Solar cell, cell assembly and photovoltaic system

Abstract

The utility model is suitable for the technical field of solar cells, and provides a solar cell piece, a cell assembly and a photovoltaic system, a first caulking groove is formed in a first polarity doping layer, a second polarity doping layer is arranged in the first caulking groove, a first passivation film layer covers the second polarity doping layer, and a second passivation film layer covers the second polarity doping layer. The roughness of the surface, making contact with the first passive film layer, of the second polarity doping layer is larger than that of the surface, making contact with the first passive film layer, of the first polarity doping layer, and in the thickness direction of the solar cell piece, the first welding point and the second polarity doping layer are at least partially overlapped. Therefore, the bonding tension between the first passive film layer and the second polarity doping layer is greater than the bonding tension between the first passive film layer and the first polarity doping layer, so that the welding tension of the first welding spot during welding can be effectively improved by arranging the first welding spot above the second polarity doping layer; therefore, the first welding spot is effectively prevented from being separated during welding, and the welding reliability is improved.

Description

Technical Field

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

[0002] At present, in solar cells (such as Topcon solar cells, HJT solar cells, back contact solar cells, etc.), a doping layer is provided, and a fine grid and a main grid are also provided on the doping layer. The fine grid penetrates the passivation film layer and contacts the doping layer to collect current, and the main grid is connected to the fine grid to collect the current of the fine grid. When connecting two solar cells, it is necessary to set a solder joint on the cell to weld with the solder strip, and the solder joint is usually set on the passivation film layer. However, in the related art, the tension between the doping layer and the passivation film layer under the solder joint is weak, and the solder joint is prone to detachment due to insufficient solder joint tension during welding. Utility Model Content

[0003] The present application provides a solar cell, a battery assembly and a photovoltaic system, aiming to solve the technical problem in the prior art that the solder joints of the solar cell are prone to insufficient solder joint tension during welding, resulting in solder joint detachment.

[0004] The present application is implemented in this way. The solar cell of the embodiment of the present application includes:

[0005] A silicon wafer having a first surface and a second surface opposite to each other;

[0006] A first polarity doping layer stacked on the first surface, wherein a plurality of first embedded grooves are formed on the first polarity doping layer;

[0007] a second polarity doping layer disposed in the first embedded groove, wherein the polarity of the second polarity doping layer is opposite to the polarity of the first polarity doping layer;

[0008] a first passivation film layer stacked on the first polarity doped layer and the second polarity doped layer, the roughness of a surface of the second polarity doped layer in contact with the first passivation film layer being greater than the roughness of a surface of the first polarity doped layer in contact with the first passivation film layer; and

[0009] A plurality of first welding points, wherein the first welding points are arranged on the first passivation film layer, and in the thickness direction of the solar cell sheet, the first welding points at least partially overlap with the second polarity doping layer.

[0010] Furthermore, a first isolation layer is disposed on an inner wall of the first embedding groove, and the first isolation layer is disposed between the first polarity doping layer and the second polarity doping layer to separate the first polarity doping layer from the second polarity doping layer.

[0011] Furthermore, the thickness of the first isolation layer is greater than 2 nm.

[0012] Furthermore, the first isolation layer includes at least one of a silicon oxide film layer, a silicon nitride film layer, an aluminum oxide film layer, a silicon oxynitride film layer, a silicon carbide film layer and an intrinsic amorphous silicon film layer.

[0013] Furthermore, the orthographic projection of the first welding point on the first polarity doping layer is completely located in the first embedding groove.

[0014] Furthermore, the depth of the first embedded groove is 5nm-400nm.

[0015] Furthermore, the first passivation film layer includes at least one of a silicon nitride film layer, an aluminum oxide film layer, a silicon oxynitride film layer, an intrinsic amorphous silicon film layer, and a TCO film layer.

[0016] Furthermore, the solar cell further comprises a third polarity doping layer, a second passivation film layer and a plurality of second solder joints, wherein the polarity of the third polarity doping layer is opposite to the polarity of the first polarity doping layer;

[0017] Wherein, the first polarity doped layer is stacked on the first surface, the third polarity doped layer is stacked on the second surface, the second passivation film layer is stacked on the third polarity doped layer, and the second welding point is arranged on the second passivation film layer; or

[0018] The first polarity doping layer and the third polarity doping layer are both stacked on the first surface, the first passivation film layer is stacked on the first polarity doping layer, the second polarity doping layer and the third polarity doping layer, the second welding point is also arranged on the first passivation film layer, and the second passivation film layer is stacked on the second surface.

[0019] Furthermore, in the case where the third polarity doped layers are stacked on the first surface, on the first surface, a number of the first polarity doped layers and a number of the third polarity doped layers are alternately arranged in sequence along the first direction, and the first polarity doped layers and the third polarity doped layers both extend along the second direction, and the second direction intersects with the first direction.

[0020] Furthermore, in the case where the third polarity doping layer is stacked on the first surface, the first polarity doping layer includes a plurality of first sub-doping layers and a second sub-doping layer, and the third polarity doping layer includes a plurality of third sub-doping layers and a plurality of fourth sub-doping layers;

[0021] A plurality of the first sub-doping layers and a plurality of the third sub-doping layers are alternately arranged in sequence along a first direction and are disposed on the first surface at intervals and extend along a second direction, wherein the second direction intersects the first direction;

[0022] A plurality of the second sub-doping layers and a plurality of the fourth sub-doping layers are arranged alternately and spaced in sequence along the second direction on the first surface and extend along the first direction, the first sub-doping layer is disconnected at the fourth sub-doping layer and contacts the second sub-doping layer, and the third sub-doping layer is disconnected at the second sub-doping layer and contacts the fourth sub-doping layer;

[0023] A plurality of the first embedded grooves are formed on the second sub-doping layer, and the plurality of the first embedded grooves are arranged at intervals along the second direction.

[0024] Furthermore, in the first direction, the length of the first solder joint is greater than the length of the second polarity doped layer, and the ratio of the overlapping length of the first solder joint and the second polarity doped layer in the thickness direction to the total length of the first solder joint is greater than or equal to 20%.

[0025] Furthermore, a ratio of an overlapping length of the first welding spot and the second polarity doping layer to a total length of the first welding spot is greater than or equal to 50%.

[0026] Furthermore, a ratio of an area of ​​the first embedded groove to an area of ​​the second sub-doping layer is less than or equal to 50%.

