Solar cell, cell string, cell assembly and photovoltaic system

Abstract

The utility model is suitable for the technical field of solar cells, and provides a solar cell, a cell string, a cell module and a photovoltaic system. The solar battery comprises a battery piece, and the battery piece comprises a first surface and a second surface which are opposite. The plurality of first fine grids and the plurality of first welding strips are arranged on the first surface of the battery piece; the plurality of second fine grids and the plurality of second welding strips are arranged on the second surface of the battery piece; the first fine grids and the first welding strips extend in the first direction and are arranged at intervals in the second direction, the first welding strips are electrically connected with the first fine grids, and the second welding strips are electrically connected with the second fine grids; wherein the extension direction of the second fine grids and the extension direction of the first fine grids are parallel or approximately parallel or crossed. Therefore, the first welding strip and the first fine grid almost coincide together, the shading loss is reduced, and the photoelectric conversion efficiency of the solar cell is improved.

Description

Technical Field

[0001] The present application belongs to the field of solar cell technology, and in particular relates to a solar cell, a cell string, a cell assembly and a photovoltaic system. Background Art

[0002] Solar cell power generation is a sustainable source of clean energy. It uses the photovoltaic effect of semiconductor pn junctions to convert sunlight into electrical energy. In related technologies, solar cells are semiconductor devices that directly convert sunlight energy into electrical energy, and metal grid lines are used to collect and transmit current. However, when the soldering ribbon is connected to the grid lines, a small contact area will result in high resistance and large electrical losses. Both the soldering ribbon and the grid lines will cause shading losses, affecting the photoelectric conversion efficiency of the solar cell. Based on this, how to reduce shading losses and improve the photoelectric conversion efficiency of solar cells has become an urgent problem to be solved. Utility Model Content

[0003] The present application provides a solar cell, a cell string, a cell assembly and a photovoltaic system, aiming to solve the problem of how to reduce the shading loss caused by welding ribbons and grid lines to the solar cells.

[0004] The solar cell provided in the present application includes a cell sheet, which includes a first surface and a second surface facing each other; a plurality of first fine grids are arranged on the first surface of the cell sheet and a plurality of second fine grids are arranged on the second surface, the first fine grids extend along the first direction and are arranged at intervals along the second direction; a plurality of first welding strips are arranged on the first surface of the cell sheet and a plurality of second welding strips are arranged on the second surface, the first welding strips extend along the first direction and are arranged at intervals along the second direction, the first welding strips are electrically connected to the first fine grids, and the second welding strips are electrically connected to the second fine grids; wherein the extension direction of the second fine grids is parallel or approximately parallel to the extension direction of the first fine grids; or the extension direction of the second fine grids is arranged to cross the extension direction of the first fine grids.

[0005] Furthermore, the second welding strip is electrically cross-connected to the second fine grid.

[0006] Furthermore, the solar cell further includes a main grid arranged on the second surface, the main grid and the second fine grid are cross-arranged and electrically connected, and the second welding strip and the second fine grid are connected together through the main grid.

[0007] The battery string provided in the embodiment of the present application includes the solar cell described in any one of the above embodiments, the battery string includes a plurality of battery cells, the plurality of battery cells are distributed along a first direction, the plurality of battery cells include a first battery cell and an adjacent second battery cell, and the first welding strip of the first battery cell and the second welding strip of the second battery cell are electrically connected.

[0008] Furthermore, the first welding ribbon on the first side of the first battery cell and the second welding ribbon on the second side of the adjacent second battery cell are an integral continuous structure.

[0009] Furthermore, the second fine grid of the second battery cell extends along the third direction, the second welding strip extends along the fourth direction, and the second welding strip is cross-electrically connected to the second fine grid.

[0010] Furthermore, an angle β between the third direction and the fourth direction is an acute angle.

[0011] Furthermore, a plurality of main grids are provided on the second surface of the second battery cell, and a second welding strip on the second surface of the second battery cell is cross-electrically connected to the main grids.

[0012] Furthermore, the first welding ribbon on the first side of the first battery cell and the second welding ribbon on the second side of the adjacent second battery cell are non-integrated continuous structures, and the first welding ribbon and the second welding ribbon are electrically connected via a busbar.

