Main-grid-free back contact solar cell and photovoltaic module

Abstract

The invention relates to a main-grid-free back contact solar cell and a photovoltaic module, the main-grid-free back contact solar cell comprises a substrate, a first fine grid and a second fine grid, the substrate comprises a first surface and a second surface, a P-type doped region and an N-type doped region are arranged on the first surface, the first fine grid is arranged on the P-type doped region, and the second fine grid is arranged on the N-type doped region. The first fine grid is provided with a first connecting part used for being connected with the first welding strip and a first isolating part used for being isolated from the second welding strip, the second fine grid is arranged on the N-type doped region, and the second fine grid is provided with a second connecting part used for being connected with the second welding strip and a second isolating part used for being isolated from the first welding strip. The first surface comprises a plane part and a sunken part which is sunken from the plane part to the second surface, the first connecting part and the second connecting part are arranged on the plane part, and the first isolating part and the second isolating part are arranged on the sunken part. The design provides a space for the arrangement of the insulating layer, and the welding strip is not elevated by the insulating layer, so that the welding strip can be directly connected with the fine grid with the same electrical property, and the possibility of pseudo soldering between the welding strip and the fine grid is reduced.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic technology, and in particular to a main grid-free back contact solar cell and a photovoltaic module. Background Art

[0002] Busbar-free back contact solar cells can convert sunlight into electrical energy. Currently, the fine grid on busbar-free back contact solar cells is prone to cold solder joints when connected to solder strips with the same electrical properties, thereby affecting the reliability of the busbar-free back contact solar cells and affecting their working performance. Summary of the invention

[0003] In view of this, the present application provides a busbar-free back-contact solar cell and a photovoltaic module, so as to solve the problem in the prior art that the fine grid on the busbar-free back-contact solar cell is prone to cold solder joints when connected to a solder ribbon with the same electrical properties.

[0004] In a first aspect, an embodiment of the present application provides a main grid-free back contact solar cell, comprising: a substrate, a first fine grid and a second fine grid, wherein the substrate comprises a first surface and a second surface arranged opposite to each other along its own thickness direction, a P-type doping region and an N-type doping region arranged along a first direction are arranged on the first surface, a tunneling layer is arranged between the P-type doping region and the substrate and between the N-type doping region and the substrate along the thickness direction of the substrate, a first passivation layer is arranged on the side of the P-type doping region and the N-type doping region away from the substrate; a second passivation layer is arranged on the second surface, the first fine grid is arranged on the P-type doping region and penetrates the first passivation layer. layer, the first fine grid has a first connection portion arranged along the second direction for connecting to the first welding strip and a first isolation portion for isolating from the second welding strip, the second fine grid is arranged on the N-type doping region and penetrates the first passivation layer, the second fine grid has a second connection portion arranged along the second direction for connecting to the second welding strip and a second isolation portion for isolating from the first welding strip, wherein the first surface includes a planar portion and a recessed portion recessed from the planar portion to the second surface, the first connection portion and the second connection portion are arranged on the planar portion, and the first isolation portion and the second isolation portion are arranged on the recessed portion; the first direction is orthogonal to the second direction.

[0005] In a possible implementation, the first surface of the substrate has a first region and a second region arranged along a first direction, along the thickness direction of the substrate, a distance from the first region to the second surface is greater than a distance from the second region to the second surface, the P-type doped region is arranged on the first region, the N-type doped region is arranged on the second region, an isolation groove recessed from the first surface to the second surface is arranged between adjacent first regions and second regions, the planar portion includes a first planar structure, the recessed portion includes a first recessed structure, the first planar structure and the first recessed structure are located in the first region, the first planar structure and the first recessed structure are arranged along the second direction, the first connecting portion is arranged on the first planar structure, the first isolating portion is arranged on the first recessed structure, and the planar portion further includes a second planar structure, the recessed portion further includes a second recessed structure, the second planar structure and the second recessed structure are located in the second region, the second planar structure and the second recessed structure are arranged along the second direction, the second connecting portion is arranged on the second planar structure, and the second isolating portion is arranged on the second recessed structure.

[0006] In one possible embodiment, along the second direction, the first connecting parts and the first isolating parts are alternately arranged, the first planar structures and the first recessed structures are alternately arranged within the first region, the first connecting parts are arranged on their respective first planar structures, and the first isolating parts are arranged on their respective first recessed structures; and along the second direction, the second connecting parts and the second isolating parts are alternately arranged, the second planar structures and the second recessed structures are alternately arranged within the second region, the second connecting parts are arranged on their respective second planar structures, and the second isolating parts are arranged on their respective second recessed structures.

[0007] In a possible implementation manner, the first recessed structures and the second planar structures are alternately arranged along the first direction, and the second recessed structures and the first planar structures are alternately arranged along the first direction.

[0008] In a possible embodiment, along the thickness direction of the substrate, a first insulating layer is provided on the side of the first isolation portion away from the substrate, and the first insulating layer is used to isolate the first isolation portion and the second welding strip, and a second insulating layer is provided on the side of the second isolation portion away from the substrate, and the second insulating layer is used to isolate the second isolation portion and the first welding strip.

[0009] In a possible embodiment, along the thickness direction of the substrate, a distance D1 from the first insulating layer to the second surface is smaller than a distance D2 from the second connecting portion to the second surface, and a distance D3 from the second insulating layer to the second surface is smaller than a distance D4 from the first connecting portion to the second surface.

[0010] In one possible embodiment, the first insulating layer includes a first insulating portion and a second insulating portion connected to both sides of the first insulating portion along the first direction, the first insulating portion is located on a side of the first isolation portion away from the substrate along the thickness direction of the substrate, the second insulating portion is accommodated in the first recessed structure and is respectively located on both sides of the first isolation portion along the first direction, and the second insulating layer includes a third insulating portion and a fourth insulating portion connected to both sides of the third insulating portion along the first direction, the third insulating portion is located on a side of the second isolation portion away from the substrate along the thickness direction of the substrate, the fourth insulating portion is accommodated in the second recessed structure and is respectively located on both sides of the second isolation portion along the first direction.

[0011] In a possible implementation, along the thickness direction of the substrate, the first recessed structure depth H1 is greater than the second recessed structure depth H2, and / or the first recessed structure depth is H1, H1 satisfies 5μm≤H1≤25μm, and / or the second recessed structure depth is H2, H2 satisfies: 5μm≤H2≤25μm.

[0012] In a possible implementation, along the first direction, the width of the recessed portion is W1, the width of the first isolation portion and the width of the second isolation portion are both W2, and W1 and W2 satisfy: 2≤W1 / W2≤5.

[0013] In a second aspect, an embodiment of the present application provides a photovoltaic component, comprising a busbar-free back-contact solar cell, wherein the busbar-free back-contact solar cell is any one of the above busbar-free back-contact solar cells, and adjacent busbar-free back-contact solar cells are electrically connected via welding strips, wherein the welding strips comprise a first welding strip and a second welding strip arranged along the second direction, the first welding strip extends along the first direction and is directly welded to the first connection portion of the first fine grid of the busbar-free back-contact solar cell, and the second welding strip extends along the first direction and is directly welded to the second connection portion of the second fine grid of the busbar-free back-contact solar cell.

