Back contact cell, cell assembly and photovoltaic system

Abstract

The invention provides a back contact battery, a battery assembly and a photovoltaic system. The back contact cell includes a silicon substrate; the first fine grid and the second fine grid are arranged on the silicon substrate; the first main grid and the second main grid are arranged on the silicon substrate; the first main grid is connected with the first fine grid, and the second main grid is connected with the second fine grid; wherein the first fine grid comprises a first lap joint fine grid, and one or more end parts of the first lap joint fine grid are in lap joint with the first main grid; and / or, the second fine grid comprises a second lap joint fine grid, and one or more end parts of the second lap joint fine grid are in lap joint with the second main grid. According to the invention, through the connection mode of the fine grid and the main grid in which the end part of the fine grid is lapped to the main grid, the technical problem that the passivation layer at the position of the main grid is burnt through when the fine grid and the main grid are printed in the prior art is avoided, and the effects of effectively reducing the loss of the back contact battery and improving the efficiency of the back contact battery are achieved.

Description

[0001] This application claims priority to Chinese patent application No. 2024111575307, filed with the China Patent Office on August 21, 2024, and entitled “Back Contact Cells, Cell Components and Photovoltaic Systems”, the entire contents of which are incorporated by reference into this application.

[0002] This application also claims priority to the Chinese patent application No. 202422038013X, filed with the China Patent Office on August 21, 2024, and entitled “Back Contact Cells, Cell Components and Photovoltaic Systems”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present invention relates to the field of photovoltaic technology, and in particular to a back-contact battery, a battery assembly and a photovoltaic system. Background Art

[0004] Back-contact solar cells (BC structure) are a type of back-contact solar cell design, which is characterized by the fact that the battery electrodes are all on the back of the battery, rather than the traditional battery double-sided electrode design. In the case of traditional front-contact back-contact solar cells, the electrodes need to cover the surface of the battery, which will hinder the absorption of light and the transportation of charges, and reduce the battery conversion efficiency. The BC structure design can reduce the shading area on the battery surface, eliminate the light energy loss caused by the grid line shading, and improve the battery's utilization of photons, thereby bringing higher conversion efficiency to BC structure solar cells.

[0005] It is necessary to provide a design to further improve the conversion efficiency of BC cells. Summary of the invention

[0006] The inventors found that one of the reasons that affects the conversion efficiency of the battery in the back contact battery assembly is that the fine grid is usually designed to penetrate the main grid connection, and the fine grid is usually printed using a burn-through slurry. Therefore, when the fine grid penetrates the main grid connection method, the passivation layer located at the position of the main grid will also be burned through. The increase in the slurry burn-through area will cause greater damage to the battery, and more recombination centers will be generated, resulting in a decrease in the open circuit voltage of the battery and a decrease in the conversion efficiency of the battery cell. Therefore, the present invention provides a back contact battery, a battery assembly, and a photovoltaic system to solve the technical problem in the prior art that when the fine grid is connected to the main grid through printing, the passivation layer located at the main grid position will also be burned through.

[0007] The embodiment of the present invention is implemented as follows: the present invention provides a back-contact battery, a battery assembly and a photovoltaic system. The back-contact battery comprises: a silicon substrate;

[0008] First fine gates and second fine gates are arranged on the silicon substrate; a plurality of the first fine gates and a plurality of the second fine gates are alternately arranged in sequence along a first direction and extend along a second direction, and the second direction intersects the first direction;

[0009] A first main gate and a second main gate are arranged on the silicon substrate; the first main gate and the second main gate are arranged at intervals along the second direction and both extend along the first direction, the first main gate is connected to the first fine gate, and the second main gate is connected to the second fine gate; wherein the first fine gate includes a first overlapping fine gate, one or more ends of the first overlapping fine gate are overlapped to the first main gate; and / or the second fine gate includes a second overlapping fine gate, one or more ends of the second overlapping fine gate are overlapped to the second main gate.

[0010] Furthermore, the first overlapping fine grid includes a first overlapping fine grid A and a first overlapping fine grid B, and the first main grid includes a first main grid A; along the second direction, the first overlapping fine grid A has a first end and a second end that are relatively set; along the second direction, the first overlapping fine grid B has a first end and a second end that are relatively set; along the second direction, the second end of the first overlapping fine grid A and the first end of the first overlapping fine grid B are adjacent to each other; the second end of the first overlapping fine grid A and the first end of the first overlapping fine grid B are both overlapped to the first main grid A.

[0011] Furthermore, the second overlapping fine gate includes a second overlapping fine gate A and a second overlapping fine gate B, and the second main gate includes a second main gate A; along the second direction, the second overlapping fine gate A has a first end and a second end arranged oppositely; along the second direction, the second overlapping fine gate B has a first end and a second end arranged oppositely; along the second direction, the second end of the second overlapping fine gate A and the first end of the second overlapping fine gate B are adjacently arranged; the second end of the second overlapping fine gate A and the first end of the second overlapping fine gate B are both overlapped to the second main gate A.

[0012] Furthermore, along the second direction, the first overlapping fine grid A is flush with the first overlapping fine grid B.

[0013] Furthermore, the interval between the first overlapping fine gate A and the first overlapping fine gate B is greater than 250 μm.

[0014] Furthermore, along the second direction, the second overlapping fine grid A is flush with the second overlapping fine grid B.

[0015] Furthermore, the interval between the second overlapping fine gate A and the second overlapping fine gate B is greater than 250 μm.

[0016] Furthermore, along the second direction, the first overlapping fine grid A is higher or lower than the first overlapping fine grid B.

[0017] Furthermore, along the second direction, the second overlapping fine grid A is higher or lower than the second overlapping fine grid B.

[0018] Furthermore, the first overlapping fine gate includes a first overlapping fine gate C and a first overlapping fine gate D, and the first main gate includes a first main gate B; along the second direction, the first overlapping fine gate C has a first end and a second end that are relatively set; along the second direction, the first overlapping fine gate D has a first end and a second end that are relatively set; the first end of the first overlapping fine gate C and the first end of the first overlapping fine gate D are both overlapped to the first main gate B.

[0019] Furthermore, the first overlapping fine gate includes a second overlapping fine gate C and a second overlapping fine gate D, and the second main gate includes a second main gate B; along the second direction, the second overlapping fine gate C has a first end and a second end arranged oppositely; along the second direction, the second overlapping fine gate D has a first end and a second end arranged oppositely; the first end of the second overlapping fine gate C and the first end of the second overlapping fine gate D are both overlapped to the second main gate B.

[0020] Furthermore, the first overlapping fine grid includes a first overlapping fine grid E, and the first main grid includes a first main grid C and a first main grid D; along the second direction, the first overlapping fine grid E has a first end and a second end that are relatively arranged; the first end of the first overlapping fine grid E is overlapped to the first main grid C, and the second end of the first overlapping fine grid E is overlapped to the first main grid D.

[0021] Furthermore, the second overlapping fine gate includes a second overlapping fine gate E, and the second main gate includes a second main gate C and a second main gate D; along the second direction, the second overlapping fine gate E has a first end and a second end arranged opposite to each other; the first end of the second overlapping fine gate E is overlapped to the second main gate C, and the second end of the second overlapping fine gate E is overlapped to the second main gate D.

[0022] Furthermore, the first overlapping fine grid includes a first overlapping fine grid F, and the first main grid includes a first main grid E and a first main grid F; along the second direction, the first overlapping fine grid F has a first end and a second end that are relatively arranged; the first end of the first overlapping fine grid F is overlapped to the first main grid E, and the second end of the first overlapping fine grid F is connected to the first main grid F through.

[0023] Furthermore, the second overlapping fine gate includes a second overlapping fine gate F, and the second main gate includes a second main gate E and a second main gate F; along the second direction, the second overlapping fine gate F has a first end and a second end that are relatively arranged; the first end of the second overlapping fine gate F is overlapped to the second main gate E, and the second end of the second overlapping fine gate F is connected to the second main gate F through.

[0024] Furthermore, the first fine gate further includes a first through-fine gate, both ends of which are through-connected to the first main gate; and / or the second fine gate further includes a second through-fine gate, both ends of which are through-connected to the second main gate.

[0025] Furthermore, the ratio of the number of the first overlapping fine grids to the number of the first penetrating fine grids is 0.04 to 0.1.

[0026] Furthermore, a ratio of the number of the second overlapping fine grids to the number of the second penetrating fine grids is 0.04 to 0.1.

[0027] Furthermore, the first main grid includes one or more first fixed parts, and one or more ends of the first overlapping fine grid are overlapped on the first fixed parts; and / or the second main grid includes one or more second fixed parts, and one or more ends of the second overlapping fine grid are overlapped on the second fixed parts.

[0028] Furthermore, the first main grid includes a first main grid G, the first main grid G ​​includes a first fixing portion A, and a center line of the first main grid G ​​and a center line of the first fixing portion A are on the same straight line.

