Back contact solar cells, cell strings, cell modules, and photovoltaic systems

Abstract

The embodiment of the present application discloses a back contact solar cell, a cell string, a cell module and a photovoltaic system. The back contact solar cell comprises: a silicon substrate, a first surface and a second surface oppositely arranged; a first doped layer; a second doped layer; a first fine grid and a second fine grid alternately arranged along a first direction; a preset gap between the first fine grid and the second fine grid along a second direction; and a first relationship between the preset gap and the adjacent first fine grid and second fine grid along the second direction; and the silver content of the first fine grid and the second fine grid is less than 1%. The technical scheme of the embodiment of the present application can reduce the shading of the fine grid, improve the power generation capacity of the back contact solar cell, and reduce the manufacturing cost.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, and in particular to a back-contact solar cell, a cell string, a cell module, and a photovoltaic system. Background Technology

[0002] Solar cells are used to directly convert sunlight into electrical energy. With the continuous development of photovoltaic technology, solar cell products, as semiconductor devices that convert solar energy into electrical energy, have been rapidly developed, with a focus on low cost and high efficiency. Among them, back-contact (BC) cells have no grid lines on the light-facing side of the cell, and both the positive and negative electrodes are located on the back side of the cell. Therefore, BC cells have high front-side power, improving their energy conversion efficiency. However, since the current is transmitted through the grid lines on the back side of the BC cell, grid lines with a large cross-sectional area are required to reduce power loss in the BC cell.

[0003] However, using grid lines with larger cross-sectional areas not only increases costs but also increases shading of the BC battery's backlight surface, thus affecting the BC battery's backlight surface power generation capacity. Summary of the Invention

[0004] This invention provides a back-contact solar cell, a cell string, a cell module, and a photovoltaic system to improve the power generation capacity of back-contact solar cells and reduce manufacturing costs.

[0005] According to one aspect of the present invention, a back-contact solar cell is provided, the back-contact solar cell comprising:

[0006] A silicon substrate, including a first surface and a second surface disposed opposite to each other; the silicon substrate is configured with a first conductivity type;

[0007] A first doped layer, configured with a first conductivity type, is located on a first surface; a second doped layer, configured with a second conductivity type, is located on the first surface; on the first surface, the first doped layer and the second doped layer extend along a first direction and are alternately arranged along a second direction;

[0008] A first fine gate is located on the side of the first doped layer away from the first surface and is in contact with the first doped layer; a second fine gate is located on the side of the second doped layer away from the first surface and is in contact with the second doped layer; the first fine gate and the second fine gate extend along a first direction and are alternately arranged along a second direction;

[0009] Along the second direction, there is a preset gap between the first and second fine grids; and along the second direction, there is a first relationship between the preset gap and the adjacent first and second fine grids:

[0010] ;

[0011] Where L is the preset gap, L1 is the width of the first fine grid at any position in the first direction, and L2 is the width of the second fine grid at the same position as L1 in the first direction.

[0012] The silver content of both the first and second fine gates is less than one percent.

[0013] Optionally, the silver content of both the first and second fine gates is 0.

[0014] Optionally, along the second direction, the preset gap is greater than or equal to 100 micrometers and less than or equal to 400 micrometers.

[0015] Optionally, the back-contact solar cell also includes:

[0016] The first busbar is located on the side of the first fine gate away from the first doped layer and is in contact with the first fine gate; the second busbar is located on the side of the second fine gate away from the second doped layer and is in contact with the second fine gate; the first busbar and the second busbar extend along the second direction and are alternately arranged along the first direction;

[0017] Along the first direction, the first fine grid includes a first end connected to the first busbar and a second end disposed opposite to the first end; the second fine grid includes a third end connected to the second busbar and a fourth end disposed opposite to the third end;

[0018] Along the second direction, the width of the first end is greater than 1.5 times the width of the second end; and / or, along the second direction, the width of the third end is greater than 1.5 times the width of the fourth end.

[0019] Optionally, at any position between adjacent first and second busbars along the first direction, the sum of the widths of adjacent first and second grids along the second direction is the same.

[0020] Optionally, at any position in the first direction, the preset gap along the second direction remains unchanged.

[0021] Optionally, at any position between adjacent first and second busbars along the first direction, the sum of the widths of adjacent first and second fine gates along the second direction is greater than or equal to 250 micrometers and less than or equal to 800 micrometers.