[0014] The embodiment of the present application provides a main grid-free back contact solar cell and a photovoltaic module, comprising: a substrate, a first fine grid and a second fine grid, the substrate comprising a first surface and a second surface arranged opposite to each other along its own thickness direction, a P-type doping region and an N-type doping region arranged along a first direction are arranged on the first surface, a tunneling layer is arranged between the P-type doping region and the substrate and between the N-type doping region and the substrate along the thickness direction of the substrate, a first passivation layer is arranged on the side of the P-type doping region and the N-type doping region away from the substrate; a second passivation layer is arranged on the second surface, the first fine grid is arranged on the P-type doping region and penetrates the first passivation layer. The first fine grid has a first connection portion arranged along the second direction for connecting to the first welding strip and a first isolation portion for isolating from the second welding strip, the second fine grid is arranged on the N-type doped region and penetrates the first passivation layer, the second fine grid has a second connection portion arranged along the second direction for connecting to the second welding strip and a second isolation portion for isolating from the first welding strip, wherein the first surface includes a plane portion and a recessed portion recessed from the plane portion to the second surface, the first connection portion and the second connection portion are arranged on the plane portion, and the first isolation portion and the second isolation portion are arranged on the recessed portion; the first direction is orthogonal to the second direction. The isolation portion of each fine grid sinks toward the second surface of the substrate, thereby increasing the distance between the isolation portion and the welding strip in the thickness direction of the substrate, providing space for the arrangement of the insulating layer on each fine grid, so that the welding strip will not be raised by the insulating layer, and the welding strip and the fine grid with the same electrical property as the welding strip can be directly connected, thereby improving the stability and reliability of the connection between the two, reducing the possibility of cold welding between the two, and thus improving the reliability of the solar cell without main grid back contact.

[0015] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0017] Figure 1 A partial cross-sectional view of a busbar-free back contact solar cell provided in one embodiment of the present application;

[0018] Figure 2 A schematic diagram of the arrangement of fine grids and welding strips on a busbar-free back contact solar cell provided in one embodiment of the present application;

[0019] Figure 3 For along Figure 2 A local cross-sectional view along the AA direction;

[0020] Figure 4 For along Figure 2 A partial cross-sectional view along the BB direction;

[0021] Figure 5 It is a partial schematic diagram of the connection between the fine grid and the welding ribbon on the solar cell without main grid back contact in the related art;

[0022] Figure 6 It is a partial schematic diagram of the arrangement of the first planar structure, the second planar structure, the first recessed structure and the second recessed structure on the substrate in one embodiment of the present application;

[0023] Figure 7 It is a partial schematic diagram of a solar cell without a main grid back contact in one embodiment of the present application;

[0024] Figure 8 It is a partial schematic diagram of a solar cell without a main grid back contact in another embodiment of the present application;

[0025] Fig. 9 This is a partial schematic diagram of a solar cell without a main grid back contact in another embodiment of the present application;

[0026] Fig.10 This is a partial schematic diagram of a solar cell without a main grid back contact in another embodiment of the present application;

[0027] Fig.11 A partial schematic diagram of a battery string in a photovoltaic module provided in an embodiment of the present application;

[0028] Fig.12 A schematic diagram of a photovoltaic module provided in accordance with an embodiment of the present application. DETAILED DESCRIPTION

[0029] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0030] It should be clear that the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0031] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0032] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0033] like Figure 1 As shown, an embodiment of the present application provides a busbar-free back contact solar cell 1, and the busbar-free back contact solar cell 1 includes a substrate 11, and the substrate 11 can be an N-type substrate or a P-type substrate. The N-type substrate 11 can be a silicon substrate doped with an N-type element, and the N-type element can specifically be a pentavalent element such as phosphorus, arsenic, or antimony. The P-type substrate 11 can be a silicon substrate doped with a P-type element, and the P-type element can specifically be a trivalent element such as boron, indium, or gallium. The structure of the busbar-free back contact solar cell 1 is described below by taking an N-type substrate as an example.

[0034] The substrate 11 includes a first surface 111 and a second surface 112 that are arranged opposite to each other along its thickness direction Z. The first surface 111 may be the back surface of the substrate 11, that is, the surface that is not directly irradiated by sunlight. The second surface 112 may be the front surface of the substrate 11, that is, the surface that can be directly irradiated by sunlight. Both the first surface 111 and the second surface 112 can receive sunlight and convert light energy into electrical energy.

[0035] The first surface 111 includes a first region 111A and a second region 111B arranged along the first direction X. A P-type doping region 12 and an N-type doping region 13 arranged along the first direction X are arranged on the first surface 111. The P-type doping region 12 is arranged on the first region 111A. The P-type doping region 12 is doped with the above-mentioned P-type element (e.g., boron element). The P-type doping region 12 and the substrate 11 (i.e., N-type substrate) form a PN junction. The N-type doping region 13 is arranged on the second region 111B. The N-type doping region 13 is doped with the above-mentioned N-type element (e.g., phosphorus element). The concentration of the N-type element doped in the N-type doping region 13 may be greater than the concentration of the N-type element doped in the substrate 11 (i.e., N-type substrate).

[0036] Along the thickness direction Z of the substrate 11, the distance from the first region 111A to the second surface 112 can be greater than the distance from the second region 111B to the second surface 112, that is, the N-type doping region 13 can be closer to the second surface 112 than the P-type doping region 12, so that the N-type doping region 13 and the P-type doping region 12 are staggered in the thickness direction Z of the substrate 11, reducing the possibility of leakage current between the N-type doping region 13 and the P-type doping region 12, thereby improving the reliability of the busbar-free back contact solar cell 1, and improving the photoelectric conversion efficiency and output power of the busbar-free back contact solar cell 1.

[0037] Along the first direction X, an isolation groove 113 recessed from the first surface 111 to the second surface 112 may be provided between the adjacent first regions 111A and the second regions 111B. The isolation groove 113 is provided to separate the P-type doping region 12 from the N-type doping region 13, thereby reducing the possibility of leakage current between the N-type doping region 13 and the P-type doping region 12, thereby improving the reliability of the busbar-free back contact solar cell 1, and improving the photoelectric conversion efficiency and output power of the busbar-free back contact solar cell 1.

[0038] Continue as Figure 1 As shown, along the thickness direction Z of the substrate 11, a tunneling layer 14 is provided between the P-type doping region 12 and the substrate 11 and between the N-type doping region 13 and the substrate 11. The tunneling layer 14 may include at least one of silicon oxide, aluminum oxide, silicon nitride, silicon oxynitride, amorphous silicon and polycrystalline silicon. The lattice of the tunneling layer 14 may be well matched with the lattice of the substrate 11, that is, the tunneling layer 14 may well passivate the first surface 111 of the substrate 11 to reduce the rate of recombination of photogenerated electrons and photogenerated holes in the substrate 11 at the first surface 111 of the substrate 11. The tunneling layer 14 and the P-type doping region 12 may form a tunneling passivation contact structure, which may improve the efficiency of the P-type doping region 12 in collecting holes. The tunneling layer 14 and the N-type doping region 13 may form a tunneling passivation contact structure, which may improve the efficiency of the N-type doping region 13 in collecting electrons.