[0027] Furthermore, in the first direction, a distance between two adjacent first welding points is 3 mm-40 mm.

[0028] Furthermore, the third polarity doping layer is formed with a plurality of second embedded grooves, and the solar cell further comprises a fourth polarity doping layer disposed in the second embedded grooves, wherein the fourth polarity doping layer has a polarity opposite to that of the third polarity doping layer;

[0029] In the case where the third polarity doped layer is stacked on the second surface, the second passivation film layer covers the third polarity doped layer and the fourth polarity doped layer, the roughness of the surface of the fourth polarity doped layer in contact with the second passivation film layer is greater than the roughness of the surface of the third polarity doped layer in contact with the second passivation film layer, the second welding point is arranged on the second passivation film layer, and in the thickness direction of the solar cell, the second welding point at least partially overlaps with the fourth polarity doped layer;

[0030] In the case where the third polarity doped layer is stacked on the first surface, the first passivation film layer covers the first polarity doped layer, the second polarity doped layer, the third polarity doped layer and the fourth polarity doped layer, the roughness of the surface of the fourth polarity doped layer in contact with the first passivation film layer is greater than the roughness of the surface of the third polarity doped layer in contact with the first passivation film layer, the second welding point is arranged on the first passivation film layer, and in the thickness direction of the solar cell, the second welding point and the fourth polarity doped layer at least partially overlap the third polarity doped layer.

[0031] Furthermore, a second isolation layer is disposed on the inner wall of the second embedded groove, and the second isolation layer is disposed between the third polarity doping layer and the fourth polarity doping layer to separate the third polarity doping layer from the fourth polarity doping layer.

[0032] Furthermore, the orthographic projection of the second welding point on the third polarity doping layer is completely located in the second embedding groove.

[0033] Furthermore, in the case where the third polarity doping layer is stacked on the first surface, the first polarity doping layer includes a plurality of first sub-doping layers and a second sub-doping layer, and the third polarity doping layer includes a plurality of third sub-doping layers and a plurality of fourth sub-doping layers;

[0034] A plurality of the first sub-doping layers and a plurality of the third sub-doping layers are alternately arranged in sequence along a first direction and are disposed on the first surface at intervals and extend along a second direction, wherein the second direction intersects the first direction;

[0035] A plurality of the second sub-doping layers and a plurality of the fourth sub-doping layers are arranged alternately and spaced in sequence along the second direction on the first surface and extend along the first direction, the first sub-doping layer is disconnected at the fourth sub-doping layer and contacts the second sub-doping layer, and the third sub-doping layer is disconnected at the second sub-doping layer and contacts the fourth sub-doping layer;

[0036] Among them, the second sub-doping layer has a plurality of the first embedding grooves, the plurality of the first embedding grooves are arranged at intervals along the first direction, and the number of the first welding points corresponds to the number of the first embedding grooves; the fourth sub-doping layer has a plurality of the second embedding grooves, the plurality of the second embedding grooves are arranged at intervals along the first direction, and the number of the second welding point pairs corresponds to the number of the second embedding grooves.

[0037] The present application also provides a battery assembly, which includes a plurality of solar cells as described in any one of the above items.

[0038] The present application also provides a photovoltaic system, which includes the above-mentioned battery assembly.

[0039] In the solar cell, battery assembly and photovoltaic system of the embodiment of the present application, a first embedding groove is formed on the first polarity doping layer, a second polarity doping layer is arranged in the first embedding groove, a first passivation film layer is covered on the second polarity doping layer, the roughness of the surface of the second polarity doping layer in contact with the first passivation film layer is greater than the roughness of the surface of the first polarity doping layer in contact with the first passivation film layer, and the orthographic projection of the first welding point on the first polarity doping layer and the orthographic projection of the second polarity doping layer on the first polarity doping layer at least partially overlap. In this way, by arranging the second polarity doping layer in the first embedding groove of the first polarity doping layer, and the roughness of the surface of the second polarity doping layer in contact with the first passivation film layer is greater than the roughness of the surface of the first polarity doping layer in contact with the first passivation film layer, the bonding tension between the first passivation film layer and the second polarity doping layer can be greater than the bonding tension between the first passivation film layer and the first polarity doping layer. In this way, arranging the first welding point above the second polarity doping layer can effectively increase the welding tension of the first welding point during welding, thereby effectively avoiding the first welding point from being separated during welding, and improving the reliability of welding.

[0040] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a module schematic diagram of a photovoltaic system provided in an embodiment of the present application;

[0042] Figure 2 is a module schematic diagram of a battery assembly provided in an embodiment of the present application;

[0043] Figure 3 is a schematic diagram of the structure of a solar cell provided in an embodiment of the present application;

[0044] Figure 4 is another structural schematic diagram of a solar cell provided in an embodiment of the present application;

[0045] Figure 5 is a schematic diagram of the planar structure of a solar cell provided in an embodiment of the present application;

[0046] Figure 6 yes Figure 5 Schematic diagram of the cross section of the back contact cell along line VI-VI;

[0047] Figure 7 yes Figure 5 Another schematic cross-sectional view of the back contact cell along line VI-VI;

[0048] Figure 8 is another schematic diagram of the planar structure of a solar cell provided in an embodiment of the present application;

[0049] Fig. 9 yes Figure 8 Schematic diagram of the cross section of the back contact cell along line IX-IX;

[0050] Fig.10 yes Figure 8 Schematic cross-sectional view of the back contact cell along line XX;

[0051] Fig.11 This is another schematic diagram of the planar structure of the solar cell provided in the embodiment of the present application.

[0052] Description of main component symbols:

[0053] Photovoltaic system 1000, battery assembly 200, solar cell 100, silicon wafer 10, first surface 11, second surface 12, first polarity doping layer 20, first embedded groove 201, first sub-doping layer 21, second sub-doping layer 22, second polarity doping layer 30, first passivation film layer 40, first solder joint 50, first isolation layer 60, third polarity doping layer 70, second embedded groove 701, third sub-doping layer 71, fourth sub-doping layer 72, second passivation film layer 80, second solder joint 90, fourth polarity doping layer 110, second isolation layer 120. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. In addition, it should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0055] In the description of the present application, it should be understood that the terms "length", "width", "up", "down", "top", "bottom", "lateral", "longitudinal", etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0056] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0057] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0058] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0059] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, and does not indicate the relationship between the various embodiments and / or settings discussed in itself. In addition, the various specific processes and examples of materials provided by the present application, but those of ordinary skill in the art can be aware of the application of other processes and / or the use scenarios of other materials.