[0022] Optionally, the first busbar includes a first solder strip, and the second busbar includes a second solder strip;

[0023] Along the second direction, the first solder strip contacts the first fine grid and is isolated from the second fine grid by an insulating layer; the second solder strip contacts the second fine grid and is isolated from the first fine grid by an insulating layer; the insulating layer includes insulating adhesive or insulating film.

[0024] Optionally, the first busbar includes a first main grid and a third solder strip, and the second busbar includes a second main grid and a fourth solder strip;

[0025] Along the second direction, the first main gate contacts the third solder strip; the second main gate contacts the fourth solder strip.

[0026] Optionally, along the first direction, the width of the first fine grid in the second direction gradually decreases from the first end to the second end;

[0027] and / or;

[0028] Along the first direction, the width of the second fine grid gradually decreases from the third end to the fourth end in the second direction.

[0029] Optionally, along the first direction, the width of the first fine grid in the second direction decreases in a stepped manner from the first end to the second end, having at least one step.

[0030] and / or;

[0031] Along the first direction, the width of the second fine grid in the second direction decreases in a stepped manner from the third end to the fourth end, with at least one step.

[0032] Optionally, the width difference between two adjacent steps along the first direction is greater than or equal to 20 micrometers and less than or equal to 150 micrometers in the second direction.

[0033] Optionally, along the second direction, the width of the first end is greater than or equal to 200 micrometers and less than or equal to 700 micrometers; the width of the second end is greater than or equal to 80 micrometers and less than or equal to 300 micrometers.

[0034] Optionally, along the second direction, the width of the third end is greater than or equal to 200 micrometers and less than or equal to 700 micrometers; the width of the fourth end is greater than or equal to 80 micrometers and less than or equal to 300 micrometers.

[0035] Optionally, along the second direction, the width of the first end is equal to the width of the third end; the width of the second end is equal to the width of the fourth end.

[0036] According to another aspect of the present invention, a battery string is provided, including a back-contact solar cell according to any embodiment of the present invention.

[0037] According to another aspect of the present invention, a battery assembly is provided, including a back-contact solar cell or a battery string according to any embodiment of the present invention.

[0038] According to another aspect of the present invention, a photovoltaic system is provided, including a battery module according to any embodiment of the present invention.

[0039] The technical solution of this invention, by setting a preset gap between the first and second fine grids, and ensuring a first relationship between the preset gap and the widths of the first and second fine grids, guarantees the power generation capacity of the back-contact solar cell while preventing leakage and short circuits, thus improving the reliability of the back-contact solar cell. Furthermore, the silver content of both the first and second fine grids is less than one percent, achieving low-silver-content grid line fabrication. Copper paste technology can be applied to fabricate the first and second fine grids by coating copper particles, saving manufacturing costs.

[0040] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a schematic diagram of the back surface structure of a back-contact solar cell according to an embodiment of the present invention;

[0043] Figure 2 It is provided according to the embodiments of the present invention. Figure 1 A schematic diagram of the cross-sectional structure along the second direction Y.

[0044] Figure 3 This is a schematic diagram of the back surface structure of another back-contact solar cell according to an embodiment of the present invention;

[0045] Figure 4 This is a schematic diagram of an adjacent first fine gate and second fine gate structure provided according to an embodiment of the present invention. Detailed Implementation

[0046] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0047] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0048] Figure 1 This is a schematic diagram of the back surface structure of a back-contact solar cell according to an embodiment of the present invention. Figure 2 It is provided according to the embodiments of the present invention. Figure 1 A schematic diagram of the cross-sectional structure along the second direction Y. (See diagram below.) Figure 1 and Figure 2 As shown, the back-contact solar cell 100 includes: a silicon substrate 10, including a first surface 101 and a second surface 102 disposed opposite to each other; the silicon substrate 10 is configured with a first conductivity type; a first doped layer 20, configured with the first conductivity type, and located on the first surface 101; a second doped layer 30, configured with the second conductivity type, and located on the first surface 101; on the first surface 101, the first doped layer 20 and the second doped layer 30 extend along a first direction X and are alternately disposed along a second direction Y; a first fine grid 40 is located on the side of the first doped layer 20 away from the first surface 101 and is in contact with the first doped layer 20; a second fine grid 50 is located on the side of the second doped layer 30 away from the first surface 101 and is in contact with the second doped layer 30; the first fine grid 40 and the second fine grid 50 extend along the first direction X and are alternately disposed along the second direction Y; along the second direction Y, there is a preset gap L between the first fine grid 40 and the second fine grid 50; and along the second direction Y, there is a first relationship between the preset gap and adjacent first fine grid 40 and second fine grid 50:

