Back contact cell, cell assembly and photovoltaic system

Abstract

The utility model 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 utility model, 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 increasing the efficiency of the back contact battery are achieved.

Description

[0001] The present application claims priority to the Chinese patent application No. 2024111575307, filed on August 21, 2024, entitled “Back contact cell, cell assembly and photovoltaic system”, the content of which is incorporated herein by reference in its entirety.

[0002] The present application also claims priority to the Chinese patent application No. 202422038013X, filed on August 21, 2024, entitled “Back contact cell, cell assembly and photovoltaic system”, the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The utility model relates to photovoltaic technology field especially relates to a back contact cell, cell assembly and photovoltaic system. BACKGROUND

[0004] Back contact cell (Back-contact solar cells, for short "BC structure") is a design type of back contact cell, which is characterized by electrode design of the cell on the back surface of the cell, instead of the traditional double-sided electrode design. The traditional front contact back contact cell will hinder light absorption and charge transport under the condition that the electrode needs to cover the surface of the cell, resulting in loss of cell conversion efficiency. The BC structure design can reduce the shading area on the surface of the cell, eliminate the light energy loss caused by grid line shading, and improve the utilization rate of photons for the cell, thereby bringing higher conversion efficiency to the BC structure cell.

[0005] It is necessary to provide a design to further improve the conversion efficiency of the BC cell. UTILITY MODEL CONTENT

[0006] The utility model person found that in the back contact cell assembly, one of the reasons affecting the conversion efficiency of the cell is that because the fine grid is usually a through main grid connection design, and the fine grid is usually printed by using a burn-through type paste, when printing by using the fine grid through main grid connection method, the passivation layer located at the through main grid position will also be burned through, increasing the paste burn-through area, the greater the damage to the cell, more recombination centers will be generated, resulting in a decrease in open-circuit voltage of the cell and a decrease in conversion efficiency of the cell. Therefore, the utility model provides a back contact cell, cell assembly and photovoltaic system to solve the technical problem that in the prior art, the fine grid and the main grid are connected through, and when printing, the passivation layer located at the main grid position will also be burned through.

[0007] The utility model embodiment is realized in this way, and the utility model provides a back contact cell, cell assembly and photovoltaic system. The back contact cell comprises a silicon substrate;

[0008] a first fine grid and a second fine grid disposed on the silicon substrate; a plurality of the first fine grids and a plurality of the second fine grids are arranged alternately and spaced along a first direction, and each extends along a second direction intersecting the first direction;

[0009] a first main grid and a second main grid disposed on the silicon substrate; the first main grid and the second main grid are spaced along the second direction, and each extends along the first direction, 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 overlapped fine grid, one or more ends of the first overlapped fine grid are overlapped on the first main grid; and / or the second fine grid comprises a second overlapped fine grid, one or more ends of the second overlapped fine grid are overlapped on the second main grid.

[0010] Further, the first overlapped fine grid comprises a first overlapped fine grid A and a first overlapped fine grid B, the first main grid comprises a first main grid A; along the second direction, the first overlapped fine grid A has a first end and a second end oppositely arranged; along the second direction, the first overlapped fine grid B has a first end and a second end oppositely arranged; along the second direction, the second end of the first overlapped fine grid A and the first end of the first overlapped fine grid B are arranged adjacent to each other; the second end of the first overlapped fine grid A and the first end of the first overlapped fine grid B are overlapped on the first main grid A.

[0011] Further, the second overlapped fine grid comprises a second overlapped fine grid A and a second overlapped fine grid B, the second main grid comprises a second main grid A; along the second direction, the second overlapped fine grid A has a first end and a second end oppositely arranged; along the second direction, the second overlapped fine grid B has a first end and a second end oppositely arranged; along the second direction, the second end of the second overlapped fine grid A and the first end of the second overlapped fine grid B are arranged adjacent to each other; the second end of the second overlapped fine grid A and the first end of the second overlapped fine grid B are overlapped on the second main grid A.

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

[0013] Further, the interval between the first overlapped fine grid A and the first overlapped fine grid B is greater than 250 μm.

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

[0015] Further, the interval between the second overlapped fine grid A and the second overlapped fine grid B is greater than 250 μm.

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

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

[0018] Further, the first fine overlap grid comprises a first fine overlap grid C and a first fine overlap grid D, and the first main grid comprises a first main grid B; along the second direction, the first fine overlap grid C has oppositely arranged first and second ends; along the second direction, the first fine overlap grid D has oppositely arranged first and second ends; the first end of the first fine overlap grid C and the first end of the first fine overlap grid D are both overlapped on the first main grid B.

[0019] Further, the first fine overlap grid comprises a second fine overlap grid C and a second fine overlap grid D, and the second main grid comprises a second main grid B; along the second direction, the second fine overlap grid C has oppositely arranged first and second ends; along the second direction, the second fine overlap grid D has oppositely arranged first and second ends; the first end of the second fine overlap grid C and the first end of the second fine overlap grid D are both overlapped on the second main grid B.

[0020] Further, the first fine overlap grid comprises a first fine overlap grid E, and the first main grid comprises a first main grid C and a first main grid D; along the second direction, the first fine overlap grid E has oppositely arranged first and second ends; the first end of the first fine overlap grid E is overlapped on the first main grid C, and the second end of the first fine overlap grid E is overlapped on the first main grid D.

[0021] Further, the second fine overlap grid comprises a second fine overlap grid E, and the second main grid comprises a second main grid C and a second main grid D; along the second direction, the second fine overlap grid E has oppositely arranged first and second ends; the first end of the second fine overlap grid E is overlapped on the second main grid C, and the second end of the second fine overlap grid E is overlapped on the second main grid D.

[0022] Further, the first fine overlap grid comprises a first fine overlap grid F, and the first main grid comprises a first main grid E and a first main grid F; along the second direction, the first fine overlap grid F has oppositely arranged first and second ends; the first end of the first fine overlap grid F is overlapped on the first main grid E, and the second end of the first fine overlap grid F is connected through the first main grid F.

[0023] Further, the second fine grid includes a second 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 fine grid F has oppositely arranged first and second ends; the first end of the second fine grid F is lapped onto the second main grid E, and the second end of the second fine grid F is connected through the second main grid F.

[0024] Further, the first fine grid further includes a first through fine grid, and two ends of the first through fine grid are connected through the first main grid; and / or, the second fine grid further includes a second through fine grid, and two ends of the second through fine grid are connected through the second main grid.

[0025] Further, the ratio of the number of the first fine grid to the number of the first through fine grid is 0.04 to 0.1.

[0026] Further, the ratio of the number of the second fine grid to the number of the second through fine grid is 0.04 to 0.1.

[0027] Further, the first main grid includes one or more first fixed parts, and one or more ends of the first fine grid are lapped onto the first fixed part; and / or, the second main grid includes one or more second fixed parts, and one or more ends of the second fine grid are lapped onto the second fixed part.

[0028] Further, the first main grid includes a first main grid G, and the first main grid G includes a first fixed part A, and the center line of the first main grid G and the center line of the first fixed part A are on the same straight line.

[0029] Further, the second main grid includes a second main grid G, and the second main grid G includes a second fixed part A, and the center line of the second main grid G and the center line of the second fixed part A are on the same straight line.

[0030] Further, the first main grid includes a first main grid H, and the first main grid H includes a first fixed part B, and the center line of the first main grid H and the center line of the first fixed part B are not on the same straight line.

[0031] Further, the second main grid includes a second main grid H, and the second main grid H includes a second fixed part B, and the center line of the second main grid H and the center line of the second fixed part B are not on the same straight line.

[0032] Further, the first main grid is connected with a plurality of first fine grids; wherein the first fine grid connected with the first fixed part in the first main grid is the first overlapped fine grid, and the first fine grid connected with the part other than the first fixed part in the first main grid is the first through fine grid.

