Back-contact solar cell, battery assembly and photovoltaic system

Abstract

A back-contact solar cell, a battery assembly and a photovoltaic system. First busbars (23) of a back-contact solar cell (100) are in contact with first finger pre-plated coatings (211), and second busbars (24) of same are in contact with second finger pre-plated coatings (221); a first conductive connector (30) and a second conductive connector (40) are respectively arranged on two ends of each first busbar (23) and two ends of each second busbar (24); and the first conductive connector (30) is connected to the ends of all the first busbars (23) facing away from the second conductive connector (40), and the second conductive connector (40) is connected to the ends of all the second busbars (24) facing away from the first conductive connector (30). In this way, when first finger electroplated coatings (212) and second finger electroplated coatings (222) are formed, the first finger electroplated coatings (212) and the second finger electroplated coatings (222) can be respectively formed on all the first finger pre-plated coatings (211) and all the second finger pre-plated coatings (221) by means of simply connecting a cathode of an electroplating device to the first conductive connector (30) and the second conductive connector (40), thereby effectively simplifying the electroplating process, and improving the electroplating efficiency.

Description

Back-contact solar cells, modules and photovoltaic systems

[0001] The present disclosure claims priority from a patent document filed on July 27, 2023, with application number 202310934646.6 and titled “Back-contact solar cell, battery assembly and photovoltaic system”, the entire contents of which are incorporated by reference into the present disclosure. Technical Field

[0002] The present disclosure relates to the technical field of solar cells, and in particular to a back-contact solar cell, a cell assembly, and a photovoltaic system. Background Art

[0003] A back-contact solar cell is a solar cell in which both the P region and the N region are arranged on the back of the cell. The front of this type of cell is not blocked by any metal electrode, which can effectively increase the short-circuit current of the cell and improve the cell efficiency. The P region and the N region on the back are arranged alternately, and a sub-grid is provided on each of the P region and the N region. The sub-grid is connected to the main grid of the corresponding polarity. In order to avoid short circuit, the sub-grid is usually connected to the main grid of the same polarity and disconnected at the main grids of different polarities. For example, the positive sub-grid is disconnected at the negative main grid, and the negative sub-grid is disconnected at the positive main grid. That is, the sub-grid is an intermittent design and is divided into multiple sub-grid segments.

[0004] In the related art, the secondary grid of the back-contact solar cell can be designed by electroplating. For example, a discontinuous secondary grid metal layer can be pre-set in the area where the secondary grid is required, and then electroplating is performed on the secondary grid metal layer through electroplating equipment to form an electroplated layer (for example, copper electroplating), thereby forming the final secondary grid.

[0005] However, in such a case, since the auxiliary grid is designed to be discontinuous, each auxiliary grid is divided into several independent auxiliary grid segments. During the electroplating process, in order to ensure that all auxiliary grid segments have a plating layer, the cathode of the electroplating equipment needs to be connected to each independent auxiliary grid segment in turn or connected to the main grid in contact with the auxiliary grid segments in turn so that all auxiliary grid segments can be plated with a plating layer. The electroplating process is relatively complicated and the electroplating efficiency is low.

[0006] Summary of the Invention

[0007] The present disclosure provides a back-contact solar cell, a cell assembly and a photovoltaic system, aiming to solve the technical problems of relatively complex electroplating process and low electroplating efficiency when electroplating the back electrode of the existing back-contact solar cell.

[0008] The present disclosure is implemented as follows: a back-contact solar cell according to an embodiment of the present disclosure includes a substrate and a back electrode structure provided on a backlight surface of the substrate, wherein the back electrode structure includes:

[0009] a plurality of first auxiliary grids and a plurality of second auxiliary grids spaced apart and alternately arranged in sequence along a first direction, wherein the first auxiliary grid comprises a first auxiliary grid pre-plating layer forming an ohmic contact with the substrate and a first auxiliary grid electroplating layer plated on the first auxiliary grid pre-plating layer, and the second auxiliary grid comprises a second auxiliary grid pre-plating layer forming an ohmic contact with the substrate and a second auxiliary grid electroplating layer plated on the second auxiliary grid pre-plating layer;

[0010] a plurality of first main grids and a plurality of second main grids spaced apart and alternately arranged in sequence along a second direction, the first direction intersecting the second direction, the first main grids contacting the first auxiliary grid pre-plating layer, the first auxiliary grid being disconnected at the second main grid, the second main grids contacting the second auxiliary grid pre-plating layer, and the second auxiliary grid being disconnected at the first main grid; and

[0011] A first conductive connector and a second conductive connector, wherein the first conductive connector and the second conductive connector are respectively arranged at both ends of the first main grid and the second main grid, the first conductive connector connects all ends of the first main grid away from the second conductive connector, and the second conductive connector connects all ends of the second main grid away from the first conductive connector.

[0012] In some exemplary embodiments, the width of the first conductive connection member is greater than the width of the first auxiliary grid pre-plating layer, and the width of the second conductive connection member is greater than the width of the second auxiliary grid pre-plating layer.

[0013] In some exemplary embodiments, the width of the first auxiliary grid pre-plating layer is 0.03 mm-1 mm, and the width of the first conductive connecting member is 0.1 mm-10 mm.

[0014] In some exemplary embodiments, the width of the first auxiliary grid pre-plating layer is 0.03 mm-0.6 mm, and the width of the first conductive connection is 0.1 mm-5 mm.

[0015] In some exemplary embodiments, the width of the second auxiliary grid pre-plating layer is 0.03 mm-1 mm, and the width of the second conductive connecting member is 0.1 mm-10 mm.

[0016] In some exemplary embodiments, the width of the second auxiliary grid pre-plating layer is 0.03-0.6 mm, and the width of the second conductive connecting member is 0.1-5 mm.

[0017] In some exemplary embodiments, the first conductive connection member and the second conductive connection member are both parallel to the first sub-grid pre-plating layer and the second sub-grid pre-plating layer.

[0018] In some exemplary embodiments, the first conductive connection forms an ohmic contact with the substrate; and / or

[0019] The second conductive connecting member forms an ohmic contact with the substrate.

[0020] In some exemplary embodiments, along the first direction, the backlight surface of the substrate has a plurality of electrode arrangement areas, and each of the electrode arrangement areas is provided with the back electrode structure.