[0049] ;

[0050] Wherein, L is the preset gap, L1 is the width of the first fine gate 40 at any position in the first direction X, and L2 is the width of the second fine gate 50 at the same position as L1 in the first direction X; the silver content of both the first fine gate 40 and the second fine gate 50 is less than one percent.

[0051] Specifically, the back-contact solar cell 100 includes a silicon substrate 10. The silicon substrate 10 includes a first surface 101 and a second surface 102. For example, the first surface 101 can be a non-light-receiving surface (backlight surface), and the second surface 102 can be a light-receiving surface. The light-receiving surface is the side that receives illumination from a light source, while the backlight surface is located on the side opposite to the light-receiving surface. The first doped layer 20 and the second doped layer 30 are both disposed on the backlight surface of the silicon substrate 10, i.e., the first surface 101. The first doped layer 20 and the second doped layer 30 can also be alternately disposed on the backlight surface of the silicon substrate 10.

[0052] The second doped layer 30 has an opposite conductivity type to the silicon substrate 10, while the first doped layer 20 has the same conductivity type as the silicon substrate 10. The first conductivity type can be N-type or P-type; and the first conductivity type is opposite to the second conductivity type. When the first conductivity type is N-type, the second conductivity type is P-type; when the first conductivity type is P-type, the second conductivity type is N-type. For example, the silicon substrate 10 can be an N-type silicon substrate, the first doped layer 20 can be an N-type doped layer, and the second doped layer 30 can be a P-type doped layer. Alternatively, the silicon substrate 10 can be a P-type silicon substrate, the first doped layer 20 can be a P-type doped layer, and the second doped layer 30 can be an N-type doped layer. The P-type dopant can be at least one of boron (B), aluminum (Al), or gallium (Ga), and this invention does not specifically limit its composition. The N-type dopant can be at least one of phosphorus (P), arsenic (As), or antimony (Sb), and this invention does not specifically limit its composition.

[0053] For example, the silicon substrate 10 can be an N-type silicon substrate, the first doped layer 20 can be an N-type polycrystalline silicon doped layer, and the second doped layer 30 can be a P-type polycrystalline silicon doped layer. The first doped layer 20 is used to collect electrons, and the second doped layer 30 is used to collect holes. The collected carriers are then transferred to electrodes connected to the first doped layer 20 and the second doped layer 30, respectively, forming a path with the external load. Therefore, the first doped layer 20 and the second doped layer 30 cannot be in direct contact; otherwise, the carriers cannot be effectively collected.

[0054] Along the second direction Y, a predetermined gap L exists between the first fine grid 40 and the second fine grid 50. This predetermined gap L is greater than or equal to the absolute value of half the difference between the width L1 of the first fine grid 40 and the width L2 of the second fine grid 50 at any position in the first direction X, and less than or equal to the square root of the product of the width L1 of the first fine grid 40 and the width L2 of the second fine grid 50 at any position in the first direction X. This arrangement prevents leakage and short circuits, improving the reliability of the back-contact solar cell. Furthermore, the silver content of both the first fine grid 40 and the second fine grid 50 is less than one percent, meaning their silver content is relatively low. Copper paste technology can be used to prepare the first fine grid 40 and the second fine grid 50 by coating copper particles, reducing the manufacturing cost of the grid lines.

[0055] The technical solution of this invention, by setting a preset gap between the first and second fine grids, and ensuring a first relationship between the preset gap and the widths of the first and second fine grids, guarantees the power generation capacity of the back-contact solar cell while preventing leakage and short circuits, thus improving the reliability of the back-contact solar cell. Furthermore, the silver content of both the first and second fine grids is less than one percent, achieving low-silver-content grid line fabrication. Copper paste technology can be applied to fabricate the first and second fine grids by coating copper particles, saving manufacturing costs.

[0056] In an optional embodiment of the present invention, the silver content of both the first fine gate 40 and the second fine gate 50 is 0.