[0039] The P-type doping region 12 may include at least one of P-type doped amorphous silicon, P-type doped polycrystalline silicon, P-type doped microcrystalline silicon, and P-type doped silicon carbide.

[0040] The N-type doping region 13 may include at least one of N-type doped amorphous silicon, N-type doped polycrystalline silicon, N-type doped microcrystalline silicon, and N-type doped silicon carbide.

[0041] A first passivation layer 15 may be provided on the first surface 111, and the first passivation layer 15 may be located on the side of the P-type doping region 12 and the N-type doping region 13 away from the substrate 11. The first passivation layer 15 may include at least one of silicon oxide, silicon nitride, silicon oxynitride, titanium oxide, and aluminum oxide. A second passivation layer 16 may be provided on the second surface 112, and the first passivation layer 15 may include at least one of silicon oxide, silicon nitride, silicon oxynitride, titanium oxide, and aluminum oxide. Providing the first passivation layer 15 and the second passivation layer 16 can enhance the surface carrier concentration of the busbar-free back contact solar cell 1, improve the short-circuit current and open-circuit voltage of the busbar-free back contact solar cell 1, and thus improve the battery efficiency.

[0042] The busbar-free back-contact solar cell 1 has all the grid lines (i.e., metal electrodes) arranged on the back side of the substrate 11 (i.e., the first surface 111 mentioned above), and the front side of the substrate 11 (i.e., the second surface 112 mentioned above) is not blocked by the grid lines, thereby reducing the shading area of ​​the front side of the substrate 11 to eliminate the shading current loss of the grid lines and realize the maximum utilization of the incident photons, thereby improving the photoelectric conversion efficiency of the busbar-free back-contact solar cell 1.

[0043] Continue as Figure 1 As shown, the busbar-free back contact solar cell 1 is provided with a first fine grid 17 and a second fine grid 18. The first fine grid 17 is provided on the P-type doping region 12 and penetrates the first passivation layer 15. The first fine grid 17 can be regarded as the positive electrode of the busbar-free back contact solar cell 1. The second fine grid 18 is provided on the N-type doping region 13 and penetrates the first passivation layer 15. The second fine grid 18 can be regarded as the negative electrode of the busbar-free back contact solar cell 1.

[0044] like Figure 2 As shown, the first fine grids 17 and the second fine grids 18 are alternately arranged along the first direction X, the first welding strips 2 and the second welding strips 3 are alternately arranged along the second direction Y, the first direction X is orthogonal to the second direction Y, and the thickness direction Z of the substrate 11 (such as Figure 1 ) are orthogonal to the first direction X and the second direction Y respectively. The first fine grid 17 can be electrically connected to the first welding ribbon 2, and the second fine grid 18 can be electrically connected to the second welding ribbon 3, so that the first welding ribbon 2 and the second welding ribbon 3 can output the electric energy generated by the main grid-free back contact solar cell 1 to the outside, wherein the first welding ribbon 2 can be regarded as a welding ribbon with the same electrical properties as the first fine grid 17, and the second welding ribbon 3 can be regarded as a welding ribbon with the same electrical properties as the second fine grid 18. In the embodiment of the present application, the solar cell adopts the main grid-free (0BB, 0-Busbar) technology, and the welding ribbon is used to replace the original main grid line, that is, the welding ribbon can be directly connected to the fine grid. Since there is no need to set the main grid line, the consumption of metal slurry is reduced, thereby reducing the production cost of the main grid-free back contact solar cell 1.

[0045] like Figures 2 to 4 As shown, the first fine grid 17 has a first connection portion 171, and the first connection portion 171 is connected to the first welding strip 2. The second fine grid 18 has a second connection portion 181, and the second connection portion 181 is connected to the second welding strip 3, so that the first welding strip 2 and the second welding strip 3 can output the current on the first fine grid 17 and the second fine grid 18 to the outside respectively, wherein the first connection portion 171 can be directly welded to the first welding strip 2, and the second connection portion 181 can be directly welded to the second welding strip 3.

[0046] Since the electrical properties of the first welding ribbon 2 and the second welding ribbon 3 are opposite, in order to prevent the main grid-free back contact solar cell 1 from short-circuiting, the first welding ribbon 2 needs to be insulated from the second thin grid 18, and the second welding ribbon 3 needs to be insulated from the first thin grid 17. The first thin grid 17 has a first isolation portion 172, which is used to isolate the second welding ribbon 3 to avoid electrical connection between the first thin grid 17 and the second welding ribbon 3. The second thin grid 18 has a second isolation portion 182, which is used to isolate the first welding ribbon 2 so that the second thin grid 18 is electrically connected to the first welding ribbon 2.

[0047] The first isolation portion 172 and the first connection portion 171 are arranged along the second direction Y, the first isolation portion 172 and the first connection portion 171 are connected to each other, and the first isolation portion 172 and the first connection portion 171 are formed by printing a metal paste on the substrate 11. The second isolation portion 182 and the second connection portion 181 are arranged along the second direction Y, the second isolation portion 182 and the second connection portion 181 are connected to each other, and the second isolation portion 182 and the second connection portion 181 are formed by printing a metal paste on the substrate 11.

[0048] In some embodiments, the first fine gate 17 may have a relatively uniform thickness, that is, the thickness of the first connecting portion 171 may be substantially the same as the thickness of the first isolation portion 172, and the thickness of the first fine gate 17 is 3 μm to 20 μm, for example, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 12 μm, 14 μm, 15 μm, 16 μm, 18 μm or 20 μm.

[0049] The second fine gate 18 may also have a relatively uniform thickness, that is, the thickness of the second connecting portion 181 may be substantially the same as the thickness of the second isolating portion 182, and the thickness of the second fine gate 18 is 3 μm to 20 μm, for example, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 12 μm, 14 μm, 15 μm, 16 μm, 18 μm or 20 μm.

