Solar cell and photovoltaic module

Abstract

The invention provides a solar cell and a photovoltaic module, and the solar cell comprises a cell sheet which comprises a transparent conductive layer; the auxiliary grid lines are located on the transparent conductive layer, extend in the first direction and are arranged at intervals in the second direction, and the first direction intersects with the second direction; the multiple welding wires are located on the sides, away from the transparent conductive layer, of the multiple auxiliary grid lines, and the multiple welding wires extend in the second direction and are arranged at intervals in the first direction; the first grid line segments are located between the auxiliary grid lines and the transparent conductive layer, and the intersection positions of the auxiliary grid lines and the welding wires are located on the first grid line segments in a one-to-one correspondence mode. The problem of low current transmission efficiency of the solar cell in the prior art is solved.

Description

Solar cells and photovoltaic modules Technical Field

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

[0002] In the field of solar cells, electrode structure design is crucial for improving cell efficiency and reducing costs. In traditional electrode designs, the main grid line and the sub-grid line are connected by a large contact area (like a centipede's legs). This ensures good electrical contact even if the welding wire shifts during the welding process, and the main grid line collects current from the sub-grid line through the contact area. However, this design requires current to flow from the sub-grid line to the contact area on the main grid line before being output through the welding wire. This process involves significant contact and transmission resistance, impacting current transfer efficiency. Summary of the Invention

[0003] The main objective of this application is to provide a solar cell and a photovoltaic module to at least solve the problem of low current transmission efficiency in solar cells in the prior art.

[0004] To achieve the above objectives, according to one aspect of this application, a solar cell is provided, comprising: a solar cell including a transparent conductive layer; a plurality of sub-grid lines located on the transparent conductive layer, the plurality of sub-grid lines extending along a first direction and spaced apart along a second direction, the first direction intersecting the second direction; a plurality of welding wires located on the side of the plurality of sub-grid lines away from the transparent conductive layer, the plurality of welding wires extending along the second direction and spaced apart along the first direction; and a plurality of first grid line segments located between the sub-grid lines and the transparent conductive layer, the intersection positions of the sub-grid lines and the welding wires being located one-to-one on the first grid line segments.

[0005] In some embodiments, the width of the first gate line segment in the second direction is less than or equal to the width of the sub-gate line in the second direction.

[0006] In some embodiments, a plurality of the first gate segments are arranged at intervals along the first direction and the second direction, and along the second direction, the line connecting the center points of the plurality of the first gate segments is one of a straight line, a broken line or an arc.

[0007] In some embodiments, the width of the welding wire in the first direction is less than or equal to the width of the first grid segment in the first direction.

[0008] In some embodiments, the shape of the orthographic projection of the first grid segment onto the battery cell includes at least one of a rectangle, a circle, an ellipse, a trapezoid, and a triangle.

[0009] In some embodiments, the solar cell further includes: a plurality of second grid segments located on the transparent conductive layer and correspondingly located between two adjacent first grid segments along the second direction, wherein the two ends of the second grid segments are respectively connected to the two adjacent first grid segments; and a plurality of third grid segments located on the transparent conductive layer and correspondingly located on the side of the target grid segment away from each of the second grid segments, wherein one end of the third grid segment is connected to the target grid segment, and the target grid segment is the first grid segment located at the edge along the second direction.

[0010] In some embodiments, along the second direction, a plurality of the second gate segments and two of the third gate segments are arranged in a straight line.

[0011] In some embodiments, a plurality of first gate segments, a plurality of second gate segments, and a plurality of third gate segments are integrally formed.

[0012] In some embodiments, the sub-gate line includes a first conductive material and a first adhesive material, and the first gate line segment includes a second conductive material and a second adhesive material. The proportion of the first conductive material in the sub-gate line is greater than the proportion of the second conductive material in the first gate line segment, and the proportion of the first adhesive material in the sub-gate line is less than the proportion of the second adhesive material in the first gate line segment.

[0013] According to another aspect of this application, a photovoltaic module is provided, comprising any of the solar cells described herein.

