a first welding section 201 corresponding to the second series connection area 14, that is, the first grid line 20 is continuous at each second series connection area 14 and has a first welding section 201 for welding with a welding strip at the second series connection area 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 section 301 corresponding to the first series connection area 13 (including the first edge series connection area 131), that is, the second grid line 30 is continuous at each first series connection area 13 and has a second welding section 301 for welding with a welding strip at the first series connection area 13.

[0064] In some embodiments, in the first collecting grid line 21, the width of the first welding section 201 (ie, the length in the second direction) may be greater than the width of the remaining portion, so as to increase the contact area between the first collecting grid line 21 and the welding strip and improve the stability of welding.

[0065] In some embodiments, the first welding section 201 may be a double-layer structure. Specifically, in some embodiments, the first gate line 20 may include a first collection layer penetrating the back passivation film layer 104 and a first welding layer stacked on the first collection layer and not penetrating the back passivation film layer 104 .

[0066] In some embodiments, the first collection layer may be continuous at the second series connection area 14 and discontinuous at the first series connection area 13, and the first welding layer may be arranged at the second series connection area 14 and located on the first collection layer. In this case, in the first gate line 20, the portion corresponding to the first welding layer is the first welding segment 201.

[0067] Of course, in other embodiments, the first welding section 201 may be a single-layer structure. In this case, the first collection layer is interrupted at both the second series connection area 14 and the first series connection area 13, and the first welding layer is disposed at the second series connection area 14 and is electrically connected to the two ends of the first collection layer formed at the second series connection area 14. It is not difficult to understand that in these cases, the portion corresponding to the first welding layer is the first welding section 201.

[0068] In some embodiments, the width of the first welding layer can be set to be greater than the width of the first collection layer, where the width refers to the length of the two in the second direction, so that the welding area can be increased during welding and the reliability of welding can be improved.

[0069] In some embodiments, the second welding section 301 may also be a double-layer structure. Specifically, in some embodiments, the second gate line 30 may include a second collection layer penetrating the back passivation film layer 104 and a second welding layer stacked on the second collection layer and not penetrating the back passivation film layer 104 .

[0070] In some embodiments, the second collection layer may be continuous at the first series connection area 13 and discontinuous at the second series connection area 14, and the second welding layer may be arranged at the first series connection area 13 and located on the second collection layer. In this case, in the second grid line 30, the part corresponding to the second welding layer is the second welding section 301.

[0071] Of course, in other embodiments, the second collection 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 collection layer formed at the first series connection area 13. It is not difficult to understand that in these cases, the portion corresponding to the second welding layer is the second welding segment 301.

[0072] In some embodiments, the width of the second welding layer may also be set to be greater than the width of the second collection layer, where the width refers to the length of both in the second direction.

[0073] In some embodiments, the depression depth of the first groove 15 is less than half of the thickness of the substrate 10. Specifically, the “depression depth” refers to: in the thickness direction, the distance between the bottom surface of the first groove 15 and the outermost surface of the back passivation film layer 104 away from the back surface 12, that is, the distance between the bottom surface of the first groove 15 and the back surface 12 of the substrate 10.

[0074] Thus, by setting the depth of the first groove 15 within this reasonable range, the risk of cold solder joints caused by the first insulating layer 50 can be reduced or even eliminated while avoiding a significant reduction in the strength of the back contact solar cell 100 due to excessive recess depth.

[0075] Specifically, in such a case, the recessed depth of the first groove 15 may be, for example, one third, one quarter, one fifth, etc. of the thickness of the substrate 10 .

[0076] In some embodiments, the first groove 15 may penetrate the back passivation film layer 104 and the first doping layer 102, so that the silicon substrate 101 is exposed from the first groove 15, and the portion of the first busbar line 22 located in the first groove 15 is in contact with the silicon substrate 101. In this way, after the substrate 10 is manufactured, the first groove 15 can be directly opened on the substrate 10 by etching (such as laser etching, etc.), without inserting an etching and grooving process in the process of preparing the substrate 10.

[0077] Specifically, in such a case, a complete substrate 10 may be provided first, and then a groove process may be performed directly at the position where the first insulating layer 50 is to be placed on the substrate 10 , and then the first gate line 20 and the second gate line 30 may be printed, and then the first insulating layer 50 may be arranged at the first groove 15 .

[0078] Of course, in some other embodiments, a first recessed groove may be formed on the silicon substrate 101 at a position corresponding to the first edge series region 131 and the first bus line 22, and the first doping layer 102 and the back passivation film layer 104 may be recessed toward the side where the front side 11 is located at the first recessed groove to form a first groove 15 on the substrate 10.

[0079] Specifically, in such a case, during the manufacturing process, before preparing the first doping layer 102, a first recessed groove can be opened in the silicon substrate 101 at a position where the first doping layer 102 needs to be prepared and the first insulating layer 50 needs to be placed, and then the first doping layer 102 and the back passivation film layer 104 are prepared to form the substrate 10. Since the first recessed groove is opened on the silicon substrate 101, the above-mentioned first groove 15 can be formed correspondingly on the substrate 10, and then the first gate line 20 and the second gate line 30 are printed, and then the first insulating layer 50 is set at the first groove 15.

[0080] See also Figure 3 , Figure 4 and Figure 6 In some embodiments, the back contact solar cell 100 may further include a first auxiliary connection line 60, which may be disposed in the first edge series connection area 131. In the second direction, at least one side of the first busbar line 22 is provided with the first auxiliary connection line 60, and the first auxiliary connection line 60 connects at least two second busbar lines 30 located on the same side of the first busbar line 22. Figure 4 and Figure 6 As shown, in some embodiments, the at least two second gate lines 30 connected to the first auxiliary connection line 60 preferably include the second gate line 30 adjacent to the first bus gate line 22 (ie Figure 3 and Figure 4 That is, in some embodiments, the first auxiliary connection line 60 is preferably connected to the second grid line 30 closest to the first bus grid line 22, and the first auxiliary connection line 60 is also connected to at least one of the remaining second grid lines 30 on the same side as the second grid line 30. That is, the first auxiliary connection line 60 is preferably connected to at least the second grid line 30 adjacent to the first bus grid line 22 and at least one of the remaining second grid lines 30 on the same side.

[0081] In this way, by setting the first auxiliary connecting line 60, the risk of cold soldering caused by the first insulating layer 50 can be further reduced. Even if a cold soldering occurs between the second grid line 30 and the welding strip near the first insulating layer 50 due to the setting of the first insulating layer 50, due to the existence of the first auxiliary connecting line 60, the second grid line 30 with cold soldering can also realize the current convergence output through the first auxiliary connecting line 60, thereby reducing the impact caused by the cold soldering, thereby ensuring the efficiency of the back-contact solar cell 100.

[0082] like Figure 3 and Figure 4 As shown, in the embodiment of the present application, in order to reduce the influence of cold solder joints as much as possible, when the second grid lines 30 are provided on both sides of the first bus grid line 22 , first auxiliary connection lines 60 are preferably provided on both sides of the first bus grid line 22 .

[0083] In some embodiments, the width of the first busbar line 22 (i.e., the length in the second direction) may be greater than the width of the portion of the first collecting gate line 21 located outside the second series connection region 14 (i.e., the portion of the first collecting gate line 21 except the first welding section 201).

[0084] Thus, since the first bus grid lines 22 need to bear the function of current collection and transmission, setting the width of the first bus grid lines 22 to be wider can reduce the transmission loss in the current collection process and improve the efficiency.

[0085] In addition, if Figure 3 , Figure 4 as well as Figure 7 As shown, in the embodiment of the present application, in the first bus grid line 22, it is continuous only at the first edge series connection area 131, and is disconnected at the other first series connection areas 13. At the same time, the first bus grid line 22 is continuous at the second series connection area 14 and has a first welding section 201 at the second series connection area 14. Only the section of the first bus grid line 22 closest to the first edge 121 has the bus function. Therefore, in some embodiments, in order to save slurry and reduce costs, only this part of the grid line segment can be set to be wider. In this case, please refer to Figure 3 , Figure 4 and Figure 7 , the plurality of second series connection regions 14 may include a second edge series connection region 141 closest to the first edge 121. The first busbar line 22 may include a first busbar segment 221 located between the second edge series connection region 141 and the first edge 121. In some embodiments, the width (i.e., the length in the second direction) of the first busbar segment 221 may be greater than the width of the remaining portion of the first busbar line 22 located outside the second series connection region 14 (i.e., the portion other than the first welding segment 201 of the portion other than the first busbar segment 221).