[0013] Furthermore, a busbar connecting the first welding ribbon of the first battery cell and the second welding ribbon of the adjacent second battery cell is located between the first battery cell and the second battery cell.

[0014] Furthermore, the busbar connecting the first welding ribbon of the first battery cell and the second welding ribbon of the adjacent second battery cell is located on the second surface of the second battery cell.

[0015] Furthermore, the first welding ribbon of the first battery cell and the second welding ribbon of the second battery cell are connected to the same surface or opposite surfaces of the busbar.

[0016] Furthermore, the first welding ribbon of the first battery cell and the second welding ribbon of the second battery cell are electrically connected to the busbar through conductive glue or welding points.

[0017] Furthermore, the first welding strip is a flat welding strip, a round welding strip, or a triangular welding strip, and the second welding strip is a flat welding strip, a round welding strip, or a triangular welding strip.

[0018] Furthermore, when the first surface is a light-receiving surface and the first welding strip is a round welding strip, the diameter of the round welding strip is 0.05 mm-0.3 mm.

[0019] Furthermore, when the first surface is a light-receiving surface and the first welding strip is a flat welding strip, the width of the flat welding strip along the third direction is 0.2 mm-0.8 mm.

[0020] Furthermore, when the first surface is a light-receiving surface and the first welding strip is a triangular welding strip, the width of the bottom edge of the triangular welding strip along the third direction is 0.05 mm-0.5 mm.

[0021] The battery assembly provided in the embodiments of the present application includes the battery string described in any of the above embodiments.

[0022] The photovoltaic system provided in the embodiments of the present application includes the battery assembly described in the above embodiments.

[0023] In the solar cell, cell string, cell module, and photovoltaic system of the embodiments of the present application, the solar cell includes a cell, the cell including a first and a second opposite side; a plurality of first fine grids disposed on the first side of the cell and a plurality of second fine grids disposed on the second side, the first fine grids extending in a first direction and spaced apart along a second direction; a plurality of first welding ribbons disposed on the first side of the cell and a plurality of second welding ribbons disposed on the second side of the cell, the first welding ribbons extending in the first direction and spaced apart along the second direction, the first welding ribbons electrically connected to the first fine grids, and the second welding ribbons electrically connected to the second fine grids; wherein the second fine grids extend in a direction parallel or approximately parallel to the direction of the first fine grids, or the second fine grids extend in a direction intersecting the direction of the first fine grids. In this manner, the first welding ribbons and the first fine grids nearly overlap, reducing shading losses and improving the photoelectric conversion efficiency of the solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a partial structural diagram of a solar cell according to an embodiment of the present application;

[0025] Figure 2 This is another partial structural diagram of a solar cell according to an embodiment of the present application;

[0026] Figure 3 is another partial structural diagram of a solar cell according to an embodiment of the present application;

[0027] Figure 4 This is another partial structural diagram of a solar cell according to an embodiment of the present application;

[0028] Figure 5 1 is a schematic diagram of the module structure of a battery string according to an embodiment of the present application;

[0029] Figure 6 This is another partial structural diagram of a solar cell according to an embodiment of the present application;

[0030] Figure 7 This is another partial structural diagram of a solar cell according to an embodiment of the present application;

[0031] Figure 8 This is another partial structural diagram of a solar cell according to an embodiment of the present application;

[0032] Figure 9 This is another partial structural diagram of a solar cell according to an embodiment of the present application;

[0033] Figure 10 This is another partial structural diagram of a solar cell according to an embodiment of the present application;

[0034] Figure 11 This is another partial structural diagram of a solar cell according to an embodiment of the present application;

[0035] Figure 12 This is another partial structural diagram of a solar cell according to an embodiment of the present application;

[0036] Figure 13 This is another partial structural diagram of a solar cell according to an embodiment of the present application;

[0037] Figure 14 1 is a schematic diagram of the module structure of a battery assembly according to an embodiment of the present application;

[0038] Figure 15 It is a schematic diagram of the module structure of a photovoltaic system according to an embodiment of the present application.