[0021] In some exemplary embodiments, in two adjacent back electrode structures, the second conductive connecting members in the two back electrode structures are adjacent to each other.

[0022] In some exemplary embodiments, in two adjacent back electrode structures, two adjacent second conductive connecting members are integrally formed structures.

[0023] In some exemplary embodiments, in two adjacent back electrode structures, the first conductive connection in one of the back electrode structures is adjacent to the second conductive connection in the other back electrode structure.

[0024] In some exemplary embodiments, in two adjacent back electrode structures, the first main grid in one of the back electrode structures is aligned with the first main grid in the other back electrode structure along the first direction, and the second main grid in one of the back electrode structures is aligned with the second main grid in the other back electrode structure along the first direction; or

[0025] The first main gate in one of the back electrode structures is aligned with the second main gate in another of the back electrode structures along the first direction, and the second main gate in one of the back electrode structures is aligned with the first main gate in another of the back electrode structures along the first direction.

[0026] In some exemplary embodiments, the first auxiliary gate pre-plating layer and the second auxiliary gate pre-plating layer both include a seed layer, and the seed layer is manufactured by a physical vapor deposition method.

[0027] In some exemplary embodiments, the seed layer comprises copper, aluminum, or nickel.

[0028] In some exemplary embodiments, the first sub-gate pre-plating layer and the second sub-gate pre-plating layer are made by a light-induced electroplating method or a chemical plating method.

[0029] In some exemplary embodiments, the first auxiliary gate pre-plating layer and the second auxiliary gate pre-plating layer include copper or nickel.

[0030] In some exemplary embodiments, the first main grid includes a first main grid pre-plating layer in contact with the first auxiliary grid pre-plating layer and a first main grid electroplating layer plated on the first main grid pre-plating layer, and the first main grid pre-plating layer is in contact with the first conductive connecting member. The second main grid includes a second main grid pre-plating layer in contact with the second auxiliary grid pre-plating layer and a second main grid electroplating layer plated on the second main grid pre-plating layer, and the second main grid pre-plating layer is in contact with the second conductive connecting member.

[0031] The present disclosure further provides a battery assembly, comprising a plurality of back-contact solar cells as described above; or a plurality of sliced ​​cells obtained by cutting and / or splitting the back-contact solar cells as described above.

[0032] The present disclosure also provides a photovoltaic system, which includes the above-mentioned battery assembly.

[0033] In the back-contact solar cell, battery assembly and photovoltaic system of the embodiments of the present disclosure, through the setting of the first conductive connector and the second conductive connector, the first conductive connector can connect the ends of all the first main grids to communicate with the first auxiliary grid pre-plating layer in contact with the first main grid, and the second conductive connector can connect the ends of all the second main grids to communicate with the second auxiliary grid pre-plating layer in contact with the second main grid. In this way, when forming the first auxiliary grid electroplating layer and the second auxiliary grid electroplating layer, it is only necessary to connect the cathode of the electroplating equipment to the first conductive connector and the second conductive connector respectively to form the first auxiliary grid electroplating layer and the second auxiliary grid electroplating layer on all the first auxiliary grid pre-plating layers and the second auxiliary grid pre-plating layers respectively, without the need to connect the cathode of the electroplating equipment to each first main grid, each second main grid or to each disconnected first auxiliary grid pre-plating layer and second auxiliary grid pre-plating layer in sequence to complete the electroplating process, which effectively simplifies the electroplating process and improves the electroplating efficiency.

[0034] Additional aspects and advantages of the present disclosure will be given in part in the description that follows and, in part, will be obvious from the description that follows, or will be learned through practice of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] FIG1 is a schematic diagram of a module of a photovoltaic system provided by an embodiment of the present disclosure;

[0036] FIG2 is a schematic diagram of a module of a battery assembly provided by an embodiment of the present disclosure;

[0037] FIG3 is a schematic diagram of a planar structure of a back-contact solar cell provided by an embodiment of the present disclosure;

[0038] FIG4 is a schematic cross-sectional view of the back contact solar cell along line IV-IV in FIG3 ;

[0039] FIG5 is another schematic plan view of the back contact solar cell provided by an embodiment of the present disclosure;

[0040] FIG6 is another schematic plan view of the back-contact solar cell provided by an embodiment of the present disclosure;

[0041] FIG7 is another schematic plan view of the back-contact solar cell according to an embodiment of the present disclosure;

[0042] FIG8 is another schematic plan view of the back-contact solar cell according to an embodiment of the present disclosure;

[0043] FIG9 is another schematic plan view of the back-contact solar cell provided by an embodiment of the present disclosure;

[0044] FIG10 is a schematic cross-sectional view of the back contact solar cell along line XX in FIG3 ;

[0045] FIG11 is a schematic diagram of the cross-sectional structure of the back-contact solar cell along line XI-XI in FIG3 .

[0046] Explanation of the main component symbols: Photovoltaic system 1000, battery assembly 200, back contact solar cell 100, substrate 10, silicon wafer 11, first polarity doping layer 12, second polarity doping layer 13, electrode setting area 14, back electrode structure 20, first auxiliary grid 21, first auxiliary grid pre-plating layer 211, first auxiliary grid electroplating layer 212, second auxiliary grid 22, second auxiliary grid pre-plating layer 221, second auxiliary grid electroplating layer 222, first main grid 23, first main grid pre-plating layer 231, first main grid electroplating layer 232, second main grid 24, second main grid pre-plating layer 241, second main grid electroplating layer 242, first conductive connector 30, second conductive connector 40, passivation film layer 50. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solutions and advantages of the present disclosure more clear, the present disclosure is further described in detail below with reference to the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present disclosure and are not to be construed as limiting the present disclosure. In addition, it should be understood that the specific embodiments described herein are only used to explain the present disclosure and are not intended to limit the present disclosure.

[0048] In the description of the present disclosure, it should be understood that the terms "upper", "lower", "horizontal", "longitudinal", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present disclosure.

[0049] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the described features. Throughout the present disclosure, "plurality" means two or more, unless otherwise specifically defined.