[0086] In this way, only by setting the width of the first conduit segment 221 to be wider, the use of slurry can be reduced while reducing the conduit transmission loss, thereby reducing costs.

[0087] Specifically, as described above, in such an embodiment, the first busbar line 22 is continuous at the second edge series connection area 141 and has a first welding section 201 at the second edge series connection area 141. The first bus section 221 can converge the current to the welding strip disposed at the second edge series connection area 141, and only a portion of the first bus section 221 is disposed wider to reduce the use of slurry. In this case, the first bus section 221 penetrates the back passivation film layer 104 and contacts the first doping layer 102.

[0088] See also 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, it is equivalent to increasing the cross-sectional area of ​​the first bus segment 221, which can also reduce transmission loss. At the same time, the first bus layer 70 can be made of a slurry with a lower cost than that of the first bus segment 221, which can reduce costs.

[0089] Specifically, in such an embodiment, the first bus layer 70 can be made of a non-burn-through slurry, the first bus layer 70 does not penetrate the back passivation film layer 104 and contact the first doping layer 102, and the slurry cost of the first bus layer 70 is lower than the slurry cost of the first bus segment 221. It can be understood that since the first bus segment 221 is provided with the first bus layer 70, it is not necessary to widen the first bus segment 221, which can also achieve the purpose of reducing transmission loss.

[0090] 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 collecting grid line 21 outside the second series connection area 14 (i.e., the portion of the first collecting grid line 21 except the first welding section 201). In this way, by increasing the width of the first bus layer 70, the transmission capacity can be further improved and the transmission loss can be reduced.

[0091] Specifically, in such an embodiment, the width of the first busbar layer 70 may be the same as the width of the first welding segment 201. In this article, the width of the first welding segment 201 refers to the length of the first welding segment 201 in the second direction. As shown above, when the width of the first welding layer is greater than the width of the first collection layer, the width of the first welding segment 201 is the width of the first welding layer (i.e., the length in the second direction). Similar descriptions appear below, which can be understood by referring to them.

[0092] In this way, it can be ensured that no large transmission loss will be caused during the convergence process. At the same time, during the printing process, the first convergence layer 70 can be printed simultaneously with the first welding layer at the first welding section 201. When the same screen is used for printing, there is no need to open screen slots of different sizes on the screen, which saves manufacturing processes and reduces manufacturing difficulty.

[0093] See also Figure 7 In some embodiments, the width (length in the first direction) of the first edge bus line 40 may be greater than the width (length in the second direction) of the portion of the first collecting gate line 21 located outside the second series connection area 14 (i.e., the portion of the first collecting gate line 21 except the first welding section 201).

[0094] Thus, since the first edge bus line 40 needs to bear the function of current collection and transmission, setting the width of the first edge bus line 40 to be wider can also reduce the transmission loss in the current collection process and improve the efficiency.

[0095] Specifically, in such an embodiment, the width of the first edge bus line 40 may be the same as the width of the first welding section 201. In this way, it can be ensured that no large bus loss will be caused during the bus process. At the same time, during printing, only the same size of screen slots need to be opened on the screen to print the three at the same time, which can effectively save manufacturing processes and reduce manufacturing difficulty.

[0096] Also, please read Figure 7 In some embodiments, the width (length in the first direction) of the first auxiliary connection line 60 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 series connection area 14 (i.e., the portion of the first collection gate line 21 except the first welding section 201).

[0097] Thus, since the first auxiliary connection line 60 plays the role of transmitting and converging current when cold soldering occurs, setting the width of the first auxiliary connection line 60 wider can also reduce transmission loss during the converging process and improve efficiency.

[0098] In some embodiments, the width of the first auxiliary connection line 60 may be the same as the width of the first edge bus line 40 .

[0099] See also Figure 3 and Figure 4 In some embodiments, the first edge bus line 40 is electrically connected to all the first collecting gate lines 21 .

[0100] In this way, the current collected by the isolated gate line segments between the first edge series connection region 131 and the first edge 121 in all the first collecting gate lines 21 can be converged, thereby maximizing the efficiency of the back contact solar cell 100 .

[0101] Of course, in some embodiments, the first edge bus line 40 may be electrically connected to only some of the first collecting grid lines 21. In this case, the number of first collecting grid lines 21 that are not electrically connected to the first edge bus line 40 is less than or equal to 4. In this way, even if some of the first collecting grid lines 21 are not connected to the first edge bus line 40, the number is small and will not cause excessive efficiency loss and result in product defects.

[0102] In some embodiments, the first auxiliary connection line 60 connects 2-20 second gate lines 30. Thus, by setting the number of second gate lines 30 connected to the first auxiliary connection line 60 within this reasonable range, the influence of cold solder joints can be reduced as much as possible or even eliminated.

[0103] In the embodiment of the present application, the number of the first bus grid line 22 may be single. In this case, the first auxiliary connection line 60 may be provided only on one side of the first bus grid line 22, or may be provided on both sides of the first bus grid line 22, and the specific details are not limited here. When the second grid lines 30 are provided on both sides of the first bus grid line 22, the first auxiliary connection line 60 is preferably provided on both sides.

[0104] In addition, it should be noted that, in the present application, when there are multiple first bus bars 22, the first auxiliary connection line 60 may be provided on only one side or both sides of some of the first bus bars 22, while the first auxiliary connection line 60 may not be provided on both sides of the remaining first bus bars 22. In this case, it can also solve the problem of cold solder joints in some positions. In the present application, it is preferred that the first auxiliary connection line 60 is provided on both sides of each first bus bar line 22. Of course, if the first bus bar line 22 is located at the third edge 123, the first auxiliary connection line 60 only needs to be provided on one side of the first bus bar line 22.

[0105] Of course, see Figure 3 and Figure 4 In some embodiments, the number of the first bus grid lines 22 may be multiple. Providing multiple first bus grid lines 22 can shorten the current converging path, effectively reduce the converging transmission loss, and improve efficiency.

[0106] In this case, a first auxiliary connection line 60 is disposed between two adjacent first bus gate lines 22 , and the first auxiliary connection line 60 between two adjacent first bus gate lines 22 connects all second gate lines 30 between two adjacent first bus gate lines 22 .

[0107] In this way, the first auxiliary connection line 60 is connected to all the second grid lines 30 between two adjacent first bus grid lines 22, which can substantially completely eliminate the influence of cold solder joints and improve the efficiency of the back contact solar cell 100 as much as possible.

[0108] Specifically, in such an embodiment, the number of the first busbar lines 22 in the back-contact solar cell 100 can be selected according to actual conditions such as the size of the solar cell and the loss during the transmission process, and is not limited here.

[0109] See also Figure 3 and Figure 4 as well as Figure 8 and Fig. 9In some embodiments, there are multiple first bus grid lines 22, and the substrate 10 has a third edge 123 and a fourth edge 124 in the second direction. Among the first grid lines 20 and the second grid lines 30, the grid line closest to the third edge 123 is the first bus grid line 22, and / or the grid line closest to the fourth edge 124 is the first bus grid line 22.

[0110] In this way, 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 convergence can be achieved at the edge positions, and the scope affected by the cold solder joint can also be reduced.

[0111] Specifically, Figure 3 and Figure 4 As shown, in such an embodiment, in addition to the first bus grid lines 22 at the third edge 123 and / or the fourth edge 124, a plurality of first bus grid lines 22 may be arranged in the middle area, and a first auxiliary connecting line 60 is arranged between two adjacent first bus grid lines 22, and the first auxiliary connecting line 60 connects all the second grid lines 30 between two adjacent first bus grid lines 22, so that the influence caused by the cold solder joint can be basically completely eliminated, and the efficiency of the back contact solar cell 100 can be guaranteed to the greatest extent.

[0112] Of course, it can be understood that, in some embodiments, among the first gate lines 20 and the second gate lines 30, the gate line closest to the third edge 123 may also be the first collecting gate line 21. In this case, the first auxiliary connecting line 60 between the first bus gate line 22 closest to the third edge 123 and the third edge 123 is connected to all the second gate lines 30 between the first bus gate line 22 closest to the third edge 123 and the third edge 123, that is, Figure 3 and Figure 4 The first bus gate line 22 closest to the third edge 123 is changed into the first collecting gate line 21 .

[0113] In some embodiments, among the first gate lines 20 and the second gate lines 30, the gate line closest to the fourth edge 124 may also be the first collecting gate line 21, and the first auxiliary connecting line 60 between the first bus gate line 22 closest to the fourth edge 124 and the fourth edge 124 is connected to all the second gate lines 30 between the first bus gate line 22 closest to the fourth edge 124 and the fourth edge 124, that is, Figure 3 and Figure 4 The first bus gate line 22 closest to the third edge 123 is changed into the first collecting gate line 21 .