[0014] By applying the technical solution of this application, the sub-grid line is directly connected to the welding wire, allowing the current collected by the sub-grid line to flow directly and smoothly into the welding wire. This ensures low contact resistance and transmission resistance during current transmission, thereby achieving efficient current transmission and enhancing the overall electrical performance of the solar cell. Furthermore, this application positions the sub-grid line between the first grid line segment and the welding wire. A first grid line segment is positioned below each intersection point of the sub-grid line and the welding wire, allowing the sub-grid line to connect to the transparent conductive layer through the first grid line segment. The first grid line segment effectively bonds the sub-grid line to the transparent conductive layer, ensuring the connection reliability of the solar cell and mitigating the problem of poor welding reliability caused by directly welding the sub-grid line to the transparent conductive layer. Attached Figure Description

[0015] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0016] Figure 1 shows a top view of a solar cell provided in an embodiment of this application;

[0017] Figure 2 shows a schematic diagram of the cross-sectional structure obtained along the dashed line AA' in Figure 1;

[0018] Figure 3 shows a top view of another solar cell provided in an embodiment of this application;

[0019] Figure 4 shows a schematic diagram of wire pull-out after welding of a sub-grid line;

[0020] Figure 5 shows a schematic diagram of wire pull-out after welding of a conventional main grid line.

[0021] The above figures include the following reference numerals:

[0022] 10. Solar cell; 11. Sub-busbar; 111. Sub-busbar; 12. Welding wire; 13. First busbar segment; 14. Second busbar segment; 15. Third busbar segment; 16. Main busbar; 161. Main busbar. Detailed Implementation

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0024] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0025] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application 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 for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover 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.

[0026] As described in the background section, existing solar cells suffer from low current transmission efficiency. To address this technical problem, embodiments of this application provide a solar cell and a photovoltaic module.

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0028] This application provides a solar cell. Figure 1 exemplarily shows a top view of a solar cell according to an embodiment of this application, and Figure 2 is a cross-sectional view of the solar cell obtained along the dashed line AA' in Figure 1. As shown in Figures 1 and 2, the solar cell includes:

[0029] Solar cell 10 includes a transparent conductive layer;

[0030] Specifically, the aforementioned solar cell 10 serves as the foundation of the solar cell, used to collect and extract photogenerated carriers. The aforementioned transparent conductive layer, also known as a TCO (Transparent Conductive Oxide) film, has high optical transmittance and good conductivity, and is a key film layer for collecting current on the solar cell 10.

[0031] Multiple sub-gate lines 11 are located on the above-mentioned transparent conductive layer. The multiple sub-gate lines 11 extend along a first direction and are spaced apart along a second direction. The first direction intersects the second direction.

[0032] Optionally, the first direction can be perpendicular to the second direction. The sub-gate line 11 is used to collect charge carriers in the transparent conductive layer.

[0033] Multiple welding wires 12 are located on the side of the multiple sub-gate lines 11 away from the transparent conductive layer, and the multiple welding wires 12 extend along the second direction and are spaced apart along the first direction.

[0034] Specifically, the welding wire 12 serves as a connection medium between the battery cells 10, and is connected to the sub-grid line 11 to output the current collected on the sub-grid line 11.

[0035] Multiple first gate line segments 13 are located between the sub-gate line 11 and the transparent conductive layer, and the intersection positions of the sub-gate line 11 and the welding wire 12 are located on the first gate line segments 13 respectively.

[0036] Specifically, the sub-grid line 11 is located on the surface of the first grid line segment 13 away from the transparent conductive layer. The first grid line segment 13 enables an effective connection between the sub-grid line 11 and the transparent conductive layer. Furthermore, through the direct connection between the sub-grid line 11 and the first grid line segment 13, the current collected by the solar cell 10 can be quickly and efficiently transmitted to the welding wire 12, avoiding energy loss caused by multiple current jumps within the complex electrode structure.

[0037] In the above embodiments, the sub-grid line is directly connected to the welding wire, allowing the current collected by the sub-grid line to flow directly and smoothly into the welding wire. This ensures low contact resistance and transmission resistance during current transmission, thereby achieving efficient current transmission and enhancing the overall electrical performance of the solar cell. Furthermore, this application positions the sub-grid line between the first grid line segment and the welding wire. A first grid line segment is positioned below each intersection point of the sub-grid line and the welding wire, allowing the sub-grid line to connect to the transparent conductive layer through the first grid line segment. The first grid line segment effectively bonds the sub-grid line to the transparent conductive layer, ensuring the connection reliability of the solar cell and mitigating the problem of poor welding reliability caused by directly welding the sub-grid line to the transparent conductive layer.

[0038] In specific applications, the aforementioned solar cell can be a single-sided cell, meaning that only the front side of the cell 10 receives solar energy. Alternatively, the aforementioned solar cell can be a double-sided cell, meaning that both the front and back sides of the cell 10 are used to receive solar energy.

[0039] In some exemplary embodiments, the solar cell described above can be a heterojunction technology (HJT) solar cell, a perovskite solar cell, a cadmium telluride solar cell, an organic solar cell, or a perovskite / silicon tandem solar cell, etc.