[0029] Furthermore, the second main grid includes a second main grid G, the second main grid G ​​includes a second fixing portion A, and a center line of the second main grid G ​​and a center line of the second fixing portion A are on the same straight line.

[0030] Furthermore, the first main grid includes a first main grid H, the first main grid H includes a first fixing portion B, and a center line of the first main grid H and a center line of the first fixing portion B are not on the same straight line.

[0031] Furthermore, the second main grid includes a second main grid H, the second main grid H includes a second fixing portion B, and a center line of the second main grid H and a center line of the second fixing portion B are not on the same straight line.

[0032] Furthermore, the first main grid is connected to a plurality of the first fine grids; wherein the first fine grids connected to the first fixed portion of the first main grid are all the first overlapping fine grids, and the first fine grids connected to the portion of the first main grid other than the first fixed portion are all the first penetrating fine grids.

[0033] Furthermore, the second main grid is connected to a plurality of the second fine grids; wherein the second fine grids connected to the second fixed portion of the second main grid are all the second overlapping fine grids, and the second fine grids connected to the portion other than the second fixed portion of the second main grid are all the second through fine grids.

[0034] Furthermore, the back contact battery further includes a first welding strip and a second welding strip, wherein the first welding strip is welded to the first fixing portion through a first welding layer; and the second welding strip is welded to the second fixing portion through a second welding layer.

[0035] Furthermore, the first main grid is connected to a plurality of the first fine grids, and the first fine grids are all the first overlapping fine grids.

[0036] Furthermore, a distance from one end of the first overlapping fine grid to the first main grid along the second direction is greater than 20 μm.

[0037] Furthermore, it also includes a P-type doped layer and an N-type doped layer arranged on the silicon substrate; the P-type doped layer is correspondingly connected to the first fine gate, and the N-type doped layer is correspondingly connected to the second fine gate; or, the P-type doped layer is correspondingly connected to the second fine gate, and the N-type doped layer is correspondingly connected to the first fine gate; wherein the thickness of the P-type doped layer is greater than the thickness of the N-type doped layer.

[0038] Furthermore, the thickness of the P-type doping layer is greater than or equal to 100 nm and less than or equal to 300 nm; and / or the thickness of the N-type doping layer is greater than or equal to 50 nm and less than or equal to 300 nm.

[0039] Furthermore, the thickness of the P-type doping layer minus the thickness of the N-type doping layer is less than or equal to 100 nm.

[0040] Furthermore, the crystallization depth of the first fine gate and the P-type doping layer is greater than the crystallization depth of the second fine gate and the N-type doping layer; or, the crystallization depth of the second fine gate and the P-type doping layer is greater than the crystallization depth of the first fine gate and the N-type doping layer.

[0041] Furthermore, the crystallization depth of the first fine gate and the P-type doping layer is 100 nm-220 nm; or the crystallization depth of the second fine gate and the P-type doping layer is 100 nm-220 nm.

[0042] Furthermore, the crystallization depth of the first fine gate and the N-type doping layer is 30nm-90nm; or the crystallization depth of the second fine gate and the N-type doping layer is 30nm-90nm.

[0043] Furthermore, the first main grid includes a first overlap and a first non-overlap, one or more ends of the first overlap fine grid overlap the first main grid, and the glass content of the first overlap is greater than that of the first non-overlap.

[0044] Furthermore, the second main grid includes a second overlap and a second non-overlap, one or more ends of the second overlap fine grid overlap the second main grid, and the glass content of the first overlap is greater than that of the second non-overlap.

[0045] An embodiment of the present invention further provides a battery assembly, which includes the back-contact battery as described above.

[0046] An embodiment of the present invention further provides a photovoltaic system, which includes the battery assembly as described above.

[0047] The embodiment of the present invention provides a back contact cell, a cell assembly and a photovoltaic system. The back contact cell includes a silicon substrate; a first fine grid and a second fine grid arranged on the silicon substrate; a plurality of the first fine grids and a plurality of the second fine grids are alternately arranged in a first direction and extend in a second direction, and the second direction intersects with the first direction; a first main grid and a second main grid arranged on the silicon substrate; the first main grid and the second main grid are arranged in a second direction and extend in the first direction, the first main grid is connected to the first fine grid, and the second main grid is connected to the second fine grid; wherein the first fine grid includes a first overlapped fine grid, and one or more ends of the first overlapped fine grid overlap the first main grid; and / or the second fine grid includes a second overlapped fine grid, and one or more ends of the second overlapped fine grid overlap the second main grid. The present invention effectively avoids the technical problem that the passivation layer located at the main grid position will be burned through when the fine grid and the main grid are printed in the prior art through the connection mode of the fine grid and the main grid, thereby effectively reducing the loss of the back contact cell and increasing the efficiency of the back contact cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0049] Figure 1 A schematic diagram of the module structure of a photovoltaic system provided by an embodiment of the invention;

[0050] Figure 2 A schematic diagram of the module structure of a battery assembly provided in an embodiment of the invention;

[0051] Figure 3 A schematic diagram of the structure of a back contact battery provided by an embodiment of the invention;

[0052] Figure 4 for Figure 3 A schematic diagram of the overlap distance of the first overlap main grid in the back contact battery described in;

[0053] Figure 5 for Figure 3 A schematic diagram of a part of the structure of the first fixing structure and the first welding layer provided on the first main grid in the back contact battery described in the embodiment;

[0054] Figure 6 for Figure 3 A partial structural schematic diagram of a second fixing structure and a second welding layer provided on the second main grid in the back contact battery described in the embodiment;

[0055] Figure 7 for Figure 3 A schematic structural diagram of a back contact battery in which a first welding strip and a second welding strip are provided;

[0056] Figure 8 for Figure 3 A schematic diagram of the local structure of the first main grid A in the back contact battery described in ;

[0057] Fig. 9 for Figure 8 A schematic diagram of the spacing between the first overlapping fine grid A and the first overlapping fine grid B in the first main grid A;

[0058] Fig.10 for Figure 3 A schematic diagram of the partial structure of the second main grid A in the back contact battery described in ;

[0059] Fig.11 for Fig.10 A schematic diagram of the spacing between the second overlapping fine grid A and the second overlapping fine grid B in the first main grid A;

[0060] Fig.12 for Figure 3 A schematic diagram of the partial structure of the first main grid A in the back contact battery described in the figure, wherein the first overlapping fine grid A and the first overlapping fine grid B are not aligned;

[0061] Fig.13 for Figure 3 A schematic diagram of the partial structure of the second main grid A in the back contact battery described in the figure, wherein the second overlapping fine grid A and the second overlapping fine grid B are not flush;

[0062] Fig.14 for Figure 3 Schematic diagram of the local structure of the first main grid B in the back contact battery described in;

[0063] Fig.15 for Figure 3 Schematic diagram of the partial structure of the second main grid B in the back contact battery described in ;

[0064] Fig.16 for Figure 3 Schematic diagram of the partial structure of the first main grid C and the first main grid D in the back contact battery described in ;

[0065] Fig.17 for Figure 3 A schematic diagram of the partial structure of the second main grid C and the second main grid D in the back contact battery described in ;

[0066] Fig.18 for Figure 3 Schematic diagram of the partial structure of the first main grid E and the first main grid F in the back contact battery described in ;

[0067] Fig.19 for Figure 3 Schematic diagram of the partial structure of the second main grid E and the second main grid F in the back contact battery described in ;

[0068] Fig. 20 for Figure 3 Schematic diagram of the partial structure of the first main grid G ​​in the back contact battery described in ;

[0069] Fig.21 for Figure 3 Schematic diagram of the local structure of the first main grid H in the back contact battery described in ;

[0070] Fig. 22 for Figure 3 Schematic diagram of the partial structure of the second main grid G ​​in the back contact battery described in ;

[0071] Fig.23 for Figure 3 Schematic diagram of the partial structure of the second main grid H in the back contact battery described in ;

[0072] Fig.24 for Figure 3 A partial side structural diagram of a P-type doped layer and an N-type doped layer in the back contact battery described in;

[0073] Fig.25 for Figure 3 Another partial side structural schematic diagram of the P-type doping layer and the N-type doping layer in the back contact battery;

[0074] Fig.26 for Fig.24 A schematic diagram of the crystallization depth of the P-type doping layer and the N-type doping layer;

[0075] Fig. 27 for Fig.25 A schematic diagram of the crystallization depth of the P-type doping layer and the N-type doping layer;

[0076] Fig.28 for Figure 3 A schematic diagram of a portion of the structure of a first overlapping portion and a first non-overlapping portion of a first main grid in the back contact battery;

[0077] Fig.29 for Figure 3 A partial structural schematic diagram of the second overlapping portion and the second non-overlapping portion of the second main grid in the back contact battery.