[0039] Description of main component symbols:

[0040] Solar cell 100, battery cell 10, first battery cell 11, second battery cell 12, first surface 20, first fine grid 21, first welding ribbon 22, second surface 30, second fine grid 31, second welding ribbon 32, main grid 40, busbar 50, battery string 200, battery assembly 300, photovoltaic system 400. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application is further described in detail below with reference to the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and are not to be construed as limiting the present application. In addition, it should be understood that the specific embodiments described herein are merely used to explain the present application and are not intended to limit the present application.

[0042] In the description of this application, it should be understood that the terms "length", "width", "up", "down", "left", "right", "horizontal", "top", "bottom", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on this application.

[0043] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the described features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0044] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections, electrical connections, or mutual communication; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0045] In this application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0046] The disclosure below provides many different embodiments or examples for realizing different structures of the present application. In order to simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present application. In addition, the present application may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those skilled in the art will appreciate the application of other processes and / or the use scenarios of other materials.

[0047] In the related art, a solar cell is a semiconductor device that converts sunlight energy directly into electrical energy. However, in the prior art, when the soldering ribbon is connected to the grid line, a small contact area will result in a large resistance and a large electrical loss. At the same time, both the soldering ribbon and the grid line will cause shading losses, affecting the photoelectric conversion efficiency of the solar cell. In the embodiment of the present application, by setting the extension direction of the first soldering ribbon and the first fine grid, the first soldering ribbon and the first fine grid extend in the same direction and almost overlap, thereby increasing the contact area between the first soldering ribbon and the first fine grid, reducing resistance, reducing shading losses to the battery cell, and improving the photoelectric conversion efficiency of the solar cell.

[0048] Example 1

[0049] See also Figures 1 to 3 In a solar cell 100 according to an embodiment of the present application, the solar cell 100 includes a cell 10, the cell 10 including a first surface 20 and a second surface 30 opposite to each other; a plurality of first fine grids 21 on the first surface 20 of the cell 10 and a plurality of second fine grids 31 on the second surface 30, the first fine grids 21 extending in a first direction and spaced apart in a second direction; a plurality of first welding ribbons 22 on the first surface 20 of the cell 10 and a plurality of second welding ribbons 32 on the second surface 30, the first welding ribbons 22 extending in the first direction and spaced apart in the second direction, the first welding ribbons 22 being electrically connected to the first fine grids 21, and the second welding ribbons 32 being electrically connected to the second fine grids 31; wherein the extension direction of the second fine grids 31 is parallel or approximately parallel to the extension direction of the first fine grids 21; or the extension direction of the second fine grids 31 is arranged to intersect with the extension direction of the first fine grids 21.

[0050] In a solar cell 100 according to an embodiment of the present application, the solar cell 100 includes a cell 10, which includes a first side 20 and a second side 30 facing each other. A plurality of first fine grids 21 are disposed on the first side 20 of the cell 10, and a plurality of second fine grids 31 are disposed on the second side 30. The first fine grids 21 extend in a first direction and are spaced apart in a second direction. A plurality of first welding ribbons 22 are disposed on the first side 20 of the cell 10, and a plurality of second welding ribbons 32 are disposed on the second side 30 of the cell 10. The first welding ribbons 22 extend in the first direction and are spaced apart in the second direction. The first welding ribbons 22 are electrically connected to the first fine grids 21, and the second welding ribbons 32 are electrically connected to the second fine grids 31. The second fine grids 31 extend in a direction parallel or approximately parallel to the direction of the first fine grids 21, or the second fine grids 31 extend in a direction intersecting the direction of the first fine grids 21. In this manner, the first welding ribbons 22 and the first fine grids 21 nearly overlap, reducing shading losses and improving the photoelectric conversion efficiency of the solar cell 100.