[0114] In this way, the gate line closest to the third edge 123 and / or the fourth edge 124 is set as the first collecting gate line 21, and the first bus gate line 22 is only set in the middle area, which can eliminate the need to set the first insulating layer 50 at the position of the third edge 123 and the fourth edge 124, thereby reducing the use of insulating glue and reducing costs. At the same time, in such a case, by performing the above-mentioned connection setting on the first bus gate line 22 closest to the third edge 123 and the first auxiliary connecting line 60 between the third edge 123, the influence of the cold solder joint caused by the first insulating layer 50 can also be basically completely eliminated.

[0115] See also Figure 4 and Figure 8 In some embodiments, the substrate 10 has a third edge 123 and a fourth edge 124 in the second direction. At the junction where the first gate line 20 closest to the third edge 123 is connected to the first edge bus line 40, the first edge bus line 40 has a first protrusion 41 protruding toward the third edge 123.

[0116] See also Figure 4 and Fig. 9 In some embodiments, at the junction where the first gate line 20 closest to the fourth edge 124 is connected to the first edge bus line 40 , the first edge bus line 40 has a second protrusion 42 protruding toward the fourth edge 124 .

[0117] In this way, the setting 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 solar cell 100 located at the first edge 121, thereby avoiding inaccurate printing during the printing process, which may result in the slurry being unable to form a complete filling at the corner and causing poor contact between the first edge bus line 40 and the first grid line 20 closest to the third edge 123.

[0118] Specifically, in such a case, in some embodiments, the first gate line 20 closest to the third edge 123 and the first gate line 20 closest to the fourth edge 124 can both be the first bus gate line 22. In such a case, when the first bus layer 70 is provided on the first bus gate line 22, the first edge bus line 40 and the first bus layer 70 can be directly printed as one piece, and providing the first protrusion 41 and the second protrusion 42 at the intersection of the two can ensure the integrity of the printed filling and ensure that the two form good contact.

[0119] In addition, if Figure 8 and Fig. 9 As shown, in some embodiments, in the back contact solar cell 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 correspondingly arranged at the chamfers. Figure 8 and Fig. 9As shown, in order to achieve the connection between the first edge bus line 40 and the first grid line 20, the first edge bus line 40 has a bent portion at both chamfers. Of course, it can be understood that in some embodiments, if the back contact solar cell 100 does not have a chamfer, there is no need to set a bent portion.

[0120] See also Figure 8 and Fig. 9 In some embodiments, at the junction of the first gate line 20 (including the first collecting gate line 21 and the first bus gate line 22) and the first edge bus line 40, at least part of the first gate line 20 has a first gate line protrusion 202 protruding toward the first edge 121 side compared to the first edge bus line 40.

[0121] Thus, the first gate line protrusion 202 can ensure the stability of the electrical connection between the first gate line 20 and the first edge bus line 40, effectively avoiding the phenomenon that some first gate lines 20 cannot form stable contact with the first edge bus line 40 due to printing accuracy during the printing process.

[0122] See also Figure 3 , Figure 4 and Figure 7 In some embodiments, the plurality of second series connection regions 14 include a second edge series connection region 141 closest to the first edge 121 (i.e., a second series connection region 14 adjacent to the first edge series connection region 131), the first grid line 20 is continuous at the second edge series connection region 141, and the second grid line 30 is discontinuous at the second edge series connection region 141, and the back-contact solar cell 100 further includes a second auxiliary connection line 90, which is disposed in the second edge series connection region 141, and in the 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.

[0123] Thus, by disposing the second auxiliary connection line 90 in the second edge series connection area 141 , it is possible to effectively avoid the phenomenon that the welding strip in the second edge series connection area 141 has a cold solder joint or poor contact at the first bus bar line 22 , which results in the current transmitted from the first bus bar line 22 not being collected.

[0124] Specifically, Figure 4 and Figure 7As shown, in such an embodiment, the number of second auxiliary connecting lines 90 can be consistent with the number of first bus grid lines 22, and the two correspond one to one. When the first bus grid line 22 is located in the middle position (that is, there are first collecting grid lines 21 on both sides of the first bus grid line 22), the second auxiliary connecting line 90 connects the first bus grid line 22, and also connects two first collecting grid lines 21 adjacent to the first bus grid line 22 (that is, the first collecting grid lines 21 located on both sides of the first bus grid line 22 and adjacent to it).

[0125] When the gate line closest to the third edge 123 is the first bus gate line 22, only one side of the first bus gate line 22 has the first collecting gate line 21. In this case, the second auxiliary connection line 90 connected to the first bus gate line 22 located at the third edge 123 is connected to at least the first collecting gate line 21 adjacent to the first bus gate line 22. The number of first collecting gate lines 21 connected to the second auxiliary connection line 90 is 1-6. Figure 3 and Figure 4 In the embodiment, the second auxiliary connection line 90 connects the six first collecting gate lines 21 closest to the third edge 123, and the details are not limited here.

[0126] Similarly, when the gate line closest to the fourth edge 124 is the first bus gate line 22, only one side of the first bus gate line 22 has the first collecting gate line 21. In this case, the second auxiliary connection line 90 connected to the first bus gate line 22 located at the fourth edge 124 is connected to at least the first collecting gate line 21 adjacent to the first bus gate line 22, and the number of first collecting gate lines 21 connected to the second auxiliary connection line 90 is 1-6. Figure 3 and Figure 4 In the embodiment, the second auxiliary connection line 90 connects the six first collecting gate lines 21 closest to the fourth edge 124, and the details are not limited here.

[0127] 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 outside the second series connection area 14 (i.e., the portion of the first collecting grid line 21 except the first welding section 201). In this way, since the second auxiliary connection line 90 plays the role of transmitting and converging current when a cold weld occurs at the first bus grid line 22, setting the width of the second auxiliary connection line 90 wider can also reduce the transmission loss in the converging process and improve efficiency.

[0128] In some embodiments, the distance between the first edge series connection region 131 and the first edge 121 is greater than or equal to 2 mm and less than or equal to 20 mm.

[0129] In this way, it is possible to avoid the distance between the first edge series connection region 131 and the first edge 121 being too small, which causes the welding position to be too close to the first edge 121, thereby causing hidden cracks in the back contact solar cell 100, thereby reducing the risk of hidden cracks. It is also possible to avoid the distance between the first edge series connection region 131 and the first edge 121 being too large, which causes the length of the isolated gate line segment roughly located between the first edge series connection region 131 and the first edge 121 to be too long, thereby causing excessive loss during the transmission path.

[0130] Specifically, in such an embodiment, the distance between the first edge series area 131 and the first edge 121 may be, for example, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm or any value between 2mm-20mm, and is not limited here.

[0131] See also Figure 3 as well as Figure 10-13 In some embodiments, the plurality of second serial connection areas 14 include a third edge serial connection area 142 closest to the second edge 122, and there is no first serial connection area 13 between the third edge serial connection area 142 and the second edge 122. That is, Figure 3 and Fig.10 As shown, in the first series connection area 13 and the second series connection area 14, the series connection area closest to the second edge 122 is the second series connection area 14, and the second series connection area 14 is represented as the third edge series connection area 142, and there is no other series connection area between the third edge series connection area 142 and the second edge 122. Fig.12 As shown, a second groove 16 is formed on the substrate 10 in the third edge series connection area 142 .

[0132] The second gate lines 30 include a plurality of second collecting gate lines 31 and at least one second bus gate line 32 . The second collecting gate lines 31 are discontinuous at the third edge series connection area 142 and continuous at the first series connection area 13 . The second bus gate lines 32 are continuous at the third edge series connection area 142 . The first gate lines 20 are continuous at the second edge series connection area 141 .

[0133] That is, the second gate line 30 includes at least two types of gate lines, one is the second collecting gate line 31, and the other is the second bus gate line 32. The second collecting gate line 31 is interrupted at the third edge series area 142, and the second bus gate line 32 is continuous at the third edge series area 142. The first gate line 20 is also continuous at the third edge series area 142.

[0134] The second bus line 32 is partially located in the second groove 16. In some embodiments, in the second direction, the second bus line 32 may extend along one sidewall of the second groove 16 to the bottom of the second groove 16 and extend from the other sidewall of the second groove 16 to the outside of the second groove 16. The portion of the second bus line 32 corresponding to the second groove 16 does not fill the entire second groove 16, that is, in the thickness direction of the back-contact solar cell 100, the height of the portion of the second bus line 32 corresponding to the second groove 16 is less than the height of the opening of the second groove 16.