[0078] Main component symbol description: 1000, photovoltaic system; 1001, battery assembly; 100, back contact battery; 10, silicon substrate; 21, first fine grid; 22, second fine grid; 31, first main grid; 32, second main grid; 41, first welding strip; 42, second welding strip; 51, first welding layer; 52, second welding layer; 61, P-type doped layer; 62, N-type doped layer; 211, first overlapping fine grid; 212, first through-fine grid ; 221, second overlapping fine grid; 222, second through fine grid; 2111, first overlapping fine grid A; 2112, first overlapping fine grid B; 2113, first overlapping fine grid C; 2114, first overlapping fine grid D; 2115, first overlapping fine grid E; 2116, first overlapping fine grid F; 2211, second overlapping fine grid A; 2212, second overlapping fine grid B; 2213, second overlapping fine grid C; 2214, second overlapping fine grid D; 2215, second overlapping fine grid E; 2216, second overlapping fine grid F; 311, first main grid A; 312, first main grid B; 313, first main grid C; 314, first main grid D; 315, first main grid E; 316, first main grid F; 317, first main grid G; 318, first main grid H; 321, second main grid A; 322, second main grid B; 323, second main grid C; 324, second main grid D; 325 , second main grid E; 326, second main grid F; 327, second main grid G; 328, second main grid H; 310, first fixed part; 3101, first fixed part A; 3102, second fixed part B; 3103, first overlapping part; 3104, first non-overlapping part; 320, second fixed part; 3201, second fixed part A; 3202, second fixed part B; 3203, second overlapping part; 3204, second non-overlapping part. DETAILED DESCRIPTION

[0079] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. In addition, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0080] In the description of the present invention, it is necessary to understand that the terms "length", "width", "up", "down", "top", "bottom", "lateral", "longitudinal" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0081] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0082] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0083] In the present invention, 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.

[0084] The disclosure below provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are merely examples, and the purpose is not to limit the present invention. In addition, the present invention may repeat reference numbers and / or reference letters in different examples, and such repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those of ordinary skill in the art may be aware of the application of other processes and / or the use scenarios of other materials.

[0085] It should be noted that the drawings provided in this application are schematic diagrams, and some elements are not shown in the drawings. The purpose is to clearly describe the technical solution and highlight the key points of the invention. It is not intended to limit the technical solution to not including these unshown elements. For example, Figure 3 , Figure 5 , Figure 6 , Figure 7In the figure, only part of the electrode (e.g., main grid, fine grid, etc.) is shown, and not all the electrodes. In fact, the electrode may include more parts. For example, Figure 3 In the embodiment, a second fine grid 22 (eg, a second overlapping fine grid 221 and / or a second penetrating fine grid 222) not shown may be included. The second fine grid 22 and the first fine grid 21 are arranged in an interdigitated manner. For example, Figure 3 In the embodiment, the first fine gate 21 (eg, the first overlapping fine gate 211 and / or the first penetrating fine gate 212) may be included. The second fine gate 22 and the first fine gate 21 are arranged in an interdigitated manner.

[0086] For another example, Figure 3 , Figure 5 , Figure 6 , Figure 7 In FIG. 1 , only the portion of the through-fine gate between the two main gates is shown. In fact, the through-fine gate may include a portion outside the two main gates. Figure 3 In the figure, the first through-fine gate 212 may extend leftward to the edge of the silicon substrate 10. The first through-fine gate 212 may extend rightward to the third first main gate 31 and overlap the third first main gate 31, or penetrate the third first main gate 31 and continue to extend rightward.

[0087] See also Figure 1 and Figure 2 The photovoltaic system 1000 in the embodiment of the present invention may include the battery assembly 1001 in the embodiment of the present invention, and the battery assembly 1001 in the embodiment of the present invention may include a plurality of battery strings, and the battery string may include a plurality of back-contact batteries 100 in the embodiment of the present invention. In the present invention, a plurality of back-contact batteries 100 in the battery assembly 1001 may be connected in series in sequence through welding strips to form a battery string. The battery strings in the battery assembly 1001 may be connected in series, in parallel, or in series-parallel combination to realize the bus output of current, for example, the connection between the battery strings may be realized through a bus bar.

[0088] See also Figure 3 The back contact cell 100 in the embodiment of the present invention has a silicon substrate 10, on which a first fine grid 21 and a second fine grid 22 are arranged, and a plurality of first fine grids 21 and second fine grids 22 are alternately arranged in sequence along a first direction and all extend along a second direction, and the second direction intersects with the first direction.

[0089] The first fine grid 21 and the second fine grid 22 can be specifically configured as the first fine grid 21 being a negative fine grid and the second fine grid 22 being a positive fine grid; or the first fine grid 21 can be configured as a positive fine grid and the second fine grid 22 can be configured as a negative fine grid, which is not limited here.

[0090] The first direction may specifically be the width direction of the first fine gate 21 and the second fine gate 22, that is, Figure 3 The second direction may specifically be the length direction of the first fine grid 21 and the second fine grid 22, ie Figure 3 Of course, in other embodiments, the first direction and the second direction may also be other directions, such as a diagonal direction, etc., which is not specifically limited here.

[0091] The silicon substrate 10 is also provided with a first main gate 31 and a second main gate 32, which are arranged at intervals along the second direction and extend along the first direction, the first main gate 31 is connected to the first fine gate 21, and the second main gate 32 is connected to the second fine gate 22. The first main gate 31 and the second main gate 32 can be specifically set as the first main gate 31 as a negative main gate and the second main gate 32 as a positive main gate; or the first main gate 31 can be set as a positive main gate and the second fine gate 22 as a negative main gate, which is not limited here. Of course, in the embodiment of the present application, the polarity of the first main gate 31 and the first fine gate 21 connected to each other is the same, and the polarity of the second main gate 32 and the second fine gate 22 connected to each other is the same.

[0092] Along the thickness direction of the silicon substrate 10 , the first main gate 31 is disposed between the passivation layer and the first fine gate 21 ; and the second main gate 32 is disposed between the passivation layer and the second fine gate 22 .

[0093] The first fine grid 21 includes a first overlapping fine grid 211, one or more ends of the first overlapping fine grid 211 are overlapped on the first main grid 31; and / or the second fine grid 22 includes a second overlapping fine grid 221, one or more ends of the second overlapping fine grid 221 are overlapped on the second main grid 32. The first fine grid 21 and the second fine grid 22 are made of a burn-through slurry, and the first main grid 31 and the second main grid 32 are made of a non-burn-through slurry. The number of the first overlapping fine grid 211 can be one or more, which is not limited here; similarly, the number of the second overlapping fine grid 221 can be one or more, which is not limited here.

[0094] Specifically, in the prior art, the fine grid in the back contact battery 100 is usually connected to the main grid through penetration, and the fine grid is usually printed using a burn-through paste to burn through the passivation layer to make contact between the fine grid and the doping layer, and the main grid is usually printed using a non-burn-through paste, which will not burn through the passivation layer set on the surface of the doping layer. However, when the fine grid and the main grid are connected through penetration, the passivation layer located at the main grid position will also be burned through when the fine grid and the main grid are printed, which will cause losses to the back contact battery 100 and reduce the efficiency of the back contact battery 100.

[0095] The through-connection method of the fine grid and the main grid specifically refers to that the main grid passes through the fine grid for connection, and the main grid is arranged below the fine grid, or in other words, the fine grid is arranged above the main grid and connected to the main grid.

[0096] Therefore, in the present invention, unlike the conventional method of penetrating the fine grid and the main grid, an overlapping fine grid is provided in the fine grid in the back contact cell 100, that is, one or more ends of the first overlapping fine grid 211 are overlapped on the first main grid 31, that is, the first overlapping fine grid 211 is connected to the first main grid 31 by partially overlapping its end with the first main grid 31; similarly, one or more ends of the second overlapping fine grid 221 are overlapped on the second main grid 32, that is, the second overlapping fine grid 221 is connected to the second main grid 32 by partially overlapping its end with the second main grid 32. Specifically, as Figure 4 As shown, a distance L3 from one end of the first overlapping fine gate 211 to the first main gate 31 along the second direction is greater than 20 μm.

[0097] When printing the first overlapping fine grid 211 and the second overlapping fine grid 221, the first overlapping fine grid 211 of the burn-through type paste is overlapped on the first main grid 31 of the non-burn-through type paste; the second overlapping fine grid 221 of the burn-through type paste is overlapped on the second main grid 32 of the non-burn-through type paste. Then the burn-through type paste directly contacts the main grid instead of directly contacting the passivation layer, so at the overlap of the first overlapping fine grid 211 and the first main grid 31 and at the overlap of the second overlapping fine grid 221 and the second main grid 32, the fine grid paste cannot directly contact, and cannot effectively burn through the passivation layer under the first main grid 31 and under the second main grid 32, thereby achieving the effect of effectively reducing the loss of the back contact battery 100 and increasing the efficiency of the back contact battery 100.

