A gridless back-contact solar cell and photovoltaic module

Abstract

This application relates to a gridless back-contact solar cell and photovoltaic module, including a substrate, a first fine grid, and a second fine grid. The substrate includes a first surface and a second surface. The first surface has P-type doped regions and N-type doped regions. The first fine grid is disposed on the P-type doped regions and has a first connecting portion for connecting with a first solder ribbon and a first isolating portion for isolating from a second solder ribbon. The second fine grid is disposed on the N-type doped regions and has a second connecting portion for connecting with a second solder ribbon and a second isolating portion for isolating from the first solder ribbon. The first surface includes a planar portion and a recessed portion extending from the planar portion into the second surface. The first and second connecting portions are disposed on the planar portion, and the first and second isolating portions are disposed on the recessed portion. This design provides space for the insulating layer, preventing the solder ribbon from being raised by the insulating layer, allowing the solder ribbon and the fine grid with the same electrical properties to be directly connected, reducing the possibility of poor soldering.

Description

Technical Field

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

[0002] Back-contact solar cells can convert sunlight into electrical energy. Currently, the fine grids on back-contact solar cells are prone to poor soldering when connected to solder strips with the same electrical properties, which affects the reliability of back-contact solar cells and their working performance. Summary of the Invention

[0003] In view of this, this application provides a gridless back-contact solar cell and photovoltaic module to solve the problem that the fine grid on the gridless back-contact solar cell in the prior art is prone to poor soldering when connected to the solder strip with the same electrical properties.

[0004] In a first aspect, embodiments of this application provide a gridless back-contact solar cell, comprising: a substrate, a first fine grid, and a second fine grid. The substrate includes a first surface and a second surface disposed opposite to each other along its own thickness direction. P-type doped regions and N-type doped regions arranged along a first direction are disposed on the first surface. A tunneling layer is disposed between the P-type doped region and the substrate, and between the N-type doped region and the substrate, along the thickness direction of the substrate. A first passivation layer is disposed on the side of the P-type doped region and the N-type doped region away from the substrate. A second passivation layer is disposed on the second surface. The first fine grid is disposed on the P-type doped region and penetrates the first passivation layer. The first fine gate has a first connecting portion for connecting with a first solder strip and a first isolation portion for isolating from a second solder strip, arranged along a second direction. The second fine gate is disposed on the N-type doped region and penetrates the first passivation layer. The second fine gate has a second connecting portion for connecting with a second solder strip and a second isolation portion for isolating from a first solder strip, arranged along a second direction. The first surface includes a planar portion and a recessed portion recessed from the planar portion to the second surface. The first connecting portion and the second connecting portion are disposed on the planar portion, and the first isolation portion and the second isolation portion are disposed on the recessed portion. The first direction is orthogonal to the second direction.

[0005] In one 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, the distance from the first region to the second surface is greater than the distance from the second region to the second surface. A P-type doped region is disposed on the first region, and an N-type doped region is disposed on the second region. An isolation groove recessed from the first surface to the second surface is disposed between adjacent first and second regions. The planar portion includes a first planar structure, and the recessed portion includes a first recessed structure. The first planar structure and the first recessed structure are located in the first region and are arranged along a second direction. A first connecting portion is disposed on the first planar structure, and a first isolation portion is disposed on the first recessed structure. The planar portion also includes a second planar structure, and the recessed portion also includes a second recessed structure. The second planar structure and the second recessed structure are located in the second region and are arranged along a second direction. A second connecting portion is disposed on the second planar structure, and a second isolation portion is disposed on the second recessed structure.

[0006] In one possible implementation, along the second direction, the first connecting portion and the first isolating portion are arranged alternately, the first planar structure and the first recessed structure are arranged alternately in the first region, the first connecting portion is disposed on its respective first planar structure, and the first isolating portion is disposed on its respective first recessed structure; and along the second direction, the second connecting portion and the second isolating portion are arranged alternately, the second planar structure and the second recessed structure are arranged alternately in the second region, the second connecting portion is disposed on its respective second planar structure, and the second isolating portion is disposed on its respective second recessed structure.

[0007] In one possible implementation, the first recessed structure and the second planar structure are arranged alternately along the first direction, and the second recessed structure and the first planar structure are arranged alternately along the first direction.

[0008] In one possible implementation, 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, the first insulating layer being used to isolate the first isolation portion and the second solder strip, and a second insulating layer is provided on the side of the second isolation portion away from the substrate, the second insulating layer being used to isolate the second isolation portion and the first solder strip.

[0009] In one possible implementation, along the thickness direction of the substrate, the distance D1 from the first insulating layer to the second surface is less than the distance D2 from the second connection to the second surface, and the distance D3 from the second insulating layer to the second surface is less than the distance D4 from the first connection to the second surface.

[0010] In one possible implementation, 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 the side of the first insulating portion away from the substrate along the thickness direction of the substrate. The second insulating portion is housed within the first recessed structure and is located on both sides of the first insulating portion along the first direction. The second insulating layer also 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 the side of the second insulating portion away from the substrate along the thickness direction of the substrate. The fourth insulating portion is housed within the second recessed structure and is located on both sides of the second insulating portion along the first direction.