[0057] Specifically, the silver content of both the first fine gate 40 and the second fine gate 50 is 0, achieving silver-free fine gate fabrication and reducing manufacturing costs. It should be noted that the 0 silver content of the first fine gate 40 and the second fine gate 50 is a relative concept. Even if the first fine gate 40 and the second fine gate 50 are made of copper or other metals, silver can still exist as a trace element. However, the trace amount of silver is negligible here. Therefore, this embodiment of the invention describes the silver content of both the first fine gate 40 and the second fine gate 50 as 0.

[0058] In an optional embodiment of the present invention, along the second direction Y, the preset gap L is greater than or equal to 100 micrometers and less than or equal to 400 micrometers.

[0059] In an optional embodiment of the present invention, reference is made to... Figure 1 and Figure 2The back-contact solar cell further includes: a first busbar 60 located on the side of the first fine grid 40 away from the first doped layer 20 and in contact with the first fine grid 40; a second busbar 70 located on the side of the second fine grid 50 away from the second doped layer 30 and in contact with the second fine grid 50; the first busbar 60 and the second busbar 70 extend along a second direction Y and are alternately arranged along a first direction X; along the first direction X, the first fine grid 40 includes a first end 401 connected to the first busbar 60 and a second end 402 disposed opposite to the first end 401; the second fine grid 50 includes a third end 501 connected to the second busbar 70 and a fourth end 502 disposed opposite to the third end 501; along the second direction Y, the width of the first end 401 is greater than 1.5 times the width of the second end 402; and / or, along the second direction Y, the width of the third end 501 is greater than 1.5 times the width of the fourth end 502.

[0060] The first busbar 60 contacts the first fine grid 40, and the second busbar 70 contacts the second fine grid 50, enabling the first and second fine grids 40 and 50 to collect charge carriers, and the first and second busbars 60 and 70 to produce electrode structures. Along the second direction Y, the connection points (first end 401) between the first fine grid 40 and the first busbar 60, and (third end 501) between the second fine grid 50 and the second busbar 70, are key nodes for current collection, where the current density is much higher than at the second end 402 and the fourth end 502. By designing a gradient width for the fine grids and setting the width of the first end 401 to be 1.5 times greater than the width of the second end 402, and the width of the third end 501 to be 1.5 times greater than the width of the fourth end 502, the contact resistance at the connection points can be effectively reduced, losses during current transmission can be decreased, current collection efficiency can be improved, and thus the power generation capacity of the back-contact solar cell can be increased.

[0061] In the technical solution of this invention embodiment, the carriers collected by the first fine grid 40 flow to the first end 401 through the second end 402, and the carriers collected by the second fine grid 50 flow to the third end 501 through the fourth end 502. They converge to the first busbar 60 and the second busbar 70 through the first end 401 and the third end 501, respectively. The current at the fine grid port farther from the busbar is smaller, while the current at the fine grid port closer to the busbar is larger. That is, the current at the first end 401 and the third end 501 is larger. Therefore, along the second direction Y, the width of the first end 401 is set to be greater than 1.5 times the width of the second end 402, and the width of the third end 501 is greater than 1.5 times the width of the fourth end 502. This can not only effectively reduce the contact resistance of the connection end, reduce the loss in the current transmission process, and ensure the current collection efficiency, but also save manufacturing costs by saving the amount of the first fine grid 40 and the second fine grid 50. At the same time, it can reduce the shading of the solar cell by the first fine grid 40 and the second fine grid 50, and improve the power generation capacity of the back contact solar cell.

[0062] In an optional embodiment of the present invention, reference is made to... Figure 1 and Figure 2 At any position between adjacent first busbars 60 and second busbars 70 along the first direction X, the sum of the widths of adjacent first grids 40 and second grids 50 along the second direction Y is the same.

[0063] Specifically, at any position between adjacent first busbars 60 and second busbars 70 along the first direction X, such as Figure 1 As shown in Figures 11, 12, and 13, the sum of the widths of adjacent first fine gates 40 and second fine gates 50 along the second direction Y is the same. The core function of the fine gate is to collect photogenerated carriers and transport them to the current collector. The current density is directly related to the width of the fine gate (wide gate lines have strong current carrying capacity and low current density; narrow gate lines have weak current carrying capacity and high current density). The fact that the sum of the widths of adjacent first fine gates 40 and second fine gates 50 along the second direction Y ensures that the total current carrying capacity of each group of adjacent fine gates remains constant in the first direction X. The current can be evenly distributed among adjacent fine gates, balancing the current density, avoiding local current concentration, and reducing losses. At the same time, this setting can optimize the distribution of light absorption, avoid local light-blocking imbalance, and simplify process control and improve mass production consistency in the screen printing process for fabricating fine gates.