[0098] That is, in the present invention, the connection method between the fine grid and the main grid by overlapping the end of the fine grid to the main grid effectively avoids the technical problem of burning through the passivation layer located at the main grid position when printing the fine grid and the main grid in the prior art, thereby achieving the effect of effectively reducing the loss of the back contact battery 100 and increasing the efficiency of the back contact battery 100.

[0099] Further, in a possible implementation manner, as Figure 3 and Figure 5 As shown, the first main grid 31 is connected to a plurality of first fine grids 21, and the first fine grids 21 are all first overlapped fine grids 211. Specifically, in the present invention, it can be arranged that all the first fine grids 21 connected to each first main grid 31 are first overlapped fine grids 211. That is, the first main grid 31 and the first fine grids 21 are all connected in an overlapped manner, so as to further effectively reduce the loss of the back contact battery 100 and increase the efficiency of the back contact battery 100.

[0100] Furthermore, in a possible implementation, Figure 3 and Figure 6 As shown, the second main grid 32 is connected to a plurality of second fine grids 22, and the second fine grids 22 are all second overlapped fine grids 221. Specifically, in the present invention, it can also be arranged that all the second fine grids 22 connected to each second main grid 32 are second overlapped fine grids 221. That is, the second main grid 32 and the second fine grids 22 are all connected by overlapping. Therefore, in the back contact battery 100, it can be arranged that all the main grids are connected to the main grid by overlapping, that is, the first fine grids 21 are all first overlapped fine grids 211, and the second fine grids 22 are all second overlapped fine grids 221, so as to minimize the loss of the back contact battery 100 and increase the efficiency of the back contact battery 100.

[0101] In the present invention, in combination with the drawings provided in the present application, the first end of each fine gate specifically refers to the end on the left side of the fine gate, and the second end of each fine gate specifically refers to the end on the right side of the fine gate for explanation; of course, in other embodiments, the first end of each fine gate specifically refers to the end on the right side of the fine gate, and the second end of each fine gate specifically refers to the end on the left side of the fine gate, and there is no limitation here.

[0102] Furthermore, if Figure 3 , Fig.28 and Fig.29 As for the overlap between the first main grid 31 and the first fine grid 21, in a possible implementation, the first main grid 31 includes a first overlap 3103 and a first non-overlap 3104, one or more ends of the first overlap fine grid 211 overlap the first overlap 3103 of the first main grid 31, and the glass content of the first overlap 3103 is greater than that of the first non-overlap 3104.

[0103] Specifically, the first main grid 31 may include a first overlap 3103 overlapped with one or more ends of the first overlap fine grid 211, and the first main grid 31 also includes a first non-overlap 3104 outside the first overlap 3103. For a first main grid 31, the glass frit content of the first overlap 3103 is greater than the glass frit content of the first non-overlap 3104. A higher glass frit content generally helps to improve the contact quality between metal particles during welding or sintering, and more glass frit can provide better adhesion and stability between metal particles. Therefore, in the present invention, more glass frit is arranged on the first overlap 3103 of the first main grid 31 to achieve the effect of enhancing the electrical connection between the overlap of the first main grid 31 and the first overlap fine grid 211 to ensure reliable.

[0104] Likewise, if Figure 3 , Fig.28 and Fig.29As for the overlap between the second main grid 32 and the second fine grid 22, in a possible implementation, the second main grid 32 includes a second overlap 3203 and a second non-overlap 3204, one or more ends of the second overlap fine grid 221 overlap the second overlap 3203 of the second main grid 32, and the glass content of the second overlap 3203 is greater than that of the second non-overlap 3204.

[0105] Specifically, the second main grid 32 may include a second overlap 3203 overlapped with one or more ends of the second overlap fine grid 221, and the second main grid 32 also includes a second non-overlap 3204 other than the second overlap. For a second main grid 32, the glass frit content of the second overlap 3203 is greater than the glass frit content of the second non-overlap 3204. Therefore, in the present invention, more glass frit is arranged on the second overlap 3203 of the second main grid 32 to achieve the effect of enhancing the electrical connection between the overlap of the second main grid 32 and the second overlap fine grid 221.

[0106] Of course, in the present invention, in addition to setting the overlapping thin grid, in order to further increase the tension of the main grid. Increasing the tension of the main grid specifically refers to increasing the connection strength between the main grid and the battery. The main grid with a stronger connection to the battery requires a greater pulling force to peel the main grid from the battery. Correspondingly, it can be said that the main grid has a greater pulling force.

[0107] In a possible implementation, Figure 3 As shown. The first fine grid 21 also includes a first through-fine grid 212, and both ends of the first through-fine grid 212 are through-connected with the first main grid 31; and / or, the second fine grid 22 also includes a second through-fine grid 222, and both ends of the second through-fine grid 222 are through-connected with the second main grid 32. Because the tension of the main grid on the back contact battery 100 can be increased by the through-connection of the fine grid and the main grid, in the present invention, the first fine grid 21 can also include the first through-fine grid 212, and the second fine grid 22 can also include the second through-fine grid 222. Both ends of the first through-fine grid 212 are through-connected with the first main grid 31, and both ends of the second through-fine grid 222 are through-connected with the second main grid 32. In the present invention, the first through-fine grid 212 is provided to increase the tension of the first main grid 31, and the second through-fine grid 222 is provided to increase the tension of the second main grid 32 on the back contact battery 100, thereby achieving the effect of improving the stability and reliability of the back contact battery 100.

[0108] Further, in a possible implementation manner, the ratio of the number of the first overlapping fine gates 211 to the number of the first penetrating fine gates 212 is 0.04 to 0.1. The ratio of the number of the second overlapping fine gates 221 to the number of the second penetrating fine gates 222 is 0.04 to 0.1.

[0109] Specifically, in the embodiment of the present invention, the first fine grid 21 can include two types of fine grids, namely, a first through-fine grid 212 and a first overlapping fine grid 211. Because the first through-fine grid 212 can increase the tension of the first main grid 31 connected to the first through-fine grid 212, the reliability of the loss of the back contact battery 100 is improved; the first overlapping fine grid 211 can prevent the passivation layer at the first main grid 31 overlapped with the first overlapping fine grid 211 from being burned through, effectively reducing the loss of the back contact battery 100. Therefore, by setting the ratio of the number of the first overlapping fine grid 211 to the number of the first through-fine grid 212 in the range of 0.04 to 0.1, the reliability of the loss of the back contact battery 100 can be improved while reducing the loss of the back contact battery 100.

[0110] Similarly, in the embodiment of the present invention, the second fine grid 22 can include two types of fine grids, namely, a second through-fine grid 222 and a second overlapping fine grid 221. Because the second through-fine grid 222 can increase the tension of the second main grid 32 connected to the second through-fine grid 222, the reliability of the loss of the back contact battery 100 is improved; the second overlapping fine grid 221 can prevent the passivation layer at the second main grid 32 overlapped with the second overlapping fine grid 221 from being burned through, effectively reducing the loss of the back contact battery 100. Therefore, by setting the ratio of the number of the second overlapping fine grid 221 to the number of the second through-fine grid 222 in the range of 0.04 to 0.1, the reliability of the loss of the back contact battery 100 can be improved while reducing the loss of the back contact battery 100.

[0111] Furthermore, the specific overlapping method of the first overlapping fine grid 211 and the first main grid 31 is as follows. Figure 3 , Figure 8 and Fig. 9 As shown, in a possible embodiment, the first overlapping fine gate 211 includes a first overlapping fine gate A and a first overlapping fine gate B, and the first main gate 31 includes a first main gate A; along the second direction, the first overlapping fine gate A has a first end and a second end that are relatively set; along the second direction, the first overlapping fine gate B has a first end and a second end that are relatively set; along the second direction, the second end of the first overlapping fine gate A and the first end of the first overlapping fine gate B are adjacent to each other; the second end of the first overlapping fine gate A and the first end of the first overlapping fine gate B are both overlapped to the first main gate A.

[0112] like Figure 3 , Fig.10 and Fig.11As shown, the first overlapping fine grid A2111 and the first overlapping fine grid B2112 are both overlapped to the first main grid A311 and connected to the first main grid A311. And along the second direction, the second end of the first overlapping fine grid A2111 and the first end of the first overlapping fine grid B2112 are arranged adjacent to each other, that is, the first overlapping fine grid A2111 and the first overlapping fine grid B2112 are two adjacent first fine grids 21 in the second direction. As for the overlapping mode of the first overlapping fine grid A2111 and the first overlapping fine grid B2112, specifically, the second end of the first overlapping fine grid A2111 and the first end of the first overlapping fine grid B2112 are both overlapped to the first main grid A311. That is, the second end of the first overlapping fine grid A2111 and the first end of the first overlapping fine grid B2112 are overlapped on the first main grid A311.