[0051] Specifically, the first side 20 of the cell 10 can be the light-facing side, and the second side 30 of the cell 10 can be the backlight-facing side. First and second doped layers of opposite polarity are distributed on the first and second sides 20, 30 of the cell 10, respectively. A first fine grid 21 and a first soldering ribbon 22 are provided on the first side 20. The first fine grid 21 is used to conduct current from the first doped layer and electrically connect to the first soldering ribbon 22, while also transmitting and converging current to the first soldering ribbon 22. Both the first fine grid 21 and the first soldering ribbon 22 extend along a first direction and are spaced apart along a second direction. This allows the first fine grid 21 to fully utilize the spatial position of the first side 20, thereby fully conducting current generated in the first doped layer. Furthermore, the first fine grid 21 and the first soldering ribbon 22, extending in the same direction on the first side 20, are nearly aligned, increasing the contact area, reducing electrical resistance, lowering shading losses, and improving the photoelectric conversion efficiency of the solar cell 100.

[0052] Furthermore, a second fine grid 31 and a second welding ribbon 32 are provided on the second side 30 of the solar cell 10. The second fine grid 31 conducts the current generated by the second doping layer and electrically connects to the second welding ribbon 32, transmitting and converging the current to the second welding ribbon 32. At the same time, the extension direction of the second fine grid 31 can be parallel to the extension direction of the first fine grid 21, which facilitates the connection of different solar cells 10. For example, multiple solar cells 10 are connected in series by welding with welding ribbons to form a solar cell string 200, and the distribution positions of the second fine grid 31 and the second welding ribbon 32 on the second side 30 are almost overlapped, thereby increasing the contact area, reducing resistance, reducing shading loss, and improving the photoelectric conversion efficiency of the solar cell 100. Alternatively, the extension direction of the second fine grid 31 can be approximately parallel to the extension direction of the first fine grid 21, which facilitates the connection of the two solar cells 10 while improving the structural strength of the solar cell 10. At the same time, because the first side 20 and the second side 30 of the solar cell 10 are opposite sides of the solar cell 10, the light intensity and light direction received by the first side 20 and the second side 30 are significantly different. The second fine grid 31 and the first fine grid 21 extend in different directions, facilitating the absorption of different light rays by the first and second surfaces 20 and 30 of the cell 10, thereby improving the photoelectric conversion efficiency of the first and second surfaces 20 and 30 of the cell 10. Alternatively, the extension direction of the second fine grid 31 and the extension direction of the first fine grid 21 can be arranged to intersect. When the angle of intersection is large, the first fine grid 21 on the first and second surfaces 30 of the same cell 10 can form an interlaced grid-like projection in the thickness direction of the cell 10, further increasing the structural strength of the cell 10. Furthermore, the second fine grid 31 and the first fine grid 21 extend in different directions, facilitating the absorption of different light rays by the first and second surfaces 20 and 30 of the cell 10, thereby improving the photoelectric conversion efficiency of the first and second surfaces 20 and 30 of the cell 10. In this way, the second fine grid 31 can be arranged with different extension directions according to different situations to maximize the use of light rays directly or indirectly incident on the second surface 30. The specific extension direction of the second fine grid 31 is not limited in the present embodiment to meet various needs.

[0053] Example 2

[0054] See also Figure 1 and Figure 3 In some optional embodiments, the second welding strip 32 is electrically connected to the second fine grid 31 in a cross-connection manner.

[0055] In this way, the second welding ribbon 32 and the second fine grid 31 extend in different directions, allowing the second welding ribbon 32 and the second fine grid 31 to cross-connect. Different crossing angles can achieve various effects, such as increasing the contact area between the welding ribbon and the fine grid and reducing the obstruction of light received by the solar cell by the welding ribbon and the fine grid.

[0056] Specifically, when the second welding strip 32 is cross-connected with the second fine grid 31 at a large angle (such as Figure 3 ), such as being connected perpendicularly to each other, the second welding ribbons 32 and the second fine grids 31 can be staggered to form a grid. One second welding ribbon 32 can be connected to multiple second fine grids 31, and one second fine grid 31 can also be connected to multiple second welding ribbons 32. In this way, the currents in different second fine grids 31 can be converged to the same second welding ribbon 32, or the currents in the same second fine grid 31 can be dispersed to different second welding ribbons 32, thereby balancing the current generated by the battery cell 10 and reducing the overall resistance loss of the circuit. In addition, the cross-mesh structure can increase the structural strength of the battery cell 10.