[0033] Further, the second main grid is connected with a plurality of second fine grids; wherein the second fine grid connected with the second fixed part in the second main grid is the second overlapped fine grid, and the second fine grid connected with the part other than the second fixed part in the second main grid is the second through fine grid.

[0034] Further, the back contact cell further comprises a first solder strip and a second solder strip, the first solder strip is soldered to the first fixed part through a first solder layer; and the second solder strip is soldered to the second fixed part through a second solder layer.

[0035] Further, the first main grid is connected with a plurality of first fine grids, and the first fine grid is the first overlapped fine grid.

[0036] Further, the overlapped distance of one end of the first overlapped fine grid to the first main grid along the second direction is greater than 20 μm.

[0037] Further, a P-type doped layer and an N-type doped layer are arranged on the silicon substrate; the P-type doped layer is connected with the first fine grid in correspondence, and the N-type doped layer is connected with the second fine grid in correspondence; or, the P-type doped layer is connected with the second fine grid in correspondence, and the N-type doped layer is connected with the first fine grid in correspondence; wherein the thickness of the P-type doped layer is greater than the thickness of the N-type doped layer.

[0038] Further, the thickness of the P-type doped 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 doped layer is greater than or equal to 50 nm and less than or equal to 300 nm.

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

[0040] Further, the crystallization depth of the first fine grid and the P-type doped layer is greater than the crystallization depth of the second fine grid and the N-type doped layer; or, the crystallization depth of the second fine grid and the P-type doped layer is greater than the crystallization depth of the first fine grid and the N-type doped layer.

[0041] Further, the crystallization depth of the first fine grid and the P-type doped layer is 100 nm-220 nm; or the crystallization depth of the second fine grid and the P-type doped layer is 100 nm-220 nm.

[0042] Further, the first fine grid and the N-type doped layer have a crystallization depth of 30-90nm; or the second fine grid and the N-type doped layer have a crystallization depth of 30-90nm.

[0043] Further, the first main grid comprises a first lap joint and a first non-lap joint, one or more ends of the first lap fine grid are lapped to the first lap joint of the first main grid, and the glass frit content of the first lap joint is greater than that of the first non-lap joint.

[0044] Further, the second main grid comprises a second lap joint and a second non-lap joint, one or more ends of the second lap fine grid are lapped to the second lap joint of the second main grid, and the glass frit content of the first lap joint is greater than that of the second non-lap joint.

[0045] The utility model embodiment further provides a battery assembly, the battery assembly includes the back contact battery as described above.

[0046] The utility model embodiment further provides a photovoltaic system, the photovoltaate system includes the battery assembly as described above.

[0047] The utility model embodiment provides a back contact battery, a battery assembly and a photovoltaic system. The back contact battery comprises 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 arranged alternately and spaced apart along a first direction, and both extend along a second direction, the second direction intersects 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 spaced apart along the second direction, and both extend along the first direction, 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 fine grid, one or more ends of the first lap fine grid are lapped to the first main grid, and / or the second fine grid comprises a second lap fine grid, one or more ends of the second lap fine grid are lapped to the second main grid. The connection mode of the fine grid lapped to the main grid at the end of the fine grid of the utility model avoids the technical problem that the passivation layer at the position of the main grid is also burned through when printing the fine grid and the main grid in the prior art, effectively reduces the loss of the back contact battery, and increases the efficiency of the back contact battery. BRIEF DESCRIPTION OF DRAWINGS

[0048] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 A schematic diagram of the module structure of a photovoltaic system provided for an embodiment of the utility model;

[0050] Figure 2 A schematic diagram of the module structure of the battery assembly provided for an embodiment of the utility model;

[0051] Figure 3 A schematic diagram of the structure of the back contact battery provided for an embodiment of the utility model;

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

[0053] Figure 5 for Figure 3 A partial structural diagram of the first fixing structure and the first welding layer provided in the first main grid of the back contact battery described herein;

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

[0055] Figure 7 for Figure 3 A schematic diagram of the structure of the back contact battery described herein, wherein the first solder strip and the second solder strip are provided;

[0056] Figure 8 for Figure 3 A partial structural diagram of the first main grid A in the back contact battery described herein;

[0057] Figure 9 for Figure 8 A schematic diagram showing the spacing between the first overlapping fine grid A and the first overlapping fine grid B in the first main grid A described above;

[0058] Figure 10 for Figure 3 A partial structural diagram of the second main grid A in the back contact battery described herein;

[0059] Figure 11 for Figure 10 A schematic diagram showing the spacing between the second overlapping fine grid A and the second overlapping fine grid B in the first main grid A described above;

[0060] Figure 12 For Figure 3 The partial structure schematic diagram of the first main grid A in the back contact cell described in the foregoing embodiment;

[0061] Figure 13 For Figure 3 The partial structure schematic diagram of the second main grid A in the back contact cell described in the foregoing embodiment;

[0062] Figure 14 For Figure 3 The partial structure schematic diagram of the first main grid B in the back contact cell described in the foregoing embodiment;

[0063] Figure 15 For Figure 3 The partial structure schematic diagram of the second main grid B in the back contact cell described in the foregoing embodiment;

[0064] Figure 16 For Figure 3 The partial structure schematic diagram of the first main grid C and the first main grid D in the back contact cell described in the foregoing embodiment;

[0065] Figure 17 For Figure 3 The partial structure schematic diagram of the second main grid C and the second main grid D in the back contact cell described in the foregoing embodiment;

[0066] Figure 18 For Figure 3 The partial structure schematic diagram of the first main grid E and the first main grid F in the back contact cell described in the foregoing embodiment;

[0067] Figure 19 For Figure 3 The partial structure schematic diagram of the second main grid E and the second main grid F in the back contact cell described in the foregoing embodiment;

[0068] Figure 20 For Figure 3 The partial structure schematic diagram of the first main grid G in the back contact cell described in the foregoing embodiment;

[0069] Figure 21 For Figure 3 The partial structure schematic diagram of the first main grid H in the back contact cell described in the foregoing embodiment;

[0070] Figure 22 For Figure 3 The partial structure schematic diagram of the second main grid G in the back contact cell described in the foregoing embodiment;

[0071] Figure 23 For Figure 3 The partial structure schematic diagram of the second main grid H in the back contact cell described in the foregoing embodiment;

[0072] Figure 24 A partial side view of a back contact cell with a P-type doped layer and an N-type doped layer as described herein; Figure 3

[0073] Figure 25 A partial side view of a back contact cell with a P-type doped layer and an N-type doped layer as described herein; Figure 3

[0074] Figure 26 A partial side view of a back contact cell with a P-type doped layer and an N-type doped layer as described herein; Figure 24

[0075] Figure 27 A partial side view of a back contact cell with a P-type doped layer and an N-type doped layer as described herein; Figure 25

[0076] Figure 28 A partial side view of a back contact cell with a P-type doped layer and an N-type doped layer as described herein; Figure 3

[0077] Figure 29 A partial side view of a back contact cell with a P-type doped layer and an N-type doped layer as described herein; Figure 3

[0078] ​​​​​​Main element symbol explanation: 1000, photovoltaic system; 1001, battery assembly; 100, back contact cell; 10, silicon substrate; 21, first fine grid; 22, second fine grid; 31, first main grid; 32, second main grid; 41, first solder strip; 42, second solder strip; 51, first solder layer; 52, second solder layer; 61, P type doped layer; 62, N type doped layer; 211, first lap fine grid; 212, first through fine grid; 221, second lap fine grid; 222, second through fine grid; 2111, first lap fine grid A; 2112, first lap fine grid B; 2113, first lap fine grid C; 2114, first lap fine grid D; 2115, first lap fine grid E; 2116, first lap fine grid F; 2211, second lap fine grid A; 2212, second lap fine grid B; 2213, second lap fine grid C; 2214, second lap fine grid D; 2215, second lap fine grid E; 2216, second lap 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 lap; 3104, first non-lap; 320, second fixed part; 3201, second fixed part A; 3202, second fixed part B; 3203, second lap; 3204, second non-lap. DETAILED DESCRIPTION

[0079] In order to make the purpose, technical scheme and advantages of the utility model more clearly, the following will be further described in detail in combination with the drawings and examples. The examples described below by referring to the drawings are exemplary, and are only used to explain the utility model, and cannot be understood as limiting the utility model. In addition, it should be understood that the specific examples described herein are only used to explain the utility model, and are not used to limit the utility model.