[0113] Therefore, in the present invention, through this arrangement, one end of the two first fine grids 21 can be overlapped on the same first main grid 31, ensuring that the current can be smoothly conducted from the two first fine grids 21 to the main grid, and then transmitted to the external circuit through the first main grid 31, so as to optimize the current collection and transmission path; at the same time, when printing the first overlapping fine grid A2111 and the first overlapping fine grid B2112, the passivation layer at the first main grid A311 is effectively avoided from being burned through, thereby achieving the effect of effectively reducing the loss of the back contact battery 100 and increasing the efficiency of the back contact battery 100.

[0114] In addition, the heights of the first overlapping fine grid A2111 and the first overlapping fine grid B2112 are set as follows: Figure 8 , Fig. 9 and Fig.12 As shown, the first overlapping fine gate A2111 and the first overlapping fine gate B2112 may be flush. That is, in a possible embodiment, along the second direction, the first overlapping fine gate A2111 is flush with the first overlapping fine gate B2112. In the present invention, by arranging the first overlapping fine gate A2111 and the first overlapping fine gate B2112 flush, the process of manufacturing the first overlapping fine gate A2111 and the first overlapping fine gate B2112 can be facilitated, which helps to improve the stability and repeatability of the production process. When the first overlapping fine gate A2111 is flush with the first overlapping fine gate B2112, the spacing L1 between the first overlapping fine gate A2111 and the first overlapping fine gate B2112 is in the range of greater than 250μm.

[0115] Of course, the first overlapping fine grid A2111 and the first overlapping fine grid B2112 may also be uneven. That is, in a possible implementation, along the second direction, the first overlapping fine grid A2111 is higher or lower than the first overlapping fine grid B2112, and the first overlapping fine grid A2111 may be uneven with the first overlapping fine grid B2112. Therefore, two adjacent first overlapping fine grids 211 in the second direction may have a variety of arrangement modes, thereby achieving the effect of improving the flexibility of the arrangement of the first overlapping fine grids 211.

[0116] Similarly, for the specific overlapping manner of the second overlapping fine grid 221 and the second main grid 32, as shown in FIG. Figure 3 , Fig.10 and Fig.11 As shown, in a possible embodiment, the second overlapping fine gate 221 includes a second overlapping fine gate A2211 and a second overlapping fine gate B2212, and the second main gate 32 includes a second main gate A321; along the second direction, the second overlapping fine gate A2211 has a first end and a second end that are relatively set; along the second direction, the second overlapping fine gate B2212 has a first end and a second end that are relatively set; along the second direction, the second end of the second overlapping fine gate A2211 and the first end of the second overlapping fine gate B2212 are adjacently set; the second end of the second overlapping fine gate A2211 and the first end of the second overlapping fine gate B2212 are both overlapped to the second main gate A321.

[0117] like Fig.10 , Fig.11 and Fig.13 As shown, the second overlapping fine grid A2211 and the second overlapping fine grid B2212 are both overlapped to the second main grid A321 to connect with the second main grid A. And along the second direction, the second end of the second overlapping fine grid A2211 and the first end of the second overlapping fine grid B2212 are arranged adjacent to each other, that is, the second overlapping fine grid A2211 and the second overlapping fine grid B2212 are two adjacent second fine grids 22 in the second direction. As for the overlapping mode of the second overlapping fine grid A2211 and the second overlapping fine grid B2212, specifically, the second end of the second overlapping fine grid A2211 and the first end of the second overlapping fine grid B2212 are both overlapped to the second main grid A321. That is, the second end of the second overlapping fine grid A2211 and the first end of the second overlapping fine grid B2212 are overlapped on the second main grid A321.

[0118] Therefore, in the present invention, through this arrangement, one end of the two second fine grids 22 can be overlapped on the same second main grid 32, ensuring that the current can be smoothly conducted from the two second fine grids 22 to the second main grid 32 and then transmitted to the external circuit through the second main grid 32, so as to optimize the current collection and transmission path; at the same time, when printing the second overlapping fine grid A2211 and the second overlapping fine grid B2212, the passivation layer at the second main grid A321 is effectively avoided from being burned through, thereby achieving the effect of effectively reducing the loss of the back contact battery 100 and increasing the efficiency of the back contact battery 100.

[0119] In addition, the heights of the second overlapping fine grid A2211 and the second overlapping fine grid B2212 are set as follows: Fig.10 , Fig.11 and Fig.13 As shown, the second overlapping fine gate A2211 and the second overlapping fine gate B2212 may be flush. That is, in a possible embodiment, along the second direction, the second overlapping fine gate A2211 and the second overlapping fine gate B2212 are flush. In the present invention, by arranging the second overlapping fine gate A2211 and the second overlapping fine gate B2212 flush, the process of manufacturing the second overlapping fine gate A2211 and the second overlapping fine gate B2212 can be facilitated, which helps to improve the stability and repeatability of the production process. When the second overlapping fine gate A2211 and the second overlapping fine gate B2212 are flush, the spacing L2 between the second overlapping fine gate A2211 and the second overlapping fine gate B2212 is greater than 250μm.

[0120] Of course, the second overlapping fine grid A2211 and the second overlapping fine grid B2212 may also be uneven. That is, in a possible implementation, along the second direction, the second overlapping fine grid A2211 is higher or lower than the second overlapping fine grid B2212, and the second overlapping fine grid A2211 may be uneven with the second overlapping fine grid B2212. Therefore, two second overlapping fine grids 221 adjacently arranged in the second direction may have a variety of arrangement modes, thereby achieving the effect of improving the flexibility of the arrangement of the second overlapping fine grids 221.

[0121] Furthermore, for the specific overlapping manner of the first overlapping fine grid 211 and the first main grid 31, as shown in FIG. Figure 3 , Fig.14 and Fig.15As shown, in a possible embodiment, the first overlapped fine gate 211 includes a first overlapped fine gate C2113 and a first overlapped fine gate D2114, and the first main gate 31 includes a first main gate B312; along the second direction, the first overlapped fine gate C2113 has a first end and a second end that are relatively set; along the second direction, the first overlapped fine gate D2114 has a first end and a second end that are relatively set; the first end of the first overlapped fine gate C2113 and the first end of the first overlapped fine gate D2114 are both overlapped to the first main gate B312.

[0122] like Fig.14 As shown, the first overlapping fine gate C2113 and the first overlapping fine gate D2114 are both overlapped to the first main grid B312 to be connected to the first main grid B312. As for the overlapping mode of the first overlapping fine gate C2113 and the first overlapping fine gate D2114, specifically, the first end of the first overlapping fine gate C2113 and the first end of the first overlapping fine gate D2114 are both overlapped to the first main grid B312. That is, the first end of the first overlapping fine gate C2113 and the first end of the first overlapping fine gate D2114 are overlapped on the first main grid B312.

[0123] Therefore, in the present invention, through this arrangement, one end of the two first fine grids 21 can be overlapped on the same first main grid 31, ensuring that the current can be smoothly conducted from the two first fine grids 21 to the first main grid 31 and then transmitted to the external circuit through the first main grid 31, so as to optimize the current collection and transmission path; at the same time, when printing the first overlapping fine grid C2113 and the first overlapping fine grid D2114, the passivation layer at the first main grid B312 is effectively avoided from being burned through, thereby achieving the effect of effectively reducing the loss of the back contact battery 100 and increasing the efficiency of the back contact battery 100.

[0124] Similarly, for the specific overlapping manner of the second overlapping fine grid 221 and the second main grid 32, as shown in FIG. Figure 3 , Fig.14 and Fig.15 As shown, in a possible embodiment, the second overlapped fine gate 221 includes a second overlapped fine gate C2213 and a second overlapped fine gate D2214, and the second main gate 32 includes a second main gate B322; along the second direction, the second overlapped fine gate C2213 has a first end and a second end that are relatively set; along the second direction, the second overlapped fine gate D2214 has a first end and a second end that are relatively set; the first end of the second overlapped fine gate C2213 and the first end of the second overlapped fine gate D2214 are both overlapped to the second main gate B322.

[0125] like Fig.15As described above, the second overlapping fine grid C2213 and the second overlapping fine grid D2214 are both overlapped to the second main grid B322 to be connected to the second main grid B322. As for the overlapping mode of the second overlapping fine grid C2213 and the second overlapping fine grid D2214, specifically, the first end of the second overlapping fine grid C2213 and the first end of the second overlapping fine grid D2214 are both overlapped to the second main grid B322. That is, the first end of the second overlapping fine grid C2213 and the first end of the second overlapping fine grid D2214 are overlapped to the second main grid B322.

[0126] Therefore, in the present invention, through this arrangement, one end of the two second fine grids 22 can be overlapped on the same second main grid 32, ensuring that the current can be smoothly conducted from the two second fine grids 22 to the second main grid 32 and then transmitted to the external circuit through the second main grid 32, so as to optimize the current collection and transmission path; at the same time, when printing the second overlapping fine grid C2213 and the second overlapping fine grid D2214, the passivation layer at the second main grid B322 is effectively avoided from being burned through, thereby achieving the effect of effectively reducing the loss of the back contact battery 100 and increasing the efficiency of the back contact battery 100.