[0060] See also Figure 1-Figure 2 , the photovoltaic system 1000 in the embodiment of the present application may include the battery assembly 200 in the embodiment of the present application, the battery assembly 200 in the embodiment of the present application may include a plurality of battery strings, and the battery string may include a plurality of solar cells 100 in the embodiment of the present application. In the present application, the plurality of solar cells 100 in the battery assembly 200 may be connected in series in sequence through welding strips to form a battery string. The battery strings in the battery assembly 200 may be connected in series, in parallel, or in series-parallel combination to realize the bus output of current, for example, the connection between the battery strings may be realized through bus bars.

[0061] See also Figure 3 The solar cell 100 in this embodiment may include a silicon wafer 10 , a first polarity doping layer 20 , a second polarity doping layer 30 , a first passivation film layer 40 and a first solder joint 50 .

[0062] The silicon wafer 10 has a first surface 11 and a second surface 12 opposite to each other, which are the front side and the back side respectively. A first polarity doping layer 20 is stacked on the first surface 11, and a plurality of first embedding grooves 201 are formed on the first polarity doping layer 20. A second polarity doping layer 30 is disposed in the first embedding grooves 201, and the polarity of the second polarity doping layer 30 is opposite to that of the first polarity doping layer 20.

[0063] The first passivation film layer 40 is stacked on the second polarity doping layer 30 and the first polarity doping layer 20 . Specifically, the first passivation film layer 40 may cover the entire first polarity doping layer 20 and the second polarity doping layer 30 .

[0064] like Figure 3 As shown, the roughness of the surface 301 where the second polarity doping layer 30 contacts the first passivation film layer 40 is greater than the roughness of the surface 202 where the first polarity doping layer 20 contacts the first passivation film layer 40, and the first solder joint 50 can be arranged on the first passivation film layer 40, and in the thickness direction of the solar cell 100, the first solder joint 50 at least partially overlaps with the second polarity doping layer 30.

[0065] That is, the orthographic projection of the first solder joint 50 on the first polarity doping layer 20 and the orthographic projection of the second polarity doping layer 30 on the first polarity doping layer 20 at least partially overlap. "Orthographic projection" refers to the orthographic projection along the thickness direction of the solar cell 100. In the following, if there is the same description, it can be understood by referring to it. It can be understood that in the present application, the second polarity doping layer 30 is located in the first embedding groove 201, which can be that all parts of the first polarity doping layer 30 are completely contained in the first embedding groove 201, or the first polarity doping layer 30 can partially extend out of the first embedding groove 201 in the thickness direction, and there is no specific limitation here.

[0066] In the solar cell of the embodiment of the present application, a first embedding groove 201 is formed on the first polarity doping layer 20, a second polarity doping layer 30 is provided in the first embedding groove 201, the second polarity doping layer 30 is covered with a first passivation film layer 40, the roughness of a surface 301 where the second polarity doping layer 30 contacts the first passivation film layer 40 is greater than the roughness of a surface 202 where the first polarity doping layer 20 contacts the first passivation film layer 40, and in the thickness direction of the solar cell 100, the first welding point 50 at least partially overlaps with the second polarity doping layer 30. In this way, by arranging the second polarity doping layer 30 in the first embedding groove 201 of the first polarity doping layer 20, and the roughness of the surface 301 of the second polarity doping layer 30 in contact with the first passivation film layer 40 is greater than the roughness of the surface 202 of the first polarity doping layer 20 in contact with the first passivation film layer 40, the bonding tension between the first passivation film layer 40 and the second polarity doping layer 30 can be greater than the bonding tension between the first passivation film layer 40 and the first polarity doping layer 20. In this way, arranging the first welding point 50 above the second polarity doping layer 30 (that is, in the thickness direction of the solar cell 100, the first welding point 50 and the second polarity doping layer 30 at least partially overlap) can effectively increase the welding tension of the first welding point 50 during welding, thereby effectively avoiding the first welding point 50 from detaching during welding, and improving the reliability of welding.

[0067] Specifically, in the present application, the solar cell 100 may be a back contact cell, a Topcon solar cell, an HJT solar cell, or the like having a first polarity doping layer 20 and requiring solder joints to be set on the first polarity doping layer 20, and no specific limitation is made here.

[0068] In the present application, the first polarity doping layer 20 and the second polarity doping layer 30 can be a P-type doping layer and an N-type doping layer, respectively, as long as the polarities of the two are opposite. For example, in some embodiments, the first polarity doping layer 20 can be a P-type polycrystalline silicon layer, a P-type amorphous silicon layer, or a P-type microcrystalline silicon layer, which is not specifically limited here. Similarly, the second polarity doping layer 30 can be an N-type polycrystalline silicon layer, an N-type amorphous silicon layer, or an N-type microcrystalline silicon layer, which is not specifically limited here.

[0069] In some embodiments, a tunneling oxide layer or an intrinsic amorphous silicon layer (not shown) may be provided between the first polarity doped layer 20 and the first surface 11 of the silicon wafer 10. Specifically, when the solar cell is a Topcon solar cell or a back contact cell, a tunneling oxide layer may be provided between the first polarity doped layer 20 and the silicon wafer 10, and when the solar cell is a HJT solar cell, an intrinsic amorphous silicon layer may be provided between the first polarity doped layer 20 and the silicon wafer 10.

[0070] See also Figure 4 In some embodiments, a first isolation layer 60 is disposed on the inner wall of the first embedding groove 201 , and the first isolation layer 60 is disposed between the first polarity doping layer 20 and the second polarity doping layer 30 to separate the first polarity doping layer 20 from the second polarity doping layer 30 .

[0071] In this way, the second polarity doping layer 30 can be separated from the first polarity doping layer 20 by the first isolation layer 60 to avoid direct contact between the two, while also ensuring the passivation effect of the first polarity doping layer 20 .

[0072] Of course, it is understandable that in some embodiments, it is not necessary to set the first isolation layer 60 to separate the first polarity doping layer 20 and the second polarity doping layer 30. It is only necessary to set the metal grid line in contact with the first polarity doping layer 20 in the solar cell 100 to not contact the second polarity doping layer 30. No specific limitation is made here.