[0135] The back contact solar cell 100 may further include a second edge bus line 110 and a second insulating layer 120 . The second edge bus line 110 is closer to the second edge 122 than the third edge series connection region 142 , and is electrically connected to at least a portion of the second collecting grid lines 31 and to the second bus grid lines 32 .

[0136] Specifically, in order to avoid welding at the edge of the second edge 122 and causing hidden cracks in the battery, the second edge bus line 110 is not used for welding, but is used to collect the current in the second collecting grid line 31 located between the third edge series connection area 142 and the second edge 122, and then converge to the first series connection area 13 (i.e., the first series connection area 142) adjacent to the third edge series connection area 142 through the second bus grid line 32. Figure 3 and Fig.10 The same polarity welding strip in the first series connection area 13) on the far right side of the second grid line 30 is connected to collect the current of the grid line segment in the edge area located at the second edge 122, thereby improving the efficiency of the back contact solar cell 100. If the second edge bus line 110 and the second bus grid line 32 are not set, the portion of the second grid line 30 located between the third edge series connection area 142 and the second edge 122 will form an isolated grid line segment, resulting in the inability to collect the current in this portion.

[0137] like Figure 3 and Fig.12 As shown, the second insulating layer 120 is disposed at the second groove 16 in the third edge series connection area 142, and the second insulating layer 120 is at least partially disposed in the second groove 16 and located on the second bus grid line 32. That is, the second insulating layer 120 is disposed on the portion of the second bus grid line 32 located in the second groove 16, and the second insulating layer 120 is at least partially disposed in the second groove 16. The second insulating layer 120 is disposed to insulate and separate the opposite polarity welding strip in the third edge series connection area 142 from the second bus grid line 32 to avoid short circuit.

[0138] In which, in the thickness direction of the back-contact solar cell 100 (that is, the direction from the front side 11 to the back side 12), the height of the second insulating layer 120 is flush with the height of the first welding section 201, or the height of the second insulating layer 120 is less than the height of the first welding section 201, or the height of the second insulating layer 120 is greater than the height of the first welding section 201, and the height difference between the second insulating layer 120 and the first welding section 201 is less than or equal to 15um.

[0139] In this way, by setting the second edge bus line 110 and the second bus grid line 32, the current collected by at least part of the isolated section of the second grid line 30 located between the third edge series area 142 and the second edge 122 can be converged to the welding strip of the same polarity in the second series area 14 adjacent to the third edge series area 142, which can effectively avoid hidden cracks caused by welding at the second edge 122 of the back contact solar cell 100 while ensuring the efficiency of the back contact solar cell 100. At the same time, by forming a second groove 16 on the substrate 10, the second insulating layer 120 is at least partially arranged in the second groove 16, so that the height of the second insulating layer 120 is less than the height of the first welding section 201, or the second insulating layer 120 is flush with the first welding section 201, or the height of the second insulating layer 120 is greater than the first welding section 201 and the height difference between the two is less than or equal to 15um. In this way, the height difference between the second insulating layer 120 and the grid line welding section can be reduced or even eliminated, thereby reducing the risk of cold solder joints caused by the second insulating layer 120, further reducing the impact of cold solder joints on the back contact solar cell 100, and improving the performance of the back contact solar cell 100.

[0140] Specifically, as shown above, it is not difficult to understand that in the present application, the second edge busbar 110 is not used for welding, but is only used for current transmission and collection, and the function of the second busbar 32 is to collect and transmit. Figure 3 and Fig.10 It is known that in Figure 3 and Fig.10 In the example shown, if the second edge bus line 110 and the second bus grid line 32 are not provided, the second grid line 30 is disconnected at the third edge series connection area 142, and the current of the partial grid line segment of the second grid line 30 located between the third edge series connection area 142 and the second edge 122 cannot be collected. Therefore, by providing the second edge bus line 110 and the second bus grid line 32, the current of at least a portion of the isolated grid line segment of the second grid line 30 located in the edge area can be transmitted to the welding strip provided in the adjacent second series connection area 14, thereby effectively avoiding efficiency loss.

[0141] Since the second bus grid line 32 is continuously arranged in the third edge series connection area 142, in order to avoid the welding strip on the third edge series connection area 142 from contacting with the second bus grid line 32 and causing a short circuit, a second insulating layer 120 (such as insulating glue) needs to be arranged at the position corresponding to the second bus grid line 32 and the third edge series connection area 142. However, in this case, when the second groove 16 is not provided, the height of the second insulating layer 120 is higher than the height of the first welding section 201 of the second grid line 30, that is, in the thickness direction, the protruding height of the second insulating layer 120 is higher than the height of the first welding section 201 of the second grid line 30. In this case, the welding strip in the third edge series connection area 142 is easy to be damaged during the welding process. It is easy for a cold solder joint to occur with the second grid line 30, resulting in the inability to effectively collect the current on part of the second grid line 30 (especially the second grid line 30 adjacent to the second bus grid line 32, which is most likely to have a cold solder joint). Based on this, the present application opens a second groove 16 on the substrate 10 and at least partially disposes the second insulating layer 120 in the second groove 16, so that the height of the second insulating layer 120 is flush with or less than the height of the first welding section 201, or the height between the second insulating layer 120 and the first welding section 201 is less than 15um, thereby reducing or even eliminating the risk of a cold solder joint, thereby improving the reliability of welding and ensuring the performance of the back-contact solar cell 100.

[0142] Furthermore, in some embodiments, the number of the second bus grid lines 32 may be multiple, the number of the second insulating layers 120 may correspond to the number of the second bus grid lines 32, and the number of the second grooves 16 may correspond to the number of the second insulating layers 120. In this way, the risk of cold solder joints caused by all the second insulating layers 120 can be reduced or even eliminated. Of course, in some possible embodiments, only some of the second bus grid lines 32 may be provided with the second grooves 16, that is, only some of the second insulating layers 120 may have the second grooves 16 opened below them, and no second grooves 16 may be opened at other positions. In this case, the cold solder joint problem caused by some of the second insulating layers 120 can be solved.

[0143] When the height of the second insulating layer 120 is greater than the height of the first welding section 201, the height difference between the two may be 1um, 2um, 3um, 4um, 5um, 9um, 7um, 8um, 9um, 10um, 11um, 12um, 13um, 14um, 15um or any value between 0-15um.

[0144] In some embodiments, when the height of the second insulating layer 120 is greater than the height of the first welding section 201, the height difference between the second insulating layer 120 and the first welding section 201 may be preferably less than 8um, such as 0.5um, 1um, 2um, 3um, 4um, 5um, 9um, 7um, 8um. Specifically, after repeated research and verification by the inventors of the present application, it is found that by setting the height difference between the two preferably within the preferred range of less than 8um, the risk of cold solder joints caused by the second insulating layer 120 can be substantially eliminated.

[0145] In some embodiments, the depression depth of the second groove 16 is less than half of the thickness of the substrate 10. Specifically, the “depression depth” refers to: in the thickness direction, the distance between the bottom surface of the second groove 16 and the outermost surface of the back passivation film layer 104 away from the back surface 12, that is, the distance between the bottom surface of the second groove 16 and the back surface 12 of the substrate 10.

[0146] Thus, by setting the depth of the second groove 16 within this reasonable range, the risk of cold solder joints caused by the second insulating layer 120 can be reduced or even eliminated while avoiding a significant reduction in the strength of the back contact solar cell 100 due to excessive recess depth.

[0147] Specifically, in such a case, the recessed depth of the second groove 16 may be, for example, one third, one fourth, one fifth, etc. of the thickness of the substrate 10 .

[0148] In some embodiments, the second groove 16 may penetrate the back passivation film layer 104 and the second doping layer 103, so that the silicon substrate 101 is exposed from the second groove 16, and the portion of the first busbar line 22 located in the second groove 16 is in contact with the silicon substrate 101. In this way, after the substrate 10 is manufactured, the second groove 16 can be directly opened on the substrate 10 by etching (such as laser etching, etc.), without inserting an etching and grooving process in the process of preparing the substrate 10.

[0149] Specifically, in such a case, a complete substrate 10 may be provided first, and then a groove process may be performed directly at the position where the second insulating layer 120 is to be placed on the substrate 10 , and then the first gate line 20 and the second gate line 30 may be printed, and then the second insulating layer 120 may be disposed at the second groove 16 .