[0057] Of course, the second welding strip 32 and the second fine grid 31 can also be cross-connected at a smaller angle, so that the second welding strip 32 can only be connected to fewer second fine grids 31, or can only be connected to one second fine grid 31. When the cross-connection angle of the second welding strip 32 and the second fine grid 31 is so small that the second welding strip 32 and the second fine grid 31 almost overlap (e.g. Figure 1 ), which can reduce the light blocking of the second surface 30 by the second welding ribbon 32 and the second fine grid 31, thereby improving the performance of the cell 10. The embodiment of the present application does not limit the intersection angle of the second welding ribbon 32 and the second fine grid 31 to meet various needs.

[0058] Example 3

[0059] See also Figure 4 In some optional embodiments, the solar cell 100 further includes a main grid 40 disposed on the second surface 30 , the main grid 40 is cross-arranged with and electrically connected to the second fine grid 31 , and the second welding strip 32 and the second fine grid 31 are connected together through the main grid 40 .

[0060] In this way, the provision of the main grid 40 can further disperse the current density on the second side 30 of the cell 10 , reduce resistance loss, increase the structural strength of the cell 10 , improve current collection efficiency, and simplify the welding process of the second welding ribbon 32 .

[0061] Specifically, the main grid 40 and the second fine grid 31 on the second surface 30 are arranged crosswise and electrically connected. The intersection angle of the main grid 40 and the second fine grid 31 can be various (such as an obtuse angle, a right angle, or an acute angle, preferably a right angle in the embodiment of the present application), so that one main grid 40 can be connected to multiple second fine grids 31, and one second fine grid 31 can also be connected to multiple main grids 40. In this way, the current in different second fine grids 31 can be converged to the same main grid 40, or the current in the same second fine grid 31 can be dispersed to different main grids 40, balancing the current on the second surface 30 of the battery cell 10, increasing the structural strength of the battery cell 10, reducing the overall resistance loss of the circuit, and improving the current collection efficiency.

[0062] Furthermore, the second fine grid 31, the main grid 40, and the second welding ribbon 32 are connected together in the order of the second fine grid 31 connecting to the main grid 40 and then connecting to the second welding ribbon 32. Furthermore, the second welding ribbon 32 at least partially covers the main grid 40, so that the current in the second fine grid 31 is converged or dispersed by the main grid 40 and then transmitted to the second welding ribbon 32, and then conducted through the second welding ribbon 32. For example, the second welding ribbon 32 conducts the current to the external power grid by connecting to the busbar 50. In this process, the second welding ribbon 32 is not directly connected to the second fine grid 31, but is indirectly connected to the second fine grid 31 through the main grid 40, which acts as a "bridge." Because the fine grid is relatively thin, if the second welding ribbon 32 is directly electrically connected to the second fine grid 31, welding will be difficult. This method of indirectly connecting the welding ribbon to the fine grid through the main grid 40 ensures smooth current transmission and simplifies the welding process.

[0063] Example 4

[0064] See also Figure 1 、 Figure 2 and Figure 5 The battery string 200 of the embodiment of the present application includes the solar cell 100 of any of the above-mentioned embodiments, and the battery string 200 includes a plurality of battery cells 10, and the plurality of battery cells 10 are distributed along a first direction. The plurality of battery cells 10 include a first battery cell 11 and an adjacent second battery cell 12, and the first welding ribbon 22 of the first battery cell 11 and the second welding ribbon 32 of the second battery cell 12 are electrically connected.

[0065] In this way, different battery cells 10 can be connected together through welding ribbons to form a battery string 200.

[0066] Specifically, the battery string 200 can be a plurality of sheet-shaped solar cells 100 connected in series by welding ribbons and busbars 50 in the order of first battery cell 11, second battery cell 12, first battery cell 11, second battery cell 12, etc. from left to right along the first direction. It is understandable that in the battery string 200, the battery string 200 may include two battery cells 10 connected in series, three battery cells 10 connected in series, or other larger numbers of battery cells 10. The number of battery cells 10 that need to be connected in series can be determined based on actual usage. In addition, in the embodiment of the present application, there is no limitation on the size and type of the solar cell 100. The specifications and sizes of adjacent battery cells 10 can be the same or different to meet different needs.