[0080] In the description of the utility model, it should be understood that the terms "length", "width", "upper", "lower", "top", "bottom", "transverse", "longitudinal" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the utility model and simplifying the description, and therefore cannot be understood as limiting the indicated device or element to have a specific orientation, to be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the utility model.

[0081] In addition, the terms "first", "second", "third", etc. are used only for descriptive purposes and do not connote or imply a relative importance or a specific order of execution. Thus, features defined with "first", "second" or "third" can include one or more of the features so designated. In the description of the present application, the meaning of "a plurality of" is two or more, unless explicitly specified and limited otherwise.

[0082] In the description of the present application, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection or can communicate with each other; it can be directly connected, or indirectly connected through intermediate medium, or the communication between two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0083] In the present application, unless explicitly specified and limited otherwise, "on" or "under" of the first feature to the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, "on", "above" and "above" of the first feature to the second feature include that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. "Below", "below" and "below" of the first feature to the second feature include that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0084] The following disclosure provides many different embodiments or examples for implementing different structures of the present application. In order to simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeatedly refer to numbers and / or letters in different examples, and such repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those skilled in the art can realize the application of other processes and / or the use of other materials.

[0085] It should be noted that the drawings provided by the present application are schematic drawings, and some elements are not shown in the drawings. The purpose is to clearly describe the technical scheme and highlight the key points of the present application. It is not intended to limit the technical scheme and not to include these non-displayed elements. For example, Figure 3 , Figure 5 , Figure 6 ,Figure 7 In the embodiment, only part of the electrodes (e.g., the main grid, the fine grid, etc.) are shown, and all the electrodes are not shown. In fact, the electrodes can include more parts. For example, Figure 3 In the embodiment, the second fine grid 22 (e.g., the second lap fine grid 221 and / or the second through fine grid 222) not shown can be included. The second fine grid 22 and the first fine grid 21 are arranged in an interdigital manner. For example, Figure 3 In the embodiment, the first fine grid 21 (e.g., the first lap fine grid 211 and / or the first through fine grid 212) not shown can be included. The second fine grid 22 and the first fine grid 21 are arranged in an interdigital manner.

[0086] For another example, Figure 3 , Figure 5 , Figure 6 , Figure 7 In the embodiment, only the part of the through fine grid between the two main grids is shown. In fact, the through fine grid can include the part outside the two main grids. For example, in the embodiment, Figure 3 In the embodiment, the first through fine grid 212 can extend to the edge of the silicon substrate 10 leftward. The first through fine grid 212 can extend to the third first main grid 31 rightward, and lap on the third first main grid 31, or pass through the third first main grid 31 and continue to extend rightward.

[0087] Please refer to Figure 1 and Figure 2 The photovoltaic system 1000 in the embodiment of the utility model can include the battery assembly 1001 in the embodiment of the utility model, the battery assembly 1001 in the embodiment of the utility model can include a plurality of battery strings, and the battery string can include a plurality of back contact cells 100 in the embodiment of the utility model. In the embodiment of the utility model, the plurality of back contact cells 100 in the battery assembly 1001 can be sequentially connected together by the welding strip to form the battery string. The battery string in the battery assembly 1001 can be connected in series, in parallel or in series-parallel combination to realize the current bus output, for example, the connection between the battery strings can be realized by the bus bar.

[0088] Please refer to Figure 3 The back contact cell 100 in the embodiment of the utility model has the silicon substrate 10, the first fine grid 21 and the second fine grid 22 are arranged on the silicon substrate 10, a plurality of first fine grids 21 and second fine grids 22 are alternately and spaced arranged along the first direction, and all extend along the 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 arranged as the first fine grid 21 being a negative electrode fine grid and the second fine grid 22 being a positive electrode fine grid, or can be arranged as the first fine grid 21 being a positive electrode fine grid and the second fine grid 22 being a negative electrode fine grid, which is not limited herein.

[0090] The first direction can be specifically a width direction of the first fine grid 21 and the second fine grid 22, that is, a vertical direction in the figure; and the second direction can be specifically a length direction of the first fine grid 21 and the second fine grid 22, that is, a horizontal direction in the figure. Of course, in other embodiments, the first direction and the second direction can also be other directions, for example, diagonal directions, and the like, which are not specifically limited here. Figure 3 The first direction can be specifically a width direction of the first fine grid 21 and the second fine grid 22, that is, a vertical direction in the figure; and the second direction can be specifically a length direction of the first fine grid 21 and the second fine grid 22, that is, a horizontal direction in the figure. Of course, in other embodiments, the first direction and the second direction can also be other directions, for example, diagonal directions, and the like, which are not specifically limited here. Figure 3

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

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

[0093] The first fine grid 21 includes a first lap joint fine grid 211, one or more end portions of the first lap joint fine grid 211 are lap jointed to the first main grid 31; and / or the second fine grid 22 includes a second lap joint fine grid 221, one or more end portions of the second lap joint fine grid 221 are lap jointed to the second main grid 32. The first fine grid 21 and the second fine grid 22 are made of a burn-through type paste, and the first main grid 31 and the second main grid 32 are made of a non-burn-through type paste. The number of the first lap joint fine grid 211 can be specifically one or more, which is not limited here; similarly, the number of the second lap joint fine grid 221 can be specifically 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 with the main grid in a through connection mode, the fine grid is usually printed by using a burn-through type paste to burn through the passivation layer to make the fine grid contact with the doped layer, and the main grid is usually printed by using a non-burn-through type paste, which will not burn through the passivation layer arranged on the surface of the doped layer. However, the through connection mode of the fine grid and the main grid will burn through the passivation layer at the position of the main grid when the fine grid and the main grid are printed, thereby causing the problem of loss of the back contact battery 100 and reduction of the efficiency of the back contact battery 100.

[0095] ​The through connection mode of the fine grid and the main grid specifically refers to that the main grid is connected through the fine grid, the main grid is arranged below the fine grid, or the fine grid is arranged above the main grid and connected with the main grid.

[0096] Therefore, in the utility model, unlike the traditional through connection mode of the fine grid and the main grid, the first lapping fine grid 211 is lapped to the first main grid 31 at one or more ends, that is, the first lapping fine grid 211 is connected with the first main grid 31 by the end partially overlapping the first main grid 31; similarly, one or more ends of the second lapping fine grid 221 are lapped to the second main grid 32, that is, the second lapping fine grid 221 is connected with the second main grid 32 by the end partially overlapping the second main grid 32. Figure 4 As shown in the figure, the distance L3 of one end of the first lapping fine grid 211 lapped to the first main grid 31 in the second direction ranges from greater than 20 microns.