[0150] Of course, in some other embodiments, a second recessed groove may be formed on the silicon substrate 101 at a position corresponding to the first edge series region 131 and the first bus line 22, and the second doping layer 103 and the back passivation film layer 104 may be recessed toward the side where the front side 11 is located at the second recessed groove to form a second groove 16 on the substrate 10.

[0151] Specifically, in such a case, during the manufacturing process, before preparing the second doping layer 103, a second recessed groove can be opened in the silicon substrate 101 at the position where the second doping layer 103 needs to be prepared and the second insulating layer 120 needs to be placed, and then the second doping layer 103 and the back passivation film layer 104 are prepared to form the substrate 10. Since the second recessed groove is opened on the silicon substrate 101, the above-mentioned second groove 16 can be formed correspondingly on the substrate 10, and then the first gate line 20 and the second gate line 30 are printed, and then the second insulating layer 120 is set at the second groove 16.

[0152] See also Figure 3 , Fig.10 as well as Fig.12 In some embodiments, the back contact solar cell 100 may further include a third auxiliary connection line, the third auxiliary connection line 130 is arranged in the third edge series connection area 142, and in the second direction, at least one side of the second bus grid line 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 bus grid line 32. In some embodiments, the at least two first grid lines 20 preferably connected to the third auxiliary connection line 130 include the first grid line 20 adjacent to the second bus grid line 32 (i.e. Figure 3 and Fig.10 In other words, in some embodiments, the third auxiliary connection line 130 is preferably connected to the first gate line 20 closest to the second bus gate line 32, and the third auxiliary connection line 130 is also connected to at least one of the remaining first gate lines 20 on the same side as the second gate line 30. In other words, the third auxiliary connection line 130 is preferably connected to at least the first gate line 20 adjacent to the second bus gate line 32 and at least one of the remaining first gate lines 20 on the same side.

[0153] In this way, by setting the third auxiliary connecting line 130, the risk of cold soldering caused by the second insulating layer 120 can be further reduced. Even if a cold soldering occurs between the first gate line 20 and the welding strip near the second insulating layer 120 due to the setting of the second insulating layer 120, due to the existence of the third auxiliary connecting line 130, the first gate line 20 with the cold soldering can also realize the current convergence output through the third auxiliary connecting line 130, thereby reducing the impact caused by the cold soldering, thereby ensuring the efficiency of the back-contact solar cell 100.

[0154] See also Figure 3 and Fig.10In some embodiments, the back-contact solar cell 100 is a busbar-free back-contact solar cell. Among the plurality of second grid lines 30, the second collection grid line 31 is disconnected at the second series connection area 14 and is continuous at the first series connection area 13, the second collection grid line 32 is continuous at the third edge series connection area 142 and is disconnected at the remaining second series connection areas 14, and is continuous at the first series connection area 13.

[0155] like Figure 3 and Fig.10 As shown, in the embodiment of the present application, in order to reduce the influence of cold soldering as much as possible, when the first grid lines 20 are provided on both sides of the second bus grid line 32 , third auxiliary connection lines 130 are preferably provided on both sides of the second bus grid line 32 at the same time.

[0156] In some embodiments, in the second collecting grid line 31, the width of the second welding section 301 (ie, the length in the second direction) may be greater than the width of the remaining portion, so as to increase the contact area between the second collecting grid line 31 and the welding strip and improve the stability of welding.

[0157] In some embodiments, the width of the second bus grid line 32 (i.e., the length in the second direction) may be greater than the width (i.e., the length in the second direction) of the portion of the second collecting grid line 31 located outside the first series connection area 13 (i.e., the portion of the second collecting grid line 31 except the second welding section 301).

[0158] Thus, since the second bus grid lines 32 need to bear the function of current collection and transmission, setting the width of the second bus grid lines 32 to be wider can reduce the transmission loss in the current collection process and improve the efficiency.

[0159] In addition, in the embodiment of the present application, in the second bus grid line 32, it is continuous only in the third edge series connection area 142, and is disconnected in the other second series connection area 14. At the same time, the second bus grid line 32 is continuous in the first series connection area 13 and has a second welding section 301 in the first series connection area 13. Only the section of the second bus grid line 32 closest to the first edge 121 has the bus function. Therefore, in some embodiments, in order to save slurry and reduce costs, only this part of the grid line segment can be set to be wider. In this case, please refer to Figure 3 , Fig.10 and Fig.13, the first series connection areas 13 may include a fourth edge series connection area 132 closest to the first edge 121. The second busbar line 32 may include a second busbar segment 321 located between the fourth edge series connection area 132 and the first edge 121, and the width of the second busbar segment 321 (i.e., the length in the second direction) is greater than the width of the rest of the second busbar line 32 located outside the first series connection area 13 (i.e., the portion of the second busbar line 32 except the second busbar segment 321 and the second welding segment 301).

[0160] In this way, only by setting the width of the second conduit segment 321 to be wider, the use of slurry can be reduced while reducing the conduit transmission loss, thereby reducing costs.

[0161] Specifically, as described above, in such an embodiment, the second busbar line 32 is continuous at the fourth edge series connection area 132 and has a second welding section 301 at the fourth edge series connection area 132, and the second bus section 321 can converge the current to the welding strip arranged at the fourth edge series connection area 132, and only part of the second bus section 321 is arranged to be wider to reduce the use of slurry. In this case, the second bus section 321 penetrates the back passivation film layer 104 and contacts the second doping layer 103.

[0162] See also Fig.13 In other embodiments, a second bus layer 140 may be provided on the second bus segment 321. Thus, by providing the second bus layer 140 on the second bus segment 321, it is equivalent to increasing the cross-sectional area of ​​the second bus segment 321, which can also reduce transmission loss. At the same time, the second bus layer 140 can be made of a slurry with a lower cost than the second bus segment 321, which can reduce costs.

[0163] Specifically, in such an embodiment, the second bus layer 140 can be made of a non-burn-through slurry, the second bus layer 140 does not penetrate the back passivation film layer 104 to contact the first doping layer 102, and the slurry cost of the second bus layer 140 is lower than the slurry cost of the second bus segment 321. It can be 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, which can also achieve the purpose of reducing transmission loss.

[0164] 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 collecting grid line 31 located outside the first series connection area 13 (i.e., the portion of the second collecting grid line 31 except the second welding section 301). In this way, by increasing the width of the second bus layer 140, the transmission capacity can be further improved and the transmission loss can be reduced.

[0165] Specifically, in such an embodiment, the width of the second busbar layer 140 may be the same as the width of the second welding segment 301. In this article, the width of the second welding segment 301 refers to the length of the second welding segment 301 in the second direction. As shown above, when the width of the second welding layer is greater than the width of the second collector layer, the width of the second welding segment 301 is the width of the second welding layer (i.e., the length in the second direction). Similar descriptions appear below, which can be understood by referring to them. In this article, the width of the second welding segment 301 may be the same as the width of the first welding segment 201.

[0166] In this way, it can be ensured that no large transmission loss will be caused during the convergence process. At the same time, during the printing process, the second convergence layer 140 can be printed simultaneously with the first welding layer. When the same screen is used for printing, there is no need to open screen slots of different sizes on the screen, which saves manufacturing processes and reduces manufacturing difficulty.

[0167] See also Fig.13 In some embodiments, the width (length in the first direction) of the second edge bus line 110 is greater than the width (length in the second direction) of the portion of the second collecting gate line 31 located outside the first series connection area 13 (i.e., the portion of the second collecting gate line 31 except the second welding section 301).

[0168] Thus, since the second edge bus line 110 needs to bear the function of current collection and transmission, setting the width of the second edge bus line 110 to be wider can also reduce the transmission loss in the current collection process and improve the efficiency.

[0169] Specifically, in such an embodiment, the width of the second edge bus line 110 may be the same as the width of the second welding section 301. In this way, it can be ensured that no large bus loss will be caused during the bus process. At the same time, during printing, only the same size of screen slots need to be opened on the screen to print the three at the same time, which can effectively save manufacturing processes and reduce manufacturing difficulty.

[0170] Also, please read Fig.13 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 gate line 31 located outside the first series area 13 (i.e., the portion of the second collection gate line 31 except the second welding section 301).

[0171] Thus, since the third auxiliary connection line 130 plays the role of transmitting and converging current when cold soldering occurs, setting the width of the third auxiliary connection line 130 wider can also reduce transmission loss during the converging process and improve efficiency.

[0172] 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 .

[0173] See also Figure 3 and Fig.10 In some embodiments, the second edge bus line 110 is electrically connected to all the second collecting grid lines 31. In this way, the current collected by the isolated grid line segments between the third edge series connection region 142 and the second edge 122 in all the second collecting grid lines 31 can be combined, thereby maximizing the efficiency of the back contact solar cell 100.