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

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

[0013] Secondly, embodiments of this application provide a photovoltaic module, including a gridless back-contact solar cell. The gridless back-contact solar cell is any of the gridless back-contact solar cells described above. Adjacent gridless back-contact solar cells are electrically connected by solder strips. The solder strips include a first solder strip and a second solder strip arranged along a second direction. The first solder strip extends along the first direction and is directly welded to a first connecting portion of the first fine grid of the gridless back-contact solar cell. The second solder strip extends along the first direction and is directly welded to a second connecting portion of the second fine grid of the gridless back-contact solar cell.

[0014] This application provides a gridless back-contact solar cell and photovoltaic module, including: a substrate, a first fine grid, and a second fine grid. The substrate includes a first surface and a second surface disposed opposite to each other along its own thickness direction. P-type doped regions and N-type doped regions are disposed on the first surface along a first direction. A tunneling layer is disposed between the P-type doped region and the substrate, and between the N-type doped region and the substrate, along the thickness direction of the substrate. A first passivation layer is disposed on the side of the P-type and N-type doped regions away from the substrate. A second passivation layer is disposed on the second surface. The first fine grid is disposed on the P-type doped region and penetrates the first passivation layer. The first passivation layer has a first fine gate with a first connecting portion arranged along a second direction for connecting with a first solder strip and a first isolation portion for isolating from a second solder strip. The second fine gate is disposed on an N-type doped region and penetrates the first passivation layer. The second fine gate has a second connecting portion arranged along the second direction for connecting with a second solder strip and a second isolation portion for isolating from the first solder strip. The first surface includes a planar portion and a recessed portion recessed from the planar portion to the second surface. The first connecting portion and the second connecting portion are disposed on the planar portion, and the first isolation portion and the second isolation portion are disposed on the recessed portion. The first direction is orthogonal to the second direction. The isolation portions of each fine gate are recessed towards the second surface of the substrate, thereby increasing the distance between the isolation portion and the solder strip in the thickness direction of the substrate. This provides space for the insulating layer on each fine gate, preventing the solder strip from being raised by the insulating layer and allowing the solder strip and the fine gate with the same electrical properties as the solder strip to be directly connected. This improves the stability and reliability of the connection between the two, reduces the possibility of poor soldering, and thus improves the reliability of the gridless back contact solar cell.

[0015] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a partial cross-sectional view of a gridless back-contact solar cell provided in an embodiment of this application;

[0018] Figure 2 This is a schematic diagram of the arrangement of fine grids and solder ribbons on a gridless back-contact solar cell provided in an embodiment of this application;

[0019] Figure 3 For along Figure 2 A partial sectional view along the AA direction;

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

[0021] Figure 5 This is a partial schematic diagram of the connection between the fine grid and the solder strip on a gridless back contact solar cell in related technologies.

[0022] Figure 6 This is a partial schematic diagram showing 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 this application.

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

[0024] Figure 8 This is a partial schematic diagram of a solar cell without a main grid back contact according to another embodiment of this application;

[0025] Figure 9 This is a partial schematic diagram of a solar cell without a main grid back contact in another embodiment of this application;

[0026] Figure 10 This is a partial schematic diagram of a solar cell without a main grid back contact in another embodiment of this application;

[0027] Figure 11 This is a partial schematic diagram of a cell string in a photovoltaic module provided in an embodiment of this application;

[0028] Figure 12 This is a schematic diagram of a photovoltaic module provided in one embodiment of this application. Detailed Implementation

[0029] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0030] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0031] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0032] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0033] like Figure 1 As shown, this application provides a gridless back-contact solar cell 1. The gridless back-contact solar cell 1 includes a substrate 11, which 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, specifically 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, specifically a trivalent element such as boron, indium, or gallium. The structure of the gridless back-contact solar cell 1 will be described below using an N-type substrate as an example.

[0034] The substrate 11 includes a first surface 111 and a second surface 112 disposed opposite to each other along its own thickness direction Z. The first surface 111 can be the back side of the substrate 11, that is, the surface that is not directly exposed to sunlight. The second surface 112 can be the front side of the substrate 11, that is, the surface that can be directly exposed to 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 a first direction X. A P-type doped region 12 and an N-type doped region 13 are disposed on the first surface 111 along the first direction X. The P-type doped region 12 is disposed on the first region 111A and is doped with the aforementioned P-type element (e.g., boron). The P-type doped region 12 and the substrate 11 (i.e., the N-type substrate) form a PN junction. The N-type doped region 13 is disposed on the second region 111B and is doped with the aforementioned N-type element (e.g., phosphorus). The concentration of the N-type element in the N-type doped region 13 can be greater than the concentration of the N-type element in the substrate 11 (i.e., the 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. In other words, the N-type doped region 13 can be closer to the second surface 112 than the P-type doped region 12, so that the N-type doped region 13 and the P-type doped region 12 are misaligned in the thickness direction Z of the substrate 11. This reduces the possibility of leakage current between the N-type doped region 13 and the P-type doped region 12, thereby improving the reliability of the gridless back contact solar cell 1 and improving the photoelectric conversion efficiency and output power of the gridless 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 can be provided between adjacent first regions 111A and second regions 111B. The isolation groove 113 separates the P-type doped region 12 and the N-type doped region 13, reducing the possibility of leakage current between the N-type doped region 13 and the P-type doped region 12, thereby improving the reliability of the gridless back contact solar cell 1 and improving the photoelectric conversion efficiency and output power of the gridless back contact solar cell 1.