[0050] The disclosure below provides many different embodiments or examples for realizing different structures of the present disclosure. In order to simplify the disclosure of the present disclosure, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present disclosure. In addition, the present disclosure may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present disclosure provides examples of various specific processes and materials, but those of ordinary skill in the art will recognize the application of other processes and / or the use scenarios of other materials.

[0051] In the present disclosure, through the arrangement of the first conductive connector and the second conductive connector, the first conductive connector can connect the ends of all the first main grids to communicate with the first sub-grid pre-plating layer in contact with the first main grid, and the second conductive connector can connect the ends of all the second main grids to communicate with the second sub-grid pre-plating layer in contact with the second main grid. In this way, when forming the first sub-grid electroplating layer and the second sub-grid electroplating layer, it is only necessary to connect the cathode of the electroplating equipment to the first conductive connector and the second conductive connector respectively to form the first sub-grid electroplating layer and the second sub-grid electroplating layer on all the first sub-grid pre-plating layers and the second sub-grid pre-plating layers respectively, without having to connect the cathode of the electroplating equipment to each first main grid, each second main grid, or to each disconnected first sub-grid pre-plating layer and second sub-grid pre-plating layer in sequence to complete the electroplating process, which effectively simplifies the electroplating process and improves the electroplating efficiency.

[0052] Example 1

[0053] Please refer to Figures 1 and 2. The photovoltaic system 1000 in the embodiment of the present disclosure may include the battery assembly 200 in the embodiment of the present disclosure. The battery assembly 200 in the embodiment of the present disclosure may include multiple back-contact solar cells 100 in the embodiment of the present disclosure or include multiple sliced ​​cells obtained by cutting and / or splitting the back-contact solar cells 100 in the embodiment of the present disclosure. It should be noted that the sliced ​​cells can be divided into two, three, four, etc., and there is no specific limitation here.

[0054] In the battery assembly 200, multiple back-contact solar cells 100 or multiple sliced ​​cells can be connected in series in sequence to form multiple battery strings. The battery strings can be connected in series, in parallel, or in a combination of series and parallel to achieve current bus output. For example, the connection between the individual battery cells can be achieved by welding welding strips, and the connection between the individual battery strings can be achieved by bus bars.

[0055] 3 and 4 , the back-contact solar cell 100 in the embodiment of the present disclosure may include a substrate 10 and a back electrode structure 20 disposed on the backlight surface of the substrate 10 .

[0056] The substrate 10 may include a silicon wafer 11 and first polarity doped layers 12 and second polarity doped layers 13 alternately disposed on the back side of the silicon wafer 11. The silicon wafer 11 may be a P-type silicon wafer or an N-type silicon wafer, without limitation. The backlight side of the substrate 10 is the back side of the back-contact solar cell 100. The first polarity doped layers 12 and the second polarity doped layers 13 have opposite polarities. For example, the first polarity doped layers 12 may be a P-type doped layer, and the second polarity doped layers 13 may be an N-type doped layer. In another example, the first polarity doped layers 12 may be an N-type doped layer, and the second polarity doped layers 13 may be a P-type doped layer, without limitation.

[0057] 3 , the back electrode structure 20 may include a plurality of first sub-grids 21 , a plurality of second sub-grids 22 , a plurality of first main grids 23 , a plurality of second main grids 24 , a first conductive connector 30 , and a second conductive connector 40 .

[0058] A plurality of first auxiliary gates 21 and a plurality of second auxiliary gates 22 may be spaced apart and alternately arranged along a first direction, and a plurality of first main gates 23 and a plurality of second main gates 24 may be spaced apart and alternately arranged along a second direction, with the first direction intersecting the second direction. The first auxiliary gates 21 may be correspondingly arranged on the first polarity doped layer 12, and the second auxiliary gates 22 may be correspondingly arranged on the second polarity doped layer 13.

[0059] In an embodiment of the present disclosure, the first direction and the second direction may be perpendicular to each other. For example, as shown in FIG3 , the first direction may be the longitudinal direction of the back-contact solar cell 100, and the second direction may be the transverse direction of the back-contact solar cell 100. The first auxiliary grid 21 and the second auxiliary grid 22 may be alternately arranged along the longitudinal direction and extend along the transverse direction, and the first main grid 23 and the second main grid 24 may be alternately arranged along the transverse direction and extend along the longitudinal direction.

[0060] 4 , the first auxiliary grid 21 may include a first auxiliary grid pre-plating layer 211 forming an ohmic contact with the substrate 10 and a first auxiliary grid electroplating layer 212 plated on the first auxiliary grid pre-plating layer 211. The second auxiliary grid 22 may include a second auxiliary grid pre-plating layer 221 forming an ohmic contact with the substrate 10 and a second auxiliary grid electroplating layer 222 plated on the second auxiliary grid pre-plating layer 221. The first main grid 23 contacts the first auxiliary grid pre-plating layer 211, the first auxiliary grid 21 is disconnected at the second main grid 24, the second main grid 24 contacts the second auxiliary grid pre-plating layer 221, and the second auxiliary grid 22 is disconnected at the first main grid 23.

[0061] Specifically, the first auxiliary gate pre-plating layer 211 can form an ohmic contact with the first polarity doped layer 12, and the second auxiliary gate pre-plating layer 221 can form an ohmic contact with the second polarity doped layer 13. The first auxiliary gate 21 is used to collect current in the area of ​​the silicon wafer 11 corresponding to the first polarity doped layer 12, and the second auxiliary gate 22 is used to collect current in the area of ​​the silicon wafer 11 corresponding to the second polarity doped layer 13. As shown in Figure X, the first auxiliary gate 21 is disconnected at the second main gate 24 to form multiple auxiliary gate segments. That is, the second auxiliary gate 22 is disconnected at the first main gate 23 to form multiple auxiliary gate segments.

[0062] It should be noted that, in the present disclosure, the first polarity doping layer 12 and the second polarity doping layer 13 on the silicon wafer 11 can be formed by deposition, laser doping, metal doping, etc., which are not limited here. In addition, in the present disclosure, the first polarity doping layer 12 and the second polarity doping layer 13 may be in direct contact or not, and preferably they are not in direct contact. In such a case, the two can be separated by physical isolation. For example, the first polarity doping layer 12 and the second polarity doping layer 13 can be directly spaced apart. For example, the two can be isolated by opening a groove on the silicon wafer 11. For example, a groove can be opened on the silicon wafer 11 and one of the first polarity doping layer 12 and the second polarity doping layer 13 can be set in the groove to achieve isolation.