[0064] In an optional embodiment of the present invention, reference is made to... Figure 1 and Figure 2 At any position in the first direction X, the preset gap L along the second direction Y remains unchanged.

[0065] This configuration ensures consistent carrier collection paths, reduces transmission losses, prevents local power generation efficiency differences caused by excessively narrow or wide pre-set gaps L, and guarantees stable overall output power of the back-contact solar cell.

[0066] In an optional embodiment of the present invention, reference is made to... Figure 1 and Figure 2 At any position between adjacent first busbars 60 and second busbars 70 along the first direction X, the sum of the widths of adjacent first grids 40 and second grids 50 along the second direction Y is greater than or equal to 250 micrometers and less than or equal to 800 micrometers.

[0067] Specifically, a lower limit is set for the sum of the widths of adjacent first fine gates 40 and second fine gates 50 along the second direction Y. This ensures that the total current-carrying capacity of adjacent first fine gates 40 and second fine gates 50 is not less than the maximum generation rate of photogenerated carriers, avoiding insufficient current-carrying capacity and ensuring current transmission efficiency. An upper limit is set for the sum of the widths of adjacent first fine gates 40 and second fine gates 50 along the second direction Y. This avoids excessively large shading areas, ensuring light absorption efficiency, reducing shading losses, and controlling manufacturing costs. It also avoids excessively small gate gaps, ensuring process feasibility.

[0068] In an optional embodiment of the present invention, reference is made to... Figure 1 The first busbar 60 includes a first solder strip 601, and the second busbar 70 includes a second solder strip 701. Along the second direction Y, the first solder strip 601 contacts the first fine grid 40 and is isolated from the second fine grid 50 by an insulating layer 80; the second solder strip 701 contacts the second fine grid 50 and is isolated from the first fine grid 40 by an insulating layer 80; the insulating layer 80 includes insulating adhesive or an insulating film.

[0069] Specifically, the insulating layer 80 is typically an epoxy resin-based adhesive, possessing both insulating and adhesive properties. The solder ribbon is typically a tin-plated copper ribbon, possessing both conductivity and solderability, serving both to collect the current from the fine grid and as the welding interface between the battery cell and external components. The first solder ribbon 601 contacts the first fine grid 40 to collect the current transmitted by the first fine grid 40; the second solder ribbon 701 contacts the second fine grid 50 to collect the current transmitted by the second fine grid 50, ensuring that currents of different conductivity types can be collected independently, avoiding current confusion. To prevent short circuits caused by solder ribbons contacting non-corresponding fine grids, the overlapping areas of the first solder ribbon 601 and the second fine grid 50 are separated by the insulating layer 80, and the overlapping areas of the second solder ribbon 701 and the first fine grid 40 are separated by the insulating layer 80. This not only blocks unnecessary electrical connections but also enhances the adhesion between the first solder ribbon 601, the second solder ribbon 701, and the battery surface. This configuration can also be adapted to high-efficiency battery technology that generates electricity from both sides.

[0070] Figure 3 This is a schematic diagram of the back surface structure of another back-contact solar cell according to an embodiment of the present invention. Figure 3 As shown, based on the above embodiment, the first busbar 60 includes a first main gate 602 and a third solder strip 603, and the second busbar 70 includes a second main gate 702 and a fourth solder strip 703; along the second direction Y, the first main gate 602 is in contact with the third solder strip 603; the second main gate 702 is in contact with the fourth solder strip 703.

[0071] Specifically, the main grid and the fine grid are usually made of the same material, and the solder strip is a tin-plated copper strip. The two are connected by physical contact or sintering to form a conductive connection. Setting up a first main grid 602 and a second main grid 702 can reduce the contact resistance between the fine grid and the solder strip, reduce current transmission loss, and at the same time disperse the mechanical stress of the solder strip on the fine grid, thereby improving the reliability of the back contact solar cell package.