[0097] When printing the first lapping fine grid 211 and the second lapping fine grid 221, the first lapping fine grid 211 of the burn-through type paste is lapped on the first main grid 31 of the non-burn-through type paste; the second lapping fine grid 221 of the burn-through type paste is lapped on the second main grid 32 of the non-burn-through type paste. Then the burn-through type paste directly contacts the main grid, not the passivation layer, so that the fine grid paste cannot directly contact the passivation layer at the lapping position of the first lapping fine grid 211 and the first main grid 31 and at the lapping position of the second lapping fine grid 221 and the second main grid 32, and cannot effectively burn through the passivation layer below the first main grid 31 and the second main grid 32, thereby 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 utility model, the connection mode of the fine grid and the main grid through the end of the fine grid lapped to the main grid effectively avoids the technical problem that the passivation layer at the position of the main grid is also burned through when printing the fine grid and the main grid in the prior art, thereby 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 mode, as shown in Figure 3 and Figure 5 The first main grid 31 is connected with a plurality of first fine grids 21, and the first fine grids 21 are all first lapping fine grids 211. Specifically, in the utility model, the first fine grids 21 connected with each first main grid 31 can all be first lapping fine grids 211. That is, the first main grid 31 and the first fine grid 21 are all connected by lapping, 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] Further, in a possible implementation, as shown in Figure 3 and Figure 6 , the second main grid 32 is connected with a plurality of second fine grids 22, and each of the second fine grids 22 is a second overlapped fine grid 221. Specifically, in the utility model, the second fine grid 22 connected with each second main grid 32 can all be the second overlapped fine grid 221. That is, the second main grid 32 is connected with the second fine grid 22 by the overlapping mode. Therefore, in the back contact battery 100, all the main grids can be connected with the main grid by the overlapping mode, that is, the first fine grid 21 is the first overlapped fine grid 211, and the second fine grid 22 is the second overlapped fine grid 221, so as to achieve the effect of reducing the loss of the back contact battery 100 and increasing the efficiency of the back contact battery 100 to the maximum extent.

[0101] In the utility model, in combination with the drawings provided by the present application, the first end of each fine grid specifically refers to the end portion on the left side of the fine grid, and the second end of each fine grid specifically refers to the end portion on the right side of the fine grid. Of course, in other embodiments, the first end of each fine grid can specifically refer to the end portion on the right side of the fine grid, and the second end of each fine grid can specifically refer to the end portion on the left side of the fine grid, which is not limited herein.

[0102] Further, as shown in Figure 3 , Figure 28 and Figure 29 , for the overlapping portion of the first main grid 31 and the first fine grid 21, in a possible implementation, the first main grid 31 includes a first overlapping portion 3103 and a first non-overlapping portion 3104, and one or more end portions of the first overlapped fine grid 211 are overlapped on the first overlapping portion 3103 of the first main grid 31, and the glass frit content of the first overlapping portion 3103 is greater than that of the first non-overlapping portion 3104.

[0103] Specifically, the first main grid 31 can specifically include the first overlapping portion 3103 overlapped with one or more end portions of the first overlapped fine grid 211, and the first main grid 31 further includes the first non-overlapping portion 3104 other than the first overlapping portion 3103. For one first main grid 31, the glass frit content of the first overlapping portion 3103 is greater than that of the first non-overlapping portion 3104. Higher glass frit content usually helps to improve the contact quality between metal particles during welding or sintering process, and more glass frit can provide better adhesion and stability between metal particles. Therefore, more glass frit is provided on the first overlapping portion 3103 of the first main grid 31 in the utility model, so as to achieve the effect of improving the reliable electrical connection of the overlapping portion of the first main grid 31 and the first overlapped fine grid 211.

[0104] Similarly, as shown in Figure 3 , Figure 28and Figure 29 As shown. In one possible embodiment, the second main grid 32 includes a second overlap 3203 and a second non-overlap 3204 at the overlap of the second main grid 32 and the second fine grid 221. One or more ends of the second overlapping fine grid 221 overlap onto the second overlap 3203 of the second main grid 32. 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 portion 3203 that overlaps with one or more ends of the second overlapping fine grid 221. The second main grid 32 also includes a second non-overlap portion 3204 other than the second overlap portion. For a second main grid 32, the glass content of the second overlap portion 3203 is greater than the glass content of the second non-overlap portion 3204. Therefore, in this invention, more glass is provided on the second overlap portion 3203 of the second main grid 32 to improve the reliability of the electrical connection between the second main grid 32 and the second overlapping fine grid 221.

[0106] Of course, in this invention, in addition to setting overlapping fine grids, the main grid's tensile strength is further increased. Increasing the main grid's tensile strength specifically refers to increasing the connection strength between the main grid and the battery cells. A main grid with a stronger connection to the battery requires greater tensile strength to peel off from the battery. Correspondingly, it can be said that the main grid has greater tensile strength.

[0107] In one possible implementation, such as Figure 3 As shown. The first fine grid 21 further includes a first through-grid 212, the two ends of which are connected through to the first main grid 31; and / or, the second fine grid 22 further includes a second through-grid 222, the two ends of which are connected through to the second main grid 32. Because the through-grid connection between the fine grid and the main grid increases the pulling force of the main grid on the back contact battery 100, in this invention, the first fine grid 21 may also include the first through-grid 212, and the second fine grid 22 may also include the second through-grid 222. Both ends of the first through-grid 212 are connected through to the first main grid 31, and both ends of the second through-grid 222 are connected through to the second main grid 32. In this invention, the first through-grid 212 is provided to increase the pulling force of the first main grid 31, and the second through-grid 222 is provided to increase the pulling force of the second main grid 32 on the back contact battery 100, thereby improving the stability and reliability of the back contact battery 100.

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

[0109] Specifically, in the embodiment of the utility model, the first fine grid 21 can simultaneously include two kinds of fine grids of the first penetrating fine grid 212 and the first lap fine grid 211. Because the first penetrating fine grid 212 can increase the pulling force of the first main grid 31 connected with the first penetrating fine grid 212, the reliability of the back contact battery 100 loss is improved;The first lap fine grid 211 can prevent the passivation layer at the first main grid 31 lap joint with the first lap fine grid 211 from being also burnt through, effectively reducing the back contact battery 100 loss. Therefore, by setting the ratio of the number of the first lap fine grid 211 to the number of the first penetrating fine grid 212 in the range of 0.04 to 0.1, the reliability of the back contact battery 100 loss can be improved while reducing the back contact battery 100 loss.

[0110] Similarly, in the embodiment of the utility model, the second fine grid 22 can simultaneously include two kinds of fine grids of the second penetrating fine grid 222 and the second lap fine grid 221. Because the second penetrating fine grid 222 can increase the pulling force of the second main grid 32 connected with the second penetrating fine grid 222, the reliability of the back contact battery 100 loss is improved;The second lap fine grid 221 can prevent the passivation layer at the second main grid 32 lap joint with the second lap fine grid 221 from being also burnt through, effectively reducing the back contact battery 100 loss. Therefore, by setting the ratio of the number of the second lap fine grid 221 to the number of the second penetrating fine grid 222 in the range of 0.04 to 0.1, the reliability of the back contact battery 100 loss can be improved while reducing the back contact battery 100 loss.

[0111] Further, for the specific lap joint mode of the first lap fine grid 211 and the first main grid 31. As shown in Figure 3 、 Figure 8 and Figure 9 in a possible implementation, the first lap fine grid 211 includes the first lap fine grid A and the first lap fine grid B, and the first main grid 31 includes the first main grid A;Along the second direction, the first lap fine grid A has oppositely arranged first end and second end;Along the second direction, the first lap fine grid B has oppositely arranged first end and second end;Along the second direction, the second end of the first lap fine grid A and the first end of the first lap fine grid B are adjacent;The second end of the first lap fine grid A and the first end of the first lap fine grid B are both lap joint to the first main grid A.

[0112] As shown in Figure 3 、 Figure 10 and Figure 11As shown in the first and second directions, the first end of the first fine grid A2111 and the second end of the first fine grid B2112 are adjacent to each other, that is, the first fine grid A2111 and the first fine grid B2112 are two first fine grids 21 adjacent to each other in the second direction. For the first fine grid A2111 and the first fine grid B2112, the first end of the first fine grid A2111 and the second end of the first fine grid B2112 are both connected to the first main grid A311. That is, the first end of the first fine grid A2111 and the second end of the first fine grid B2112 are connected to the first main grid A311.