[0063] Of course, it can be understood that in some embodiments, the first polarity doping layer 12 and the second polarity doping layer 13 may also be in contact with each other in a local area, or there may be a small part of the first polarity doping layer 12 in the multiple first polarity doping layers 12 and the multiple second polarity doping layers 13 in contact with the second polarity doping layer 13, and there is no specific limitation here.

[0064] Referring to Figure 3 , the first conductive connector 30 and the second conductive connector 40 can be respectively disposed at both ends of the first busbar 23 and the second busbar 24. As shown in Figure 3 , the first conductive connector 30 and the second conductive connector 40 can be respectively disposed at the upper and lower sides of the first busbar 23 and the second busbar 24. The first conductive connector 30 connects the ends of all first busbars 23 facing away from the second conductive connector 40, and the second conductive connector 40 connects the ends of all second busbars 24 facing away from the first conductive connector 30.

[0065] In the back-contact solar cell 100, battery assembly 200 and photovoltaic system 1000 of the embodiment of the present disclosure, the first main grid 23 contacts the first auxiliary grid pre-plating layer 211, the second main grid 24 contacts the second auxiliary grid pre-plating layer 221, and the first conductive connector 30 and the second conductive connector 40 are respectively arranged at the two ends of the first main grid 23 and the second main grid 24. The first conductive connector 30 connects all ends of the first main grid 23 away from the second conductive connector 40, and the second conductive connector 40 connects all ends of the second main grid 24 away from the first conductive connector 30. In this way, through the provision of the first conductive connector 30 and the second conductive connector 40, the first conductive connector 30 can connect the ends of all the first main grids 23 to communicate with the first auxiliary grid pre-plating layer 211 in contact with the first main grid 23, and the second conductive connector 40 can connect the ends of all the second main grids 24 to communicate with the second auxiliary grid pre-plating layer 221 in contact with the second main grid 24. In this way, when forming the first auxiliary grid electroplating layer 212 and the second auxiliary grid electroplating layer 222, it is only necessary to connect the cathode of the electroplating equipment to the first conductive connector 30 and the second conductive connector 40 respectively to form the first auxiliary grid electroplating layer 212 and the second auxiliary grid electroplating layer 222 on all the first auxiliary grid pre-plating layers 211 and the second auxiliary grid pre-plating layers 221 respectively, without having to sequentially connect the cathode of the electroplating equipment to each first main grid 23, each second main grid 24, or sequentially connect to each disconnected first auxiliary grid pre-plating layer 211 and second auxiliary grid pre-plating layer 221 to complete the electroplating process, thereby effectively simplifying the electroplating process and improving the electroplating efficiency.

[0066] In the embodiment of the present disclosure, the first sub-grid electroplating layer 212 and the second sub-grid electroplating layer 222 can both be electroplated copper layers. The first conductive connector 30 and the second conductive connector 40 can be metal connectors with conductive functions. Both can be regular or irregular shapes. For example, in some embodiments, both can be straight lines. Both can be parallel to the first sub-grid 21 and the second sub-grid 22, or can be tilted relative to the first sub-grid 21 and the second sub-grid 22. For example, in some embodiments, both can also be other shapes, such as wavy, arc-shaped, etc., which are not specifically limited here.

[0067] In addition, referring to FIG4 , in some embodiments, a passivation film layer 50 may be provided on the backlight surface of the substrate 10. The passivation film layer 50 covers the entire backlight surface. The first auxiliary gate pre-plating layer 211 penetrates the passivation film layer 50 to form an ohmic contact with the first polarity doped layer 12. The second auxiliary gate pre-plating layer 221 penetrates the passivation film layer 50 to form an ohmic contact with the second polarity doped layer 13. Furthermore, in some embodiments, a tunneling layer (not shown) may be provided between the back surface of the silicon wafer 11 and the first polarity doped layer 12 and the second polarity doped layer 13.

[0068] It is understood that in the embodiments of the present disclosure, the battery assembly 200 may further include a metal frame, a backsheet, photovoltaic glass, and an adhesive film (not shown in the figures). The adhesive film may be filled between the front surface and photovoltaic glass, the back surface and the backsheet, and adjacent cells of the back-contact solar cell 100. As a filler, it may be a transparent colloid with good light transmittance and aging resistance. For example, the adhesive film may be an EVA film or a POE film. The specific selection may be based on actual conditions and is not limited here.

[0069] Photovoltaic glass can cover the adhesive film on the front surface of the back-contact solar cell 100. The photovoltaic glass can be ultra-clear glass, which has high light transmittance, high transparency, and excellent physical, mechanical, and optical properties. For example, ultra-clear glass can have a light transmittance of over 92%, protecting the back-contact solar cell 100 while minimizing the impact on its efficiency. The adhesive film can also bond the photovoltaic glass and back-contact solar cell 100 together, providing sealing, insulation, and waterproofing for the back-contact solar cell 100.

[0070] A backsheet can be attached to the film on the back of the back-contact solar cell 100. The backsheet protects and supports the back-contact solar cell 100, providing reliable insulation, water resistance, and aging resistance. A variety of backsheet options are available, typically including tempered glass, organic glass, and aluminum alloy TPT composite film. The specific configuration depends on the specific situation and is not limited here. The entire assembly consisting of the backsheet, back-contact solar cell 100, film, and photovoltaic glass can be mounted on a metal frame. The metal frame serves as the primary external support structure for the entire battery assembly 200 and provides stable support and installation for the battery assembly 200. For example, the metal frame can be used to install the battery assembly 200 in the desired location.

[0071] Furthermore, in this embodiment, the photovoltaic system 1000 can be applied in photovoltaic power stations, such as ground-based power stations, rooftop power stations, and water-based power stations. It can also be applied to equipment or devices that use solar energy to generate electricity, such as user solar power supplies, solar streetlights, solar cars, and solar buildings. Of course, it is understood that the application scenarios of the photovoltaic system 1000 are not limited to these. In other words, the photovoltaic system 1000 can be applied in all fields that require solar power generation. Taking a photovoltaic power generation system network as an example, the photovoltaic system 1000 may include a photovoltaic array, a combiner box, and an inverter. The photovoltaic array may be an array combination of multiple battery assemblies 200. For example, multiple battery assemblies 200 may form multiple photovoltaic arrays. The photovoltaic arrays are connected to a combiner box, which can combine the current generated by the photovoltaic arrays. The combined current flows through the inverter to convert it into the AC power required by the mains power grid and then connects to the mains power grid to achieve solar power supply.