[0072] In an optional embodiment of the present invention, reference is made to... Figure 1 Along the first direction X, the width of the first fine gate 40 in the second direction Y gradually decreases from the first end 401 to the second end 402; and / or, along the first direction X, the width of the second fine gate 50 in the second direction Y gradually decreases from the third end 501 to the fourth end 502.

[0073] Specifically, along the first direction X, the width of the first fine gate 40 in the second direction Y gradually decreases from the first end 401 to the second end 402, and the width of the second fine gate 50 in the second direction Y gradually decreases from the third end 501 to the fourth end 502. The decrease can be a continuous and smooth decrease or a step-like decrease. The embodiments of the present invention do not make specific limitations here.

[0074] The carriers collected by the first fine grid 40 flow to the first end 401 through the second end 402, and the carriers collected by the second fine grid 50 flow to the third end 501 through the fourth end 502. They converge at the first junction 60 and the second junction 70 through the first end 401 and the third end 501, respectively. The current at the fine grid port farther from the junction is smaller, while the current at the fine grid port closer to the junction is larger. That is, the current at the first end 401 and the third end 501 is larger. Therefore, along the first direction X, the width of the first fine grid 40 in the second direction Y gradually decreases from the first end 401 to the second end 402, and the width of the second fine grid 50 in the second direction Y gradually decreases from the third end 501 to the fourth end 502. This can not only effectively reduce the contact resistance of the connection end, reduce the loss in the current transmission process, and ensure the current collection efficiency, but also save manufacturing costs by saving the amount of the first fine grid 40 and the second fine grid 50. At the same time, it can reduce the shading of the first fine grid 40 and the second fine grid 50 on the solar cell and improve the power generation capacity of the back contact solar cell.

[0075] Figure 4 This is a schematic diagram of an adjacent first and second fine gate structure provided according to an embodiment of the present invention. Figure 4 As shown, in an optional embodiment of the present invention, along the first direction X, the width of the first fine grid 40 in the second direction Y decreases in a stepped manner from the first end 401 to the second end 402, having at least one step; and / or, along the first direction X, the width of the second fine grid 50 in the second direction Y decreases in a stepped manner from the third end 501 to the fourth end 502, having at least one step.

[0076] Specifically, since the first fine grid 40 and the second fine grid 50 do not have diagonal lines printed, this setting can simplify the manufacturing process of the screen for printing the fine grid, reduce fine grid printing defects, and improve the reliability of the back contact solar cell structure.

[0077] In an optional embodiment of the present invention, reference is made to... Figure 1 , Figure 3 and Figure 4 The width difference between two adjacent steps along the first direction X in the second direction Y is greater than or equal to 20 micrometers and less than or equal to 150 micrometers. In an optional embodiment of the invention, reference is made to... Figure 1 , Figure 3 or Figure 4 Along the second direction Y, the width of the first end 401 is greater than or equal to 200 micrometers and less than or equal to 700 micrometers; the width of the second end 402 is greater than or equal to 80 micrometers and less than or equal to 300 micrometers.

[0078] Specifically, the width range of the first terminal 401 is limited to ensure high current carrying capacity while avoiding excessive redundancy. The width range of the second terminal 402 is limited to ensure low light shading requirements while ensuring process feasibility.

[0079] In an optional embodiment of the present invention, reference is made to... Figure 1 , Figure 3 or Figure 4 Along the second direction Y, the width of the third end 501 is greater than or equal to 200 micrometers and less than or equal to 700 micrometers; the width of the fourth end 502 is greater than or equal to 80 micrometers and less than or equal to 300 micrometers.

[0080] Specifically, the width range of the third terminal 501 is limited to ensure high current carrying capacity while avoiding excessive redundancy. The width range of the fourth terminal 502 is limited to ensure low light shading requirements while ensuring process feasibility.

[0081] In an optional embodiment of the present invention, reference is made to... Figure 1 or Figure 4 Along the second direction Y, the width of the first end 401 is equal to the width of the third end 501; the width of the second end 402 is equal to the width of the fourth end 502.

[0082] Specifically, this setup simplifies process design and improves mass production efficiency. It also allows for precise control of silver paste usage, preventing cost waste.

[0083] This invention provides a battery string, wherein the battery string includes any back-contact solar cell provided in any of the above embodiments of this invention, and possesses the beneficial effects of any back-contact solar cell provided in any of the above embodiments of this invention. The battery string can be formed by connecting multiple back-contact solar cells in series.