[0040] Those skilled in the art can configure the structure of the solar cell 10 according to the specific type of the solar cell. For example, in the case of an HJT solar cell, the solar cell 10 further includes a substrate, a first intrinsic amorphous silicon layer, and a second intrinsic amorphous silicon layer. The substrate has a front side and a back side, the first intrinsic amorphous silicon layer is located on the front side of the substrate, and the second intrinsic amorphous silicon layer is located on the back side of the substrate. The doping type of the first intrinsic amorphous silicon layer is different from that of the substrate, while the doping type of the second intrinsic amorphous silicon layer is the same as that of the substrate. The transparent conductive layers are located on the side of the first and second intrinsic amorphous silicon layers away from the substrate. Of course, in addition to the above-mentioned film layers, the solar cell 10 may also include other film layer structures.

[0041] In some embodiments, the substrate may be a silicon substrate, and the material of the silicon substrate may include monocrystalline silicon, polycrystalline silicon, amorphous silicon, and microcrystalline silicon, etc.

[0042] In some embodiments, the front side of the substrate can be configured as a pyramidal textured surface to reduce the reflectivity of the front side of the substrate to incident light, thereby increasing the light absorption and utilization rate. The back side of the substrate can be configured as a pyramidal textured surface or a non-textured surface.

[0043] In some embodiments, the substrate can be an N-type semiconductor substrate, meaning that the substrate is doped with N-type ions, which can be any one of phosphorus, arsenic, or antimony. The first intrinsic amorphous silicon layer can be a P-type intrinsic amorphous silicon layer, doped with P-type ions, which can be any one of boron, aluminum, or gallium. The first intrinsic amorphous silicon layer forms a PN junction with the substrate. The second intrinsic amorphous silicon layer can be an N-type intrinsic amorphous silicon layer, doped with N-type ions, which can be any one of phosphorus, arsenic, or antimony.

[0044] In one alternative embodiment, the sub-grid line 11, the welding wire 12, and the first grid line segment 13 of this application may be disposed only on the front side of the battery cell 10. In another alternative embodiment, the sub-grid line 11, the welding wire 12, and the first grid line segment 13 of this application may be disposed on both the front and back sides of the battery cell 10.

[0045] Optionally, the materials of the above-mentioned transparent conductive layer include, but are not limited to, ITO (Indium Tin Oxide), AZO (Aluminum-doped Zinc Oxide), FTO (Fluorine-doped Tin Oxide), GZO (Gallium-doped Zinc Oxide), ZTO (Zinc Tin Oxide), as well as nanowires and graphene.

[0046] In some exemplary embodiments, as shown in Figures 1 and 2, the orthographic projection of the first grid line segment 13 on the solar cell 10 lies within the orthographic projection of the sub-grid line 11 on the solar cell 10. In this embodiment, by controlling the position and size of the first grid line segment 13, each of the first grid line segments 13 is positioned within the projection range of the sub-grid line 11 without additionally obstructing the effective light-receiving area of ​​the solar cell 10. This means that the solar cell 10 can receive more sunlight, which is beneficial for improving the photoelectric conversion efficiency of the solar cell, while maintaining the compactness and high efficiency of the electrode structure.

[0047] According to some alternative embodiments of this application, as shown in FIG1, the width of the first grid line segment 13 in the second direction is less than or equal to the width of the sub-grid line 11 in the second direction. FIG1 illustrates an embodiment where the width of the first grid line segment 13 in the second direction is less than the width of the sub-grid line 11 in the second direction. In this embodiment, by setting the width of the first grid line segment 13 to match or be narrower than the linewidth of the sub-grid line 11, while reliably connecting the sub-grid line 11 and the transparent conductive layer, not only is the light-shielding area of ​​the first grid line segment 13 reduced, further improving cell efficiency, but also effectively reducing the amount of paste used in the first grid line segment 13, thereby further reducing the manufacturing cost burden of the solar cell.

[0048] In one embodiment, the first grid segment 13 extends along the first direction and is arranged at intervals along the first and second directions, and the width of the first grid segment 13 in the second direction is equal to the width of the sub-grid line 11 in the second direction. In this embodiment, the arrangement directions of the first grid segment 13 and the sub-grid line 11 are matched, and the width of the first grid segment 13 is equal to the width of the sub-grid line 11, which means that they can be basically aligned in the second direction. This ensures that the current collected by the sub-grid line 11 can be transmitted to the first grid segment 13 without loss or obstruction, and then connected to the welding wire 12. This precise matching design avoids the diffusion of current in the width direction, reduces lateral resistance, and ensures efficient current flow. The consistent width of the first grid segment 13 and the sub-grid line 11 means that they have the same projected area on the solar cell 10, without increasing the additional light-shielding area. The reduction of the light-shielding area is directly related to the improvement of photoelectric conversion efficiency. The precise matching of the widths of the first grid segment 13 and the sub-grid line 11 optimizes the amount of paste used. While ensuring the quality of electrical connections and the efficiency of current transmission, it avoids increased slurry consumption caused by extra width, reduces production costs, and improves economic benefits.