[0067] Furthermore, adjacent first and second battery cells 11, 12 are electrically connected via the first welding ribbon 22 of the first battery cell 11 and the second welding ribbon 32 of the second battery cell 12. At the same time, the first welding ribbon 22 of the second battery cell 12 can be electrically connected to the second welding ribbon 32 of another adjacent first battery cell 11. Similarly, multiple battery cells 10 can be connected in series to form a battery string 200. The first welding ribbon 22 and the second welding ribbon 32 can be directly connected (e.g., the two are integrally formed) or indirectly connected (e.g., the two can be connected via a busbar 50).

[0068] The embodiments of the present application do not limit the specific connection method of adjacent battery cells 10 in order to meet different needs. In one embodiment, the edges of two adjacent battery cells 10 can be at least partially stacked together; in another embodiment, two adjacent battery cells 10 can be spaced apart. The spacing between two adjacent battery cells 10 should be within an appropriate range, so as to avoid problems such as small operating space and difficulty in welding caused by too small a spacing, and to avoid problems such as waste of space and increased costs caused by too large a spacing. Of course, the embodiments of the present application do not limit the specific spacing distance between the two battery cells 10 in order to meet a variety of needs.

[0069] Example 5

[0070] See also Figure 1 and Figure 2 In some optional embodiments, the first welding ribbon 22 on the first side 20 of the first battery cell 11 and the second welding ribbon 32 on the second side 30 of the adjacent second battery cell 12 are an integral continuous structure.

[0071] In this way, the first welding ribbon 22 and the second welding ribbon 32 of the adjacent second battery cell 12 are an integrated continuous structure, which can ensure the conductive continuity of the battery string 200.

[0072] Specifically, the first fine grid 21 and the second fine grid 31 have opposite polarities, and the first fine grid 21 connects to the first welding ribbon 22, the second welding ribbon 32, and the second fine grid 31. In this way, the first battery cell 11 and the second battery cell 12 can be connected in series to form a battery string 200. Of course, a battery string 200 with higher performance can be formed by connecting more battery cells 10 in series. The embodiments of this application do not limit the number of battery cells 10 connected in series to meet various needs.

[0073] Furthermore, the first welding ribbon 22 of the two adjacent first battery cells 11 and the second welding ribbon 32 of the second battery cell 12 are a continuous whole. The first welding ribbon 22 and the second welding ribbon 32 are not connected by traditional welding points, joints or connectors, but are a seamless or almost seamless integral continuous structure. This continuity may be achieved through casting, extrusion, stretching or other special manufacturing processes to ensure that the physical and chemical properties between the two welding ribbons remain consistent at the connection. Alternatively, the first welding ribbon 22 and the second welding ribbon 32 in the text are only used to distinguish different parts of the integral continuous welding ribbon to facilitate the reader's understanding. In this way, the continuous structure of the welding ribbon makes the formed battery string 200 structure more stable and the conductive effect smoother.

[0074] Example 6

[0075] See also Figure 1 and Figure 3 In some optional embodiments, the second fine grid 31 of the second battery cell 12 extends along the third direction, the second welding ribbon 32 extends along the fourth direction, and the second welding ribbon 32 is cross-electrically connected to the second fine grid 31 .

[0076] Thus, the second welding strip 32 and the second fine grid 31 extend in different directions and cross-connect electrically. The cross-angle can be adjusted to achieve various effects, such as balancing current, improving current collection efficiency, and increasing the structural strength of the cell 10.

[0077] Specifically, the second welding strip 32 and the second fine grid 31 are arranged crosswise and electrically connected, and the intersection angle of the second welding strip 32 and the second fine grid 31 can be various (such as obtuse angle, right angle or acute angle). Figure 3 ), one second welding ribbon 32 can be connected to multiple second fine grids 31, and one second fine grid 31 can also be connected to multiple second welding ribbons 32. In this way, the current in different second fine grids 31 can be converged into the same second welding ribbon 32, or the current in the same second fine grid 31 can be dispersed to different second welding ribbons 32, achieving the effects of balancing the current of the battery cell 10, increasing the structural strength of the battery cell 10, reducing the overall resistance loss of the circuit, and improving the current collection efficiency.