[0084] This invention provides a battery assembly, wherein the battery assembly includes any back-contact solar cell provided in any of the above embodiments of this invention, or the battery assembly includes a battery string provided in any of the above embodiments of this invention.

[0085] A solar module may include multiple solar cells, which can be connected in series to form a cell string. These cell strings can be connected in series, parallel, or a combination of series and parallel to achieve current output. For example, the connection between individual cells can be achieved by welding ribbons, or the connection between cell strings can be achieved by busbars. The solar module may also include a metal frame, a backsheet, photovoltaic glass, and an encapsulating film. The encapsulating film can be filled between the light-facing side of the solar cells and the photovoltaic glass, the back-facing side and the backsheet, and adjacent cells. As a filler, it can be a transparent colloid with good light transmittance and aging resistance. For example, the encapsulating film can be EVA film or POE film; the specific choice depends on the actual situation and is not limited here.

[0086] Photovoltaic glass can be applied to the encapsulating film on the light-facing side of solar cells. This photovoltaic glass can be ultra-clear glass, possessing high light transmittance, high transparency, and superior physical, mechanical, and optical properties. For example, ultra-clear glass can achieve a light transmittance of over 92%, protecting the solar cells while minimizing impact on their efficiency. Simultaneously, the encapsulating film bonds the photovoltaic glass and solar cells together, providing sealing, insulation, and waterproofing / moisture protection for the solar cells.

[0087] The backsheet can be attached to the film on the back side of the solar cell. The backsheet protects and supports the solar cell, providing reliable insulation, water resistance, and aging resistance. Multiple backsheet options are available, typically including tempered glass, acrylic glass, and aluminum alloy TPT composite film, etc. The specific choice depends on the specific circumstances and is not limited here. The backsheet, solar cell, film, and photovoltaic glass together can be mounted on a metal frame. The metal frame serves as the main external support structure for the entire solar module, providing stable support and installation. For example, the solar module can be installed at the desired location using the metal frame.

[0088] The battery assembly provided in the embodiments of the present invention has the beneficial effects of any back-contact solar cell or battery string provided in any of the above embodiments of the present invention.

[0089] This invention provides a photovoltaic system, wherein the photovoltaic system includes the battery module provided in the above embodiments of this invention, and has the beneficial effects of the battery module provided in the above embodiments of this invention.

[0090] Photovoltaic systems can be applied in photovoltaic power plants, such as ground-mounted, rooftop, and floating power plants, as well as in equipment or devices that utilize solar energy to generate electricity, such as user solar power supplies, solar streetlights, solar cars, and solar buildings. Of course, it's understandable that the application scenarios of photovoltaic systems are not limited to these; that is, photovoltaic systems can be applied in all fields that require solar energy to generate electricity. Taking a photovoltaic power generation network as an example, a photovoltaic system can include photovoltaic arrays, combiner boxes, and inverters. A photovoltaic array can be a combination of multiple battery modules; for example, multiple battery modules can form multiple photovoltaic arrays. The photovoltaic arrays are connected to combiner boxes, which collect the current generated by the photovoltaic arrays. The collected current flows through an inverter and is converted into AC power required by the mains grid before being connected to the mains grid to achieve solar power supply.

[0091] Since the battery module provided in the embodiments of the present invention has the beneficial effects of any back-contact solar cell or battery string provided in any of the above embodiments of the present invention, the photovoltaic system provided in the embodiments of the present invention has the beneficial effects of any back-contact solar cell or battery string provided in any of the above embodiments of the present invention.

[0092] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0093] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A back-contact solar cell, characterized in that, include: A silicon substrate, including a first surface and a second surface disposed opposite to each other; the silicon substrate is configured with a first conductivity type; The first doped layer is configured with a first conductivity type and is located on the first surface; A second doped layer, configured as a second conductivity type, is located on the first surface; on the first surface, the first doped layer and the second doped layer extend along a first direction and are alternately arranged along a second direction; The first fine gate is located on the side of the first doped layer away from the first surface and is in contact with the first doped layer; The second fine gate is located on the side of the second doped layer away from the first surface and is in contact with the second doped layer; the first fine gate and the second fine gate extend along the first direction and are alternately arranged along the second direction; Along the second direction, there is a preset gap between the first fine gate and the second fine gate; and along the second direction, there is a first relationship between the preset gap and the adjacent first fine gate and second fine gate: ； Wherein, L is the preset gap, L1 is the width of the first fine grid at any position in the first direction, and L2 is the width of the second fine grid at the same position as L1 in the first direction. The silver content of both the first and second fine gates is less than one percent.