[0073] In some embodiments, the thickness of the first isolation layer 60 may be greater than 2 nm. In this way, it is possible to avoid a situation where the thickness of the first isolation layer 60 is too small, which would significantly increase the difficulty of the process.

[0074] Furthermore, in some embodiments, the first isolation layer 60 may include at least one of a silicon oxide film layer, a silicon nitride film layer, an aluminum oxide film layer, a silicon oxynitride film layer, a silicon carbide film layer, and an intrinsic amorphous silicon film layer.

[0075] Specifically, in such an embodiment, the first isolation layer 60 may or may not have a tunneling function, and may be an insulating layer or a non-insulating layer. There is no specific limitation here, and the specific film layer may be selected according to different types of battery cells.

[0076] For example, when the cell is a Topcon solar cell and a back contact cell, the first isolation layer 60 may be at least one of a silicon oxide film layer, a silicon nitride film layer, an aluminum oxide film layer, a silicon oxynitride film layer, and a silicon carbide film layer, and the first isolation layer 60 may or may not have a tunneling function.

[0077] When the cell is a HJT solar cell, the first isolation layer 60 may be an intrinsic amorphous silicon layer. It is understood that the specific selection of the first isolation layer 60 is merely an exemplary description here, but it cannot be understood as a limitation to the present application.

[0078] like Figure 3 and Figure 4 As shown, in some embodiments, the orthographic projection of the first solder joint 50 on the first polarity doping layer 20 is completely located in the first embedding groove 201 , that is, in the thickness direction of the solar cell 100 , the first solder joint 50 is completely located above the second polarity doping layer 30 .

[0079] In this way, the first welding point 50 is completely located in the first embedding groove 201, and the entire bottom of the first welding point 50 has the second polarity doping layer, which can maximize the welding tension at the first welding point 50, thereby ensuring the reliability of welding.

[0080] Specifically, in such an embodiment, the area of ​​the first embedding groove 201 may preferably be just equal to the orthographic projection area of ​​the first welding point 50 or slightly larger than the orthographic projection area of ​​the first welding point 50 .

[0081] Of course, in some embodiments, the orthographic projection area of ​​the first solder joint 50 on the first polarity doping layer 20 may also be larger than the orthographic projection area of ​​the second polarity doping layer 30 on the first polarity doping layer 20 (that is, the area of ​​the first embedding groove 201). For example, a single first solder joint 50 may correspond to multiple second polarity doping layers 30. In this case, the first solder joint 50 may completely cover the second polarity doping layer 30. In this case, the ratio of the overlapping area of ​​the second polarity doping layer 30 and the first solder joint 50 to the total area of ​​the first solder joint 50 may be greater than 20% to avoid too small welding tension.

[0082] In addition, in some embodiments, the first solder joint 50 may be bonded to the first passivation film layer 40, may be partially embedded in the first passivation film layer 40, or may at least partially penetrate the first passivation film layer 40 to contact the second polarity doping layer 30. When the first solder joint 50 contacts the second polarity doping layer 30, the first polarity doping layer 20 and the second polarity doping layer 30 may be isolated by setting a first isolation layer 60. No specific limitation is made here.

[0083] In some embodiments, the depth of the first embedding groove 201 may be 5 nm-400 nm.

[0084] In this way, it can effectively avoid that the depth of the first embedded groove 201 is too small, resulting in the second polarity doped layer 30 being too thin, thereby resulting in poor tensile reinforcement effect, and it can also avoid that the depth of the first embedded groove 201 is too deep, resulting in the second polarity doped layer 30 being too thick, thereby increasing costs.

[0085] Specifically, the depth of the first embedded groove 201 may be 5nm, 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm or any value between 5nm and 400nm, and is not limited here.

[0086] In some embodiments, the first passivation film layer 40 may include at least one of a silicon nitride film layer, an aluminum oxide film layer, a silicon oxynitride film layer, an intrinsic amorphous silicon film layer, and a TCO film layer.

[0087] Specifically, in such an embodiment, the type of the first passivation film layer 40 can also be selected according to different types of battery cells. For example, when the battery is a Topcon solar cell and a back contact battery, the first passivation film layer 40 can be at least one of a silicon oxide film layer, a silicon nitride film layer, an aluminum oxide film layer, a silicon oxynitride film layer, and a silicon carbide film layer.

[0088] When the cell is a HJT solar cell, the first passivation film layer 40 may be a TCO film layer, which is not specifically limited here. It is understandable that the specific selection of the first passivation film layer 40 is merely exemplified here, but it cannot be understood as a limitation to the present application.

[0089] See also Figure 5-Figure 9 In some embodiments, the solar cell 100 may further include a third polarity doping layer 70 , a second passivation film layer 80 and a plurality of second solder joints 90 , and the polarity of the third polarity doping layer 70 is opposite to the polarity of the first polarity doping layer 20 .

[0090] like Figure 5 and Figure 6 As shown, in some embodiments, the first polarity doping layer 20 may be stacked on the first surface 11, the third polarity doping layer 70 may be stacked on the second surface 12, the second passivation film layer 80 is stacked on the third polarity doping layer 70, and the second solder joint 90 is disposed on the second passivation film layer 80. In this case, the solar cell 100 is a double-sided solar cell, such as a Topcon solar cell, an HJT solar cell, etc.

[0091] Similarly, in the present application, the second passivation film layer 80 may also include at least one of a silicon nitride film layer, an aluminum oxide film layer, a silicon oxynitride film layer, an intrinsic amorphous silicon film layer, and a TCO film layer.

[0092] like Figure 8 and Fig. 9As shown, in some embodiments, the first polarity doping layer 20 and the third polarity doping layer 70 may also be stacked on the first surface 11, the first passivation film layer 40 is stacked on the first polarity doping layer 20, the second polarity doping layer 30 and the third polarity doping layer 70, the second solder joint 90 is also disposed on the first passivation film layer 40, and the second passivation film layer 80 is stacked on the second surface 12. In this case, the solar cell 100 is a back contact cell, the first surface 11 is the back side of the cell, and the second surface 12 is the front side of the cell.

[0093] In an embodiment of the present application, in a solar cell 100, a first polarity doping layer 20 may be first deposited and formed, and then a first embedded groove 201 may be formed on the first polarity doping layer 20 by an etching process, and then a first isolation layer 60 and a second polarity doping layer 30 may be deposited in the first embedded groove 201 by deposition. The roughness of a surface 301 of the second polarity doping layer 30 in contact with the first passivation film layer 40 may be controlled by controlling the temperature and time of the deposition or by etching treatment, and no specific limitation is made herein.