[0050] like Figure 5As shown, in the related art, each fine grid is insulated and isolated from the welding strip with opposite electrical properties by setting a corresponding insulating layer. For example, the first fine grid 17' is provided with an insulating layer 6' at a position corresponding to the second welding strip 3'. Along the thickness direction Z of the substrate 11', the insulating layer 6' is located between the first fine grid 17' and the second welding strip 3' to play the role of isolation and insulation. Since the insulating layer 6' has a certain thickness, the second welding strip 3' is raised, which increases the distance between the second welding strip 3' and the second fine grid 18', resulting in a certain interval between the second welding strip 3' and the second fine grid 18', so that it is impossible to directly connect with the second fine grid 18'. Therefore, it is necessary to set a connection layer 7' such as solder paste between the second welding strip 3' and the second fine grid 18' to meet the connection requirements of the second fine grid 18' and the second welding strip 3'. The connection layer 7' can be conductive, so as to realize the electrical connection between the second fine grid 18' and the second welding strip 3'. In the related art, due to the need to prepare the connection layer 7', the production process of the entire solar cell is relatively cumbersome, which increases the difficulty of producing solar cells. At the same time, there is easily an error between the thickness of the connecting layer 7' and the thickness of the insulating layer 6', making the thicknesses of the two inconsistent, resulting in a cold solder joint between the second soldering strip 3' and the second fine grid 18', thereby affecting the reliability of the entire solar cell and affecting the working performance of the solar cell.

[0051] Back to Figure 3 and Figure 4 In the embodiment of the present application, the first surface 111 of the substrate 11 includes a plane portion 1111 and a recessed portion 1112 recessed from the plane portion 1111 to the second surface 112, the first connecting portion 171 and the second connecting portion 181 are arranged on the plane portion 1111, and the first isolating portion 172 and the second isolating portion 182 are arranged on the recessed portion 1112. Since the recessed portion 1112 is recessed toward the second surface 112, the distance from the bottom surface of the recessed portion 1112 to the second surface 112 along the thickness direction Z of the substrate 11 is smaller than the distance from the plane portion 1111 to the second surface 112 along the thickness direction Z of the substrate 11. The above-mentioned first isolating portion 172 and the second isolating portion 182 can both be arranged on the recessed portion 1112, so that along the thickness direction Z of the substrate 11, the distance from the first isolating portion 172 and the second isolating portion 182 to the second surface is smaller than the distance from the first connecting portion 171 and the second connecting portion 181 to the second surface 112.

[0052] It should be noted that, in the process of producing the busbar-free back contact solar cell 1, the first surface 111 and the second surface 112 of the substrate 11 are usually textured (i.e., textured surface preparation treatment is performed) to reduce the reflection of sunlight by the first surface 111 and the second surface 112, and to increase the absorption rate of sunlight by the first surface 111 and the second surface 112, thereby improving the photoelectric conversion efficiency of the busbar-free back contact solar cell 1. Therefore, the surface of the above-mentioned plane portion 1111, as a part of the substrate 11, is not completely smooth, but has a certain degree of roughness and texture characteristics.

[0053] like Figure 3 As shown, after laying the first welding tape 2, the first connecting portion 171 of the first fine grid 17 is located on the plane portion 1111 and connected to the first welding tape 2, and the second isolating portion 182 of the second fine grid 18 is arranged on the recessed portion 1112, so that the second isolating portion 182 sinks toward the second surface 112 to avoid the first welding tape 2, thereby preventing the first isolating portion 172 from contacting the second welding tape 3 and causing a short circuit in the solar cell 1 without a main grid back contact, thereby improving the reliability of the solar cell 1 without a main grid back contact. There is a certain height difference between the second isolation portion 182 of the second fine grid 18 and the first connection portion 171 of the first fine grid 17 in the thickness direction Z of the substrate 11, thereby providing sufficient space for the arrangement of an insulating layer (not shown in the figure) on the second isolation portion 182 for isolating from the first welding strip 2, reducing the possibility that the height of the insulating layer exceeds the height of the first connection portion 171 and causes the first welding strip 2 to be elevated by the insulating layer, thereby eliminating the need to arrange a connection layer between the first fine grid 17 and the first welding strip 2, and the first fine grid 17 can be directly connected to the first welding strip 2. Compared with the above-mentioned related technologies, the embodiment of the present application reduces the possibility of a cold weld between the first fine grid 17 and the first welding strip 2, improves the reliability of the busbar-free back contact solar cell 1, simplifies the production process of the busbar-free back contact solar cell, and reduces the difficulty of producing the busbar-free back contact solar cell.

[0054] like Figure 4As shown, after laying the second welding ribbon 3, the second connecting portion 181 of the second fine grid 18 is located on the plane portion 1111 and connected to the second welding ribbon 3, and the first isolating portion 172 of the first fine grid 17 is arranged on the recessed portion 1112, so that the first isolating portion 172 sinks toward the second surface 112 to avoid the second welding ribbon 3, thereby preventing the first isolating portion 172 from contacting the second welding ribbon 3 and causing a short circuit in the solar cell 1 without a main grid back contact, thereby improving the reliability of the solar cell 1 without a main grid back contact. At the same time, there is a certain height difference between the first isolation portion 172 of the first fine grid 17 and the second connection portion 181 of the second fine grid 18 in the thickness direction Z of the substrate 11, thereby providing sufficient space for the setting of an insulating layer (not shown in the figure) on the first isolation portion 172 for isolating from the second welding strip 3, reducing the possibility that the height of the insulating layer exceeds the height of the second connection portion 181 and causes the second welding strip 3 to be elevated by the insulating layer. In the embodiment of the present application, there is no need to set a connecting layer between the second fine grid 18 and the second welding strip 3, and the second fine grid 18 can be directly connected to the second welding strip 3. Compared with the above-mentioned related technologies, the embodiment of the present application reduces the possibility of cold welding between the second fine grid 18 and the second welding strip 3, improves the reliability of the main grid back contact-free solar cell 1, simplifies the production process of the main grid back contact-free solar cell, and reduces the difficulty of producing the main grid back contact-free solar cell.

[0055] In summary, the busbar-free back-contact solar cell 1 provided in the embodiment of the present application is provided with a recessed portion 1112 on the substrate 11, so that the isolation portion of each fine grid can avoid the welding strip with opposite electrical properties, thereby reducing the possibility of short circuit in the busbar-free back-contact solar cell 1. The isolation portion of each fine grid is located in the recessed portion 1112, that is, the isolation portion sinks in the direction close to the second surface 112 of the substrate 11, thereby increasing the distance between the isolation portion and the welding strip in the thickness direction Z of the substrate 11, providing space for the arrangement of the insulating layer on each fine grid, so that the welding strip will not be raised by the insulating layer, and thus there is no need to arrange a connection layer such as solder paste in the space where the welding strip is raised to meet the connection requirements between the welding strip and the fine grid with the same electrical properties as the welding strip, so that the welding strip and the fine grid with the same electrical properties as the welding strip can be directly connected, thereby improving the stability and reliability of the connection between the two, reducing the possibility of cold soldering between the two, and further improving the reliability of the busbar-free back-contact solar cell 1.

[0056] like Figure 6 As shown, in a possible implementation, the planar portion 1111 includes a first planar structure 1111a, the recessed portion 1112 includes a first recessed structure 1112a, the first planar structure 1111a and the first recessed structure 1112a are located in the first area 111A, and the first planar structure 1111a and the first recessed structure 1112a are arranged along the second direction Y. Figure 7As shown, the first connection portion 171 is arranged on the first planar structure 1111a, and the first isolation portion 172 is arranged on the first recessed structure 1112a. By arranging the first planar structure 1111a and the first recessed structure 1112a in the first region 111A, a stable connection between the first fine grid 17 and the first welding strip 2 is achieved, and at the same time, the first fine grid 17 can avoid the second welding strip 3, thereby reducing the possibility of short circuit of the battery without main grid back contact caused by the contact between the first fine grid 17 and the second welding strip 3.