[0174] Of course, in some embodiments, the second edge bus line 110 may also be electrically connected to some of the second collecting grid lines 31. In this case, the number of the second collecting grid lines 31 that are not electrically connected to the second edge bus line 110 is less than or equal to 4. In this way, even if some of the second collecting grid lines 31 are not connected to the second edge bus line 110, the number is very small, and will not cause excessive efficiency loss and result in product defects.

[0175] In some embodiments, the third auxiliary connection line 130 connects 2-20 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 influence of cold solder joints can be reduced as much as possible or even eliminated.

[0176] In the embodiment of the present application, the number of the second bus grid line 32 may be single. In this case, the third auxiliary connection line 130 may be provided only on one side of the second bus grid line 32, or may be provided on both sides of the second bus grid line 32, and the specific details are not limited here. When the first grid lines 20 are provided on both sides of the second bus grid line 32, the third auxiliary connection line 130 is preferably provided on both sides.

[0177] In addition, it should be noted that, in the present application, when there are multiple second bus bars 32, the third auxiliary connection line 130 may be provided only on one side or both sides of some of the second bus bars 32, while the third auxiliary connection line 130 may not be provided on both sides of the remaining second bus bars 32. In this case, the problem of cold solder joints at some locations can also be solved. In the present application, it is preferred that the third auxiliary connection line 130 is provided on both sides of each second bus bar line 32.

[0178] Of course, see Figure 3 and Fig.10 In some embodiments, the number of the second bus grid lines 32 may be multiple. Providing multiple second bus grid lines 32 can shorten the current converging path, effectively reduce the converging transmission loss, and improve efficiency.

[0179] In this case, a third auxiliary connection line 130 is disposed between two adjacent second bus gate lines 32 , and the third auxiliary connection line 130 between two adjacent second bus gate lines 32 connects all first gate lines 20 between two adjacent second bus gate lines 32 .

[0180] In this way, the third auxiliary connection line 130 is connected to all the first grid lines 20 between two adjacent second bus grid lines 32, which can substantially completely eliminate the influence caused by the cold solder joint and improve the efficiency of the back contact solar cell 100 as much as possible.

[0181] Of course, in some less preferred embodiments, the third auxiliary connection line 130 may be disposed only on one side of the second bus bar line 32 , which is not specifically limited herein.

[0182] Specifically, in such an embodiment, the number of the second busbar lines 32 in the back-contact solar cell 100 can be selected according to actual conditions such as the size of the solar cell and the loss during the transmission process, and is not limited here.

[0183] Please refer to the figure Figure 3 and Fig.10 as well as Fig.14 and Fig.15 In some embodiments, there are multiple second bus grid lines 32, and the substrate 10 has a third edge 123 and a fourth edge 124 in the second direction. Among the second grid lines 30 and the first grid lines 20, the grid line closest to the third edge 123 may be the first grid line 20, and the third auxiliary connection line 130 between the second bus grid line 32 closest to the third edge 123 and the third edge 123 connects all the first grid lines 20 between the second bus grid line 32 closest to the third edge 123 and the third edge 123.

[0184] Among the second gate lines 30 and the first gate lines 20, the gate line closest to the fourth edge 124 may also be the first gate line 20, and the third auxiliary connecting line 130 between the second bus gate line 32 closest to the fourth edge 124 and the fourth edge 124 connects all the first gate lines 20 between the second bus gate line 32 closest to the fourth edge 124 and the fourth edge 124.

[0185] In this way, by performing the above-mentioned connection setting on the third auxiliary connection line 130 between the second bus bar line 32 closest to the third edge 123 and the third edge 123 , the influence of cold solder joint caused by the second insulating layer 120 can be substantially completely eliminated.

[0186] See also Fig.10 , Fig.14 and Fig.15In some embodiments, the second edge bus line 110 may include a middle bus segment 113, a first edge bus segment 111, and a second edge bus segment 112, and the middle bus segment 113, the first edge bus segment 111, and the second edge bus segment 112 all extend along the second direction. Fig.12 As shown, the three can be arranged in parallel and spaced apart along the first direction. The middle bus section 113 is closer to the second edge 122 than the first edge bus section 111 and the second edge bus section 112 .

[0187] The first edge bus section 111 is disposed near the third edge 123, and the second edge bus section 112 is disposed near the fourth edge 124. The second edge bus line 110 further includes a first connecting section 114 and a second connecting section 115, and the first connecting section 114 and the second connecting section 115 both extend along the first direction. The first connecting section 114 connects the middle bus section 113 and the first edge bus section 111, and the second connecting section 115 connects the middle bus section 113 and the second edge bus section 112; The first edge bus section 111 connects the two second grid lines 30 closest to the third edge 123. At the junction of the first edge bus section 111 and the first connecting section 114, the first edge bus section 111 has a third convex portion 1101 protruding toward the fourth edge 124, and the first connecting section 114 has a fourth convex portion 1102 protruding toward the first edge 121. At the junction of the middle bus section 113 and the first connecting section 114, the middle bus section 113 has a fifth convex portion 1103 protruding toward the third edge 123, and the first connecting section 114 has a sixth convex portion 1104 protruding toward the second edge 122; and / or The second edge bus section 112 connects the two second grid lines 30 closest to the fourth edge 124. At the junction of the second edge bus section 112 and the second connecting section 115, the second edge bus section 112 has a seventh protrusion 1105 protruding toward the third edge 123, and the second connecting section 115 has an eighth protrusion 1106 protruding toward the first edge 121. At the junction of the middle bus section 113 and the second connecting section 115, the middle bus section 113 has a ninth protrusion 1107 protruding toward the fourth edge 124, and the second connecting section 115 has a tenth protrusion 1108 protruding toward the second edge 122.

[0188] Thus, when the connection between the second edge 122 and the third edge 123 and the fourth edge 124 has a chamfer, the second edge bus line 110 is configured as a structure of 3 vertical segments + 2 horizontal segments, so that the chamfer can be avoided and the printing difficulty can be reduced. At the same time, corresponding convex portions are provided at the junction of each bus segment, and redundancy can be provided at the corner of the second edge 122, so as to avoid poor contact between each bus segment due to inaccurate printing during the printing process, which causes the slurry to fail to form a complete filling at the corner.

[0189] 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 bus line 110 can also be arranged in the same manner as the first edge bus line 40 (for example, there is a bent portion), and the specifics are not limited here. Of course, it is understood that in some embodiments, if the back contact solar cell 100 does not have a chamfer, it is sufficient to set a second edge bus line 110 that extends vertically and continuously along the second direction.

[0190] See also Fig.14 and Fig.15 In some embodiments, at the junction of the second grid lines 30 (including the second collecting grid lines 31 and the second bus grid lines 32) and the second edge bus lines 110, at least some of the second grid lines 30 have second grid line protrusions 302 that protrude toward the first edge 121 compared to the second edge bus lines 110.

[0191] Thus, the second gate line protrusion 302 can ensure the stability of the electrical connection between the second gate line 30 and the second edge bus line 110, effectively avoiding the phenomenon that some second gate lines 30 cannot form stable contact with the second edge bus line 110 due to printing accuracy during the printing process.

[0192] See also Figure 3 , Fig.10 as well as Fig.13 In some embodiments, the first series connection areas 13 may further include a fourth edge series connection area 132 closest to the second edge 122 (i.e., the first series connection area 13 adjacent to the third edge series connection area 142), the second grid line 30 is continuous at the fourth edge series connection area 132, and the first grid line 20 is interrupted at the fourth edge series connection area 132. The back-contact solar cell 100 may further include a fourth auxiliary connection line 160, which is disposed in the fourth edge series connection area 132. 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.

[0193] Thus, by disposing the fourth auxiliary connection line 160 in the fourth edge series connection area 132 , it is possible to effectively avoid the phenomenon that the welding strip in the fourth edge series connection area 132 has a cold solder joint or poor contact at the second bus bar line 32 , resulting in the current transmitted from the second bus bar line 32 not being collected.

[0194] Specifically, Fig.10 and Fig.13 As shown, in such an embodiment, the number of fourth auxiliary connection lines 160 can be consistent with the number of second bus grid lines 32, and the two correspond one to one. When the second bus grid line 32 is located in the middle position (that is, there are second collection grid lines 31 on both sides of the second bus grid line 32), the fourth auxiliary connection line connects the second bus grid line 32 and connects two second collection grid lines 31 adjacent to the second bus grid line 32 (that is, the second collection grid lines 31 located on both sides of the second bus grid line 32 and adjacent to it).