[0094] It can be understood that when the solar cell 100 is a double-sided solar cell, a plurality of first sub-grids (not shown in the figure) are arranged on the first passivation film layer 40, and the first sub-grids penetrate the first passivation film layer 40 and contact the first polarity doping layer 20, and a plurality of second sub-grids (not shown in the figure) are also arranged on the second passivation film layer 80, and the second sub-grids penetrate the second passivation film layer 80 and contact the third polarity doping layer 70. In the double-sided solar cell, a first main grid (not shown in the figure) cross-contacting the first auxiliary grid and a second main grid (not shown in the figure) cross-contacting the second auxiliary grid are also provided. The first welding point 50 can be provided on the first main grid, which can be located on the first passivation film layer 40 or partially embedded in the first passivation film layer 40 or penetrate the first passivation film layer 40 and contact the second polarity doping layer 30 below the first passivation film layer 40. The first welding point 50 is used for welding with the welding strip. Similarly, the second welding point 90 can be provided on the second main grid, which can be located on the second passivation film layer 80 or partially embedded in the second passivation film layer 80 or penetrate the second passivation film layer 80. The second welding point 90 is also used for welding with the welding strip.

[0095] When the solar cell 100 is a back-contact cell, the first passivation film layer 40 is provided with a third sub-grid (not shown) and a fourth sub-grid (not shown). The third sub-grid penetrates the first passivation film layer 40 and contacts the first polarity doping layer 20 , and the fourth sub-grid penetrates the first passivation film layer 40 and contacts the third polarity doping layer 70 .

[0096] When the solar cell 100 is a back contact cell, it can be divided into the following two cases:

[0097] The first type: Figure 8As shown, in some embodiments, on the first surface 11, a plurality of first polarity doped layers 20 and a plurality of third polarity doped layers 70 may be arranged alternately in sequence along the first direction, and the first polarity doped layers 20 and the third polarity doped layers 70 both extend along the second direction, and the second direction intersects the first direction, and the two directions may be the longitudinal direction and the transverse direction of the solar cell 100, respectively. Figure 8 It can be seen that in this embodiment, the first polarity doping layer 20 and the third polarity doping layer 70 are doping layers that are continuous and unbroken along the second direction, and the two are alternately arranged along the first direction.

[0098] In a back-contact battery, a main grid may be set or not. When a main grid is set, it includes a plurality of third main grids (not shown) and a plurality of fourth main grids (not shown). The plurality of third main grids and the plurality of fourth main grids are alternately arranged along the second direction. The third auxiliary grid is connected to the third main grid and disconnected at the fourth main grid. The fourth auxiliary grid is connected to the fourth main grid and disconnected at the third main grid. The first welding point 50 is set at the third main grid and connected to the third main grid. The second welding point 90 is set at the fourth main grid and connected to the fourth main grid. A plurality of first welding points 50 may be set along the extension direction of the third main grid, and a plurality of second welding points 90 may be set along the extension direction of the fourth main grid.

[0099] When the main grid is not provided, the first welding point 50 and the second welding point 90 can be directly provided in the area covered by the welding strip of the battery. For example, the first welding point 50 can be provided at the disconnection of the third auxiliary grid, and the second welding point 90 can be provided at the disconnection of the fourth auxiliary grid. In this way, the welding point can be directly connected to the welding point through the welding strip in the absence of the main grid. It can be understood that in this case, the welding strip welded to the first welding point 50 can be electrically connected to all the third auxiliary grids, and the welding strip welded to the second welding point 90 can be electrically connected to all the fourth auxiliary grids. Of course, in some embodiments, the third auxiliary grid and the fourth auxiliary grid may not be disconnected, but an insulating glue is provided at the main grid or welding strip of opposite polarity for isolation, which is not specifically limited here.

[0100] The second type: Fig.11As shown, in some embodiments, the first polarity doping layer 20 may include a plurality of first sub-doping layers 21 and a second sub-doping layer 22, and the third polarity doping layer 70 may include a plurality of third sub-doping layers 71 and a plurality of fourth sub-doping layers 72. The plurality of first sub-doping layers 21 and the plurality of third sub-doping layers 71 are arranged alternately and spaced in sequence along the first direction on the first surface 11 and extend along the second direction. The plurality of second sub-doping layers 22 and the plurality of fourth sub-doping layers 72 are arranged alternately and spaced in sequence along the second direction on the first surface 11 and extend along the first direction, the first sub-doping layer 21 is disconnected at the fourth sub-doping layer 72 and contacts the second sub-doping layer 22, and the third sub-doping layer 71 is disconnected at the second sub-doping layer 22 and contacts the fourth sub-doping layer 72. Among them, a plurality of first embedding grooves 201 are formed on the second sub-doping layer 22, and the plurality of first embedding grooves 201 are arranged at intervals along the second direction, and the number of first welding points 50 may correspond to the number of first embedding grooves 201. In this case, the first solder joint 50 may be disposed on the second sub-doping layer 22 , and the second solder joint 90 may be disposed on the fourth sub-doping layer 72 .

[0101] Specifically, it is not difficult to understand that if Fig.11 As shown, in such an embodiment, the first sub-doping layer 21 and the second sub-doping layer 22 together form a comb-tooth-shaped first polarity doping layer 20, and the third sub-doping layer 71 and the fourth sub-doping layer 72 together form a comb-tooth-shaped third polarity doping layer 70. The first sub-doping layer 21 and the second sub-doping layer 22 can be formed by the same process, and the third polarity doping layer 71 and the fourth sub-doping layer 72 can be formed by the same process.

[0102] Furthermore, if Fig.11 As shown, in such an embodiment, in the first direction, the length of the first solder joint 50 is greater than the length of the second polarity doping layer 30, and the ratio of the overlapping length of the first solder joint 50 and the second polarity doping layer 30 in the thickness direction to the total length of the first solder joint 50 is greater than or equal to 20%.

[0103] In this way, when the length of the first solder joint 50 in the first direction is relatively large, setting the ratio between the overlapping length of the first solder joint 50 and the second polarity doping layer 30 (i.e., the overlapping length of the orthographic projection of the first solder joint 50 in the thickness direction and the second polarity doping layer 30) and the total length of the first solder joint 50 to be greater than or equal to 20% can effectively ensure the welding tension of the first solder joint 50 and avoid insufficient welding tension.