[0057] Back to Figure 6 The planar portion 1111 further includes a second planar structure 1111b, and the recessed portion 1112 further includes a second recessed structure 1112b. The second planar structure 1111b and the second recessed structure 1112b are located in the second region 111B, and the second planar structure 1111b and the second recessed structure 1112b are arranged along the second direction Y. Figure 8 As shown, the second connection portion 181 is arranged on the second planar structure 1111b, and the second isolation portion 182 is arranged on the second recessed structure 1112b. By arranging the second planar structure 1111b and the second recessed structure 1112b in the second region 111B, a stable connection between the second fine grid 18 and the second welding strip 3 is achieved, and at the same time, the second fine grid 18 can avoid the first welding strip 2, thereby reducing the possibility of the second fine grid 18 contacting the first welding strip 2 and causing a short circuit in the battery without main grid back contact.

[0058] like Figure 2 , Figure 7 and Figure 8 As shown, in a possible implementation manner, the number of the first welding strip 2 and the second welding strip 3 can be multiple, and the first welding strip 2 and the second welding strip 3 are arranged alternately along the second direction Y. The first fine grid 17 can have multiple first isolation parts 172 and multiple first connection parts 171, and along the second direction Y, the first connection parts 171 and the first isolation parts 172 are arranged alternately. The first planar structure 1111a and the first recessed structure 1112a are arranged alternately in the first area 111A, and the first connection part 171 is arranged on each first planar structure 1111a and connected to the corresponding first welding strip 2, and the first isolation part 172 is arranged on each first recessed structure 1112a and isolated from the corresponding second welding strip 3. The first planar structure 1111a is arranged corresponding to the first connecting portion 171, and the first recessed structure 1112a is arranged corresponding to the first isolating portion 172, so that the first fine grid 17 is stably connected to the first welding strip 2 at a position corresponding to the first welding strip 2, and is insulated and isolated from the second welding strip 3 at a position corresponding to the second welding strip 3, thereby reducing the possibility of short circuit in the main grid back contact-free solar cell 1 and improving the reliability of the main grid back contact-free solar cell 1.

[0059] The second fine grid 18 may have a plurality of second isolation portions 182 and a plurality of second connection portions 181. The second connection portions 181 and the second isolation portions 182 are arranged alternately along the second direction Y. The second planar structures 1111b and the second recessed structures 1112b are arranged alternately in the second region 111B. The second connection portions 181 are arranged on respective second planar structures 1111b and connected to the corresponding second welding strips 3. The second isolation portions 182 are arranged on respective second recessed structures 1112b and isolated from the corresponding first welding strips 2. The second planar structures 1111b and the second connection portions 181 are arranged correspondingly, and the second recessed structures 1112b and the second isolation portions 182 are arranged correspondingly, so that the second fine grid 18 is stably connected to the second welding strips 3 at the position corresponding to the second welding strips 3, and is insulated and isolated from the first welding strips 2 at the position corresponding to the first welding strips 2, thereby reducing the possibility of short circuit of the busbar-free back contact solar cell 1 and improving the reliability of the busbar-free back contact solar cell 1.

[0060] like Figure 6 As shown, in a possible implementation manner, the first recessed structures 1112a and the second planar structures 1111b are arranged alternately along the first direction X. Figure 2 , the second welding strip 3 extends along the first direction X. The arrangement direction of the first recessed structure 1112a and the second planar structure 1111b is the same as the extension direction of the second welding strip 3, so that the second welding strip 3 can be isolated from the first isolation portion 172 of the first fine grid 17 and connected to the second connection portion 181 of the second fine grid 18 at the same time.

[0061] Continue to refer to Figure 2 and Figure 6 , the second recessed structures 1112b and the first planar structures 1111a are alternately arranged along the first direction X, and the second welding strip 3 extends along the first direction X. The arrangement direction of the second recessed structures 1112b and the first planar structures 1111a is the same as the extension direction of the first welding strip 2, so that the first welding strip 2 can be isolated from the second isolation portion 182 of the second fine grid 18, and connected to the first connection portion 171 of the first fine grid 17 at the same time. The above design facilitates the first welding strip 2 and the second welding strip 3 to collect and output the current on the corresponding fine grid, so as to ensure the normal operation of the main grid-free back contact battery.

[0062] like Fig. 9 As shown, in a possible implementation manner, along the thickness direction Z of the substrate 11 , a first insulating layer 4 is provided on a side of the first isolation portion 172 away from the substrate 11 , and the first insulating layer 4 is used to isolate the first isolation portion 172 from the second welding strip 3 .

[0063] The first insulating layer 4 may be located outside the first recessed structure 1112a, or a part of the structure of the first insulating layer 4 may be contained in the first recessed structure 1112a. The material of the first insulating layer 4 may be epoxy resin or acrylic resin. The first insulating layer 4 is provided to reduce the possibility of the first fine grid 17 contacting the second welding strip 3 and causing a short circuit in the solar cell 1 without a main grid back contact. The first isolating portion 172 is located in the first recessed structure 1112a, which increases the spacing distance between the first isolating portion 172 and the second connecting portion 181 in the thickness direction Z of the substrate 11, that is, increases the spacing distance between the first isolating portion 172 and the second welding strip 3, thereby providing space for the arrangement of the first insulating layer 4, and reducing the possibility that the second welding strip 3 is elevated by the first insulating layer 4 and cannot be directly connected to the second connecting portion 181 of the second fine grid 18.

[0064] The depth of the first recessed structure 1112a is H1, and the height of the first isolation portion 172 is h1. When H1-h1>5μm, the depth of the first recessed structure 1112a is greater than the height of the first isolation portion 172, and the difference between the two is relatively large. This allows the first isolation portion 172 and the second soldering strip 3 to have a sufficient spacing in the thickness direction Z of the substrate 11, and the second soldering strip 3 is difficult to contact the first isolation portion 172. At this time, the isolation between the first isolation portion 172 and the second soldering strip 3 can be achieved without providing the first insulating layer 4, so that the first fine grid 17 and the second soldering strip 3 are kept insulated.

[0065] When H1-h1≤5μm, the depth of the first recessed structure 1112a is close to the height of the first isolation portion 172, the first isolation portion 172 and the second welding strip 3 are spaced relatively small in the thickness direction Z of the substrate 11, and the second welding strip 3 is easily in contact with the first isolation portion 172, increasing the risk of short circuit of the busbar-free back contact solar cell 1. At this time, a first insulating layer 4 may be provided on the first isolation portion 172 to isolate the first isolation portion 172 from the second welding strip 3, so that the first fine grid 17 and the second welding strip 3 are insulated, so as to improve the reliability of the busbar-free back contact solar cell 1.