[0038] Continue as Figure 1 As shown, tunneling layers 14 are disposed between the P-type doped region 12 and the substrate 11, and between the N-type doped region 13 and the substrate 11, along the thickness direction Z of 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 can be well matched with the lattice of the substrate 11, that is, the tunneling layer 14 can effectively passivate the first surface 111 of the substrate 11, thereby reducing the recombination rate of photogenerated electrons and holes on the first surface 111 of the substrate 11. The tunneling layer 14 and the P-type doped region 12 can form a tunneling passivation contact structure, which can improve the hole collection efficiency of the P-type doped region 12. The tunneling layer 14 and the N-type doped region 13 can form a tunneling passivation contact structure, which can improve the electron collection efficiency of the N-type doped region 13.

[0039] The P-type doped 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 doped 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 disposed on the first surface 111. The first passivation layer 15 may be located on the side of the P-type doped region 12 and the N-type doped 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 disposed on the second surface 112. The first passivation layer 15 may include at least one of silicon oxide, silicon nitride, silicon oxynitride, titanium oxide, and aluminum oxide. The first passivation layer 15 and the second passivation layer 16 can enhance the carrier concentration on the surface of the gridless back contact solar cell 1, increase the short-circuit current and open-circuit voltage of the gridless back contact solar cell 1, thereby improving the cell efficiency.

[0042] The gridless back-contact solar cell 1 places all the grid lines (i.e., metal electrodes) 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 grid lines, which reduces the light-shielding area on the front side of the substrate 11, eliminates the light-shielding current loss of the grid lines, maximizes the utilization of incident photons, and thus improves the photoelectric conversion efficiency of the gridless back-contact solar cell 1.

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

[0044] like Figure 2 As shown, the first fine gate 17 and the second fine gate 18 are arranged alternately along the first direction X, and the first solder strip 2 and the second solder strip 3 are arranged alternately along the second direction Y. The first direction X and the second direction Y are orthogonal, and the thickness direction Z of the substrate 11 is (as shown in the figure). Figure 1 (As shown) 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 solder strip 2, and the second fine grid 18 can be electrically connected to the second solder strip 3, so that the first solder strip 2 and the second solder strip 3 can output the electrical energy generated by the gridless back contact solar cell 1. The first solder strip 2 can be regarded as a solder strip with the same electrical properties as the first fine grid 17, and the second solder strip 3 can be regarded as a solder strip with the same electrical properties as the second fine grid 18. In the embodiments of this application, the solar cell adopts gridless (OBB, O-Busbar) technology, using solder strips to replace the original main grid lines, that is, the solder strips can be directly connected to the fine grid. Since there is no need to set the main grid lines, the consumption of metal paste is reduced, thereby reducing the production cost of the gridless back contact solar cell 1.

[0045] like Figures 2 to 4 As shown, the first fine gate 17 has a first connecting portion 171, which is connected to the first solder strip 2. The second fine gate 18 has a second connecting portion 181, which is connected to the second solder strip 3, so that the first solder strip 2 and the second solder strip 3 can output the current on the first fine gate 17 and the second fine gate 18 to the outside, respectively. The first connecting portion 171 can be directly soldered to the first solder strip 2, and the second connecting portion 181 can be directly soldered to the second solder strip 3.

[0046] Since the first solder strip 2 and the second solder strip 3 have opposite electrical polarities, to prevent a short circuit in the gridless back-contact solar cell 1, the first solder strip 2 needs to be insulated from the second fine grid 18, and the second solder strip 3 needs to be insulated from the first fine grid 17. The first fine grid 17 has a first isolation portion 172, which is used to isolate it from the second solder strip 3 to prevent electrical connection between the first fine grid 17 and the second solder strip 3. The second fine grid 18 has a second isolation portion 182, which is used to isolate it from the first solder strip 2 so that the second fine grid 18 is electrically connected to the first solder strip 2.

[0047] The first isolation portion 172 and the first connecting portion 171 are arranged along the second direction Y, and are interconnected. Both the first isolation portion 172 and the first connecting portion 171 are formed by printing metal paste onto the substrate 11. The second isolation portion 182 and the second connecting portion 181 are arranged along the second direction Y, and are interconnected. Both the second isolation portion 182 and the second connecting portion 181 are formed by printing metal paste onto 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 and the thickness of the first isolation portion 172 may be approximately the same, and the thickness of the first fine gate 17 is 3μm to 20μm, for example, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 12μm, 14μm, 15μm, 16μm, 18μm or 20μm.

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

[0050] like Figure 5As shown, in related technologies, each grid is insulated from the solder strips with opposite electrical properties by setting a corresponding insulating layer. For example, an insulating layer 6' is provided at the position corresponding to the second solder strip 3' in the first grid 17', along the thickness direction Z of the substrate 11'. This insulating layer 6' is located between the first grid 17' and the second solder strip 3' and serves as an insulating layer. Because the insulating layer 6' has a certain thickness, the second solder strip 3' is raised, increasing the distance between the second solder strip 3' and the second grid 18', resulting in a certain gap between the second solder strip 3' and the second grid 18', making direct connection between them impossible. Therefore, a connecting layer 7', such as solder paste, is needed between the second solder strip 3' and the second grid 18' to meet the connection requirements of the second grid 18' and the second solder strip 3'. The connecting layer 7' is conductive, thereby achieving electrical connection between the second grid 18' and the second solder strip 3'. In related technologies, the need to prepare the connecting layer 7' makes the entire solar cell manufacturing process more complicated and increases the difficulty of solar cell production. Meanwhile, there is a tendency for errors to exist between the thickness of the connecting layer 7' and the thickness of the insulating layer 6', resulting in inconsistent thicknesses between the two. This can lead to incomplete soldering between the second solder strip 3' and the second fine grid 18', thereby affecting the overall reliability of the solar cell and its operating performance.