[0113] Therefore, in the utility model, through the setting, one end of the two first fine grids 21 can be connected to the same first main grid 31, which ensures 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 fine grid A2111 and the first fine grid B2112, the passivation layer at the first main grid A311 is effectively avoided, thereby effectively reducing the loss of the back contact battery 100 and increasing the efficiency of the back contact battery 100.

[0114] In addition, for the height of the position of the first fine grid A2111 and the first fine grid B2112, as shown in Figure 8 、 Figure 9 and Figure 12 The first fine grid A2111 and the first fine grid B2112 can be flush. That is, in a possible implementation, the first fine grid A2111 and the first fine grid B2112 are flush in the second direction. In the utility model, through the flush setting of the first fine grid A2111 and the first fine grid B2112, the process manufacturing of the first fine grid A2111 and the first fine grid B2112 can be facilitated, which helps to improve the stability and repeatability of the production process. When the first fine grid A2111 and the first fine grid B2112 are flush, the spacing L1 between the first fine grid A2111 and the first fine grid B2112 is greater than 250 μm.

[0115] Of course, the first overlapped fine grid A 2111 and the first overlapped fine grid B 2112 can also be uneven. That is, in one possible implementation, the first overlapped fine grid A 2111 is higher or lower than the first overlapped fine grid B 2112 along the second direction, and the first overlapped fine grid A 2111 can be uneven with the first overlapped fine grid B 2112. Therefore, the first overlapped fine grid 211 arranged adjacent to two in the second direction can have various arrangements, achieving the effect of improving the flexibility of the arrangement of the first overlapped fine grid 211.

[0116] Similarly, for the specific overlapping manner of the second overlapped fine grid 221 and the second main grid 32, as shown in Figure 3 、 Figure 10 and Figure 11 , in one possible implementation, the second overlapped fine grid 221 includes a second overlapped fine grid A 2211 and a second overlapped fine grid B 2212, and the second main grid 32 includes a second main grid A 321; along the second direction, the second overlapped fine grid A 2211 has oppositely arranged first and second ends; along the second direction, the second overlapped fine grid B 2212 has oppositely arranged first and second ends; along the second direction, the second end of the second overlapped fine grid A 2211 and the first end of the second overlapped fine grid B 2212 are arranged adjacent to each other; and the second end of the second overlapped fine grid A 2211 and the first end of the second overlapped fine grid B 2212 are both overlapped onto the second main grid A 321.

[0117] As shown in Figure 10 、 Figure 11 and Figure 13 , the second overlapped fine grid A 2211 and the second overlapped fine grid B 2212 are both connected to the second main grid A 321. And along the second direction, the second end of the second overlapped fine grid A 2211 and the first end of the second overlapped fine grid B 2212 are arranged adjacent to each other, that is, the second overlapped fine grid A 2211 and the second overlapped fine grid B 2212 are two second fine grids 22 adjacent in the second direction. For the overlapping manner of the second overlapped fine grid A 2211 and the second overlapped fine grid B 2212, specifically, the second end of the second overlapped fine grid A 2211 and the first end of the second overlapped fine grid B 2212 are both overlapped onto the second main grid A 321. That is, the second end of the second overlapped fine grid A 2211 and the first end of the second overlapped fine grid B 2212 are overlapped on the second main grid A 321.

[0118] Therefore, in the utility model, through the setting, one end of two second thin grids 22 can be all overlapped on the same second main grid 32, the current can be ensured to be smoothly conducted from the two second thin grids 22 to the second main grid 32 and then transmitted to the external circuit through the second main grid 32, so that the collection and transmission path of the current are optimized, meanwhile, when printing the second overlapped thin grid A 2211 and the second overlapped thin grid B 2212, the passivation layer at the second main grid A 321 is effectively avoided from being burnt through, thereby effectively reducing the loss of the back contact battery 100 and increasing the efficiency of the back contact battery 100.

[0119] In addition, the height of the position of the second overlapped thin grid A 2211 and the second overlapped thin grid B 2212 can be set as shown in Figure 10 、 Figure 11 and Figure 13 , that is, in a possible implementation, along the second direction, the second overlapped thin grid A 2211 is flush with the second overlapped thin grid B 2212. In the utility model, through the setting that the second overlapped thin grid A 2211 is flush with the second overlapped thin grid B 2212, the process manufacturing of the second overlapped thin grid A 2211 and the second overlapped thin grid B 2212 can be facilitated, and the stability and repeatability of the production process can be improved. When the second overlapped thin grid A 2211 is flush with the second overlapped thin grid B 2212, the spacing L2 between the second overlapped thin grid A 2211 and the second overlapped thin grid B 2212 ranges from greater than 250 μm.

[0120] Of course, the second overlapped thin grid A 2211 and the second overlapped thin grid B 2212 can also be not flush. That is, in a possible implementation, along the second direction, the second overlapped thin grid A 2211 is higher or lower than the second overlapped thin grid B 2212, and the second overlapped thin grid A 2211 can be not flush with the second overlapped thin grid B 2212. Therefore, the two second overlapped thin grids 221 adjacent in the second direction can have various arrangement modes, and the flexibility of the arrangement of the second overlapped thin grid 221 is improved.

[0121] Further, the specific overlapping mode of the first overlapped thin grid 211 and the first main grid 31 can be as shown in Figure 3 、 Figure 14 and Figure 15As shown, in one possible implementation, the first overlapping fine gate 211 includes a first overlapping fine gate C2113 and a first overlapping fine gate D2114, and the first main gate 31 includes a first main gate B312; along the second direction, the first overlapping fine gate C2113 has a first end and a second end disposed opposite to each other; along the second direction, the first overlapping fine gate D2114 has a first end and a second end disposed opposite to each other; the first end of the first overlapping fine gate C2113 and the first end of the first overlapping fine gate D2114 are both overlapped onto the first main gate B312.

[0122] like Figure 14 As shown, both the first overlapping fine gate C2113 and the first overlapping fine gate D2114 overlap and connect to the first main gate B312. Specifically, the first end of both the first overlapping fine gate C2113 and the first end of the first overlapping fine gate D2114 overlaps onto the first main gate B312. That is, the first ends of the first overlapping fine gate C2113 and the first ends of the first overlapping fine gate D2114 overlap onto the first main gate B312.

[0123] Therefore, in this utility model, by means of this arrangement, one end of each of the two first fine gates 21 can be overlapped on the same first main gate 31, ensuring that the current can be smoothly conducted from the two first fine gates 21 to the first main gate 31 and then transmitted to the external circuit through the first main gate 31, thereby optimizing the current collection and transmission path; at the same time, when printing the first overlap fine gates C2113 and D2114, the passivation layer at the first main gate 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, regarding the specific overlapping method of the second overlapping fine grid 221 and the second main grid 32, such as Figure 3 , Figure 14 and Figure 15 As shown, in one possible implementation, the second overlapping fine gate 221 includes a second overlapping fine gate C2213 and a second overlapping fine gate D2214, and the second main gate 32 includes a second main gate B322; along the second direction, the second overlapping fine gate C2213 has a first end and a second end disposed opposite to each other; along the second direction, the second overlapping fine gate D2214 has a first end and a second end disposed opposite to each other; the first end of the second overlapping fine gate C2213 and the first end of the second overlapping fine gate D2214 are both overlapping onto the second main gate B322.

[0125] like Figure 15The second lap fine grid C2213 and the second lap fine grid D2214 are both connected to the second main grid B322. For the connection mode of the second lap fine grid C2213 and the second lap fine grid D2214, specifically, the first end of the second lap fine grid C2213 and the first end of the second lap fine grid D2214 are both connected to the second main grid B322. That is, the first end of the second lap fine grid C2213 and the first end of the second lap fine grid D2214 are both connected to the second main grid B322.