[0078] In the embodiment of the present application, the third direction and the fourth direction are not limited to meet various needs. For example, the third direction can be perpendicular to the fourth direction (such as Figure 3 ), the fourth direction can be consistent with the first direction, so that each first welding ribbon 22 can be arranged corresponding to the second welding ribbon 32 of the adjacent battery cell 10, ensuring that the first welding ribbon 22 and the second welding ribbon 32 are connected stably. Of course, the third direction can also be almost consistent with the fourth direction (such as Figure 1), so that the intersection angle between the second welding ribbon 32 and the second fine grid 31 is small, so that the second welding ribbon 32 and the second fine grid 31 almost overlap and then increase the contact area between the second welding ribbon 32 and the second fine grid 31, thereby reducing resistance, improving conductivity efficiency, reducing the second welding ribbon 32 and the second fine grid 31 from blocking light on the second surface 30, and improving the performance of the solar cell 10. In another embodiment, the third direction can also be consistent with the fourth direction to further increase the contact area between the two, reduce resistance, reduce the second welding ribbon 32 and the second fine grid 31 from blocking light on the second surface 30, and improve the performance of the solar cell 10.

[0079] Example 7

[0080] See also Figure 1 In some optional embodiments, the angle β between the third direction and the fourth direction is an acute angle.

[0081] In this way, the second soldering ribbon 32 and the second fine grid 31 can be tilted at an acute angle, increasing the contact area between the second soldering ribbon 32 and the second fine grid 31, thereby reducing resistance and improving conductivity. At the same time, the soldering ribbon and the grid lines almost overlap, reducing shading losses and improving the photoelectric conversion efficiency of the solar cell 100.

[0082] Specifically, because the second fine grid 31 of the second cell 12 extends along the third direction and the second welding ribbon 32 extends along the fourth direction, when the angle between the third and fourth directions is an acute angle β, the angle between the second fine grid 31 and the second welding ribbon 32 is also an acute angle β. This reduces the angle between the second fine grid 31 and the second welding ribbon 32, allowing the second welding ribbon 32 to largely overlap with the second fine grid 31, increasing the contact area between the second welding ribbon 32 and the second fine grid 31 and thereby reducing electrical resistance. Furthermore, the substantial overlap between the second fine grid 31 and the second welding ribbon 32 can also reduce the shading of the cell 10 by the second welding ribbon 32 and the second fine grid 31, thereby improving the photoelectric conversion efficiency of the solar cell 100. The embodiments of this application do not limit the specific angle (acute angle β) between the third and fourth directions to meet various requirements.

[0083] Example 8

[0084] See also Figure 1 and Figure 3 In some optional embodiments, a plurality of busbars 40 are provided on the second surface 30 of the second battery cell 12 , and the second welding strips 32 on the second surface 30 of the second battery cell 12 are cross-electrically connected to the busbars 40 .

[0085] In this manner, the second welding ribbon 32 and the busbar 40 are cross-connected and electrically connected. Different cross-connection angles can have different effects on the cell 10. For example, in some embodiments, the cross-connection between the second welding ribbon 32 and the busbar 40 can balance the current on the second side 30 of the cell 10, increase the structural strength of the cell 10, reduce the overall resistance loss of the circuit, and improve the current collection efficiency.

[0086] Specifically, when the intersection angle is large (such as Figure 3 ), a second welding ribbon 32 can connect multiple main grids 40, so that the second welding ribbon 32 and the main grid 40 can form a mesh structure that intersects each other, so that the second welding ribbon 32 can gather or disperse the current in the main grid 40, reduce the overall resistance loss of the circuit, and enhance the structural strength of the battery cell 10. When the crossing angle is small (such as Figure 1 ), the second welding ribbon 32 and the busbar 40 largely overlap, increasing the contact area between the second welding ribbon 32 and the busbar 40 while reducing the shielding of the second welding ribbon 32 and the busbar 40 on the surface of the cell 10, thereby improving the performance of the cell 10. In this way, different angles of cross-connection between the second welding ribbon 32 and the busbar 40 can bring different effects to the cell 10. The embodiments of this application do not limit the angle of intersection between the cross-connected welding ribbons and the busbar 40 to meet various needs.