[0051] Return to Figure 3 and Figure 4 In this embodiment, the first surface 111 of the substrate 11 includes a planar portion 1111 and a recessed portion 1112 recessed from the planar portion 1111 toward the second surface 112. A first connecting portion 171 and a second connecting portion 181 are disposed on the planar portion 1111, and a first isolating portion 172 and a second isolating portion 182 are disposed on the recessed portion 1112. Because the recessed portion 1112 is recessed toward the second surface 112, the distance from the bottom surface of the recessed portion 1112 along the thickness direction Z of the substrate 11 to the second surface 112 is less than the distance from the planar portion 1111 along the thickness direction Z of the substrate 11 to the second surface 112. Since both the first isolating portion 172 and the second isolating portion 182 can be disposed on the recessed portion 1112, the distance from the first isolating portion 172 and the second isolating portion 182 to the second surface along the thickness direction Z of the substrate 11 is less 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 during the production of the gridless back-contact solar cell 1, texturing (i.e., texturing process) is typically performed on the first surface 111 and the second surface 112 of the substrate 11 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 gridless back-contact solar cell 1. Therefore, the aforementioned planar portion 1111, as part of the substrate 11, is not completely smooth on the surface, but has a certain degree of roughness and texture.

[0053] like Figure 3 As shown, after the first solder strip 2 is laid, the first connecting part 171 of the first fine grid 17 is located on the flat part 1111 and connected to the first solder strip 2. The second isolation part 182 of the second fine grid 18 is provided on the recessed part 1112, so that the second isolation part 182 sinks down towards the second surface 112 to avoid the first solder strip 2, thus preventing the first isolation part 172 from contacting the second solder strip 3 and causing a short circuit in the gridless back contact solar cell 1, thereby improving the reliability of the gridless back contact solar cell 1. There is a certain height difference between the second isolation portion 182 of the second fine grid 18 and the first connecting portion 171 of the first fine grid 17 in the thickness direction Z of the substrate 11. This provides sufficient space for the installation of an insulating layer (not shown in the figure) on the second isolation portion 182 for isolating from the first solder ribbon 2, reducing the possibility that the height of the insulating layer exceeds the height of the first connecting portion 171, causing the first solder ribbon 2 to be raised by the insulating layer. Therefore, there is no need to set a connecting layer between the first fine grid 17 and the first solder ribbon 2, and the first fine grid 17 can be directly connected to the first solder ribbon 2. Compared with the above-mentioned related technologies, the embodiments of this application reduce the possibility of poor soldering between the first fine grid 17 and the first solder ribbon 2, improve the reliability of the gridless back contact solar cell, simplify the production process of the gridless back contact solar cell, and reduce the production difficulty of the gridless back contact solar cell.

[0054] like Figure 4As shown, after the second solder strip 3 is laid, the second connecting portion 181 of the second grid 18 is located on the flat portion 1111 and connected to the second solder strip 3. The first isolation portion 172 of the first grid 17 is provided on the recessed portion 1112, so that the first isolation portion 172 sinks towards the second surface 112 to avoid the second solder strip 3, thus preventing the first isolation portion 172 from contacting the second solder strip 3 and causing a short circuit in the gridless back contact solar cell 1, thereby improving the reliability of the gridless back contact solar cell 1. Meanwhile, there is a certain height difference between the first isolation portion 172 of the first fine grid 17 and the second connecting portion 181 of the second fine grid 18 in the thickness direction Z of the substrate 11. This provides sufficient space for the setting of the insulating layer (not shown in the figure) on the first isolation portion 172 for isolating from the second solder ribbon 3, reducing the possibility that the height of the insulating layer exceeds the height of the second connecting portion 181, causing the second solder ribbon 3 to be raised by the insulating layer. In this embodiment, there is no need to set a connecting layer between the second fine grid 18 and the second solder ribbon 3. The second fine grid 18 can be directly connected to the second solder ribbon 3. Compared with the above-mentioned related technologies, this embodiment reduces the possibility of poor soldering between the second fine grid 18 and the second solder ribbon 3, improves the reliability of the gridless back contact solar cell, simplifies the production process of the gridless back contact solar cell, and reduces the production difficulty of the gridless back contact solar cell.

[0055] In summary, the gridless back-contact solar cell 1 provided in this application embodiment, by providing a recessed portion 1112 on the substrate 11, allows the isolation portion of each fine grid to avoid solder strips with opposite electrical properties, reducing the possibility of short circuits in the gridless back-contact solar cell 1. The isolation portion of each fine grid is located within the recessed portion 1112, that is, the isolation portion sinks towards the second surface 112 of the substrate 11, thereby increasing the distance between the isolation portion and the solder strip in the thickness direction Z of the substrate 11. This provides space for the installation of insulating layers on each fine grid, preventing the solder strip from being raised by the insulating layer. Therefore, it is unnecessary to install a connecting layer such as solder paste in the space where the solder strip is raised to meet the connection requirements between the solder strip and the fine grid with the same electrical property as the solder strip. This allows the solder strip and the fine grid with the same electrical property to be directly connected, thereby improving the stability and reliability of the connection, reducing the possibility of poor soldering, and ultimately improving the reliability of the gridless back-contact solar cell 1.