[0049] In another embodiment, the first gate line segment 13 extends along the first direction and is arranged at intervals along the first and second directions. The width of the first gate line segment 13 in the second direction is smaller than the width of the sub-gate line 11 in the second direction. In this embodiment, designing the width of the first gate line segment 13 to be smaller than the design width of the sub-gate line 11 reduces the light-shielding effect of the first gate line segment 13 and also helps to reduce the amount of paste consumed per unit area. The first gate line segment 13 is positioned below the sub-gate line 11. The first gate line segment 13 has high adhesion, forming a high-strength connection with both the transparent conductive layer and the sub-gate line 11, thus achieving a high adhesion effect. After welding with the welding wire 12, the first gate line segment 13 is not easily detached, resulting in high reliability. Furthermore, the design of using the sub-gate line 11 as a straight-through welding wire 12, combined with the low transmission resistance and low contact resistance characteristics of the sub-gate line 11, is more conducive to current transmission.

[0050] In some specific implementations, multiple first grid segments 13 are arranged at intervals along the first and second directions. Along the second direction, the line connecting the center points of the multiple first grid segments 13 is a straight line, a broken line, or an arc. By adjusting the arrangement of the first grid segments 13, effective contact between the sub-grid lines 11 and the welding wire 12 can be ensured, and different cell shapes and sizes can be flexibly accommodated, enhancing the adaptability and efficiency of solar cell design. Furthermore, due to the discontinuous distribution of the first grid segments 13, the amount of paste used is significantly reduced, lowering production costs.

[0051] Specifically, the straight-line layout of the first grid segment 13 facilitates control and positioning during manufacturing, simplifying the production process and reducing manufacturing costs and process complexity. The straight-line design makes precise alignment and uniform coverage easier to achieve in printing or deposition processes, improving production quality and efficiency. For the zigzag or arc-shaped layout of the first grid segment 13, in cases where the solar cell 10 has a non-uniform illumination distribution, designing the zigzag or arc-shaped path of the first grid segment 13 ensures that the sub-grid lines 11 collect current at the optimal position without excessively blocking the effective illumination area. The zigzag or arc-shaped layout of the first grid segment 13 can disperse the deformation stress of the solar cell 10 during manufacturing or installation, reducing the risk of breakage or poor contact and improving the mechanical stability of the solar cell 10.

[0052] According to some exemplary embodiments of this application, as shown in FIG2, the width of the welding wire 12 in the first direction is less than or equal to the width of the first gate segment 13 in the first direction. This arrangement ensures that even if there is a positional deviation in the welding wire 12, the first gate segment 13 can still play a good overlapping role, thereby maintaining an effective and reliable electrical connection between the welding wire 12, the sub-gate line 11, and the transparent conductive layer.

[0053] In this application, the thickness (or height) of the first gate line segment 13 is less than the thickness of the sub-gate line 11. For example, the thickness of the first gate line segment 13 can be 9-10 μm, and the thickness of the sub-gate line 11 can be 13-14 μm. The thicknesses of the first gate line segment 13, the second gate line segment 14, and the third gate line segment 15 can be the same.

[0054] In practical applications, those skilled in the art can set the shape of the first grid segment 13 according to actual design needs. Optionally, the shape of the orthographic projection of the first grid segment 13 on the solar cell 10 includes at least one of rectangle, circle, ellipse, trapezoid, and triangle. Different shapes of the first grid segment 13 orthographic projection help those skilled in the art to optimize its contact with the sub-grid line 11 and the welding wire 12, ensuring that the current is collected efficiently and uniformly from the surface of the solar cell 10 and transmitted to the external circuit, further reducing resistance loss during current transmission; by finely adjusting the geometry of the first grid segment 13, the shading of the effective light-illuminated area of ​​the solar cell 10 can also be minimized, thereby further improving the light absorption efficiency and photoelectric conversion efficiency of the solar cell 10; the diverse shape design also increases the range of manufacturing processes for the first grid segment 13, enabling better adaptation to different manufacturing technologies and improving production efficiency and battery quality consistency.

[0055] Of course, in addition to the shape described above, the shape of the orthographic projection of the first grid segment 13 onto the battery cell 10 can also be other regular or irregular polygonal shapes.