[0104] Preferably, in such an embodiment, in order to ensure the welding tension of the first welding spot 50 , the ratio of the overlapping length of the first welding spot 50 and the second polarity doping layer 30 in the thickness direction to the total length of the first welding spot 50 is greater than or equal to 50%.

[0105] In some embodiments, the ratio of the area of ​​the first embedded groove 201 to the area of ​​the second sub-doped layer 22 is less than 50%. In this way, it is possible to avoid the second polarity doped layer 30 being too large in area, which may cause the second polarity doped layer 30 to be more easily recombined with the second sub-doped layer 22 and cause greater recombination loss.

[0106] Specifically, in such an embodiment, "the ratio of the area of ​​the first embedded groove 201 to the area of ​​the second sub-doping layer 22 is less than 50%" can mean that the ratio of the area of ​​all first embedded grooves 201 on a single second sub-doping layer 22 to the area of ​​a single second sub-doping layer 22 is less than 50%, or it can be that the ratio of the sum of the areas of all first embedded grooves 201 on the entire back contact battery to the sum of the areas of all second sub-doping layers 22 is less than 50%. There is no specific limitation here, and the first one is preferred.

[0107] Furthermore, if Fig.11 As shown, in such an embodiment, in the first direction, the distance between two adjacent first welding points 50 may be 3 mm-40 mm.

[0108] In this way, by setting the distance between two adjacent first solder joints 50 within this reasonable range, the first solder joints 50 can be basically within a reasonable distance, so that there can be enough first solder joints 50 on the same second sub-doping layer 22, thereby avoiding cold solder joints when welding solder strips and ensuring the reliability of welding.

[0109] Specifically, in such an embodiment, the spacing between two adjacent first welding points 50 may be, for example, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm or any value between 3mm-40mm, and is not limited here.

[0110] like Figure 7 and Fig.10 As shown, in some embodiments, the third polarity doping layer 70 may be formed with a plurality of second embedding grooves 701, and the solar cell 100 may further include a fourth polarity doping layer 110 disposed in the second embedding grooves 701, wherein the fourth polarity doping layer 110 has a polarity opposite to that of the third polarity doping layer 70;

[0111] like Figure 7As shown, in the case where the third polarity doping layer 70 is stacked on the second surface 12, the second passivation film layer 80 covers the third polarity doping layer 70 and the fourth polarity doping layer 110, the roughness of the surface 111 of the fourth polarity doping layer 110 in contact with the second passivation film layer 80 is greater than the roughness of the surface 702 of the third polarity doping layer 70 in contact with the second passivation film layer 80, and the second solder joint 90 is arranged on the second passivation film layer 80, and in the thickness direction of the solar cell 100, the second solder joint 90 at least partially overlaps with the fourth polarity doping layer 110.

[0112] like Fig.10 As shown, when the third polarity doping layer 70 is stacked on the first surface 11, the first passivation film layer 40 covers the first polarity doping layer 20, the second polarity doping layer 30, the third polarity doping layer 70 and the fourth polarity doping layer 110, and the roughness of the surface 111 of the fourth polarity doping layer 110 in contact with the first passivation film layer 40 is greater than the roughness of the surface 702 of the third polarity doping layer 70 in contact with the first passivation film layer 40, and in the thickness direction of the solar cell 100, the second welding point 90 at least partially overlaps with the fourth polarity doping layer 110.

[0113] In this way, while increasing the tensile force of the first welding point 50 during welding, the tensile force of the second welding point 90 during welding can also be effectively increased, thereby effectively preventing the second welding point 90 from detaching during welding.

[0114] See also Figure 7 and Fig.10 In some embodiments, a second isolation layer 120 is provided on the inner wall of the second embedded groove 701 , and the second isolation layer 120 is stacked between the third polarity doping layer 70 and the fourth polarity doping layer 110 to separate the third polarity doping layer 70 from the fourth polarity doping layer 110 .

[0115] In this way, the fourth polarity doping layer 110 can be separated from the third polarity doping layer 70 by the second isolation layer 120 to avoid direct contact between the two, while also ensuring the passivation effect of the third polarity doping layer 70 .

[0116] Of course, it is understandable that, in some embodiments, it is not necessary to provide the second isolation layer 120 to separate the third polarity doping layer 70 and the fourth polarity doping layer 110 , and this is not specifically limited herein.

[0117] In some embodiments, the thickness of the second isolation layer 120 may be greater than 2 nm. In this way, it is possible to avoid a situation where the thickness of the second isolation layer 120 is too small, which would significantly increase the difficulty of the process.

[0118] Furthermore, in some embodiments, the second isolation layer 120 may include at least one of a silicon oxide film layer, a silicon nitride film layer, an aluminum oxide film layer, a silicon oxynitride film layer, a silicon carbide film layer, and an intrinsic amorphous silicon film layer.

[0119] Specifically, in such an embodiment, the second isolation layer 120 may or may not have a tunneling function, and may be an insulating layer or a non-insulating layer. There is no specific limitation here, and the specific film layer may be selected according to different types of battery cells.

[0120] For example, when the cell is a Topcon solar cell and a back contact cell, the second isolation layer 120 may be at least one of a silicon oxide film layer, a silicon nitride film layer, an aluminum oxide film layer, a silicon oxynitride film layer, and a silicon carbide film layer, and the second isolation layer 120 may or may not have a tunneling function.

[0121] When the cell is a HJT solar cell, the second isolation layer 120 may be an intrinsic amorphous silicon layer. It is understood that the specific selection of the second isolation layer 120 is merely exemplified herein, but it cannot be construed as a limitation to the present application.

[0122] In some embodiments, the orthographic projection of the second solder joint 90 on the third polarity doping layer 70 is completely located in the second embedding groove 701 , that is, in the thickness direction of the solar cell 100 , the second solder joint 90 is completely located above the fourth polarity doping layer 110 .

[0123] In this way, the second welding point 90 is completely located in the second embedding groove 701, and the entire bottom of the second welding point 90 has the fourth polarity doping layer 110, which can maximize the welding tension at the second welding point 90, thereby ensuring the reliability of welding.

[0124] Specifically, in such an embodiment, the area of ​​the second embedding groove 701 may preferably be just equal to the orthographic projection area of ​​the second welding point 90 or slightly larger than the orthographic projection area of ​​the second welding point 90 .