[0072] In some embodiments, the first auxiliary gate pre-plating layer 211 and the second auxiliary gate pre-plating layer 221 may include a seed layer, which may be formed by physical vapor deposition. In this way, the seed layer can form a stable ohmic contact with the first polarity doping layer 12 and the second polarity doping layer 13.

[0073] Specifically, the seed layer may be a metal material, which may preferably be an alloy material. In some embodiments, the main component of the seed layer may include copper, aluminum, or nickel.

[0074] In some embodiments, the seed layer may include a main component and a strengthening component. The main component may include any one or more of metals such as aluminum, silver, copper, and magnesium, and the strengthening component may include any one or more of various metals such as molybdenum, titanium, tungsten, and nickel. Of course, in some possible embodiments, the seed layer may also be a single metal layer, as long as it can achieve the subsequent electroplating function, and this is not limited here.

[0075] In such an embodiment, a passivation film layer 50 may be first deposited on the substrate 10, and then openings may be formed in the passivation film layer 50 corresponding to the first sub-gate pre-plating layer 211 and the second sub-gate pre-plating layer 221. Then, a seed layer may be deposited at each opening by physical vapor deposition to form the first sub-gate pre-plating layer 211 and the second sub-gate pre-plating layer 221 that form ohmic contacts with the first polarity doping layer 12 and the second polarity doping layer 13, respectively.

[0076] In addition, in some embodiments, the first auxiliary grid pre-plating layer 211 and the second auxiliary grid pre-plating layer 221 can also be formed by a light-induced electroplating method or a chemical plating method, which is not limited herein. In such a case, the first auxiliary grid pre-plating layer 211 and the second auxiliary grid pre-plating layer 221 can be composed of copper or nickel.

[0077] Example 2

[0078] Referring to FIG. 3 , in some embodiments, the width of the first conductive connecting member 30 is greater than the width of the first auxiliary grid pre-plating layer 211 , and the width of the second conductive connecting member 40 is greater than the width of the second auxiliary grid pre-plating layer 221 .

[0079] Thus, setting the width of the first conductive connector 30 and the second conductive connector 40 larger can facilitate the connection of the first conductive connector 30 and the second conductive connector 40 to the cathode of the electroplating equipment, thereby ensuring the reliability of electroplating.

[0080] At the same time, since the first conductive connector 30 connects all the first main grids 23 together and the second conductive connector 40 connects all the second main grids 24 together, compared with the first auxiliary grid pre-plating layer 211 and the second auxiliary grid pre-plating layer 221, the first conductive connector 30 and the second conductive connector 40 need to have better overcurrent capacity to ensure that the first conductive connector 30 and the second conductive connector 40 will not overcurrent and cause melting. Therefore, setting the width of the first conductive connector 30 and the second conductive connector 40 to be larger can also ensure the reliability of the back contact solar cell 100.

[0081] It should be noted that, in this article, "width" refers to the size of each component in the first direction (ie, the longitudinal direction). In the following text, if there is the same description, it can also be understood by reference here.

[0082] Example 3

[0083] In some embodiments, the width of the first auxiliary grid pre-plating layer 211 may be 0.03 mm-1 mm, and the width of the first conductive connection member 30 may be 0.1 mm-10 mm.

[0084] In this way, setting the width of the first sub-grid pre-plating layer 211 within a reasonable range of 0.03mm-1mm can ensure the electroplating effect while forming a reliable ohmic contact with the substrate 10, and setting the width of the first conductive connector 30 within a reasonable range of 0.1mm-10mm can ensure the reliability of the cathode connection with the electroplating equipment while ensuring the current flow capacity of the first conductive connector 30, thereby ensuring the reliability of the back-contact solar cell 100.

[0085] Specifically, in such an embodiment, the width of the first sub-grid pre-plating layer 211 may be, for example, 0.03mm, 0.04mm, 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm or any value between 0.03mm-1mm, and is not limited here.

[0086] The width of the first conductive connection 30 may be, for example, 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm or any value between 0.1mm-10mm, and is not limited here.

[0087] Furthermore, in such an embodiment, the width of the first auxiliary grid pre-plating layer 211 may preferably be 0.03 mm-0.6 mm, and the width of the first conductive connection member 30 may preferably be 0.1 mm-5 mm.

[0088] Specifically, the inventors of the present disclosure have discovered through verification and research that if the width of the first auxiliary grid pre-plating layer 211 is less than 0.03 mm, it will easily lead to unstable ohmic contact between it and the substrate 10, and will also affect the subsequent electroplating effect. If the width of the first auxiliary grid pre-plating layer 211 is greater than 0.6 mm, it will lead to a significant increase in costs. Therefore, setting the width of the first auxiliary grid pre-plating layer 211 within the preferred range of 0.03 mm to 0.6 mm can effectively reduce costs while ensuring contact reliability and electroplating effect.

[0089] Furthermore, the inventors of this disclosure have discovered through verification and research that if the width of the first conductive connector 30 is less than 0.1 mm, poor contact with the electrode can occur during the electroplating process. After the electroplating is completed, the first conductive connector 30 is also prone to overcurrent and melting, reducing the reliability of the back-contact solar cell 100. Furthermore, if the width of the first conductive connector 30 is greater than 5 mm, costs can be significantly increased. Therefore, setting the width of the first conductive connector 30 within the preferred range of 0.1 mm to 5 mm can effectively control costs while ensuring electroplating reliability and the reliability of the back-contact solar cell 100.

[0090] Example 4

[0091] In some embodiments, the width of the second auxiliary grid pre-plating layer 221 may be 0.03 mm-1 mm, and the width of the second conductive connection member 40 may be 0.1 mm-10 mm.