2. The back-contact solar cell according to claim 1, characterized in that, The silver content of both the first and second fine gates is 0.

3. The back-contact solar cell according to claim 1, characterized in that, Along the second direction, the preset gap is greater than or equal to 100 micrometers and less than or equal to 400 micrometers.

4. The back-contact solar cell according to claim 1, characterized in that, Also includes: The first busbar is located on the side of the first fine gate away from the first doped layer and is in contact with the first fine gate; The second busbar is located on the side of the second fine gate away from the second doped layer and is in contact with the second fine gate; the first busbar and the second busbar extend along the second direction and are alternately arranged along the first direction; Along the first direction, the first fine gate includes a first end connected to the first busbar and a second end disposed opposite to the first end; the second fine gate includes a third end connected to the second busbar and a fourth end disposed opposite to the third end; Along the second direction, the width of the first end is greater than 1.5 times the width of the second end; and / or, along the second direction, the width of the third end is greater than 1.5 times the width of the fourth end.

5. The back-contact solar cell according to claim 4, characterized in that, At any position between adjacent first and second busbars along the first direction, the sum of the widths of adjacent first and second fine gates along the second direction is the same.

6. The back-contact solar cell according to claim 1, characterized in that, At any position in the first direction, the preset gap along the second direction remains unchanged.

7. The back-contact solar cell according to claim 4, characterized in that, At any position between adjacent first and second busbars along the first direction, the sum of the widths of adjacent first and second fine gates along the second direction is greater than or equal to 250 micrometers and less than or equal to 800 micrometers.

8. The back-contact solar cell according to claim 4, characterized in that, The first busbar includes a first solder strip, and the second busbar includes a second solder strip; Along the second direction, the first solder strip contacts the first fine gate and is isolated from the second fine gate by an insulating layer; the second solder strip contacts the second fine gate and is isolated from the first fine gate by an insulating layer; the insulating layer includes insulating adhesive or insulating film.

9. The back-contact solar cell according to claim 4, characterized in that, The first busbar includes a first main grid and a third solder strip, and the second busbar includes a second main grid and a fourth solder strip; Along the second direction, the first main gate contacts the third solder strip; the second main gate contacts the fourth solder strip.

10. The back-contact solar cell according to claim 4, characterized in that, Along the first direction, the width of the first fine gate in the second direction gradually decreases from the first end to the second end; and / or; Along the first direction, the width of the second fine grid in the second direction gradually decreases from the third end to the fourth end.

11. The back-contact solar cell according to claim 10, characterized in that, Along the first direction, the width of the first fine grid in the second direction decreases in a stepped manner from the first end to the second end, having at least one step. and / or; Along the first direction, the width of the second fine grid in the second direction decreases in a stepped manner from the third end to the fourth end, with at least one step.

12. The back-contact solar cell according to claim 11, characterized in that, The width difference between two adjacent steps along the first direction is greater than or equal to 20 micrometers and less than or equal to 150 micrometers in the second direction.

13. The back-contact solar cell according to claim 4, characterized in that, Along the second direction, the width of the first end is greater than or equal to 200 micrometers and less than or equal to 700 micrometers; the width of the second end is greater than or equal to 80 micrometers and less than or equal to 300 micrometers.

14. The back-contact solar cell according to claim 4, characterized in that, Along the second direction, the width of the third end is greater than or equal to 200 micrometers and less than or equal to 700 micrometers; the width of the fourth end is greater than or equal to 80 micrometers and less than or equal to 300 micrometers.

15. The back-contact solar cell according to claim 4, characterized in that, Along the second direction, the width of the first end is equal to the width of the third end; the width of the second end is equal to the width of the fourth end.

16. A battery string, characterized in that, Including the back-contact solar cell as described in any one of claims 1-15.

17. A battery assembly, characterized in that, This includes a back-contact solar cell as described in any one of claims 1-15 or a battery string as described in claim 16.

18. A photovoltaic system, characterized in that, Includes the battery assembly as described in claim 17.

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