[0056] In some embodiments, FIG3 exemplarily shows a top view of another solar cell in an embodiment of the present application. As shown in FIG3, the solar cell further includes: a plurality of second grid segments 14 located on the transparent conductive layer and located one-to-one between two adjacent first grid segments 13 along the second direction. The two ends of the second grid segments 14 are respectively connected to the two adjacent first grid segments 13.

[0057] In the above embodiment, in addition to the first grid segment 13 with optimized layout and shape, the solar cell also features a plurality of second grid segments 14, located on the surface of the transparent conductive layer and correspondingly positioned between two adjacent first grid segments 13 along the second direction, with both ends connected to these two first grid segments 13. The arrangement of the second grid segments 14 further refines the current path from the sub-grid line 11 to the first grid segment 13, improving current collection efficiency. As a bridge between the first grid segment 13 and the sub-grid line 11, it ensures smooth current transition and efficient current transmission. Furthermore, the tight connection between the second grid segment 14 and the first grid segment 13 enhances the mechanical stability of the entire electrode system. Even in complex processing or usage environments, this enhanced connection reduces breakage or poor contact caused by stress variations.

[0058] Based on the above embodiments, as shown in FIG3, the solar cell of this application further includes: a plurality of third grid segments 15, located on the above transparent conductive layer, and correspondingly located on the side away from each of the second grid segments 14 of the target grid segment. One end of the third grid segment 15 is connected to the target grid segment, which is the first grid segment 13 located at the edge along the second direction. In this embodiment, by setting the third grid segment 15 between the first grid segment 13 at the edge and the sub-grid line 11, the electrode network structure is improved, avoiding the problem of insufficient electrode connection in the edge area, and ensuring the integrity and consistency of the electrode network from the edge to the center area of ​​the cell 10. In addition, the connection between the third grid segment 15 and the first grid segment 13 at the edge enhances the mechanical stability of the electrode structure, especially at the edge, where these positions are easily affected by stress during cell production and use. The setting of the third grid segment 15 helps to reduce electrode breakage or poor contact caused by edge stress.

[0059] According to some alternative embodiments of this application, along the aforementioned second direction, a plurality of the aforementioned second gate segments 14 and two of the aforementioned third gate segments 15 are arranged in a straight line. This layout design simplifies the complexity of the electrode structure, makes the electrode pattern more regular, and is conducive to improving the accuracy and efficiency of the printing process.

[0060] In other embodiments not shown, the arrangement of the second grid segment 14 and the third grid segment 15 can also be fine-tuned according to actual production needs, for example, by adopting an interlaced or oblique arrangement to adapt to different welding processes or further optimize the current collection path. Exemplarily, along the second direction, the line connecting the center points of the plurality of the second grid segments 14 and the two third grid segments 15 can be a broken line or an arc. Exemplarily, along the second direction, the third grid segment 15 located at one edge of the battery cell 10, the plurality of the second grid segments 14, and the third grid segment 15 located at the other edge of the battery cell 10 are arranged in an interlaced manner.

[0061] In one optional embodiment, the plurality of first grid segments 13, the plurality of second grid segments 14, and the plurality of third grid segments 15 are integrally formed. That is, the first grid segments 13, the second grid segments 14, and the third grid segments 15 are located in the same film layer and are formed in a single process. The integral forming process reduces multiple printing and alignment steps, lowering the operational complexity and potential process errors in the manufacturing process. Simultaneously, by reducing the number of individual printing steps, the amount of paste used is effectively saved, reducing production costs. The integral forming technology allows for rapid continuous printing of all grid segments (first, second, and third grid segments 15), increasing production speed. Integral forming also ensures a strong connection between all grid segments, reducing alignment errors and poor connection problems that may arise from independent printing of each grid segment, and improving the overall stability of the electrode structure. The integrally formed grid structure also allows for a more uniform current distribution, avoiding localized high resistance or breakpoints that may be encountered when current is transmitted between different grid segments, thereby reducing current loss within the battery and improving current transmission efficiency.