[0127] Furthermore, for the specific overlapping manner of the first overlapping fine grid 211 and the first main grid 31, as shown in FIG. Figure 3 and Fig.16 As shown, in a possible embodiment, the first overlapping fine gate 211 includes a first overlapping fine gate E2115, and the first main gate 31 includes a first main gate C313 and a first main gate D314; along the second direction, the first overlapping fine gate E2115 has a first end and a second end that are relatively arranged; the first end of the first overlapping fine gate E2115 is overlapped to the first main gate C313, and the second end of the first overlapping fine gate E2115 is overlapped to the first main gate D314.

[0128] like Fig.16 As shown, the two ends of the first overlapping fine grid E2115 are respectively connected to the first main grid C313 and the first main grid D314. Both ends of the first overlapping fine grid E2115 are connected to a main grid by overlapping. Therefore, when printing the first overlapping fine grid E2115, the passivation layer at the first main grid C313 and the first main grid D314 is effectively avoided from being burned through, thereby achieving the effect of effectively reducing the loss of the back contact battery 100 and increasing the efficiency of the back contact battery 100.

[0129] Similarly, for the specific overlapping manner of the second overlapping fine grid 221 and the second main grid 32, as shown in FIG. Figure 3 and Fig.17As shown, in a possible embodiment, the second overlapping fine gate 221 includes a second overlapping fine gate E2215, and the second main gate 32 includes a second main gate C323 and a second main gate D324; along the second direction, the second overlapping fine gate E2215 has a first end and a second end that are relatively arranged; the first end of the second overlapping fine gate E2215 is overlapped to the second main gate C323, and the second end of the second overlapping fine gate E2215 is overlapped to the second main gate D324.

[0130] like Fig.17 As described above, the two ends of the second overlapping fine grid E2215 are respectively connected to the second main grid C323 and the second main grid D324 by overlapping. Both ends of the second overlapping fine grid E2215 are connected to a main grid by overlapping. Therefore, when printing the second overlapping fine grid E2215, the passivation layer at the second main grid C323 and the second main grid D324 is effectively avoided from being burned through, thereby achieving the effect of effectively reducing the loss of the back contact battery 100 and increasing the efficiency of the back contact battery 100.

[0131] Furthermore, for the specific overlapping manner of the first overlapping fine grid 211 and the first main grid 31, as shown in FIG. Figure 3 and Fig.18 As shown, in a possible embodiment, the first overlapping fine gate 211 includes a first overlapping fine gate F2116, and the first main gate 31 includes a first main gate E315 and a first main gate F316; along the second direction, the first overlapping fine gate F2116 has a first end and a second end that are relatively arranged; the first end of the first overlapping fine gate F2116 is overlapped to the first main gate E315, and the second end of the first overlapping fine gate F2116 is connected to the first main gate F316.

[0132] like Fig.18 As shown, the two ends of the first overlapping fine grid F2116 are respectively connected to the first main grid E315 and the first main grid F316 by overlapping and penetrating. One end of the first overlapping fine grid F2116 is connected to a main grid by overlapping, and the other end of the first overlapping fine grid F2116 is connected to another main grid by penetrating. Because the penetration connection between the fine grid and the main grid can increase the pulling force of the main grid on the back contact battery 100, reduce the risk of the fine grid or the main grid breaking, thereby achieving the effect of improving the stability and reliability of the back contact battery 100. Therefore, when printing the first overlapping fine grid F2116, it is effectively avoided to burn through the passivation layer at the first main grid E315, thereby achieving the effect of effectively reducing the loss of the back contact battery 100 and increasing the efficiency of the back contact battery 100; and it can also increase the pulling force of the first main grid E315 on the back contact battery 100, thereby achieving the effect of improving the stability and reliability of the back contact battery 100.

[0133] Similarly, for the specific overlapping manner of the second overlapping fine grid 221 and the second main grid 32, as shown in FIG. Figure 3 and Fig.19 As shown, in a possible embodiment, the second overlapping fine gate 221 includes a second overlapping fine gate F2216, and the second main gate 32 includes a second main gate E325 and a second main gate F326; along the second direction, the second overlapping fine gate F2216 has a first end and a second end that are relatively arranged; the first end of the second overlapping fine gate F2216 is overlapped to the second main gate E325, and the second end of the second overlapping fine gate F2216 is through-connected to the second main gate F326.

[0134] like Fig.19 As shown, the two ends of the second overlapping fine grid F2216 are respectively connected to the second main grid E325 and the second main grid F326 by overlapping and penetrating. One end of the second overlapping fine grid F2216 is connected to a main grid by overlapping, and the other end of the second overlapping fine grid F2216 is connected to another main grid by penetrating. Because the way in which the fine grid is connected to the main grid through penetration can increase the pulling force of the main grid on the back contact battery 100, reducing the risk of the fine grid or the main grid breaking. Therefore, when printing the second overlapping fine grid F2216, it is effectively avoided to burn through the passivation layer at the second main grid E325, thereby achieving the effect of effectively reducing the loss of the back contact battery 100 and increasing the efficiency of the back contact battery 100; and it can also achieve the effect of increasing the pulling force of the second main grid F326, thereby achieving the effect of improving the stability and reliability of the back contact battery 100.

[0135] Furthermore, in addition to preventing the passivation layer at the main gate, the overlapping fine gate can also, in a possible implementation manner, Figure 3 , Figure 5 and Figure 6 The first main grid 31 includes one or more first fixed portions 310, and one or more ends of the first overlapping fine grid 211 are overlapped on the first fixed portion 310; and / or the second main grid 32 includes one or more second fixed portions 320, and one or more ends of the second overlapping fine grid 221 are overlapped on the second fixed portion 320.

[0136] Specifically, the first main grid 31 may include one or more first fixing parts 310, and the first fixing parts 310 may be used for welding the welding strip, that is, the first main grid 31 may be welded to the welding strip through the first fixing parts 310, and the first fixing parts 310 may also be used for volt-ampere testing, and the first fixing parts 310 may be specifically PAD points. The first main grid 31 may include one or more second fixing parts 320, and the second fixing parts 320 may be used for welding the welding strip, that is, the second main grid 32 may be welded to the welding strip through the second fixing parts 320, and the second fixing parts 320 may also be used for volt-ampere testing, and the second fixing parts 320 may be specifically PAD points.

[0137] In the prior art, the PAD point of the main grid is usually connected to the fine grid through the PAD point. Therefore, when the welding strip is welded to the main grid through the PAD point, the solder will not only be distributed to the PAD point, but also to the fine grid set on the PAD point. The welding strip is prone to cold welding, resulting in insufficient welding tension of the PAD point to the welding strip. However, by overlapping the PAD point with the fine grid, the fine grid part connected to the PAD point can be reduced, and the solder can be distributed more on the PAD point, thereby increasing the tension of the PAD point on the welding strip and reducing cold welding.

[0138] Therefore, in the present invention, one or more ends of the first overlapping fine grid 211 are overlapped onto the first fixed portion 310; and / or, one or more ends of the second overlapping fine grid 221 are overlapped onto the second fixed portion 320, so as to increase the pulling force of the first fixed portion and the second fixed portion 320 on the welding strip, thereby achieving the effect of reducing the cold welding of the welding strip.

[0139] Further, with respect to the distribution of overlapping fine grids and penetrating fine grids in the fine grids, in a possible implementation, the first main grid 31 is connected to a plurality of first fine grids 21; wherein the first fine grids 21 connected to the first fixed portion 310 of the first main grid 31 are all first overlapping fine grids 211, and the first fine grids 21 connected to the portion other than the first fixed portion 310 of the first main grid 31 are all first penetrating fine grids 212. The second main grid 32 is connected to a plurality of second fine grids 22; wherein the second fine grids 22 connected to the second fixed portion 320 of the second main grid 32 are all second overlapping fine grids 221, and the second fine grids 22 connected to the portion other than the second fixed portion 320 of the second main grid 32 are all second penetrating fine grids 222.

[0140] Specifically, a plurality of first fine grids 21 are connected to each first main grid 31, and each first fine grid 21 is connected to the first fixing portion 310 of the first main grid 31 or to a place other than the first fixing portion 310 of the first main grid 31. In the embodiment of the present invention, in order to reduce the cold soldering of the soldering strip, all the first fine grids 21 connected to the first fixing portion 310 of the first main grid 31 are set to be first overlapping fine grids 211, so as to increase the pulling force of the first fixing portion 310 on the soldering strip and reduce the cold soldering of the soldering strip; at the same time, all the first fine grids 21 connected to the part other than the first fixing portion 310 of each first main grid 31 are set to be first through fine grids 212, so as to maximize the pulling force of each first main grid 31, thereby achieving the effect of improving the stability and reliability of the back contact battery 100.