[0092] In this way, setting the width of the second sub-grid pre-plating layer 221 within a reasonable range of 0.03mm-1mm can ensure the electroplating effect while forming a reliable ohmic contact with the substrate 10, and setting the width of the second conductive connector 40 within a reasonable range of 0.1mm-10mm can ensure the reliability of the cathode connection with the electroplating equipment while ensuring the current flow capacity of the second conductive connector 40, thereby ensuring the reliability of the back-contact solar cell 100.

[0093] Specifically, in such an embodiment, the width of the second sub-grid pre-plating layer 221 may be, for example, 0.03mm, 0.04mm, 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm or any value between 0.03mm-1mm, and is not limited here.

[0094] The width of the second conductive connection 40 may be, for example, 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm or any value between 0.1mm-10mm, and is not limited here.

[0095] Furthermore, in such an embodiment, the width of the second auxiliary grid pre-plating layer 221 may preferably be 0.03 mm-0.6 mm, and the width of the second conductive connection member 40 may preferably be 0.1 mm-5 mm.

[0096] Specifically, the inventors of the present disclosure have discovered through verification and research that if the width of the second auxiliary grid pre-plating layer 221 is less than 0.03 mm, it will easily lead to unstable ohmic contact between it and the substrate 10, and will also affect the subsequent electroplating effect. If the width of the second auxiliary grid pre-plating layer 221 is greater than 0.6 mm, it will lead to a significant increase in costs. Therefore, setting the width of the second auxiliary grid pre-plating layer 221 within the preferred range of 0.03 mm to 0.6 mm can effectively reduce costs while ensuring contact reliability and electroplating effect.

[0097] Furthermore, through verification and research, the inventors of the present disclosure have discovered that if the width of the second conductive connector 40 is less than 0.1 mm, poor contact with the electrode can occur during the electroplating process. After the electroplating is completed, the second conductive connector 40 is also prone to overcurrent and melting, reducing the reliability of the back-contact solar cell 100. Furthermore, if the width of the second conductive connector 40 is greater than 5 mm, this can significantly increase costs. Therefore, setting the width of the second conductive connector 40 within the preferred range of 0.1 mm to 5 mm can effectively control costs while ensuring electroplating reliability and the reliability of the back-contact solar cell 100.

[0098] Example 5

[0099] 3 , in some embodiments, the first conductive connector 30 and the second conductive connector 40 are parallel to the first auxiliary grid pre-plating layer 211 and the second auxiliary grid pre-plating layer 221. This arrangement can avoid the first conductive connector 30 and the second conductive connector 40 being arranged at an angle, which would occupy a larger space and increase the size of the back-contact solar cell 100.

[0100] Example 6

[0101] In some embodiments, the first conductive connector 30 can form an ohmic contact with the substrate 10. Specifically, the first polarity doped layer 12 can be disposed in the region corresponding to the first conductive connector 30, and the first conductive connector 30 can penetrate the passivation film 50 to form an ohmic contact with the corresponding first polarity doped layer 12.

[0102] In this way, the first conductive connection member 30 can connect to the first main grid 23 and also collect carriers in the silicon wafer 11 , thereby effectively improving efficiency.

[0103] Similarly, in some embodiments, the second conductive connector 40 may also form an ohmic contact with the substrate 10. Specifically, the second polarity doped layer 13 may be disposed in the region corresponding to the second conductive connector 40, and the second conductive connector 40 may penetrate the passivation film 50 to form an ohmic contact with the corresponding second polarity doped layer 13.

[0104] In this way, the second conductive connection member 40 can connect to the second main grid 24 and also realize the function of collecting carriers in the silicon wafer 11, which can effectively improve the efficiency.

[0105] Of course, it is understood that in other embodiments, the first conductive connector 30 may not be in contact with the substrate 10, but may be connected to the first main grid 23 and suspended from the substrate 10. Similarly, in some embodiments, the second conductive connector 40 may not be in contact with the silicon wafer 11, but may be connected to the second main grid 24 and suspended from the substrate 10. In such cases, the first conductive connector 30 and the second conductive connector 40 may be directly suspended or disposed on the passivation film layer 50 without penetrating the passivation film layer 50.

[0106] Example 7

[0107] 5 to 9 , along the first direction, the backlight surface of the substrate 10 may have a plurality of electrode arrangement regions 14 , and each electrode arrangement region 14 is provided with a back electrode structure 20 .

[0108] In this way, the backlight surface of the substrate 10 is divided into several electrode setting areas 14, and a back electrode structure 20 is set in each area. The back contact solar cell 100 can be cut and / or split subsequently to divide the back contact solar cell 100 into multiple sliced ​​cells. That is, the first sub-grid pre-plating layer 211 and the second sub-grid pre-plating layer 221 in all the electrode setting areas 14 can be electroplated through a plating process, and then divided to obtain sliced ​​cells.

[0109] Specifically, as shown in FIG5 to FIG8 , in the embodiments shown in FIG5 to FIG8 , the back contact solar cell 100 may have two electrode setting areas 14 . In this case, two sliced ​​cells can be obtained after being divided.

[0110] In the embodiment shown in FIG9 , the back-contact solar cell 100 may have three electrode arrangement regions 14. In this case, after segmentation, three-piece sliced ​​cells can be obtained. Of course, the back-contact solar cell 100 may also have three or more electrode arrangement regions 14. In this way, more sliced ​​cells can be obtained after segmentation. In other words, when the number of electrode arrangement regions 14 is N (N is a positive integer greater than 1), N-piece sliced ​​cells can be obtained after segmentation.

[0111] Example 8

[0112] Referring to FIG. 5 , in some embodiments, in two adjacent back electrode structures 20 , the second conductive connecting members 40 in the two back electrode structures 20 are adjacent to each other.

[0113] In this way, the second conductive connectors 40 of two adjacent back electrode structures 20 are adjacent. When it is necessary to divide the cells into slices, the cells can be divided along the space between the two second conductive connectors 40 to obtain sliced ​​cells. After the division is completed, the sliced ​​cells can be connected by welding ribbons to form a cell string. When it is not necessary to divide the cells into slices, the two adjacent second conductive connectors 40 can be directly connected by welding ribbons or bus bars to connect the adjacent back electrode structures 20.

[0114] Further, referring to FIG. 6 , in such an embodiment, when the back contact solar cell 100 does not need to be divided, two adjacent second conductive connectors 40 can be an integrally formed structure, that is, two adjacent back electrode structures 20 share one second conductive connector 40 .