[0062] The solar cell described in this application can be a gridless solar cell, i.e., OBB (Zero Bus bar) technology. This design can reduce the amount of silver paste used by reducing the number of grids, thereby reducing costs and improving production efficiency. It has significant economic and practical advantages in the production process of photovoltaic cells, and is especially suitable for the manufacture of heterojunction (HJT) cells. Specifically, there are four welding schemes for gridless solar cells: The first is the Smart Wire scheme, which first fabricates an organic thin film (copper wire composite film) with embedded circular copper welding wire, then connects the cells in series, and finally alloys the welding wire and the cells through lamination. This scheme requires a copper wire composite film. The second is the IFC (Interconnection Framework Component) scheme, which uses a one-time direct lamination process to press the welding wire onto the front and back of the cells for series connection, and then alloys the welding wire and the cells through lamination. The third method is the dispensing method. First, adhesive dots (UV adhesive, hot melt adhesive, etc.) are applied between the sub-busbars. The entire welding wire is then cured onto the solar cell using a UV lamp. Finally, lamination is used to alloy the welding wire to the solar cell. This method differs from the welding-dispensing method in that it does not require welding; dispensing is sufficient for fixation. The fourth method is the welding-dispensing method. First, the welding wire is welded onto the solar cell, with the series connection process and welding alloying occurring simultaneously. Then, adhesive is applied to further bond the welding wire to the solar cell. This method differs from the dispensing-lamination method in that welding is required; welding provides initial fixation, and adhesive dispensing provides further fixation.

[0063] The solar cell described in this application can also be a solar cell with a main grid. In the case of a solar cell without a main grid, the solar cell may not require solder pads.

[0064] In one optional embodiment, as shown in FIG3, the first gate line segment 13, the second gate line segment 14, and the third gate line segment 15 located in the same row along the second direction constitute a main gate line 16, thereby obtaining multiple main gate lines 16 extending along the second direction and spaced apart along the first direction. In this application, the transparent conductive layer, the main gate line 16, the sub-gate line 11, and the welding wire 12 are arranged sequentially. The sub-gate line 11 passes directly through the welding wire 12, and the collected current can flow directly into the welding wire 12 without passing through the main gate line 16, further reducing the transmission resistance. The high adhesion of the main gate line 16 can firmly bond the sub-gate line 11 and the transparent conductive layer, preventing the slurry of the sub-gate line 11 from falling off after welding, further improving the connection reliability between the sub-gate line 11 and the transparent conductive layer.

[0065] In some embodiments, the sub-gate line 11 includes a first conductive material and a first adhesive material, the first gate line segment 13 includes a second conductive material and a second adhesive material, the proportion of the first conductive material in the sub-gate line 11 is greater than the proportion of the second conductive material in the first gate line segment 13, and the proportion of the first adhesive material in the sub-gate line 11 is less than the proportion of the second adhesive material in the first gate line segment 13.

[0066] In the above embodiment, the sub-grid line 11 includes a first conductive material and a first adhesive material, and the first grid line segment 13 includes a second conductive material and a second adhesive material. To optimize the electrical performance and mechanical stability of the electrode structure, the proportion of the first conductive material in the sub-grid line 11 is set higher than the proportion of the second conductive material in the first grid line segment 13. This means that the sub-grid line 11 has higher conductivity, reducing contact resistance and transmission resistance, thereby improving the overall electrical efficiency of the cell. Simultaneously, the proportion of the first adhesive material in the sub-grid line 11 is less than the proportion of the second adhesive material in the first grid line segment 13. This design ensures stronger adhesion between the first grid line segment 13 and the transparent conductive layer, enhancing the mechanical strength and reliability of the electrode, especially its resistance to pull-out during the welding process. Through this precise control of material ratios, this embodiment not only achieves lightweight and high-efficiency electrode structure but also optimizes both electrical and mechanical performance, providing a superior electrode design strategy for heterojunction solar cells.

[0067] Specifically, the first conductive material and the second conductive material can be the same material or different conductive materials. The first conductive material and the second conductive material can be independently selected from one or more combinations of silver, copper, nickel, palladium, aluminum, and gold.

[0068] Specifically, the first adhesive material and the second adhesive material can be the same material or different adhesive materials. Both the first adhesive material and the second adhesive material can be selected from resin polymers.

[0069] In practical applications, the first grid line segment 13 and the sub-grid line 11 are prepared using a paste. Specifically, the paste can be a low-temperature paste (such as low-temperature silver paste), and its curing temperature is generally less than 200℃. In the paste, conductive materials generally account for about 90% of the low-temperature paste, dispersed in an organic carrier, playing a role in conducting electrons and providing conductive pathways, thus determining the electrical properties of the low-temperature paste. The content, microstructure, and particle size of the conductive materials significantly affect their conductivity. The binder can be a polymer resin. As the matrix binder component of the low-temperature paste, the polymer resin forms the molecular framework of the conductive material after low-temperature curing, playing a role in encapsulating and bonding the conductive material, and providing adhesion to the transparent conductive layer. Therefore, it determines the physical properties of the low-temperature paste, such as adhesion strength, impact strength, and mechanical strength. The molecular weight, content, and type of the polymer resin have a significant impact on the bending resistance, hardness, adhesion, and printability of the low-temperature paste. It also affects the dispersion of the conductive material in the organic carrier and the bonding between silver powder particles, thereby directly or indirectly affecting the conductivity of the low-temperature paste.