[0126] Therefore, in the utility model, through the arrangement, one end of two second fine grids 22 can be connected to the same second main grid 32, so 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 that the current collection and transmission path are optimized; meanwhile, when printing the second lap fine grid C2213 and the second lap fine grid D2214, the passivation layer at the second main grid B322 is effectively avoided from being burned through, so that the loss of the back contact battery 100 is effectively reduced, and the efficiency of the back contact battery 100 is increased.

[0127] Further, for the specific connection mode of the first lap fine grid 211 and the first main grid 31, as shown in Figure 3 and Figure 16 In a possible implementation, the first lap fine grid 211 includes a first lap fine grid E2115, and the first main grid 31 includes a first main grid C313 and a first main grid D314; along the second direction, the first lap fine grid E2115 has oppositely arranged first and second ends; the first end of the first lap fine grid E2115 is connected to the first main grid C313, and the second end of the first lap fine grid E2115 is connected to the first main grid D314.

[0128] As shown in Figure 16 The two ends of the first lap fine grid E2115 are connected to the first main grid C313 and the first main grid D314 respectively. The two ends of the first lap fine grid E2115 are both connected to a main grid through the connection mode. Therefore, when printing the first lap 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, so that the loss of the back contact battery 100 is effectively reduced, and the efficiency of the back contact battery 100 is increased.

[0129] Similarly, for the specific connection mode of the second lap fine grid 221 and the second main grid 32, as shown in Figure 3 and Figure 17As shown in a possible implementation, the second fine grid 221 includes a second fine grid E 2215, and the second main grid 32 includes a second main grid C 323 and a second main grid D 324; along the second direction, the second fine grid E 2215 has oppositely arranged first and second ends; the first end of the second fine grid E 2215 is connected to the second main grid C 323 by lapping, and the second end of the second fine grid E 2215 is connected to the second main grid D 324 by lapping.

[0130] As shown in a possible implementation, the second fine grid 221 includes a second fine grid E 2215, and the second main grid 32 includes a second main grid C 323 and a second main grid D 324; along the second direction, the second fine grid E 2215 has oppositely arranged first and second ends; the first end of the second fine grid E 2215 is connected to the second main grid C 323 by lapping, and the second end of the second fine grid E 2215 is connected to the second main grid D 324 by lapping. Figure 17 As shown in a possible implementation, the second fine grid 221 includes a second fine grid E 2215, and the second main grid 32 includes a second main grid C 323 and a second main grid D 324; along the second direction, the second fine grid E 2215 has oppositely arranged first and second ends; the first end of the second fine grid E 2215 is connected to the second main grid C 323 by lapping, and the second end of the second fine grid E 2215 is connected to the second main grid D 324 by lapping.

[0131] Further, the specific lapping manner of the first fine grid 211 and the first main grid 31 is as shown in a possible implementation. Figure 3 Figure 18 As shown in a possible implementation, the first fine grid 211 includes a first fine grid F 2116, and the first main grid 31 includes a first main grid E 315 and a first main grid F 316; along the second direction, the first fine grid F 2116 has oppositely arranged first and second ends; the first end of the first fine grid F 2116 is connected to the first main grid E 315 by lapping, and the second end of the first fine grid F 2116 is connected to the first main grid F 316 by penetrating.

[0132] As shown in a possible implementation, the first fine grid 211 includes a first fine grid F 2116, and the first main grid 31 includes a first main grid E 315 and a first main grid F 316; along the second direction, the first fine grid F 2116 has oppositely arranged first and second ends; the first end of the first fine grid F 2116 is connected to the first main grid E 315 by lapping, and the second end of the first fine grid F 2116 is connected to the first main grid F 316 by penetrating. Figure 18 As shown in a possible implementation, the first fine grid 211 includes a first fine grid F 2116, and the first main grid 31 includes a first main grid E 315 and a first main grid F 316; along the second direction, the first fine grid F 2116 has oppositely arranged first and second ends; the first end of the first fine grid F 2116 is connected to the first main grid E 315 by lapping, and the second end of the first fine grid F 2116 is connected to the first main grid F 316 by penetrating.

[0133] ​Likewise, for the specific connection mode of the second connection fine grid 221 and the second main grid 32, as shown in Figure 3 and Figure 19 in a possible implementation, the second connection fine grid 221 includes a second connection fine grid F2216, and the second main grid 32 includes a second main grid E325 and a second main grid F326; along the second direction, the second connection fine grid F2216 has oppositely arranged first and second ends; the first end of the second connection fine grid F2216 is connected to the second main grid E325, and the second end of the second connection fine grid F2216 is connected to the second main grid F326 through the second main grid F326.

[0134] As shown in Figure 19 , the two ends of the second connection fine grid F2216 are connected to the second main grid E325 and the second main grid F326 through connection and penetration, respectively. One end of the second connection fine grid F2216 is connected to a main grid through connection, and the other end of the second connection fine grid F2216 is connected to another main grid through penetration. Because the penetration connection between the fine grid and the main grid can improve the pulling force of the main grid on the back contact battery 100 and reduce the risk of breakage of the fine grid or the main grid. Therefore, when printing the second connection fine grid F2216, the burning through of the passivation layer at the second main grid E325 is effectively avoided, 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 also can achieve the effect of improving 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] Further, in addition to preventing the passivation layer at the main grid, the connection fine grid can also prevent the passivation layer at the main grid, as shown in Figure 3 , Figure 5 and Figure 6 in a possible implementation. The first main grid 31 includes one or more first fixed parts 310, and one or more ends of the first connection fine grid 211 are connected to the first fixed part 310; and / or, the second main grid 32 includes one or more second fixed parts 320, and one or more ends of the second connection fine grid 221 are connected to the second fixed part 320.

[0136] Specifically, the first main grid 31 can specifically include one or more first fixed parts 310, which can be specifically used for welding a solder strip, i.e., the first main grid 31 can be welded with the solder strip through the first fixed part 310, and the first fixed part 310 can also be used for voltammetric test, and the first fixed part 310 can be specifically a PAD point. The first main grid 31 can specifically include one or more second fixed parts 320, which can be specifically used for welding a solder strip, i.e., the second main grid 32 can be welded with the solder strip through the second fixed part 320, and the second fixed part 320 can also be used for voltammetric test, and the second fixed part 320 can be specifically a PAD point.

[0137] In the prior art, the position at the PAD point of the main grid is usually connected with the fine grid in a through connection manner, so when the solder strip is welded with the main grid through the PAD point, the solder will be distributed on the PAD point and the fine grid arranged on the PAD point, the solder strip is prone to false welding, thereby causing the welding tension of the PAD point to the solder strip to be insufficient. However, through the lap joint connection manner of the PAD point and the fine grid, the part of the fine grid connected with the PAD point is less, and the solder can be more distributed on the PAD point, thereby improving the welding tension of the PAD point to the solder strip and reducing false welding.

[0138] Therefore, in the utility model, one or more end portions of the first lap fine grid 211 are lapped to the first fixed part 310; and / or, one or more end portions of the second lap fine grid 221 are lapped to the second fixed part 320, that is, the welding tension of the first fixed part and the second fixed part 320 to the solder strip can be improved, and the effect of reducing false welding of the solder strip is achieved.

[0139] Further, for the distribution manner of the lap fine grid and the through fine grid in the fine grid, in a possible implementation manner, the first main grid 31 is connected with a plurality of first fine grids 21; wherein the first fine grid 21 connected with the first fixed part 310 in the first main grid 31 is all the first lap fine grid 211, and the first fine grid 21 connected with the part other than the first fixed part 310 in the first main grid 31 is all the first through fine grid 212. The second main grid 32 is connected with a plurality of second fine grids 22; wherein the second fine grid 22 connected with the second fixed part 320 in the second main grid 32 is all the second lap fine grid 221, and the second fine grid 22 connected with the part other than the second fixed part 320 in the second main grid 32 is all the second through fine grid 222.