[0141] Furthermore, similarly, multiple second fine grids 22 may be connected to each second main grid 32, and each second fine grid 22 is connected to the second fixing portion 320 of the second main grid 32 or to a place other than the second fixing portion 320 of the second main grid 32. In the embodiment of the present invention, in order to reduce the cold soldering of the soldering strip, all the second fine grids 22 connected to the second fixing portion 320 of the second main grid 32 are set to be second overlapping fine grids 221, so as to increase the pulling force of the second fixing portion 320 on the soldering strip and reduce the cold soldering of the soldering strip; at the same time, all the second fine grids 22 connected to the part other than the second fixing portion 320 of each second main grid 32 are set to be second through fine grids 222, so as to maximize the pulling force of each second main grid 32, thereby achieving the effect of improving the stability and reliability of the back contact battery 100.

[0142] Further, regarding the setting position of the first fixing portion 310, in a possible implementation manner, as shown in FIG. Figure 3 , Fig. 20 and Fig.21 As shown, the first main grid 31 includes a first main grid G317, the first main grid G317 includes a first fixed portion A3101, and the center line of the first main grid G317 and the center line of the first fixed portion A3101 are on the same straight line. Specifically, in the present invention, by setting the center lines of the first main grid G317 and the first fixed portion A3101 in the first main grid G317 to be on the same straight line, the purpose of more uniform distribution of grid lines in the area adjacent to the first fixed portion A3101 can be achieved, thereby achieving the effect of improving the current collection capacity of the back contact battery 100.

[0143] Furthermore, the first fixing portion 310 is disposed at a position such as Figure 3 , Fig. 20 and Fig.21 As shown. The first main grid 31 includes a first main grid H318, the first main grid H318 includes a first fixed portion B3102, and the center line of the first main grid H318 and the center line of the first fixed portion B3102 are not on the same straight line. Specifically, in the present invention, by setting the center lines of the first main grid H318 and the first fixed portion B3102 in the first main grid H318 not to be on the same straight line, the purpose of more uniform distribution of grid lines in the area adjacent to the first fixed portion B3102 can be achieved, thereby achieving the effect of improving the current collection capacity of the back contact battery 100.

[0144] Likewise, Figure 3 , Fig. 22 and Fig.23As shown, for the setting position of the second fixing portion 320, in a possible embodiment, the second main grid 32 includes a second main grid G327, the second main grid G327 includes a second fixing portion A3201, and the center line of the second main grid G327 and the center line of the second fixing portion A3201 are on the same straight line. Specifically, in the present invention, by setting the center lines of the second main grid G327 and the second fixing portion A3201 in the second main grid G327 on the same straight line, the purpose of more uniform distribution of grid lines in the area adjacent to the second fixing portion A3201 can be achieved, thereby achieving the effect of improving the current collection capacity of the back contact battery 100.

[0145] Furthermore, regarding the setting position of the second fixing portion 320, Figure 3 , Fig. 22 and Fig.23 As shown. The second main grid 32 includes a second main grid H328, the second main grid H328 includes a second fixed portion B3202, and the center line of the second main grid H328 and the center line of the second fixed portion B3202 are not on the same straight line. Specifically, in the present invention, by setting the center lines of the second main grid H328 and the second fixed portion B3202 in the second main grid H328 not to be on the same straight line, the purpose of more uniform distribution of grid lines in the area adjacent to the second fixed portion B3202 can be achieved, thereby achieving the effect of improving the current collection capacity of the back contact battery 100.

[0146] In the present invention, in a possible implementation manner, as Figure 3 , Figure 5 , Figure 6 and Figure 7 As shown, the back contact battery 100 further includes a first welding strip 41 and a second welding strip 42. The first welding strip 41 is welded to the first fixing portion through a first welding layer 51; the second welding strip 42 is welded to the second fixing portion 320 through a second welding layer 52. The first welding layer 51 may specifically include at least one solder such as solder paste, tin-lead, and a welding rod. Similarly, the second welding layer 52 may also specifically include at least one solder such as solder paste, tin-lead, and a welding rod.

[0147] Further, in a possible implementation manner, as Figure 3 , Fig.24 and Fig.25As shown. The back contact cell 100 further includes a P-type doping layer 61 and an N-type doping layer 62 disposed on the silicon substrate 10; the P-type doping layer 61 is connected to the first fine gate 21, and the N-type doping layer 62 is connected to the second fine gate 22; or, the P-type doping layer 61 is connected to the second fine gate 22, and the N-type doping layer 62 is connected to the first fine gate 21; wherein the thickness L4 of the P-type doping layer 61 is greater than the thickness L5 of the N-type doping layer 62. Optionally, the thickness L4 of the P-type doping layer 61 is greater than or equal to 100nm and less than or equal to 300nm; and / or, the thickness L5 of the N-type doping layer 62 is greater than or equal to 50nm and less than or equal to 300nm. Optionally, the thickness L4 of the P-type doping layer 61 minus the thickness L5 of the N-type doping layer 62 is less than or equal to 100nm.

[0148] The concentration of B (boron) atoms doped with P-type is low, and the electron transmission is poor. Therefore, when the slurry is sintered, it is necessary to form larger Ag (silver) crystals to form a good ohmic contact. Therefore, in the back contact battery 100, by thickening the thickness of the P-type doping layer 61, a larger window is provided for the formation of Ag (silver) crystals when the slurry is sintered. This effectively prevents the slurry from burning through the tunneling layer, destroying the battery structure, resulting in too many recombination centers, reducing the battery open circuit voltage, and making the conversion efficiency poor.

[0149] Furthermore, in a possible implementation, Figure 3 , Fig.26 and Fig. 27 As shown. The crystallization depth L6 of the first fine gate 21 and the P-type doping layer 61 is greater than the crystallization depth L7 of the second fine gate 22 and the N-type doping layer 62; or, the crystallization depth L6 of the second fine gate 22 and the P-type doping layer 61 is greater than the crystallization depth L7 of the first fine gate 21 and the N-type doping layer 62. Optionally, the crystallization depth L6 of the first fine gate 21 and the P-type doping layer 61 is 100nm-220nm; or the crystallization depth L6 of the second fine gate 22 and the P-type doping layer 61 is 100nm-220nm; the crystallization depth L7 of the first fine gate 21 and the N-type doping layer 62 is 30nm-90nm; or the crystallization depth L7 of the second fine gate 22 and the N-type doping layer 62 is 30nm-90nm.

[0150] Specifically, in the present invention, because it is more difficult to collect holes than electrons, the current collection and transmission performance between the fine gate and the doped layer can be increased by deepening the crystallization depth of the fine gate and the doped layer. Therefore, in the present invention, by increasing the crystallization depth L6 of the first fine gate 21 or the second fine gate 22 and the P-type doped layer 61, the hole collection ability of the back contact battery 100 can be further enhanced.

[0151] Furthermore, because the crystallization depth of the P-type doping layer 61 and the fine gate is deeper than that of the N-type doping layer 62 and the fine gate, the thickness L4 of the P-type doping layer 61 needs to be set greater than the thickness L5 of the N-type doping layer 62 to accommodate the deeper crystallization depth.

[0152] 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.

[0153] In addition, the above description is only a preferred embodiment of the present application and is 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 battery, characterized in that: include: Silicon substrate; First fine gates and second fine gates are arranged on the silicon substrate; a plurality of the first fine gates and a plurality of the second fine gates are alternately arranged in sequence along a first direction and extend along a second direction, and the second direction intersects the first direction; A first main gate and a second main gate are arranged on the silicon substrate; the first main gate and the second main gate are arranged at intervals along the second direction and both extend along the first direction, the first main gate is connected to the first fine gate, and the second main gate is connected to the second fine gate; Wherein, the first fine grid comprises a first overlapping fine grid, and one or more ends of the first overlapping fine grid are overlapped to the first main grid; and / or, The second fine grid includes a second overlapping fine grid, and one or more ends of the second overlapping fine grid are overlapped to the second main grid.

2. The back contact cell according to claim 1, characterized in that: The first overlapping fine grid includes a first overlapping fine grid A and a first overlapping fine grid B, and the first main grid includes a first main grid A; Along the second direction, the first overlapping fine grid A has a first end and a second end which are arranged opposite to each other; Along the second direction, the first overlapping fine grid B has a first end and a second end which are arranged opposite to each other; Along the second direction, the second end of the first overlapping fine grid A and the first end of the first overlapping fine grid B are arranged adjacent to each other; The second end of the first overlapping fine grid A and the first end of the first overlapping fine grid B are both overlapped to the first main grid A.

3. The back contact battery according to claim 2, characterized in that: The second overlapping fine grid includes a second overlapping fine grid A and a second overlapping fine grid B, and the second main grid includes a second main grid A; Along the second direction, the second overlapping fine grid A has a first end and a second end which are arranged opposite to each other; Along the second direction, the second overlapping fine grid B has a first end and a second end which are arranged opposite to each other; Along the second direction, the second end of the second overlapping fine grid A and the first end of the second overlapping fine grid B are arranged adjacent to each other; The second end of the second overlapping fine grid A and the first end of the second overlapping fine grid B are both overlapped to the second main grid A.