[0066] In some embodiments, the thickness of the first insulating layer 4 is 10 μm to 30 μm, for example, 10 μm, 12 μm, 15 μm, 17 μm, 20 μm, 22 μm, 25 μm, 27 μm, 30 μm. If the thickness of the first insulating layer 4 is too small, it will be difficult for the first insulating layer 4 to play a reliable insulating role, increasing the risk of short circuit of the main grid-free back contact solar cell 1. If the thickness of the first insulating layer 4 is too large, the first insulating layer 4 will raise the second welding ribbon 3, resulting in a gap between the second welding ribbon 3 and the second fine grid 18 in the thickness direction Z of the substrate 11 and unable to be directly connected. Therefore, by setting the thickness of the first insulating layer 4 within the above range, the reliability of the first insulating layer 4 itself is improved, and the laying position of the second welding ribbon 3 will not be raised, so as to achieve a stable and reliable connection between the second welding ribbon 3 and the second fine grid 18.

[0067] like Fig.10 As shown, along the thickness direction Z of the substrate 11 , a second insulating layer 5 is provided on a side of the second isolating portion 182 away from the substrate 11 , and the second insulating layer 5 is used to isolate the second isolating portion 182 from the first welding strip 2 .

[0068] The second insulating layer 5 may be located outside the second recessed structure 1112b, or a part of the second insulating layer 5 may be contained in the second recessed structure 1112b. The material of the second insulating layer 5 may be epoxy resin or acrylic resin. The second insulating layer 5 is provided to reduce the possibility that the second fine grid 18 contacts the first welding strip 2 and causes a short circuit in the solar cell 1 without a main grid back contact. The second isolating portion 182 is located in the second recessed structure 1112b, which increases the spacing distance between the second isolating portion 182 and the first connecting portion 171 in the thickness direction Z, that is, increases the spacing distance between the second isolating portion 182 and the first welding strip 2, thereby providing space for the second insulating layer 5, and reducing the possibility that the first welding strip 2 is elevated by the first insulating layer 4 and cannot be directly connected to the first connecting portion 171 of the first fine grid 17.

[0069] The depth of the second recessed structure 1112b is H2, and the height of the first isolation portion 172 is h2. When H2-h2>5μm, the depth of the second recessed structure 1112b is greater than the height of the second isolation portion 182, and the difference between the two is large, so that the second isolation portion 182 and the first welding strip 2 have a sufficient spacing in the thickness direction Z of the substrate 11, and the first welding strip 2 is difficult to contact the second isolation portion 182. At this time, there is no need to set a second insulating layer 5 to achieve isolation between the second isolation portion 182 and the first welding strip 2, so that the second fine grid 18 and the first welding strip 2 remain insulated.

[0070] When H2-h2≤5μm, the depth of the second recessed structure 1112b is close to the height of the second isolation portion 182, the distance between the second isolation portion 182 and the first welding strip 2 in the thickness direction Z of the substrate 11 is small, and the first welding strip 2 is easy to contact the second isolation portion 182, which increases the risk of short circuit of the busbar-free back contact solar cell 1. At this time, a second insulating layer 5 can be provided on the second isolation portion 182 to isolate the second isolation portion 182 from the first welding strip 2, so that the second fine grid 18 is insulated from the first welding strip 2, so as to improve the reliability of the busbar-free back contact solar cell 1.

[0071] In some embodiments, the thickness of the second insulating layer 5 is 10μm to 30μm, for example, 10μm, 12μm, 15μm, 17μm, 20μm, 22μm, 25μm, 27μm, 30μm. Similar to the first insulating layer 4 introduced above, by setting the second insulating layer 5 within the above-mentioned range, the reliability of the second insulating layer 5 itself is improved, and the laying position of the first welding strip 2 will not be raised, so as to achieve a stable and reliable connection between the first welding strip 2 and the first fine grid 17.

[0072] like Fig. 9 As shown, in a possible embodiment, along the thickness direction Z of the substrate 11, the distance D1 from the first insulating layer 4 to the second surface 112 is smaller than the distance D2 from the second connecting portion 181 to the second surface 112, so that the first insulating layer 4 will not raise the second welding strip 3, that is, it is ensured that the second welding strip 3 can be in direct contact with the second connecting portion 181 to achieve electrical connection, thereby eliminating the need to provide the above-mentioned solder paste or other connecting layers between the second connecting portion 181 and the second welding strip 3, and reducing the possibility of cold solder joints between the second fine grid 18 and the second welding strip 3, thereby improving the reliability of the main grid back contact-free solar cell 1, simplifying the production process of the main grid back contact-free solar cell, and reducing the difficulty of producing the main grid back contact-free solar cell.

[0073] like Fig.10 As shown, the distance D3 from the second insulating layer 5 to the second surface 112 is smaller than the distance D4 from the first connecting portion 171 to the second surface 112, so that the second insulating layer 5 will not raise the first welding strip 2, thereby ensuring that the first welding strip 2 can be in direct contact with the first connecting portion 171 to achieve electrical connection. Similarly, this design improves the stability and reliability of the connection between the first welding strip 2 and the first fine grid 17, and reduces the possibility of cold soldering between the first fine grid 17 and the first welding strip 2.

[0074] like Fig. 9As shown, in a possible implementation, the first insulating layer 4 includes a first insulating portion 41 and a second insulating portion 42 connected to both sides of the first insulating portion 41 along the first direction X, the first insulating portion 41 is located on the side of the first isolation portion 172 away from the substrate 11 along the thickness direction Z of the substrate 11, and the second insulating portion 42 is accommodated in the first recessed structure 1112a and is respectively located on both sides of the first isolation portion 172 along the first direction X. The first insulating portion 41 and the second insulating portion 42 wrap the first isolation portion 172, increase the contact area between the first insulating layer 4 and the first isolation portion 172, thereby improving the reliability of the first insulating layer 4, reducing the possibility of the first isolation portion 172 contacting the second welding strip 3, and further reducing the risk of short circuit of the main grid back contact solar cell 1.

[0075] like Fig.10 As shown, the second insulating layer 5 includes a third insulating portion 51 and a fourth insulating portion 52 connected to both sides of the third insulating portion 51 along the first direction X, the third insulating portion 51 is located on the side of the second isolation portion 182 away from the substrate 11 along the thickness direction Z of the substrate 11, and the fourth insulating portion 52 is accommodated in the second recessed structure 1112b and is respectively located on both sides of the second isolation portion 182 along the first direction X. The third insulating portion 51 and the fourth insulating portion 52 wrap the second isolation portion 182, increase the contact area between the second insulating layer 5 and the second isolation portion 182, thereby improving the reliability of the second insulating layer 5, reducing the possibility of the second isolation portion 182 contacting the first welding strip 2, and further reducing the risk of short circuit of the busbar-free back contact solar cell 1.