[0056] like Figure 6 As shown, in one possible implementation, the planar portion 1111 includes a first planar structure 1111a, and the recessed portion 1112 includes a first recessed structure 1112a. The first planar structure 1111a and the first recessed structure 1112a are located in a first region 111A, and the first planar structure 1111a and the first recessed structure 1112a are arranged along a second direction Y. Figure 7As shown, the first connecting portion 171 is disposed on the first planar structure 1111a, and the first isolation portion 172 is disposed on the first recessed structure 1112a. By providing 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 solder ribbon 2 is achieved. At the same time, the first fine grid 17 can avoid the second solder ribbon 3, reducing the possibility of short circuit in the non-grid back contact battery caused by contact between the first fine grid 17 and the second solder ribbon 3.

[0057] Return 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 connecting portion 181 is disposed on the second planar structure 1111b, and the second isolation portion 182 is disposed on the second recessed structure 1112b. By providing the second planar structure 1111b and the second recessed structure 1112b within the second region 111B, a stable connection between the second fine grid 18 and the second solder ribbon 3 is achieved. At the same time, the second fine grid 18 can avoid the first solder ribbon 2, reducing the possibility of a short circuit in the non-grid back contact battery caused by contact between the second fine grid 18 and the first solder ribbon 2.

[0058] like Figure 2 , Figure 7 and Figure 8 As shown, in one possible implementation, there can be multiple first solder strips 2 and second solder strips 3, which are arranged alternately along the second direction Y. The first fine grid 17 may have multiple first isolation portions 172 and multiple first connecting portions 171, which are arranged alternately along the second direction Y. The first planar structure 1111a and the first recessed structure 1112a are arranged alternately in the first region 111A. The first connecting portions 171 are disposed on their respective first planar structures 1111a and connected to the corresponding first solder strip 2. The first isolation portions 172 are disposed on their respective first recessed structures 1112a and isolated from the corresponding second solder strip 3. The first planar structure 1111a is correspondingly provided with the first connecting portion 171, and the first recessed structure 1112a is correspondingly provided with the first isolation portion 172, so that the first fine grid 17 is stably connected to the first solder strip 2 at the position corresponding to the first solder strip 2, and is insulated and isolated from the second solder strip 3 at the position corresponding to the second solder strip 3, thereby reducing the possibility of short circuit in the gridless back contact solar cell 1 and improving the reliability of the gridless back contact solar cell 1.

[0059] The second fine grid 18 may have multiple second isolation portions 182 and multiple second connecting portions 181. Along the second direction Y, the second connecting portions 181 and the second isolation portions 182 are arranged alternately. The second planar structure 1111b and the second recessed structure 1112b are arranged alternately in the second region 111B. The second connecting portions 181 are disposed on their respective second planar structures 1111b and connected to the corresponding second solder strip 3. The second isolation portions 182 are disposed on their respective second recessed structures 1112b and isolated from the corresponding first solder strip 2. The second planar structure 1111b and the second connecting portions 181 are correspondingly disposed, and the second recessed structure 1112b and the second isolation portions 182 are correspondingly disposed, so that the second fine grid 18 is stably connected to the second solder strip 3 at the position corresponding to the second solder strip 3, and is insulated from the first solder strip 2 at the position corresponding to the first solder strip 2. This reduces the possibility of short circuit in the gridless back contact solar cell 1 and improves the reliability of the gridless back contact solar cell 1.

[0060] like Figure 6 As shown, in one possible implementation, the first recessed structure 1112a and the second planar structure 1111b are arranged alternately along the first direction X, while referring to... Figure 2 The second solder 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 solder strip 3, so that the second solder strip 3 can be isolated from the first isolation portion 172 of the first fine gate 17, and simultaneously connected to the second connecting portion 181 of the second fine gate 18.

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

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

[0063] The first insulating layer 4 can be located outside the first recessed structure 1112a, or a portion of the first insulating layer 4 can be housed within the first recessed structure 1112a. The material of the first insulating layer 4 can be epoxy resin or acrylic resin. The first insulating layer 4 reduces the possibility of a short circuit in the gridless back-contact solar cell 1 caused by contact between the first grid 17 and the second solder ribbon 3. The first isolation portion 172 is located within the first recessed structure 1112a, increasing the distance between the first isolation portion 172 and the second connecting portion 181 in the thickness direction Z of the substrate 11. This increases the distance between the first isolation portion 172 and the second solder ribbon 3, thereby providing space for the first insulating layer 4 and reducing the possibility that the second solder ribbon 3 is elevated by the first insulating layer 4 and cannot be directly connected to the second connecting portion 181 of the second 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 ensures that the first isolation portion 172 and the second solder strip 3 have sufficient spacing in the thickness direction Z of the substrate 11, making it difficult for the second solder strip 3 to contact the first isolation portion 172. In this case, isolation between the first isolation portion 172 and the second solder strip 3 can be achieved without setting the first insulating layer 4, thereby keeping the first fine grid 17 and the second solder strip 3 insulated.