[0115] Embodiment 9

[0116] Referring to FIG. 7 , in some embodiments, among two adjacent back electrode structures 20 , the first conductive connecting member 30 in one back electrode structure 20 is adjacent to the second conductive connecting member 40 in the other back electrode structure 20 .

[0117] In this way, in two adjacent back electrode structures 20, the first conductive connector 30 is adjacent to the second conductive connector 40. In this case, after being divided along the interval between the first conductive connector 30 and the second conductive connector 40 to form sliced ​​cells, they are connected in series to obtain a cell string.

[0118] It should be noted that when the back-contact solar cell 100 has only two electrode arrangement regions 14 , their arrangement can be arranged according to the arrangement of the eighth or ninth embodiment.

[0119] When the back contact solar cell 100 has more than two electrode setting areas 14, two adjacent back electrode structures 20 can be arranged in the manner of Example 8, and another two adjacent back electrode structures 20 can be arranged in the manner of Example 9.

[0120] For example, when the number of electrode setting areas 14 is three, as shown in Figure 9, the second conductive connector 40 in the first back electrode structure 20 from top to bottom may be adjacent to the second conductive connector 40 in the second back electrode structure 20, and the first conductive connector 30 in the third back electrode structure 20 is adjacent to the first conductive connector 30 in the second back electrode structure 20.

[0121] Of course, it is understood that the arrangement can also be such that, from top to bottom, the second conductive connector 40 in the first back electrode structure 20 is adjacent to the first conductive connector 30 in the second back electrode structure 20, while the second conductive connector 40 in the third back electrode structure 20 is adjacent to the first conductive connector 30 in the second back electrode structure 20. In the present disclosure, there is no limitation on the arrangement of the multiple back electrode structures 20. Of course, to facilitate consistency in manufacturing, it is preferred to adopt the arrangement described in Example 8 or Example 9.

[0122] Example 10

[0123] Please refer to Figures 5 to 7. In some embodiments, in two adjacent back electrode structures 20, the first main gate 23 in one back electrode structure 20 is aligned with the first main gate 23 in the other back electrode structure 20 along the first direction, and the second main gate 24 in one back electrode structure 20 is aligned with the second main gate 24 in the other back electrode structure 20 along the first direction.

[0124] In this way, since the first main grids 23 and the second main grids 24 in the two adjacent back electrode structures 20 are aligned, after the back contact solar cell 100 is divided into sliced ​​cells, some of the sliced ​​cells can be rotated 180° so that the main grids of the same polarity between the sliced ​​cells are aligned for subsequent welding process to obtain a cell string.

[0125] In addition, referring to Figure 8, in some embodiments, in two adjacent back electrode structures 20, the first main gate 23 in one back electrode structure 20 is aligned with the second main gate 24 in the other back electrode structure 20 along the first direction, and the second main gate 24 in one back electrode structure 20 is aligned with the first main gate 23 in the other back electrode structure 20 along the first direction.

[0126] In this way, since the first main grid 23 and the second main grid 24 in the two adjacent back electrode structures 20 are aligned, after the back contact solar cell 100 is divided into sliced ​​cells, the first main grid 23 and the second main grid 24 of the two adjacent sliced ​​cells can be directly connected by welding strips to form a cell string without rotating the sliced ​​cells, eliminating the process of rotating the sliced ​​cells, saving costs, and improving production efficiency.

[0127] It can be understood that, in the embodiment of the present disclosure, welding spots may be provided on both the first main grid 23 and the second main grid 24 for welding welding strips.

[0128] Example 11

[0129] Referring to Figures 10 and 11, in some embodiments, the first main gate 23 may include a first main gate pre-plating layer 231 in contact with the first auxiliary gate pre-plating layer 211 and a first main gate electroplating layer 232 plated on the first main gate pre-plating layer 231, the first main gate pre-plating layer 231 is in contact with the first conductive connector 30, the second main gate 24 includes a second main gate pre-plating layer 241 in contact with the second auxiliary gate pre-plating layer 221 and a second main gate electroplating layer 242 plated on the second main gate pre-plating layer 241, the second main gate pre-plating layer 241 is in contact with the second conductive connector 40.

[0130] In this way, all the first main grid pre-plating layers 231 can be connected together through the first conductive connector 30, and all the second main grid pre-plating layers 241 can be connected together through the second conductive connector 40. When forming the first main grid electroplating layer 232 and the second main grid electroplating layer 242, it is only necessary to connect the cathode of the electroplating equipment with the first conductive connector 30 and the second conductive connector 40 to simultaneously plate the electroplating layer on the first sub-grid pre-plating layer 211, the second sub-grid pre-plating layer 221, the first main grid pre-plating layer 231 and the second main grid pre-plating layer 241 without the need for sequential electroplating, which can simplify the electroplating process and improve the electroplating efficiency.

[0131] Specifically, in such an embodiment, the first busbar electroplating layer 232 and the second busbar electroplating layer 242 may also be electroplated copper layers. Similar to the first auxiliary gate pre-plating layer 211 and the second auxiliary gate pre-plating layer 221, in some embodiments, the first busbar pre-plating layer 231 and the second busbar pre-plating layer 241 may each include a seed layer, which may be formed by physical vapor deposition. This allows the seed layer to form a stable ohmic contact with the first polarity doped layer 12 and the second polarity doped layer 13.

[0132] Specifically, the seed layer may be a metal material, which may preferably be an alloy material. In some embodiments, the main component of the seed layer may include copper, aluminum, or nickel.

[0133] It is understood that in some embodiments, the seed layer may include a main component and a strengthening component. The main component may be one or more of aluminum, silver, copper, and magnesium, and the strengthening component may include one or more of various metals such as molybdenum, titanium, tungsten, and nickel. Of course, in some possible embodiments, the seed layer may also be a single metal layer, as long as it can achieve the subsequent electroplating function, and this is not limited here.

[0134] In such an embodiment, a passivation film layer 50 can be deposited on the substrate 10, and then openings are made on the passivation film layer 50 in areas corresponding to the first main gate pre-coating layer 231 and areas corresponding to the second main gate pre-coating layer 241. Then, a seed layer is deposited at each opening by physical vapor deposition to enable the first main gate pre-coating layer 231 and the second main gate pre-coating layer 241 to form ohmic contacts with the first polarity doping layer 12 and the second polarity doping layer 13, respectively.