[0076] In a possible implementation, along the thickness direction Z of the substrate 11, the depth H1 of the first recessed structure 1112a is greater than the depth H2 of the second recessed structure 1112b. As mentioned above, the distance from the first region 111A to the second surface 112 may be greater than the distance from the second region 111B to the second surface 112, that is, the second region 111B sinks toward the second surface 112 relative to the first region 111A, and therefore, the depth H2 of the second recessed structure 1112b on the second region 111B may be less than the depth H1 of the first recessed structure 1112a on the first region 111A, so as to avoid the second recessed structure 1112b affecting the stability of the overall structure of the substrate 11 due to excessive depression (that is, too close to the second surface 112), and at the same time facilitate the printing of the second fine grid 18 and help improve the stability of the second fine grid 18 itself.

[0077] In some embodiments, the depth of the first recessed structure 1112a is H1, and H1 satisfies 5μm≤H1≤25μm. For example, H1 can be 5μm, 8μm, 10μm, 12μm, 14μm, 16μm, 18μm, 20μm, 22μm, 24μm or 25μm. Of course, it can also be a value within the above range. If the depth of the first recessed structure 1112a is too small, when the first insulating layer 4 is set on the first isolation portion 172, the first insulating layer 4 is likely to lift the second welding ribbon 3 and suspend it, thereby affecting the reliability and stability of the connection between the second welding ribbon 3 and the second fine grid 18. If the depth of the first recessed structure 1112a is too large, it is not convenient to print the first fine grid 17. By limiting the depth H1 of the first recessed structure 1112a, the first isolation portion 172 sinks toward the second surface 112, thereby providing a certain space for the first insulating layer 4 to be set, preventing the first insulating layer 4 from lifting the second welding strip 3 and facilitating the printing of the first fine grid 17.

[0078] In some embodiments, the depth of the second recessed structure 1112b is H2, and H2 satisfies: 5μm≤H2≤25μm. For example, H2 can be 5μm, 7μm, 9μm, 10μm, 11μm, 13μm, 15μm, 17μm, 19μm, 20μm, 21μm, 23μm or 25μm. Of course, it can also be other values ​​within the above range. If the depth of the second recessed structure 1112b is too small, when the second insulating layer 5 is set on the second isolation portion 182, the second insulating layer 5 is likely to lift the first welding ribbon 2, thereby affecting the reliability and stability of the connection between the first welding ribbon 2 and the first fine grid 17. If the depth of the second recessed structure 1112b is too large, it is not convenient to print the second fine grid 18. By limiting the depth H2 of the second recessed structure 1112b, the second isolation portion 182 sinks toward the second surface 112, thereby providing a certain space for the second insulating layer 5 to be set, preventing the second insulating layer 5 from lifting the first welding strip 2 and facilitating the printing of the second fine grid 18.

[0079] In one possible embodiment, along the first direction X, the width of the recessed portion 1112 is W1, the width of the first isolation portion 172 and the width of the second isolation portion 182 are both W2, and W1 and W2 satisfy: 2≤W1 / W2≤5. For example, W1 / W2 can be 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8, 4, 4.2, 4.4, 4.6, 4.8 or 5, and of course it can also be other values ​​within the above range.

[0080] The width of the first recessed structure 1112a and the second recessed structure 1112b may both be W1. The width of the first recessed structure 1112a is greater than the width of the first isolation portion 172, so that a part of the structure of the first insulating layer 4 (for example, the second insulating portion 42) can be arranged in the first recessed structure 1112a to increase the contact area between the first insulating layer 4 and the first isolation portion 172, so that the first insulating layer 4 can wrap the first isolation portion 172. The width of the second recessed structure 1112b is greater than the second isolation portion 182, so that a part of the structure of the second insulating layer 5 (for example, the fourth insulating portion 52) can be arranged in the second recessed structure 1112b to increase the contact area between the second insulating layer 5 and the second isolation portion 182, so that the second insulating layer 5 can wrap the second isolation portion 182. The above design improves the reliability of the first insulating layer 4 and the second insulating layer 5, and reduces the risk of short circuit of the main grid-free back contact solar cell 1.

[0081] like Fig.11 and Fig.12 As shown, an embodiment of the present application further provides a photovoltaic component 100, comprising a busbar-free back-contact solar cell 1 and a welding strip, wherein the busbar-free back-contact solar cell 1 is the busbar-free back-contact solar cell 1 in any of the above items, and adjacent busbar-free back-contact solar cells 1 are electrically connected via the welding strip; wherein the welding strip comprises a first welding strip 2 and a second welding strip 3 arranged along a second direction Y, wherein the first welding strip 2 extends along a first direction X and is directly welded to a first connection portion 171 of a first fine grid 17 of the busbar-free back-contact solar cell 1, and the second welding strip 3 extends along the first direction X and is directly welded to a second connection portion 181 of a second fine grid 18 of the busbar-free back-contact solar cell 1.

[0082] The photovoltaic module 100 has at least one battery string 10, and the battery string 10 can be formed by a plurality of busbar-free back contact solar cells 1 connected in series, wherein the plurality of busbar-free back contact solar cells 1 can be arranged along a first direction X and connected in series through a first welding ribbon 2 and a second welding ribbon 3. For a certain busbar-free back contact solar cell 1 in the battery string 10, the first welding ribbon 2 is directly welded to its first fine grid 17, and the second welding ribbon 3 is directly welded to its second fine grid 18. The first welding ribbon 2 extends along the first direction X and can be connected to the second fine grid 18 of the adjacent busbar-free back contact solar cell 1. At the same time, the second welding ribbon 3 extends along the first direction X and can be connected to the first fine grid 17 of the adjacent busbar-free back contact solar cell 1, thereby realizing the series connection between two adjacent battery cells.

[0083] The photovoltaic module 100 may also include a cover plate 20, a first adhesive film layer 30, a second adhesive film layer 40 and a back plate 50. The cover plate 20, the first adhesive film layer 30, the battery string 10, the second adhesive film layer 40 and the back plate 50 are arranged along the thickness direction Z of the photovoltaic module 100 and laminated together. Among them, the cover plate 20 may be a glass cover plate 20, and the glass cover plate 20 has a high light transmittance. The first adhesive film layer 30 bonds the cover plate 20 to the battery string 10 to encapsulate and protect the non-busbar back contact solar cell 1 in the battery string 10. The material of the first adhesive film layer 30 may be one or more of ethylene-vinyl acetate copolymer (EVA), polyolefin elastomer (POE) and polyvinyl butyral (PVB). The second adhesive film layer 40 connects the battery string 10 to the back plate 50, which also encapsulates and protects the non-busbar back contact solar cell 1 of the battery string 10. The material of the second adhesive film layer 40 may be one or more of the above-mentioned EVA, POE, and PVB. The material of the back plate 50 may be glass, or the back plate 50 may also be formed by a composite of multiple polymer film layers.