[0065] When H1-h1≤5μm, the depth of the first recessed structure 1112a is similar to the height of the first isolation portion 172. The distance between the first isolation portion 172 and the second solder strip 3 in the thickness direction Z of the substrate 11 is small, making it easy for the second solder strip 3 to come into contact with the first isolation portion 172, increasing the risk of short circuit in the gridless back contact solar cell 1. In this case, a first insulating layer 4 can be provided on the first isolation portion 172 to isolate the first isolation portion 172 from the second solder strip 3, keeping the first fine grid 17 insulated from the second solder strip 3, thereby improving the reliability of the gridless 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, or 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 provide reliable insulation, increasing the risk of short circuits in the gridless back contact solar cell 1. If the thickness of the first insulating layer 4 is too large, it will cause the first insulating layer 4 to raise the second solder ribbon 3, resulting in a gap between the second solder ribbon 3 and the second fine grid 18 in the thickness direction Z of the substrate 11, preventing direct connection. Therefore, by setting the thickness of the first insulating layer 4 within the above-mentioned range, the reliability of the first insulating layer 4 itself is improved, and the laying position of the second solder ribbon 3 is not raised, thereby achieving a stable and reliable connection between the second solder ribbon 3 and the second fine grid 18.

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

[0068] The second insulating layer 5 can be located outside the second recessed structure 1112b, or a portion of the second insulating layer 5 can be housed within the second recessed structure 1112b. The material of the second insulating layer 5 can be epoxy resin or acrylic resin. The provision of the second insulating layer 5 reduces the possibility of a short circuit in the gridless back-contact solar cell 1 caused by contact between the second grid 18 and the first solder ribbon 2. The second isolation portion 182 is located within the second recessed structure 1112b, increasing the distance between the second isolation portion 182 and the first connecting portion 171 in the thickness direction Z, i.e., increasing the distance between the second isolation portion 182 and the first solder ribbon 2. This provides space for the provision of the second insulating layer 5 and reduces the possibility that the first solder ribbon 2 is elevated by the first insulating layer 4 and cannot be directly connected to the first connecting portion 171 of the first 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. This makes it possible for the second isolation portion 182 and the first solder strip 2 to have sufficient spacing in the thickness direction Z of the substrate 11. The first solder strip 2 is difficult to contact the second isolation portion 182. At this time, it is not necessary to set the second insulating layer 5 to achieve isolation between the second isolation portion 182 and the first solder strip 2, thereby keeping the second fine grid 18 and the first solder strip 2 insulated.

[0070] When H2-h2≤5μm, the depth of the second recessed structure 1112b is similar to the height of the second isolation portion 182. The distance between the second isolation portion 182 and the first solder strip 2 in the thickness direction Z of the substrate 11 is small, making it easy for the first solder strip 2 to come into contact with the second isolation portion 182, increasing the risk of short circuit in the gridless back contact solar cell 1. In this case, a second insulating layer 5 can be provided on the second isolation portion 182 to isolate the second isolation portion 182 from the first solder strip 2, keeping the second fine grid 18 insulated from the first solder strip 2, thereby improving the reliability of the gridless 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, or 30μm. Similar to the first insulating layer 4 described above, by setting the second insulating layer 5 within the above range, the reliability of the second insulating layer 5 itself is improved, and the laying position of the first solder ribbon 2 is not raised, so as to achieve a stable and reliable connection between the first solder ribbon 2 and the first fine grid 17.

[0072] like Figure 9 As shown, in one possible implementation, along the thickness direction Z of the substrate 11, the distance D1 from the first insulating layer 4 to the second surface 112 is less than the distance D2 from the second connecting portion 181 to the second surface 112. This ensures that the first insulating layer 4 does not elevate the second solder ribbon 3, thus guaranteeing that the second solder ribbon 3 can directly contact the second connecting portion 181 to achieve electrical connection. Therefore, it is not necessary to set the aforementioned solder paste or other connecting layer between the second connecting portion 181 and the second solder ribbon 3, and the possibility of poor soldering between the second fine grid 18 and the second solder ribbon 3 is reduced. This improves the reliability of the gridless back contact solar cell, simplifies the production process of the gridless back contact solar cell, and reduces the production difficulty of the gridless back contact solar cell.

[0073] like Figure 10 As shown, the distance D3 between the second insulating layer 5 and the second surface 112 is less than the distance D4 between the first connecting part 171 and the second surface 112, so that the second insulating layer 5 will not raise the first solder strip 2, ensuring that the first solder strip 2 can directly contact the first connecting part 171 to achieve electrical connection. Similarly, this design improves the stability and reliability of the connection between the first solder strip 2 and the first fine gate 17, and reduces the possibility of poor soldering between the first fine gate 17 and the first solder strip 2.

[0074] like Figure 9As shown, in one possible embodiment, 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 insulating portion 172 away from the substrate 11 along the thickness direction Z of the substrate 11. The second insulating portion 42 is housed within the first recessed structure 1112a and is located on both sides of the first insulating portion 172 along the first direction X. The first insulating portion 41 and the second insulating portion 42 wrap around the first insulating portion 172, increasing the contact area between the first insulating layer 4 and the first insulating portion 172, thereby improving the reliability of the first insulating layer 4, reducing the possibility of the first insulating portion 172 contacting the second solder strip 3, and further reducing the risk of short circuit in the gridless back contact solar cell 1.