[0125] Of course, in some embodiments, the orthographic projection area of ​​the second solder joint 90 on the third polarity doping layer 70 may also be larger than the orthographic projection area of ​​the fourth polarity doping layer 110 on the third polarity doping layer 70 (that is, the area of ​​the second embedding groove 701). For example, a single second solder joint 90 may correspond to multiple fourth polarity doping layers 110. In this case, the second solder joint 90 may completely cover the fourth polarity doping layer 110. In this case, the ratio of the overlapping area of ​​the fourth polarity doping layer 110 and the second solder joint 90 to the total area of ​​the second solder joint 90 may be greater than 20% to avoid too small welding tension.

[0126] In some embodiments, the depth of the second embedding groove 701 may be 5 nm-400 nm.

[0127] In this way, it can effectively avoid that the second embedded groove 701 is too small to cause the fourth polarity doped layer 110 to be too thin, thereby resulting in poor tensile reinforcement effect, and it can also avoid that the second embedded groove 701 is too deep to cause the fourth polarity doped layer 110 to be too thick, thereby increasing costs.

[0128] Specifically, the depth of the second embedded groove 701 may be 5nm, 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm or any value between 5nm and 400nm, and is not limited here.

[0129] Furthermore, if Fig.11 As shown, in the case where the third polarity doping layer 70 is disposed on the first surface 11 and the first polarity doping layer 20 includes a plurality of first sub-doping layers 21 and a second sub-doping layer 22, and the third polarity doping layer 70 includes a plurality of third sub-doping layers 71 and a plurality of fourth sub-doping layers 72, the second sub-doping layer 22 may be formed with a plurality of first embedding grooves 201, and the plurality of first embedding grooves 201 are arranged at intervals along the second direction. The number of first welding points 50 may correspond to the number of first embedding grooves 201, and of course, the number of the two may not correspond, as long as the first welding points 50 at least overlap with the second doping layer 30 in the thickness direction. The fourth sub-doping layer 72 may be formed with second embedding grooves 701, and the plurality of second embedding grooves 701 are arranged at intervals along the first direction, and the number of pairs of second welding points 90 may correspond to the number of second embedding grooves 701, and similarly, the number of the two may not correspond, as long as the second welding points 90 at least overlap with the fourth doping layer 110 in the thickness direction.

[0130] like Fig.11 As shown, in such an embodiment, in the first direction, the length of the second solder joint 90 may be greater than the length of the fourth polarity doping layer 110, and the ratio of the overlapping length of the second solder joint 90 and the fourth polarity doping layer 110 in the thickness direction to the total length of the second solder joint 90 is greater than or equal to 20%.

[0131] In this way, when the length of the second solder joint 90 in the first direction is relatively large, setting the ratio between the overlapping length of the second solder joint 90 and the fourth polarity doping layer 110 in the thickness direction (i.e., the overlapping length of the orthographic projection of the second solder joint 90 in the thickness direction and the fourth polarity doping layer 110) and the total length of the second solder joint 90 to be greater than or equal to 20% can effectively ensure the welding tension of the second solder joint 90 and avoid insufficient welding tension.

[0132] Preferably, in such an embodiment, in order to ensure the welding tension of the second solder joint 90 , the ratio of the overlapping length of the second solder joint 90 and the fourth polarity doping layer 110 in the thickness direction to the total length of the second solder joint 90 is greater than or equal to 50%.

[0133] In some embodiments, the ratio of the area of ​​the second embedded groove 701 to the area of ​​the fourth sub-doped layer 72 is less than 50%. In this way, it is possible to avoid the fourth polarity doped layer 110 being too large in area, which may cause the fourth polarity doped layer 110 to be more easily recombined with the fourth sub-doped layer 72 and cause greater recombination loss.

[0134] Specifically, in such an embodiment, "the ratio of the area of ​​the second embedded groove 701 to the area of ​​the fourth sub-doping layer 72 is less than 50%" can mean that the ratio of the area of ​​all fourth polarity doping layers 110 on a single fourth sub-doping layer 72 to the single fourth sub-doping layer 72 is less than 50%, or it can be that the ratio of the sum of the areas of all fourth polarity doping layers 110 on the entire back contact battery to the sum of the areas of all fourth sub-doping layers 72 is less than 50%. There is no specific limitation here, and the first one is preferred.

[0135] Furthermore, if Fig.11 As shown, in such an embodiment, in the first direction, the distance between two adjacent second welding points 90 may be 3 mm-40 mm.

[0136] In this way, by setting the distance between two adjacent second solder joints 90 within this reasonable range, the second solder joints 90 can be basically within a reasonable distance, so that there can be enough second solder joints 90 on the same fourth sub-doping layer 72, thereby avoiding cold solder joints when welding solder strips and ensuring the reliability of welding.

[0137] Specifically, in such an embodiment, the spacing between two adjacent second welding points 90 may be, for example, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm or any value between 3mm-40mm, and is not limited here.

[0138] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0139] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A solar cell, characterized in that: include: A silicon wafer having a first surface and a second surface opposite to each other; A first polarity doping layer stacked on the first surface, wherein a plurality of first embedded grooves are formed on the first polarity doping layer; a second polarity doping layer disposed in the first embedded groove, wherein the polarity of the second polarity doping layer is opposite to the polarity of the first polarity doping layer; a first passivation film layer stacked on the first polarity doped layer and the second polarity doped layer, wherein the roughness of a surface of the second polarity doped layer in contact with the first passivation film layer is greater than the roughness of a surface of the first polarity doped layer in contact with the first passivation film layer; and A plurality of first welding points, wherein the first welding points are arranged on the first passivation film layer, and in the thickness direction of the solar cell sheet, the first welding points at least partially overlap with the second polarity doping layer.

2. The solar cell according to claim 1, characterized in that: A first isolation layer is disposed on an inner wall of the first embedded groove, and the first isolation layer is disposed between the first polarity doping layer and the second polarity doping layer to separate the first polarity doping layer from the second polarity doping layer.

3. The solar cell according to claim 2, characterized in that: The thickness of the first isolation layer is greater than 2 nm.

4. The solar cell according to claim 2, characterized in that: The first isolation layer includes at least one of a silicon oxide film layer, a silicon nitride film layer, an aluminum oxide film layer, a silicon oxynitride film layer, a silicon carbide film layer and an intrinsic amorphous silicon film layer.

5. The solar cell according to claim 1, characterized in that: The orthographic projection of the first welding point on the first polarity doping layer is completely located in the first embedding groove.