[0135] Furthermore, in some embodiments, the first busbar pre-plating layer 231 and the second busbar pre-plating layer 241 may also be formed by light-induced electroplating or chemical plating, without limitation. In such cases, the first busbar pre-plating layer 231 and the second busbar pre-plating layer 241 may contain copper or nickel.

[0136] Throughout this specification, references to terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" indicate that a specific feature, structure, material, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, illustrative uses of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0137] In addition, the above description is only a preferred embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present disclosure should be included in the scope of protection of the present disclosure.

Claims

1. A back contact solar cell, wherein: The invention comprises a substrate and a back electrode structure arranged on a backlight surface of the substrate, wherein the back electrode structure comprises: A plurality of first sub-grids and a plurality of second sub-grids are spaced and alternately arranged in sequence along a first direction, wherein the first sub-grid comprises a first sub-grid pre-plating layer forming an ohmic contact with the substrate and a first sub-grid electroplating layer plated on the first sub-grid pre-plating layer, and the second sub-grid comprises a second sub-grid pre-plating layer forming an ohmic contact with the substrate and a second sub-grid electroplating layer plated on the second sub-grid pre-plating layer; A plurality of first main grids and a plurality of second main grids are alternately arranged in sequence and at intervals along a second direction, the first direction intersects with the second direction, the first main grid is in contact with the first auxiliary grid pre-plating layer, the first auxiliary grid is disconnected at the second main grid, the second main grid is in contact with the second auxiliary grid pre-plating layer, and the second auxiliary grid is disconnected at the first main grid; and A first conductive connector and a second conductive connector, wherein the first conductive connector and the second conductive connector are respectively arranged at both ends of the first main grid and the second main grid, the first conductive connector connects all ends of the first main grid away from the second conductive connector, and the second conductive connector connects all ends of the second main grid away from the first conductive connector.

2. The back contact solar cell according to claim 1, wherein: The width of the first conductive connecting member is greater than the width of the first auxiliary grid pre-plating layer, and the width of the second conductive connecting member is greater than the width of the second auxiliary grid pre-plating layer.

3. The back contact solar cell according to claim 1, wherein: The width of the first auxiliary grid pre-plating layer is 0.03 mm-1 mm, and the width of the first conductive connecting member is 0.1 mm-10 mm.

4. The back contact solar cell according to claim 3, wherein: The width of the first auxiliary grid pre-plating layer is 0.03 mm-0.6 mm, and the width of the first conductive connecting member is 0.1 mm-5 mm.

5. The back contact solar cell according to claim 1, wherein: The width of the second sub-grid pre-plating layer is 0.03 mm-1 mm, and the width of the second conductive connecting member is 0.1 mm-10 mm.

6. The back contact solar cell according to claim 5, wherein: The width of the second auxiliary grid pre-plating layer is 0.03-0.6 mm, and the width of the second conductive connecting member is 0.1-5 mm.

7. The back contact solar cell according to claim 1, wherein: The first conductive connecting member and the second conductive connecting member are both parallel to the first auxiliary grid pre-plating layer and the second auxiliary grid pre-plating layer.

8. The back contact solar cell according to claim 1, wherein: The first conductive connecting member forms an ohmic contact with the substrate; and / or The second conductive connection member forms an ohmic contact with the substrate.

9. The back contact solar cell according to any one of claims 1 to 8, wherein: Along the first direction, the backlight surface of the substrate is provided with a plurality of electrode arrangement areas, and each of the electrode arrangement areas is provided with the back electrode structure.

10. The back contact solar cell according to claim 9, wherein: In two adjacent back electrode structures, the second conductive connecting members in the two back electrode structures are adjacent to each other.

11. The back contact solar cell according to claim 10, wherein: In two adjacent back electrode structures, two adjacent second conductive connecting members are an integrally formed structure.

12. The back contact solar cell according to claim 9, wherein: In two adjacent back electrode structures, the first conductive connecting member in one of the back electrode structures is adjacent to the second conductive connecting member in the other back electrode structure.

13. The back contact solar cell according to claim 9, wherein: In two adjacent back electrode structures, the first main grid in one of the back electrode structures is aligned with the first main grid in the other back electrode structure along the first direction, and the second main grid in one of the back electrode structures is aligned with the second main grid in the other back electrode structure along the first direction; or The first main gate in one of the back electrode structures is aligned with the second main gate in another of the back electrode structures along the first direction, and the second main gate in one of the back electrode structures is aligned with the first main gate in another of the back electrode structures along the first direction.

14. The back contact solar cell according to claim 1, wherein: The first auxiliary grid pre-plating layer and the second auxiliary grid pre-plating layer both include a seed layer, and the seed layer is made by a physical vapor deposition method.

15. The back contact solar cell according to claim 14, wherein: The seed layer comprises copper, aluminum or nickel.

16. The back contact solar cell according to claim 1, wherein: The first sub-grid pre-plating layer and the second sub-grid pre-plating layer are made by a light-induced electroplating method or a chemical plating method.

17. The back contact solar cell according to claim 16, wherein: The first sub-grid pre-plating layer and the second sub-grid pre-plating layer contain copper or nickel.

18. The back contact solar cell according to claim 1, wherein: The first main grid includes a first main grid pre-plating layer in contact with the first auxiliary grid pre-plating layer and a first main grid electroplating layer plated on the first main grid pre-plating layer, and the first main grid pre-plating layer is in contact with the first conductive connecting member. The second main grid includes a second main grid pre-plating layer in contact with the second auxiliary grid pre-plating layer and a second main grid electroplating layer plated on the second main grid pre-plating layer, and the second main grid pre-plating layer is in contact with the second conductive connecting member.

19. A battery assembly, wherein: The method comprises a plurality of back-contact solar cells according to any one of claims 1 to 18; or comprises a plurality of sliced ​​cells obtained by cutting and / or splitting the back-contact solar cells according to any one of claims 1 to 18.

20. A photovoltaic system, wherein: A battery assembly comprising the battery assembly of claim 19.

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