[0070] In addition to conductive and adhesive materials, the aforementioned slurry also includes organic solvents, curing agents, and additives. Organic solvents primarily regulate the viscosity and flowability of the low-temperature slurry, ensuring good printability and preventing breakage, line breaks, or flow. Secondly, during the curing process, the solvent's evaporation and thermal behavior play a crucial role in the sliding and rearrangement of conductive material particles, directly affecting the microstructure and overall performance of the cured slurry. Furthermore, organic solvents can dissolve polymer resins, enabling good dispersion of the conductive material within the resin, altering the substrate surface state for excellent wettability between the slurry and substrate, and determining the curing temperature and time of the low-temperature slurry. Esters, ethers, alcohols, and ketones are among the organic solvents that can be used in the slurry. Curing agents are crucial additives in the preparation of low-temperature slurries, acting to induce cross-linking and curing reactions in thermosetting resins upon heating. Epoxy resins, commonly used in low-temperature slurries, have a linear structure and require a curing agent to react and cure before forming a practically valuable three-dimensional network structure. During curing, the curing agent molecules are introduced into the epoxy resin's own molecular structure, altering the cross-linking density, morphology, and molecular weight between the three-dimensional networks. This results in changes to mechanical, thermal, and electrical properties. Therefore, the performance of cured epoxy resins largely depends on the type of curing agent. In the preparation of low-temperature slurries, other additives are often added according to actual performance requirements. For example, to obtain silver electrode grid lines with a large aspect ratio and good uniformity, thixotropic agents are typically added to the silver paste to adjust its rheological properties, giving it high shear thinning and rapid recovery, thus facilitating screen printing and maintaining a good morphology after printing. Additionally, silane coupling agents can promote compatibility between metal powders and organic carriers, improve the stability of conductive silver paste, and enhance the adhesion strength between the coating and the substrate, reduce contact resistance, and improve resin adhesion. Other additives, such as dispersants, can help to uniformly disperse the binder and functional phases, prevent agglomeration and precipitation, and improve wettability, while anti-aging agents can improve the weather resistance of the resin.

[0071] As shown in Figures 4 and 5, the inventors of this application have discovered that the prior art HJT electrode design generally consists of a main grid paste and a sub-grid paste printed sequentially and combined to form an electrode. The main grid paste and the sub-grid paste correspond to the printed main grid line 161 and sub-grid line 111, respectively. The main grid line 161 collects the current from the sub-grid line 111 and then transmits it to the welding wire. Therefore, the main grid paste needs good welding pull strength. The welding pull strength of the main grid paste is improved by increasing the resin content or the proportion of flake silver powder, resulting in relatively high volume resistivity or poor printability. The sub-grid line 111 collects current from the transparent conductive layer and transmits it to the main grid line 161. Its sub-grid paste is designed to achieve extremely low contact resistance and transmission resistance, resulting in generally poor welding performance. Actual welding verification of the sub-grid paste revealed that the phenomenon after welding is separation of the paste from the transparent conductive layer, as shown in Figure 4. The damage type is interface damage, mainly because the resin system of the sub-grid paste does not have high adhesion to the transparent conductive layer. Compared to the secondary gate line 111, the main gate line 161 has higher tensile strength. Even after the welding wire is pulled off, silver particles remain on the surface of the transparent conductive layer, as shown in Figure 5. The failure type is cohesive failure. A comparison of Figures 4 and 5 shows that the weakest point in the adhesion strength of the slurry lies in the adhesion between the slurry and the transparent conductive layer.

[0072] Based on the above comparison results, in designing the electrode structure of the solar cell, this application sets a sub-grid paste (forming a sub-grid line 11) between the main grid paste (forming a first grid line segment 13) and the welding wire 12. The sub-grid paste and the main grid paste are bonded together with resin material, and the main grid paste and the transparent conductive layer are bonded together with resin material. This electrode structure avoids the light blocking caused by the existing centipede-like structure and ensures welding strength. The current collected by the sub-grid line 11 can flow directly into the welding wire 12 without passing through the first grid line segment 13, thereby reducing the transmission resistance.

[0073] This application also provides a photovoltaic module, including any of the above-described solar cells.