[0075] like Figure 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 insulating portion 182 away from the substrate 11 along the thickness direction Z of the substrate 11. The fourth insulating portion 52 is housed within the second recessed structure 1112b and is located on both sides of the second insulating portion 182 along the first direction X. The third insulating portion 51 and the fourth insulating portion 52 wrap around the second insulating portion 182, increasing the contact area between the second insulating layer 5 and the second insulating portion 182, thereby improving the reliability of the second insulating layer 5, reducing the possibility of the second insulating portion 182 contacting the first solder strip 2, and further reducing the risk of short circuit in the gridless back contact solar cell 1.

[0076] In one 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 can be greater than the distance from the second region 111B to the second surface 112, that is, the second region 111B sinks towards the second surface 112 relative to the first region 111A. Therefore, the depth H2 of the second recessed structure 1112b on the second region 111B can be less than the depth H1 of the first recessed structure 1112a on the first region 111A, avoiding the second recessed structure 1112b from affecting the stability of the overall structure of the substrate 11 due to excessive recess (i.e., too close to the second surface 112). At the same time, it facilitates the printing of the second fine gate 18 and helps to improve the stability of the structure of the second fine gate 18 itself.

[0077] In some embodiments, the depth of the first recessed structure 1112a is H1, where H1 satisfies 5μm≤H1≤25μm. For example, H1 can be 5μm, 8μm, 10μm, 12μm, 14μm, 16μm, 18μm, 20μm, 22μm, 24μm, or 25μm, or any value within the above range. If the depth of the first recessed structure 1112a is too small, when the first insulating layer 4 is provided on the first isolation portion 172, the first insulating layer 4 will easily lift the second solder ribbon 3, thereby affecting the reliability and stability of the connection between the second solder ribbon 3 and the second fine gate 18. If the depth of the first recessed structure 1112a is too large, it will be inconvenient to print the first fine gate 17. By limiting the depth H1 of the first recessed structure 1112a, the first isolation portion 172 is sunk towards the second surface 112, thereby providing a certain space for the first insulating layer 4 to be installed, preventing the first insulating layer 4 from raising the second solder strip 3, and at the same time facilitating the printing of the first fine grid 17.

[0078] In some embodiments, the depth of the second recessed structure 1112b is H2, where H2 satisfies: 5μm≤H2≤25μm. For example, H2 can be 5μm, 7μm, 9μm, 10μm, 11μm, 13μm, 15μm, 17μm, 19μm, 20μm, 21μm, 23μm, or 25μm, or 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 provided on the second isolation portion 182, the second insulating layer 5 will easily lift the first solder ribbon 2, thereby affecting the reliability and stability of the connection between the first solder ribbon 2 and the first fine gate 17. If the depth of the second recessed structure 1112b is too large, it will be inconvenient to print the second fine gate 18. By limiting the depth H2 of the second recessed structure 1112b, the second isolation portion 182 is sunk towards the second surface 112, thereby providing a certain space for the second insulating layer 5, preventing the second insulating layer 5 from raising the first solder strip 2, and at the same time facilitating the printing of the second fine grid 18.

[0079] In one possible implementation, along the first direction X, the width of the recess 1112 is W1, and the widths of the first isolation portion 172 and the second isolation portion 182 are both W2. 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, or other values ​​within the above range.

[0080] The widths of the first recessed structure 1112a and the second recessed structure 1112b can both be W1. The width of the first recessed structure 1112a is greater than the width of the first insulating portion 172, allowing a portion of the structure of the first insulating layer 4 (e.g., the second insulating portion 42) to be disposed within the first recessed structure 1112a, thereby increasing the contact area between the first insulating layer 4 and the first insulating portion 172, enabling the first insulating layer 4 to enclose the first insulating portion 172. The width of the second recessed structure 1112b is greater than the width of the second insulating portion 182, allowing a portion of the structure of the second insulating layer 5 (e.g., the fourth insulating portion 52) to be disposed within the second recessed structure 1112b, thereby increasing the contact area between the second insulating layer 5 and the second insulating portion 182, enabling the second insulating layer 5 to enclose the second insulating portion 182. This design improves the reliability of the first insulating layer 4 and the second insulating layer 5, reducing the risk of short circuits in the gridless back-contact solar cell 1.

[0081] like Figure 11 and Figure 12 As shown, this application embodiment also provides a photovoltaic module 100, including a gridless back-contact solar cell 1 and solder strips. The gridless back-contact solar cell 1 is any of the gridless back-contact solar cells 1 mentioned above. Adjacent gridless back-contact solar cells 1 are electrically connected by solder strips. The solder strips include a first solder strip 2 and a second solder strip 3 arranged along the second direction Y. The first solder strip 2 extends along the first direction X and is directly welded to the first connecting portion 171 of the first fine grid 17 of the gridless back-contact solar cell 1. The second solder strip 3 extends along the first direction X and is directly welded to the second connecting portion 181 of the second fine grid 18 of the gridless back-contact solar cell 1.

[0082] The photovoltaic module 100 has at least one cell string 10, which can be composed of multiple gridless back-contact solar cells 1 connected in series. The multiple gridless back-contact solar cells 1 can be arranged along a first direction X and connected in series via a first solder ribbon 2 and a second solder ribbon 3. For a specific gridless back-contact solar cell 1 in the cell string 10, the first solder ribbon 2 is directly soldered to its first fine grid 17, and the second solder ribbon 3 is directly soldered to its second fine grid 18. The first solder ribbon 2 extends along the first direction X and can connect to the second fine grid 18 of an adjacent gridless back-contact solar cell 1. Simultaneously, the second solder ribbon 3 extends along the first direction X and can connect to the first fine grid 17 of an adjacent gridless back-contact solar cell 1, thereby achieving series connection between two adjacent cells.