[0195] 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 series connection area 13 (i.e., the portion of the second collection grid line 31 except the second welding section 301). In this way, since the fourth auxiliary connection line 160 plays the role of transmitting and converging current when a cold weld occurs at the second bus grid line 32, setting the width of the fourth auxiliary connection line 160 wider can also reduce the transmission loss in the converging process and improve efficiency.

[0196] In some embodiments, the distance between the third edge series connection region 142 and the second edge 122 is greater than or equal to 2 mm and less than or equal to 20 mm.

[0197] In this way, it is possible to avoid the distance between the third edge series connection area 142 and the second edge 122 being too small, which causes the welding position to be too close to the second edge 122, thereby causing hidden cracks in the back contact solar cell 100, thereby reducing the risk of hidden cracks. It is also possible to avoid the distance between the third edge series connection area 142 and the second edge 122 being too large, which causes the length of the isolated gate line segment roughly located between the third edge series connection area 142 and the second edge 122 to be too long, thereby causing excessive loss during the transmission path.

[0198] Specifically, in such an embodiment, the distance between the third edge series area 142 and the second edge 122 may be, for example, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm or any value between 2mm-20mm, and is not limited here.

[0199] In the above-mentioned embodiment, the third edge series connection area 142 has opposite polarity to the first edge series connection area 131, and the structures of the two edges of the back contact solar cell 100 in the first direction are different and asymmetric. It can be understood that in some possible embodiments, the third edge series connection area 142 and the first edge series connection area 131 may also have the same polarity. In this case, the structures of the two edges of the back contact solar cell 100 in the first direction are the same and symmetric. That is to say, in this case, in the back contact solar cell 100, the two series connection areas closest to the second edge 122 are symmetric to the first edge series connection area 131 and the second edge series connection area 141. A busbar, an auxiliary connection line and other structures are also provided on one side of the second edge 122, which are completely symmetric with one side of the first edge 121. In order to avoid redundancy, its specific structure is not described here.

[0200] See also Figure 3 In some embodiments, the substrate 10 has a third edge 123 and a fourth edge 124 in the second direction, and a fifth auxiliary connecting line 170 and a sixth auxiliary connecting line 180 are provided in the first series area 13. The fifth auxiliary connecting line 170 connects the N second gate lines 30 closest to the third edge 123, and the sixth auxiliary connecting 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.

[0201] In some embodiments, a seventh auxiliary connection line 190 and an eighth auxiliary connection line 1100 are provided in the second series area 14, the seventh auxiliary connection line 190 connects the P first gate lines closest to the third edge, and the eighth auxiliary connection line 1100 connects 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.

[0202] In this way, by respectively setting the fifth auxiliary connection line 170 and the sixth auxiliary connection line 180 at the positions of the first series connection area 13 close to the third edge 123 and the fourth edge 124, that is, by respectively setting the fifth auxiliary connection line 170 and the sixth auxiliary connection line 180 at the head and tail ends of the welding strip in the first series connection area 13, the problem that the current of some gate lines cannot be collected due to the occurrence of cold solder joints at the starting and ending solder joints of the welding strip on the first series connection area 13 can be effectively avoided. Similarly, by respectively setting the seventh auxiliary connection line 190 and the eighth auxiliary connection line 1100 at the positions of the second series connection area 14 close to the third edge 123 and the fourth edge 124, that is, by respectively setting the seventh auxiliary connection line 190 and the eighth auxiliary connection line 1100 at the head and tail ends of the welding strip in the second series connection area 14, the problem that the current of some gate lines cannot be collected due to the occurrence of cold solder joints at some positions of the starting and ending solder joints of the welding strip on the second series connection area 14 can be effectively avoided.

[0203] Specifically, Figure 3 As shown, in some embodiments, the fifth auxiliary connection line 170 in the first edge series area 131 can be an integral shared structure with the first auxiliary connection line 60 in the first edge series area 131 that is closest to the third edge 123, and the sixth auxiliary connection line 180 in the first edge series area 131 can be an integral shared structure with the first auxiliary connection line 60 in the first edge series area 131 that is closest to the fourth edge 124.

[0204] The seventh auxiliary connection line 190 in the second edge series area 141 can be an integral shared structure with the second auxiliary connection line 90 in the second edge series area 141 that is closest to the third edge 123 , and the eighth auxiliary connection line 1100 in the second edge series area 141 can be an integral shared structure with the second auxiliary connection line 90 in the second edge series area 141 that is closest to the fourth edge 124 .

[0205] The seventh auxiliary connection line 190 in the third edge series area 142 can be an integral shared structure with the third auxiliary connection line 130 in the third edge series area 142 that is closest to the third edge 123 , and the eighth auxiliary connection line 1100 in the third edge series area 142 can be an integral shared structure with the third auxiliary connection line 130 in the third edge series area 142 that is closest to the fourth edge 124 .

[0206] The fifth auxiliary connection line 170 in the fourth edge series area 132 can be an integral shared structure with the fourth auxiliary connection line 160 in the fourth edge series area 132 closest to the third edge 123, and the sixth auxiliary connection line 180 in the fourth edge series area 132 can be an integral shared structure with the fourth auxiliary connection line 160 in the fourth edge series area 132 closest to the fourth edge 124.

[0207] 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 arrange corresponding auxiliary connection lines at the corresponding positions of the edges.

[0208] See also Fig.16 In some embodiments, in the first series connection area 13, the X first gate lines 20 closest to the third edge 123 are discontinuous at the first series connection area 13, and the Y first gate lines 20 closest to the fourth edge 124 are discontinuous at the first series connection area 13, and the width of the discontinuous area formed by the X first gate lines 20 closest to the third edge 123 gradually increases in the direction toward the third edge 123, and the width of the discontinuous area formed by the Y first gate lines 20 closest to the fourth edge 124 gradually increases in the direction toward the fourth edge 124, wherein X and Y are both greater than or equal to 2; In the second series area 14, the W second gate lines 30 closest to the third edge 123 are interrupted in the second series area 14, and the Z second gate lines 30 closest to the fourth edge 124 are interrupted in the second series area 14. The width of the interrupted area formed by the W second gate lines 30 closest to the third edge 123 gradually increases in the direction toward the third edge 123, and the width of the interrupted area formed by the Z second gate lines 30 closest to the fourth edge 124 gradually increases in the direction toward the fourth edge 124, wherein W and Z are both greater than or equal to 2.

[0209] In this way, by setting the discontinuous area of ​​the grid lines at both ends of the welding strip to gradually increase toward the edge, it is possible to effectively avoid a large deviation of the two ends of the welding strip during the welding process, which may cause contact with grid lines of opposite polarity, thereby ensuring the reliability and stability of welding.

[0210] In the description of this specification, the description with reference to the terms "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0211] In addition, the above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A back contact solar cell, characterized in that: include: A substrate, wherein the substrate has a front side and a back side opposite to each other, the back side has a first edge and a second edge opposite to each other in a first direction, the back side has a plurality of first series connection areas and a plurality of second series connection areas, in the first direction, the first series connection areas and the second series connection areas are alternately arranged, the plurality of first series connection areas include a first edge series connection area closest to the first edge, there is no second series connection area between the first edge series connection area and the first edge, and a first groove is formed on the substrate in the first edge series connection area; A plurality of first grid lines and a plurality of second grid lines arranged on the back side are alternately arranged along a second direction, the second direction intersects with the first direction, the first grid lines and all the second grid lines are arranged to intersect with the first series connection area and the second series connection area, the first grid lines include a first welding section located in the second series connection area, and the second grid lines include a second welding section located in the first series connection area; the plurality of first grid lines include a plurality of first collecting grid lines and at least one first bus grid line, the first collecting grid line is discontinuous at the first edge series connection area and continuous at the second series connection area, the first bus grid line is continuous at the first edge series connection area and the first bus grid line is partially located in the first groove, and the second grid line is continuous at the first edge series connection area; a first edge bus line, the first edge bus line being closer to the first edge than the first edge series connection region, the first edge bus line being electrically connected to at least a portion of the first collector gate line and to the first bus gate line; and A first insulating layer, the first insulating layer is at least partially arranged in the first groove and located on the first bus line, wherein, in the direction from the front side to the back side, the height of the first insulating layer is flush with the height of the second welding section, or the height of the first insulating layer is less than the height of the second welding section, or the height of the first insulating layer is greater than the height of the second welding section and the height difference between the first insulating layer and the second welding section is less than or equal to 15um.

2. The back contact solar cell according to claim 1, characterized in that: The depression depth of the first groove is less than half of the thickness of the substrate.