[0074] Through the above embodiments, the photovoltaic module includes the aforementioned solar cell, in which the sub-grid lines are directly connected to the welding wire. This allows the current collected by the sub-grid lines to flow directly and smoothly into the welding wire, ensuring low contact resistance and transmission resistance during current transmission, thereby achieving efficient current transmission and enhancing the overall electrical performance of the photovoltaic module. Furthermore, this application positions the sub-grid lines between the first grid line segment and the welding wire. A first grid line segment is provided below each intersection point of the sub-grid lines and the welding wire, allowing the sub-grid lines to connect to the transparent conductive layer through the first grid line segment. The first grid line segment can effectively bond the sub-grid lines to the transparent conductive layer, thereby ensuring the connection reliability of the solar cell and alleviating the problem of poor welding reliability caused by directly welding the sub-grid lines to the transparent conductive layer, thus improving the overall reliability of the photovoltaic module.

[0075] Specifically, in the photovoltaic module, multiple solar cells are connected in series and / or in parallel to form a battery string. The photovoltaic module may also include an encapsulating film and a cover plate. The encapsulating film is used to cover the surface of the battery string, and the cover plate is used to cover the surface of the encapsulating film away from the battery string.

[0076] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0077] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0078] As can be seen from the above description, the embodiments of this application achieve the following technical effects:

[0079] In the solar cell of this application, the sub-grid lines are directly connected to the welding wire, allowing the current collected by the sub-grid lines to flow directly and smoothly into the welding wire. This ensures low contact resistance and transmission resistance during current transmission, thereby achieving efficient current transmission and enhancing the overall electrical performance of the solar cell. Furthermore, this application positions the sub-grid lines between the first grid line segment and the welding wire. A first grid line segment is positioned below each intersection point of the sub-grid lines and the welding wire, allowing the sub-grid lines to connect to the transparent conductive layer through the first grid line segment. The first grid line segment effectively bonds the sub-grid lines to the transparent conductive layer, ensuring the connection reliability of the solar cell and mitigating the problem of poor welding reliability caused by directly welding the sub-grid lines to the transparent conductive layer.

[0080] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A solar cell, characterized in that, The device includes: a battery cell, comprising a transparent conductive layer; a plurality of sub-gate lines located on the transparent conductive layer, the plurality of sub-gate lines extending along a first direction and spaced apart along a second direction, the first direction intersecting the second direction; a plurality of welding wires located on the side of the plurality of sub-gate lines away from the transparent conductive layer, the plurality of welding wires extending along the second direction and spaced apart along the first direction; and a plurality of first gate line segments located between the sub-gate lines and the transparent conductive layer, the intersection positions of the sub-gate lines and the welding wires being located one-to-one on the first gate line segments.

2. The solar cell according to claim 1, characterized in that, The width of the first gate line segment in the second direction is less than or equal to the width of the sub-gate line in the second direction.

3. The solar cell according to claim 2, characterized in that, Multiple first grid segments are arranged at intervals along the first direction and the second direction. Along the second direction, the line connecting the center points of the multiple first grid segments is one of a straight line, a broken line, or an arc.

4. The solar cell according to claim 1, characterized in that, The width of the welding wire in the first direction is less than or equal to the width of the first grid segment in the first direction.

5. The solar cell according to claim 1, characterized in that, The shape of the orthographic projection of the first grid line segment onto the battery cell includes at least one of a rectangle, a circle, an ellipse, a trapezoid, and a triangle.

6. The solar cell according to claim 1, characterized in that, The solar cell further includes: a plurality of second grid segments located on the transparent conductive layer and correspondingly located between two adjacent first grid segments along the second direction, the two ends of the second grid segments being connected to the two adjacent first grid segments respectively; and a plurality of third grid segments located on the transparent conductive layer and correspondingly located on the side of the target grid segment away from each of the second grid segments, one end of the third grid segment being connected to the target grid segment, the target grid segment being the first grid segment located at the edge along the second direction.

7. The solar cell according to claim 6, characterized in that, Along the second direction, a plurality of second gate segments and two third gate segments are arranged in a straight line.

8. The solar cell according to claim 7, characterized in that, Multiple first gate segments, multiple second gate segments, and multiple third gate segments are integrally formed.

9. The solar cell according to claim 1, characterized in that, The sub-gate line includes a first conductive material and a first adhesive material, and the first gate line segment includes a second conductive material and a second adhesive material. The proportion of the first conductive material in the sub-gate line is greater than the proportion of the second conductive material in the first gate line segment, and the proportion of the first adhesive material in the sub-gate line is less than the proportion of the second adhesive material in the first gate line segment.

10. A photovoltaic module, characterized in that, The solar cell includes any one of claims 1 to 9.

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