4. The back contact cell according to claim 2, characterized in that: The first overlapping fine grid A and the first overlapping fine grid B are aligned along the second direction.

5. The back contact cell according to claim 4, characterized in that: The spacing between the first overlapping fine gate A and the first overlapping fine gate B is greater than 250 μm.

6. The back contact cell according to claim 3, characterized in that: The second overlapping fine grid A and the second overlapping fine grid B are aligned along the second direction.

7. The back contact cell according to claim 6, characterized in that: The spacing between the second overlapping fine gate A and the second overlapping fine gate B is greater than 250 μm.

8. The back contact battery according to claim 2, characterized in that: The first overlapping fine grid A is higher or lower than the first overlapping fine grid B along the second direction.

9. The back contact battery according to claim 3, characterized in that: The second overlapping fine grid A is higher or lower than the second overlapping fine grid B along the second direction.

10. The back contact cell according to claim 1, characterized in that: The first overlapping fine grid includes a first overlapping fine grid C and a first overlapping fine grid D, and the first main grid includes a first main grid B; Along the second direction, the first overlapping fine grid C has a first end and a second end that are oppositely arranged; Along the second direction, the first overlapping fine grid D has a first end and a second end which are arranged opposite to each other; The first end of the first overlapping fine grid C and the first end of the first overlapping fine grid D are both overlapped to the first main grid B.

11. The back contact cell according to claim 10, characterized in that: The first overlapping fine grid includes a second overlapping fine grid C and a second overlapping fine grid D, and the second main grid includes a second main grid B; Along the second direction, the second overlapping fine grid C has a first end and a second end which are arranged opposite to each other; Along the second direction, the second overlapping fine grid D has a first end and a second end which are arranged opposite to each other; The first end of the second overlapping fine grid C and the first end of the second overlapping fine grid D are both overlapped to the second main grid B.

12. The back contact cell according to claim 1, characterized in that: The first overlapping fine grid includes a first overlapping fine grid E, and the first main grid includes a first main grid C and a first main grid D; Along the second direction, the first overlapping fine grid E has a first end and a second end that are oppositely arranged; The first end of the first overlapping fine grid E is overlapped on the first main grid C, and the second end of the first overlapping fine grid E is overlapped on the first main grid D.

13. The back contact cell according to claim 12, characterized in that: The second overlapping fine grid includes a second overlapping fine grid E, and the second main grid includes a second main grid C and a second main grid D; Along the second direction, the second overlapping fine grid E has a first end and a second end that are oppositely arranged; A first end of the second overlapping fine grid E is overlapped on the second main grid C, and a second end of the second overlapping fine grid E is overlapped on the second main grid D.

14. The back contact cell according to claim 1, characterized in that The first overlapping fine grid includes a first overlapping fine grid F, and the first main grid includes a first main grid E and a first main grid F; Along the second direction, the first overlapping fine grid F has a first end and a second end which are arranged opposite to each other; The first end of the first overlapping fine grid F is overlapped on the first main grid E, and the second end of the first overlapping fine grid F is connected to the first main grid F through.

15. The back contact cell according to claim 14, characterized in that The second overlapping fine grid includes a second overlapping fine grid F, and the second main grid includes a second main grid E and a second main grid F; Along the second direction, the second overlapping fine grid F has a first end and a second end which are arranged opposite to each other; The first end of the second overlapping fine grid F is overlapped on the second main grid E, and the second end of the second overlapping fine grid F is connected to the second main grid F through.

16. The back contact cell according to claim 1, characterized in that The first fine gate further includes a first through fine gate, both ends of which are through-connected to the first main gate; and / or the second fine gate further includes a second through fine gate, both ends of which are through-connected to the second main gate.

17. The back contact cell according to claim 16, characterized in that: The ratio of the number of the first overlapping fine gates to the number of the first penetrating fine gates is 0.04 to 0.

1.

18. The back contact cell according to claim 17, characterized in that The ratio of the number of the second overlapping fine grids to the number of the second penetrating fine grids is 0.04 to 0.

1.

19. The back contact cell according to claim 16, characterized in that: The first main grid includes one or more first fixing portions, and one or more ends of the first overlapping fine grid are overlapped to the first fixing portions; and / or, The second main grid includes one or more second fixing portions, and one or more ends of the second overlapping fine grid are overlapped on the second fixing portions.

20. The back contact cell according to claim 16, characterized in that The first main grid includes a first main grid G, the first main grid G ​​includes a first fixing portion A, and a center line of the first main grid G ​​and a center line of the first fixing portion A are on the same straight line.

21. The back contact cell according to claim 20, characterized in that The second main grid includes a second main grid G, the second main grid G ​​includes a second fixing portion A, and a center line of the second main grid G ​​and a center line of the second fixing portion A are on the same straight line.

22. The back contact cell according to claim 16, characterized in that The first main grid includes a first main grid H, the first main grid H includes a first fixing portion B, and a center line of the first main grid H and a center line of the first fixing portion B are not on the same straight line.

23. The back contact cell according to claim 22, characterized in that The second main grid includes a second main grid H, the second main grid H includes a second fixing portion B, and a center line of the second main grid H and a center line of the second fixing portion B are not on the same straight line.

24. The back contact cell according to claim 19, characterized in that The first main grid is connected to a plurality of the first fine grids; wherein, All first fine grids connected to the first fixed portion of the first main grid are the first overlapping fine grids, and all first fine grids connected to portions of the first main grid other than the first fixed portion are the first penetrating fine grids.

25. The back contact cell according to claim 24, characterized in that The second main grid is connected to a plurality of the second fine grids; wherein, The second fine grids connected to the second fixed portion of the second main grid are all the second overlapping fine grids, and the second fine grids connected to the portion of the second main grid other than the second fixed portion are all the second penetrating fine grids.

26. The back contact cell according to claim 19, characterized in that The back contact battery further includes a first welding strip and a second welding strip, wherein the first welding strip is welded to the first fixing portion through a first welding layer; and the second welding strip is welded to the second fixing portion through a second welding layer.

27. The back contact cell according to claim 1, characterized in that The first main grid is connected to a plurality of the first fine grids, and the first fine grids are all the first overlapping fine grids.

28. The back contact cell according to claim 23, characterized in that The second main grid is connected to a plurality of the second fine grids, and the second fine grids are all the second overlapping fine grids.

29. The back contact cell according to claim 1, characterized in that The distance between one end of the first overlapping fine grid and the first main grid along the second direction is greater than 20 μm.

30. The back contact cell according to claim 1, characterized in that Also included are a P-type doping layer and an N-type doping layer disposed on the silicon substrate; The P-type doped layer is connected to the first fine gate correspondingly, and the N-type doped layer is connected to the second fine gate correspondingly; or, the P-type doped layer is connected to the second fine gate correspondingly, and the N-type doped layer is connected to the first fine gate correspondingly; Wherein, the thickness of the P-type doping layer is greater than the thickness of the N-type doping layer.

31. The back contact cell according to claim 30, characterized in that The thickness of the P-type doping layer is greater than or equal to 100 nm and less than or equal to 300 nm; And / or, the N-type doping layer is greater than or equal to 50 nm and less than or equal to 300 nm.

32. The back contact cell according to claim 30, characterized in that The thickness of the P-type doping layer minus the thickness of the N-type doping layer is less than or equal to 100 nm.

33. The back contact cell according to claim 30, characterized in that The crystallization depth of the first fine gate and the P-type doping layer is greater than the crystallization depth of the second fine gate and the N-type doping layer; or, The crystallization depth of the second fine gate and the P-type doping layer is greater than the crystallization depth of the first fine gate and the N-type doping layer.

34. The back contact cell according to claim 30, characterized in that The crystallization depth of the first fine gate and the P-type doping layer is 100 nm-220 nm; or the crystallization depth of the second fine gate and the P-type doping layer is 100 nm-220 nm.

35. The back contact cell according to claim 30 or 34, characterized in that The crystallization depth of the first fine gate and the N-type doping layer is 30nm-90nm; or the crystallization depth of the second fine gate and the N-type doping layer is 30nm-90nm.

36. The back contact cell according to claim 1, characterized in that The first main grid includes a first overlap and a first non-overlap. One or more ends of the first overlap fine grid overlap the first main grid. The glass content of the first overlap is greater than that of the first non-overlap.

37. The back contact cell according to claim 36, characterized in that The second main grid includes a second overlap and a second non-overlap. One or more ends of the second overlap fine grid overlap the second main grid. The glass content of the first overlap is greater than that of the second non-overlap.

38. A battery assembly, characterized in that: Comprising a back contact cell as claimed in any one of claims 1 to 37.

39. A photovoltaic system, characterized in that: Comprising a battery assembly as described in claim 38.

Images