[0140] Specifically, a plurality of first fine grids 21 are connected on each first main grid 31, and each first fine grid 21 is connected to the first fixed part 310 of the first main grid 31 or to a place other than the first fixed part 310 of the first main grid 31. In the embodiment of the utility model, in order to reduce false welding of the solder strip, all the first fine grids 21 connected with the first fixed part 310 of the first main grid 31 are set to be the first lap fine grids 211, so as to improve the welding tension of the first fixed part 310 to the solder strip and reduce false welding of the solder strip; at the same time, all the first fine grids 21 connected with the part other than the first fixed part 310 in each first main grid 31 are set to be the first through fine grids 212, so as to maximize the welding tension of each first main grid 31, thereby achieving the effect of improving the stability and reliability of the back contact battery 100.

[0141] Further, same as above, a plurality of second fine grids 22 can also be connected on each second main grid 32, each second fine grid 22 being connected to the second fixed part 320 of the second main grid 32 or being connected to a position other than the second fixed part 320 of the second main grid 32. In the embodiment of the present application, in order to reduce the false welding of the welding strip, all the second fine grids 22 connected with the second fixed part 320 of the second main grid 32 are set as the second overlapping fine grids 221, so as to improve the pulling force of the second fixed part 320 on the welding strip and reduce the false welding of the welding strip; at the same time, all the second fine grids 22 connected with the part other than the second fixed part 320 of each second main grid 32 are set as the second penetrating 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, for the setting position of the first fixed part 310, in one possible implementation manner, as shown in Figure 3 、 Figure 20 and Figure 21 , the first main grid 31 includes a first main grid G317, the first main grid G317 includes a first fixed part A3101, and the center line of the first main grid G317 and the center line of the first fixed part A3101 are on the same line. Specifically, by setting the center line of both the first main grid G317 and the first fixed part A3101 in the first main grid G317 on the same line, the present application can achieve the purpose of more uniform distribution of the grid lines in the region adjacent to the first fixed part A3101, and achieve the effect of improving the current collection capability of the back contact battery 100.

[0143] Further, for the setting position of the first fixed part 310, as shown in Figure 3 、 Figure 20 and Figure 21 , the first main grid 31 includes a first main grid H318, the first main grid H318 includes a first fixed part B3102, and the center line of the first main grid H318 and the center line of the first fixed part B3102 are not on the same line. Specifically, by setting the center line of both the first main grid H318 and the first fixed part B3102 in the first main grid H318 not on the same line, the present application can achieve the purpose of more uniform distribution of the grid lines in the region adjacent to the first fixed part B3102, and achieve the effect of improving the current collection capability of the back contact battery 100.

[0144] Similarly, Figure 3 、 Figure 22 and Figure 23As shown, for the setting position of the second fixed part 320, in a possible implementation, the second main grid 32 includes a second main grid G327, the second main grid G327 includes a second fixed part A3201, and the center line of the second main grid G327 and the center line of the second fixed part A3201 are on the same straight line. Specifically, by setting the center line of both the second main grid G327 and the second fixed part A3201 in the second main grid G327 to be on the same straight line, the purpose of more uniform distribution of the grid lines in the region adjacent to the second fixed part A3201 can be achieved, and the effect of improving the current collection capability of the back contact battery 100 can be achieved.

[0145] Further, for the setting position of the second fixed part 320, Figure 3 、 Figure 22 and Figure 23 As shown, the second main grid 32 includes a second main grid H328, the second main grid H328 includes a second fixed part B3202, and the center line of the second main grid H328 and the center line of the second fixed part B3202 are not on the same straight line. Specifically, by setting the center line of both the second main grid H328 and the second fixed part B3202 in the second main grid H328 to be not on the same straight line, the purpose of more uniform distribution of the grid lines in the region adjacent to the second fixed part B3202 can be achieved, and the effect of improving the current collection capability of the back contact battery 100 can be achieved.

[0146] In the utility model, in a possible implementation, as shown in Figure 3 、 Figure 5 、 Figure 6 and Figure 7 As shown, the back contact battery 100 further includes a first solder strip 41 and a second solder strip 42, the first solder strip 41 is welded to the first fixed part through a first solder layer 51, and the second solder strip 42 is welded to the second fixed part 320 through a second solder layer 52. The first solder layer 51 can specifically include at least one solder such as tin paste, tin lead and soldering rod, and similarly, the second solder layer 52 can also specifically include at least one solder such as tin paste, tin lead and soldering rod.

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

[0148] P-type doping results in a low concentration of boron (B) atoms and poor electron transport. Therefore, larger Ag (silver) crystals need to form during sintering of the slurry to achieve a good ohmic contact. Thus, in the back contact cell 100, the thickness of the P-type doped layer 61 is increased to provide a larger window for Ag (silver) crystal formation during sintering. This effectively prevents the slurry from burning through the tunneling layer, damaging the cell structure, leading to excessive recombination centers, reducing the cell's open-circuit voltage, and resulting in poor conversion efficiency.

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

[0150] Specifically, in this invention, since hole collection is more difficult than electron collection, increasing the crystal depth of the fine gate and doped layer can improve the current collection and transmission performance between the fine gate and the doped layer. Therefore, in this invention, by increasing the crystal depth L6 of the first fine gate 21 or the second fine gate 22 and the P-type doped layer 61, the hole collection capability of the back contact battery 100 can be further enhanced.

[0151] And, because the crystallization depth of the P-type doped layer 61 and the fine gate is deeper than that of the N-type doped layer 62 and the fine gate, the thickness L4 of the P-type doped layer 61 corresponding to the need to be set is greater than the thickness L5 of the N-type doped layer 62, in order to accommodate the deeper crystallization depth.

[0152] In the description of the present specification, the description referring to the terms "some embodiments", "exemplary embodiments", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Also, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in one or more embodiments or examples.

[0153] In addition, the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A back contact cell, characterized in that, The application relates to a solar cell, comprising: 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 arranged alternately and spacedly along a first direction and extend along a second direction intersecting 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 spacedly along the second direction and extend along the first direction, 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 overlapped fine grid, one or more ends of the first overlapped fine grid are overlapped on the first main grid; and / or the second fine grid comprises a second overlapped fine grid, one or more ends of the second overlapped fine grid are overlapped on the second main grid.

2. The back contact cell of claim 1, wherein, The first overlapped fine grid comprises a first overlapped fine grid A and a first overlapped fine grid B, and the first main grid comprises a first main grid A; along the second direction, the first overlapped fine grid A has oppositely arranged first and second ends; along the second direction, the first overlapped fine grid B has oppositely arranged first and second ends; along the second direction, the second end of the first overlapped fine grid A and the first end of the first overlapped fine grid B are arranged adjacently; the second end of the first overlapped fine grid A and the first end of the first overlapped fine grid B are overlapped on the first main grid A.

3. The back contact cell of claim 2, wherein, The second overlapped fine grid comprises a second overlapped fine grid A and a second overlapped fine grid B, and the second main grid comprises a second main grid A; along the second direction, the second overlapped fine grid A has oppositely arranged first and second ends; along the second direction, the second overlapped fine grid B has oppositely arranged first and second ends; along the second direction, the second end of the second overlapped fine grid A and the first end of the second overlapped fine grid B are arranged adjacently; the second end of the second overlapped fine grid A and the first end of the second overlapped fine grid B are overlapped on the second main grid A.

4. The back contact cell of claim 2, wherein, along the second direction, the first overlapped fine grid A is flush with the first overlapped fine grid B.