6. The solar cell according to claim 1, characterized in that: The depth of the first embedded groove is 5nm-400nm.

7. The solar cell according to claim 1, characterized in that: The first passivation film layer includes at least one of a silicon nitride film layer, an aluminum oxide film layer, a silicon oxynitride film layer, an intrinsic amorphous silicon film layer, and a TCO film layer.

8. The solar cell according to claim 1, characterized in that: The solar cell further comprises a third polarity doping layer, a second passivation film layer and a plurality of second welding points, wherein the polarity of the third polarity doping layer is opposite to the polarity of the first polarity doping layer; Wherein, the first polarity doped layer is stacked on the first surface, the third polarity doped layer is stacked on the second surface, the second passivation film layer is stacked on the third polarity doped layer, and the second welding point is arranged on the second passivation film layer; or The first polarity doping layer and the third polarity doping layer are both stacked on the first surface, the first passivation film layer is stacked on the first polarity doping layer, the second polarity doping layer and the third polarity doping layer, the second welding point is also arranged on the first passivation film layer, and the second passivation film layer is stacked on the second surface.

9. The solar cell according to claim 8, characterized in that: In the case where the third polarity doped layers are stacked on the first surface, on the first surface, a number of the first polarity doped layers and a number of the third polarity doped layers are alternately arranged in sequence along the first direction, and the first polarity doped layers and the third polarity doped layers both extend along the second direction, and the second direction intersects with the first direction.

10. The solar cell according to claim 8, characterized in that: In the case where the third polarity doping layer is stacked on the first surface, the first polarity doping layer includes a plurality of first sub-doping layers and a second sub-doping layer, and the third polarity doping layer includes a plurality of third sub-doping layers and a plurality of fourth sub-doping layers; A plurality of the first sub-doping layers and a plurality of the third sub-doping layers are alternately arranged in sequence along a first direction and are disposed on the first surface at intervals and extend along a second direction, wherein the second direction intersects the first direction; A plurality of the second sub-doping layers and a plurality of the fourth sub-doping layers are arranged alternately and spaced in sequence along the second direction on the first surface and extend along the first direction, the first sub-doping layer is disconnected at the fourth sub-doping layer and contacts the second sub-doping layer, and the third sub-doping layer is disconnected at the second sub-doping layer and contacts the fourth sub-doping layer; A plurality of the first embedded grooves are formed on the second sub-doping layer, and the plurality of the first embedded grooves are arranged at intervals along the second direction.

11. The solar cell according to claim 10, characterized in that: In the first direction, the length of the first solder joint is greater than the length of the second polarity doping layer, and a ratio of an overlapping length of the first solder joint and the second polarity doping layer in the thickness direction to a total length of the first solder joint is greater than or equal to 20%.

12. The solar cell according to claim 10, characterized in that: A ratio of an overlapping length of the first welding spot and the second polarity doping layer to a total length of the first welding spot is greater than or equal to 50%.

13. The solar cell according to claim 10, characterized in that: A ratio of an area of ​​the first embedded groove to an area of ​​the second sub-doping layer is less than or equal to 50%.

14. The solar cell according to claim 10, characterized in that: In the first direction, the distance between two adjacent first welding points is 3 mm-40 mm.

15. The solar cell according to claim 8, characterized in that: The third polarity doping layer is formed with a plurality of second embedded grooves, and the solar cell further comprises a fourth polarity doping layer disposed in the second embedded grooves, wherein the fourth polarity doping layer has a polarity opposite to that of the third polarity doping layer; In the case where the third polarity doped layer is stacked on the second surface, the second passivation film layer covers the third polarity doped layer and the fourth polarity doped layer, the roughness of the surface of the fourth polarity doped layer in contact with the second passivation film layer is greater than the roughness of the surface of the third polarity doped layer in contact with the second passivation film layer, the second welding point is arranged on the second passivation film layer, and in the thickness direction of the solar cell, the second welding point at least partially overlaps with the fourth polarity doped layer; In the case where the third polarity doped layer is stacked on the first surface, the first passivation film layer covers the first polarity doped layer, the second polarity doped layer, the third polarity doped layer and the fourth polarity doped layer, the roughness of the surface of the fourth polarity doped layer in contact with the first passivation film layer is greater than the roughness of the surface of the third polarity doped layer in contact with the first passivation film layer, the second welding point is arranged on the first passivation film layer, and in the thickness direction of the solar cell, the second welding point and the fourth polarity doped layer at least partially overlap the third polarity doped layer.

16. The solar cell according to claim 15, characterized in that: A second isolation layer is disposed on the inner wall of the second embedded groove, and the second isolation layer is disposed between the third polarity doping layer and the fourth polarity doping layer to separate the third polarity doping layer from the fourth polarity doping layer.

17. The solar cell according to claim 15, characterized in that: The orthographic projection of the second welding point on the third polarity doping layer is completely located in the second embedding groove.

18. The solar cell according to claim 15, characterized in that: In the case where the third polarity doping layer is stacked on the first surface, the first polarity doping layer includes a plurality of first sub-doping layers and a second sub-doping layer, and the third polarity doping layer includes a plurality of third sub-doping layers and a plurality of fourth sub-doping layers; A plurality of the first sub-doping layers and a plurality of the third sub-doping layers are alternately arranged in sequence along a first direction and are disposed on the first surface at intervals and extend along a second direction, wherein the second direction intersects the first direction; A plurality of the second sub-doping layers and a plurality of the fourth sub-doping layers are arranged alternately and spaced in sequence along the second direction on the first surface and extend along the first direction, the first sub-doping layer is disconnected at the fourth sub-doping layer and contacts the second sub-doping layer, and the third sub-doping layer is disconnected at the second sub-doping layer and contacts the fourth sub-doping layer; Among them, the second sub-doping layer has a plurality of the first embedding grooves, the plurality of the first embedding grooves are arranged at intervals along the first direction, and the number of the first welding points corresponds to the number of the first embedding grooves; the fourth sub-doping layer has a plurality of the second embedding grooves, the plurality of the second embedding grooves are arranged at intervals along the first direction, and the number of the second welding point pairs corresponds to the number of the second embedding grooves.

19. A battery assembly, characterized in that: The invention comprises the solar cell sheets as described in any one of claims 1 to 18.

20. A photovoltaic system, characterized in that: A battery assembly comprising the battery assembly of claim 19.

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