[0084] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A busbar-free back contact solar cell, characterized in that: include: A substrate (11), the substrate (11) comprising a first surface (111) and a second surface (112) arranged opposite to each other along the thickness direction thereof, the first surface (111) being provided with a P-type doping region (12) and an N-type doping region (13) arranged along a first direction, a tunneling layer (14) being provided between the P-type doping region (12) and the substrate (11) and between the N-type doping region (13) and the substrate (11) along the thickness direction of the substrate (11), a first passivation layer (15) being provided on a side of the P-type doping region (12) and the N-type doping region (13) away from the substrate (11); and a second passivation layer (16) being provided on the second surface (112); a first fine gate (17), the first fine gate (17) being arranged on the P-type doping region (12) and penetrating the first passivation layer (15), the first fine gate (17) having a first connecting portion (171) arranged along the second direction and used for connecting to the first welding strip (2) and a first isolating portion (172) used for isolating from the second welding strip (3); a second fine gate (18), the second fine gate (18) being arranged on the N-type doping region (13) and penetrating the first passivation layer (15), the second fine gate (18) having a second connecting portion (181) arranged along a second direction and used for connecting to the second welding strip (3) and a second isolating portion (182) used for isolating from the first welding strip (2); The first surface (111) includes a planar portion (1111) and a recessed portion (1112) recessed from the planar portion (1111) toward the second surface (112); the first connecting portion (171) and the second connecting portion (181) are arranged on the planar portion (1111); the first isolating portion (172) and the second isolating portion (182) are arranged on the recessed portion (1112); and the first direction is orthogonal to the second direction.

2. The busbar-free back contact solar cell according to claim 1, characterized in that: The first surface (111) of the substrate (11) has a first region (111A) and a second region (111B) arranged along a first direction; along the thickness direction of the substrate (11), the distance from the first region (111A) to the second surface (112) is greater than the distance from the second region (111B) to the second surface (112); the P-type doping region (12) is arranged on the first region (111A); the N-type doping region (13) is arranged on the second region (111B); and an isolation groove (113) is arranged between adjacent first regions (111A) and second regions (111B) and is recessed from the first surface (111) to the second surface (112); The planar portion (1111) comprises a first planar structure (1111a), the recessed portion (1112) comprises a first recessed structure (1112a), the first planar structure (1111a) and the first recessed structure (1112a) are located in the first area (111A), the first planar structure (1111a) and the first recessed structure (1112a) are arranged along the second direction, the first connecting portion (171) is arranged on the first planar structure (1111a), the first isolating portion (172) is arranged on the first recessed structure (1112a), and; The planar portion (1111) further includes a second planar structure (1111b), and the recessed portion (1112) further includes a second recessed structure (1112b); the second planar structure (1111b) and the second recessed structure (1112b) are located in the second region (111B); the second planar structure (1111b) and the second recessed structure (1112b) are arranged along the second direction; the second connecting portion (181) is disposed on the second planar structure (1111b); and the second isolating portion (182) is disposed on the second recessed structure (1112b).

3. The busbar-free back contact solar cell according to claim 2, characterized in that: Along the second direction, the first connecting portions (171) and the first isolating portions (172) are arranged alternately, the first planar structures (1111a) and the first recessed structures (1112a) are arranged alternately in the first region (111A), the first connecting portions (171) are arranged on the respective first planar structures (1111a), the first isolating portions (172) are arranged on the respective first recessed structures (1112a), and; Along the second direction, the second connecting portions (181) and the second isolating portions (182) are arranged alternately, the second planar structures (1111b) and the second recessed structures (1112b) are arranged alternately in the second region (111B), the second connecting portions (181) are arranged on respective second planar structures (1111b), and the second isolating portions (182) are arranged on respective second recessed structures (1112b).

4. The busbar-free back contact solar cell according to claim 3, characterized in that: The first recessed structures (1112a) and the second planar structures (1111b) are arranged alternately along the first direction, and; The second recessed structures (1112b) and the first planar structures (1111a) are arranged alternately along the first direction.

5. The busbar-free back contact solar cell according to claim 4, characterized in that: A first insulating layer (4) is provided on a side of the first isolating portion (172) away from the substrate (11) along the thickness direction of the substrate (11), the first insulating layer (4) being used to isolate the first isolating portion (172) from the second welding strip (3), and; A second insulating layer (5) is provided on a side of the second isolating portion (182) away from the substrate (11), and the second insulating layer (5) is used to isolate the second isolating portion (182) from the first welding strip (2).

6. The busbar-free back contact solar cell according to claim 5, characterized in that: Along the thickness direction of the substrate (11), a distance D1 from the first insulating layer (4) to the second surface (112) is smaller than a distance D2 from the second connecting portion (181) to the second surface (112), and; A distance D3 from the second insulating layer (5) to the second surface (112) is smaller than a distance D4 from the first connecting portion (171) to the second surface (112).

7. The busbar-free back contact solar cell according to claim 5, characterized in that: The first insulating layer (4) comprises a first insulating portion (41) and second insulating portions (42) connected to the first insulating portion (41) on both sides along the first direction, the first insulating portion (41) being located on a side of the first isolating portion (172) away from the substrate (11) along the thickness direction of the substrate (11), the second insulating portion (42) being accommodated in the first recessed structure (1112a) and respectively located on both sides of the first isolating portion (172) along the first direction, and; The second insulating layer (5) comprises a third insulating portion (51) and a fourth insulating portion (52) connected to the third insulating portion (51) on both sides along the first direction, the third insulating portion (51) being located on a side of the second isolation portion (182) away from the substrate (11) along the thickness direction of the substrate (11), and the fourth insulating portion (52) being accommodated in the second recessed structure (1112b) and being respectively located on both sides of the second isolation portion (182) along the first direction.

8. The busbar-free back contact solar cell according to any one of claims 2 to 7, characterized in that: Along the thickness direction of the substrate (11), the depth H1 of the first recessed structure (1112a) is greater than the depth H2 of the second recessed structure (1112b), and / or; The first recessed structure (1112a) has a depth of H1, H1 satisfies 5 μm≤H1≤25 μm, and / or; The second recessed structure (1112b) has a depth of H2, and H2 satisfies: 5μm≤H2≤25μm.

9. The busbar-free back contact solar cell according to any one of claims 1 to 7, characterized in that: Along the first direction, the width of the recessed portion (1112) is W1, the width of the first isolation portion (172) and the width of the second isolation portion (182) are both W2, and W1 and W2 satisfy: 2≤W1 / W2≤5.

10. A photovoltaic module, characterized in that: include: A busbar-free back-contact solar cell (1), wherein the busbar-free back-contact solar cell (1) is the busbar-free back-contact solar cell (1) according to any one of claims 1 to 9, and adjacent busbar-free back-contact solar cells (1) are electrically connected via welding strips; The welding strip comprises a first welding strip (2) and a second welding strip (3) arranged along the second direction, the first welding strip (2) extending along the first direction and being directly welded to a first connection portion (171) of the first fine grid (17) of the solar cell (1) without a main grid back contact, and the second welding strip (3) extending along the first direction and being directly welded to a second connection portion (181) of the second fine grid (18) of the solar cell (1) without a main grid back contact.

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