3. The back contact solar cell according to claim 1, characterized in that: The first insulating layer is completely located in the first groove.

4. The back contact solar cell according to claim 1, characterized in that The substrate comprises a silicon substrate, a plurality of first doped layers, a plurality of second doped layers and a back passivation film layer, the silicon substrate has a first surface and a second surface opposite to each other, the first doped layers and the second doped layers are both arranged on the second surface, the plurality of first doped layers and the plurality of second doped layers are alternately arranged along a second direction, the back passivation film layer is at least stacked on the first doped layers and the second doped layers, the first gate line is arranged corresponding to the first doped layers and at least partially penetrates the back passivation film layer and is in conductive contact with the first doped layers, and the second gate line is arranged corresponding to the second doped layers and at least partially penetrates the back passivation film layer and is in conductive contact with the second doped layers; Wherein, the first groove penetrates the back passivation film layer and the first doping layer, so that the silicon substrate is exposed from the first groove, and the portion of the first busbar line located in the first groove is in contact with the silicon substrate; or A first recessed groove is formed on the silicon substrate at a position corresponding to the first busbar line in the first edge series region, and the first doping layer and the back passivation film layer are both recessed toward the front side at the first recessed groove to form the first groove on the substrate.

5. The back contact solar cell according to claim 1, characterized in that: The first edge bus line is electrically connected to all the first collecting gate lines; or The first edge bus line is electrically connected to a portion of the first collecting gate lines, and the number of the first collecting gate lines that are not electrically connected to the first edge bus line is less than or equal to four.

6. The back contact solar cell according to claim 1, characterized in that: The number of the first busbar lines is plural, and the substrate has a third edge and a fourth edge in the second direction; Among the first gate lines and the second gate lines, 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.

7. The back contact solar cell according to claim 1, characterized in that The substrate has a third edge and a fourth edge in the second direction; At the junction where the first gate line closest to the third edge is connected with the first edge bus line, the first edge bus line has a first protrusion protruding toward the third edge; and / or At a junction where the first gate line closest to the fourth edge is connected to the first edge bus line, the first edge bus line has a second protrusion protruding toward the fourth edge.

8. The back contact solar cell according to claim 1, characterized in that: The width of the first bus gate line is greater than the width of a portion of the first collecting gate line located outside the second series connection region.

9. The back contact solar cell according to claim 1, characterized in that: The plurality of second series connection regions include a second edge series connection region closest to the first edge; the first busbar line includes a first bus segment located between the second edge series connection region and the first edge; Wherein, the width of the first bus segment is greater than the width of the remaining portion of the first bus grid line located outside the second series connection area; and / or A first busbar layer is provided on the first busbar segment.

10. The back contact solar cell according to claim 9, characterized in that: The width of the first bus layer is greater than the width of a portion of the first collecting gate line located outside the second series connection area.

11. The back contact solar cell according to claim 1, characterized in that: The width of the first edge bus line is greater than the width of a portion of the first collecting gate line located outside the second series connection region.

12. The back contact solar cell according to claim 1, characterized in that: A distance between the first edge series connection area and the first edge is greater than or equal to 2 mm and less than or equal to 20 mm.

13. The back contact solar cell according to claim 1, characterized in that: The plurality of second series connection areas include a third edge series connection area closest to the second edge, the third edge series connection area and the second edge have no first series connection area between them, and a second groove is formed on the substrate in the third edge series connection area; The plurality of second gate lines include a plurality of second collecting gate lines and at least one second bus gate line, the second collecting gate lines are discontinuous at the third edge series connection area and continuous at the first series connection area, the second bus gate lines are continuous at the third edge series connection area and the first series connection area and the second bus gate lines are partially located in the second groove, and the first gate lines are continuous at the third edge series connection area; The back contact solar cell further comprises: a second edge bus line, the second edge bus line being closer to the second edge than the third edge series connection region, the second edge bus line being electrically connected to at least a portion of the second collecting grid line and to the second bus grid line; and A second insulating layer, the second insulating layer is at least partially arranged in the second groove and located on the second bus bar, the number of the second insulating layers corresponds to the number of the second bus bar, wherein, in the thickness direction of the back contact solar cell, the height of the second insulating layer is flush with the height of the first welding section, or the height of the second insulating layer is less than the height of the first welding section, or the height of the second insulating layer is greater than the height of the first welding section and the height difference between the second insulating layer and the first welding section is less than or equal to 15um.

14. The back contact solar cell according to claim 13, characterized in that: The recessed depth of the second groove is less than half of the thickness of the substrate.

15. The back contact solar cell according to claim 13, characterized in that: The second insulating layer is completely located in the second groove.

16. The back contact solar cell according to claim 13, characterized in that The substrate comprises a silicon substrate, a plurality of first doped layers, a plurality of second doped layers and a back passivation film layer, the silicon substrate has a first surface and a second surface opposite to each other, the first doped layers and the second doped layers are both arranged on the second surface, the plurality of first doped layers and the plurality of second doped layers are alternately arranged along a second direction, the back passivation film layer is at least stacked on the first doped layers and the second doped layers, the first gate line is arranged corresponding to the first doped layers and at least partially penetrates the back passivation film layer and is in conductive contact with the first doped layers, and the second gate line is arranged corresponding to the second doped layers and at least partially penetrates the back passivation film layer and is in conductive contact with the second doped layers; wherein the second groove penetrates the back passivation film layer and the second doping layer, so that the silicon substrate is exposed from the second groove, and a portion of the second busbar line located in the second groove is in contact with the silicon substrate; or A second recessed groove is formed on the silicon substrate at a position corresponding to the second edge series region and the second busbar line, and the second doping layer and the back passivation film layer are both recessed toward the front side at the second recessed groove to form the second groove on the substrate.

17. The back contact solar cell according to claim 13, characterized in that: The second edge bus line is electrically connected to all the second collecting gate lines; or The second edge bus line is electrically connected to a portion of the second collecting gate lines, and the number of the second collecting gate lines that are not electrically connected to the second edge bus line is less than or equal to four.

18. The back contact solar cell according to claim 13, characterized in that: The substrate has a third edge and a fourth edge in the second direction, the second edge bus line includes a middle bus section, a first edge bus section and a second edge bus section, the middle bus section, the first edge bus section and the second edge bus section all extend along the second direction, the middle bus section is closer to the second edge than the first edge bus section and the second edge bus section, the first edge bus section is arranged close to the third edge, and the second edge bus section is arranged close to the fourth edge; The second edge bus line further includes a first connecting section and a second connecting section, the first connecting section and the second connecting section both extend along the first direction, the first connecting section connects the middle bus section and the first edge bus section, and the second connecting section connects the middle bus section and the second edge bus section; Wherein, the first edge bus section connects two of the second grid lines closest to the third edge, and at the junction of the first edge bus section and the first connecting section, the first edge bus section has a third convex portion protruding toward the fourth edge, and the first connecting section has a fourth convex portion protruding toward the first edge, and at the junction of the middle bus section and the first connecting section, the middle bus section has a fifth convex portion protruding toward the third edge, and the first connecting section has a sixth convex portion protruding toward the second edge; and / or The second edge bus section connects the two second grid lines closest to the fourth edge. At the junction of the second edge bus section and the second connecting section, the second edge bus section 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 middle bus section and the second connecting section, the middle bus section has a ninth protrusion protruding toward the fourth edge, and the second connecting section has a tenth protrusion protruding toward the second edge.

19. The back contact solar cell according to claim 13, characterized in that: The width of the second bus gate line is greater than the width of a portion of the second collecting gate line located outside the first series connection region.

20. The back contact solar cell according to claim 13, characterized in that The first series connection regions include a fourth edge series connection region closest to the second edge; the second busbar line includes a second bus segment located between the fourth edge series connection region and the second edge; The width of the second bus segment is greater than the width of the remaining portion of the second bus grid line located outside the first series connection region; and / or A second bus layer is provided on the second bus section.

21. The back contact solar cell according to claim 20, characterized in that: The width of the second bus layer is greater than the width of a portion of the second collecting gate line located outside the first series connection area.

22. The back contact solar cell according to claim 13, characterized in that: The width of the second edge bus line is greater than the width of a portion of the second collecting gate line located outside the first series connection region.

23. The back contact solar cell according to claim 13, characterized in that: A distance between the third edge series connection area and the second edge is greater than or equal to 2 mm and less than or equal to 20 mm.

24. A battery assembly, characterized in that: A back-contact solar cell comprising any one of claims 1-23.

25. A photovoltaic system, characterized in that: A battery assembly comprising the battery assembly of claim 24.

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