[0083] The photovoltaic module 100 may further include a cover plate 20, a first encapsulating film layer 30, a second encapsulating film layer 40, and a backsheet 50. The cover plate 20, the first encapsulating film layer 30, the cell string 10, the second encapsulating film layer 40, and the backsheet 50 are arranged along the thickness direction Z of the photovoltaic module 100 and laminated together. The cover plate 20 may be a glass cover plate 20 with high light transmittance. The first encapsulating film layer 30 bonds the cover plate 20 to the cell string 10, providing encapsulation and protection for the gridless back-contact solar cells 1 in the cell string 10. The material of the first encapsulating film layer 30 may be one or more of ethylene-vinyl acetate copolymer (EVA), polyolefin elastomer (POE), and polyvinyl butyral (PVB). The second encapsulating film layer 40 connects the cell string 10 to the backsheet 50, also providing encapsulation and protection for the gridless back-contact solar cells 1 in the cell string 10. The material of the second encapsulating film layer 40 may be one or more of EVA, POE, and PVB. The material of the backplate 50 can be glass, or the backplate 50 can be composed of multiple polymer film layers.

[0084] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A gridless back-contact solar cell, characterized in that, include: A substrate (11) includes a first surface (111) and a second surface (112) disposed opposite to each other along its own thickness direction. A P-type doped region (12) and an N-type doped region (13) arranged along a first direction are disposed on the first surface (111). A tunneling layer (14) is disposed between the P-type doped region (12) and the substrate (11) and between the N-type doped region (13) and the substrate (11) along the thickness direction of the substrate (11). A first passivation layer (15) is disposed on the side of the P-type doped region (12) and the N-type doped region (13) away from the substrate (11). A second passivation layer (16) is disposed on the second surface (112). The first fine gate (17) is disposed on the P-type doped region (12) and penetrates the first passivation layer (15). The first fine gate (17) has a first connection portion (171) arranged along the second direction for connecting with the first solder strip (2) and a first isolation portion (172) for isolating from the second solder strip (3). The second fine gate (18) is disposed on the N-type doped region (13) and penetrates the first passivation layer (15). The second fine gate (18) has a second connection portion (181) arranged along the second direction for connecting with the second solder strip (3) and a second isolation portion (182) for isolating from the first solder 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 disposed on the planar portion (1111), and the first isolation portion (172) and the second isolation portion (182) are disposed on the recessed portion (1112). The first direction is orthogonal to the second direction.

2. The gridless 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 doped region (12) is disposed on the first region (111A), and the N-type doped region (13) is disposed on the second region (111B). An isolation groove (113) recessed from the first surface (111) to the second surface (112) is disposed between adjacent first regions (111A) and second regions (111B). 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 region (111A), the first planar structure (1111a) and the first recessed structure (1112a) are arranged along the second direction, the first connecting portion (171) is disposed on the first planar structure (1111a), the first isolation portion (172) is disposed 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 isolation portion (182) is disposed on the second recessed structure (1112b).

3. The gridless back-contact solar cell according to claim 2, characterized in that, Along the second direction, the first connecting portion (171) and the first isolation portion (172) are arranged alternately, the first planar structure (1111a) and the first recessed structure (1112a) are arranged alternately in the first region (111A), the first connecting portion (171) is disposed on the respective first planar structure (1111a), the first isolation portion (172) is disposed on the respective first recessed structure (1112a), and; Along the second direction, the second connecting portion (181) and the second isolating portion (182) are arranged alternately, and the second planar structure (1111b) and the second recessed structure (1112b) are arranged alternately in the second region (111B). The second connecting portion (181) is disposed on its respective second planar structure (1111b), and the second isolating portion (182) is disposed on its respective second recessed structure (1112b).

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

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

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

7. The gridless back-contact solar cell according to claim 5, characterized in that, 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. The first insulating portion (41) is located on the side of the first insulating portion (172) away from the substrate (11) along the thickness direction of the substrate (11). The second insulating portion (42) is housed in the first recessed structure (1112a) and is located on both sides of the first insulating portion (172) along the first direction. 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. The third insulating portion (51) is located on the side of the second insulating portion (182) away from the substrate (11) along the thickness direction of the substrate (11). The fourth insulating portion (52) is housed in the second recessed structure (1112b) and is located on both sides of the second insulating portion (182) along the first direction.

8. The gridless 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 depth of the first recessed structure (1112a) is H1, where H1 satisfies 5μm≤H1≤25μm, and / or; The second recessed structure (1112b) has a depth of H2, which satisfies: 5μm≤H2≤25μm.

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

10. A photovoltaic module, characterized in that, include: A gridless back-contact solar cell (1), wherein the gridless back-contact solar cell (1) is any one of claims 1 to 9, and adjacent gridless back-contact solar cells (1) are electrically connected by solder strips. The solder strips include a first solder strip (2) and a second solder strip (3) arranged along the second direction. The first solder strip (2) extends along the first direction and is directly welded to the first connection portion (171) of the first fine grid (17) of the gridless back contact solar cell (1). The second solder strip (3) extends along the first direction and is directly welded to the second connection portion (181) of the second fine grid (18) of the gridless back contact solar cell (1).

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