5. The back contact cell of claim 4, wherein, The interval between the first overlapped fine grid A and the first overlapped fine grid B is greater than 250 mu m.

6. The back contact cell of claim 3, wherein, along the second direction, the second overlapped fine grid A is flush with the second overlapped fine grid B.

7. The back contact cell of claim 6, wherein, The interval between the second overlapped fine grid A and the second overlapped fine grid B is greater than 250 mu m.

8. The back contact cell of claim 2, wherein, along the second direction, the first overlapped fine grid A is higher or lower than the first overlapped fine grid B.

9. The back contact cell of claim 3, wherein, along the second direction, the second overlapped fine grid A is higher or lower than the second overlapped fine grid B.

10. The back contact cell of claim 1, wherein, The first overlapped fine grid comprises a first overlapped fine grid C and a first overlapped fine grid D, and the first main grid comprises a first main grid B; along the second direction, the first overlapped fine grid C has oppositely arranged first and second ends; along the second direction, the first overlapped fine grid D has oppositely arranged first and second ends; the first end of the first overlapped fine grid C and the first end of the first overlapped fine grid D are overlapped on the first main grid B.

11. The back contact cell of claim 10, wherein, The first overlapped fine grid comprises a second overlapped fine grid C and a second overlapped fine grid D, and the second main grid comprises a second main grid B; Along the second direction, the second fine grid C has first and second ends arranged oppositely; Along the second direction, the second fine grid D has first and second ends arranged oppositely; The first end of the second fine grid C and the first end of the second fine grid D are both lapped onto the second main grid B.

12. The back contact cell of claim 1, wherein, The first fine grid comprises a first fine grid E, and the first main grid comprises a first main grid C and a first main grid D; Along the second direction, the first fine grid E has first and second ends arranged oppositely; The first end of the first fine grid E is lapped onto the first main grid C, and the second end of the first fine grid E is lapped onto the first main grid D.

13. The back contact cell of claim 12, wherein, The second fine grid comprises a second fine grid E, and the second main grid comprises a second main grid C and a second main grid D; Along the second direction, the second fine grid E has first and second ends arranged oppositely; The first end of the second fine grid E is lapped onto the second main grid C, and the second end of the second fine grid E is lapped onto the second main grid D.

14. The back contact cell of claim 1 wherein, The first fine grid comprises a first fine grid F, and the first main grid comprises a first main grid E and a first main grid F; Along the second direction, the first fine grid F has first and second ends arranged oppositely; The first end of the first fine grid F is lapped onto the first main grid E, and the second end of the first fine grid F is connected through the first main grid F.

15. The back contact cell of claim 14, wherein, The second fine grid comprises a second fine grid F, and the second main grid comprises a second main grid E and a second main grid F; Along the second direction, the second fine grid F has first and second ends arranged oppositely; The first end of the second fine grid F is lapped onto the second main grid E, and the second end of the second fine grid F is connected through the second main grid F.

16. The back contact cell of claim 1, wherein, The first fine grid further comprises a first through fine grid, both ends of the first through fine grid being connected through the first main grid; and / or, the second fine grid further comprises a second through fine grid, both ends of the second through fine grid being connected through the second main grid.

17. The back contact cell of claim 16, wherein, The ratio of the number of the first fine grids to the number of the first through fine grids is 0.04 to 0.

1.

18. The back contact cell of claim 17, wherein, The ratio of the number of the second fine grids to the number of the second through fine grids is 0.04 to 0.

1.

19. The back contact cell of claim 16, wherein, The first main grid comprises one or more first fixed parts, one or more ends of the first fine grid being lapped onto the first fixed parts; and / or, The second main grid comprises one or more second fixed parts, one or more ends of the second fine grid being lapped onto the second fixed parts.

20. The back contact cell of claim 16, wherein, The first main grid comprises a first main grid G, the first main grid G comprising a first fixed part A, the center line of the first main grid G and the center line of the first fixed part A being in the same straight line.

21. The back contact cell of claim 20, wherein, The second main grid comprises a second main grid G, the second main grid G comprising a second fixed part A, the center line of the second main grid G and the center line of the second fixed part A being in the same straight line.

22. The back contact cell of claim 16, wherein, The first main grid comprises a first main grid H, the first main grid H comprises a first fixed part B, and the center line of the first main grid H and the center line of the first fixed part B are not on the same straight line.

23. The back contact cell of claim 22, wherein, The second main grid comprises a second main grid H, the second main grid H comprises a second fixed part B, and the center line of the second main grid H and the center line of the second fixed part B are not on the same straight line.

24. The back contact cell of claim 19, wherein, The first main grid is connected with a plurality of first fine grids; wherein, The first fine grid connected with the first fixed part in the first main grid is the first overlapped fine grid, and the first fine grid connected with the part other than the first fixed part in the first main grid is the first penetrating fine grid.

25. The back contact cell of claim 24, wherein, The second main grid is connected with a plurality of second fine grids; wherein, The second fine grid connected with the second fixed part in the second main grid is the second overlapped fine grid, and the second fine grid connected with the part other than the second fixed part in the second main grid is the second penetrating fine grid.

26. The back contact cell of claim 19, wherein, The back contact cell further comprises a first solder strip and a second solder strip, the first solder strip is soldered to the first fixed part through a first solder layer; and the second solder strip is soldered to the second fixed part through a second solder layer.

27. The back contact cell of claim 1 wherein, The first main grid is connected with a plurality of first fine grids, and the first fine grid is the first overlapped fine grid.

28. The back contact cell of claim 23, wherein, The second main grid is connected with a plurality of second fine grids, and the second fine grid is the second overlapped fine grid.

29. The back contact cell of claim 1 wherein, The distance from one end of the first overlapped fine grid to the first main grid in the second direction is greater than 20μm.

30. The back contact cell of claim 1 wherein, Further comprising a P-type doped layer and an N-type doped layer arranged on the silicon substrate; The P-type doped layer is connected with the first fine grid in correspondence, and the N-type doped layer is connected with the second fine grid in correspondence; or, the P-type doped layer is connected with the second fine grid in correspondence, and the N-type doped layer is connected with the first fine grid in correspondence; The thickness of the P-type doped layer is greater than the thickness of the N-type doped layer.

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

32. The back contact cell of claim 30, wherein, The thickness of the P-type doped layer minus the thickness of the N-type doped layer is less than or equal to 100nm.

33. The back contact cell of claim 30, wherein, The crystallization depth of the first fine grid and the P-type doped layer is greater than the crystallization depth of the second fine grid and the N-type doped layer; or, The crystallization depth of the second fine grid and the P-type doped layer is greater than the crystallization depth of the first fine grid and the N-type doped layer.

34. The back contact cell of claim 30, wherein, The crystallization depth of the first fine grid and the P-type doped layer is 100nm-220nm; or the crystallization depth of the second fine grid and the P-type doped layer is 100nm-220nm.

35. The back contact cell of claim 30 or 34, wherein, The crystallization depth of the first fine grid and the N-type doped layer is 30nm-90nm; or the crystallization depth of the second fine grid and the N-type doped layer is 30nm-90nm.

36. The back contact cell of claim 1 wherein, The first main grid includes first lap locations and first non-lap locations, one or more ends of the first lap fine grid lap onto the first lap locations of the first main grid, the glass frit content of the first lap locations is greater than the glass frit content of the first non-lap locations.

37. The back contact cell of claim 36, wherein, The second main grid includes second lap locations and second non-lap locations, one or more ends of the second lap fine grid lap onto the second lap locations of the second main grid, the glass frit content of the first lap locations is greater than the glass frit content of the second non-lap locations.

38. A battery assembly characterized by, A back contact cell comprising any of claims 1 to 37.

39. A photovoltaic system characterized by, A cell assembly comprising the cell of claim 38.

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