[0087] Example 9

[0088] See also Figure 6 and Figure 7 In some optional embodiments, the first welding ribbon 22 on the first side 20 of the first battery cell 11 and the second welding ribbon 32 on the second side 30 of the adjacent second battery cell 12 are non-integrated continuous structures, and the first welding ribbon 22 and the second welding ribbon 32 are electrically connected through the busbar 50.

[0089] In this way, the first battery cell 11 and the second battery cell 12 can be connected through the busbar 50 , and the busbar 50 can also be connected to an external circuit to achieve multiple uses.

[0090] Specifically, the first welding ribbon 22 and the second welding ribbon 32 can be discontinuous, separate structures, and can be connected by a busbar 50. In other words, the three are connected together in the order of the first welding ribbon 22, the busbar 50, and the second welding ribbon 32. Compared with welding ribbons with a continuous structure, this can reduce the requirements for welding ribbon production precision and reduce the difficulty of welding ribbon production.

[0091] Furthermore, the busbar 50 can also be connected to an external circuit, such as connecting to other battery strings 200 to form a battery assembly 300; or connecting to other external circuits, such as a power grid, etc. The embodiments of this application do not limit the external circuits that the busbar 50 can connect to, so as to meet various needs.

[0092] In another embodiment, the first and second welding ribbons 22, 32 can be formed into a continuous, integrated structure during production. After the first welding ribbon 22 is connected to the first fine grid 21 and the second welding ribbon 32 is connected to the second fine grid 31, or after the continuous, integrated welding ribbon is produced, the connection between the first and second welding ribbons 22, 32 is cut, and a busbar 50 is then positioned at the cut location, connecting the first and second welding ribbons 22, 32 via the busbar 50. This improves welding efficiency, reduces welding steps and time, and is suitable for large-scale production. With the appropriate equipment, automated production can be achieved to improve production accuracy and consistency. Furthermore, each first and second welding ribbon 22, 32 can be electrically connected via the busbar 50, which can then be connected to other external circuits. This shortens the distance that current in the cell 10 travels to the external circuit, reducing current transmission losses.

[0093] Example 10

[0094] See also Figure 6 and Figure 7 In some optional embodiments, a busbar 50 connecting the first welding ribbon 22 of the first battery cell 11 and the second welding ribbon 32 of the adjacent second battery cell 12 is located between the first battery cell 11 and the second battery cell 12 .

[0095] In this way, the busbar 50 is located between the first battery cell 11 and the second battery cell 12, avoiding occupying the space in the thickness direction of the battery string 200. At the same time, it can avoid the busbar 50 blocking the surface of the battery cell 10, while facilitating the preparation of the battery string 200 and ensuring the performance of the battery string 200.

[0096] Specifically, the end of the first welding ribbon 22 of the first cell 11 adjacent to the bus ribbon 50 can be bent downward, while the end of the second welding ribbon 32 of the second cell 12 adjacent to the bus ribbon 50 can be bent upward, so that the first welding ribbon 22 and the second welding ribbon 32 connect the bus ribbon 50 between the two cell 10, thereby connecting the adjacent cell 10 in series. The embodiments of the present application do not limit the bending angle and length of the bent portions of the first welding ribbon 22 and the second welding ribbon 32 to meet various needs.

[0097] Example 11

[0098] See also Figures 8 to 13 In some optional embodiments, the busbar 50 connecting the first welding ribbon 22 of the first battery cell 11 and the second welding ribbon 32 of the adjacent second battery cell 12 is located on the second surface 30 of the second battery cell 12 .

[0099] In this way, the busbar 50 is arranged on the second side 30 of the battery cell 10 and connects the first welding ribbon 22 and the second welding ribbon 32 of the adjacent battery cells 10, which can avoid the busbar 50 occupying the space in the second direction of the battery string 200, thereby reducing the gap between adjacent battery cells 10 and ensuring the performance of battery strings 200 of the same length.

[0100] Specifically, the bus ribbon 50 can be at least partially disposed on the second welding ribbon 32 of the second side 30 of the second cell 12. The first welding ribbon 22 of the first cell 11 can continue to extend at one end near the bus ribbon 50. The extended portion can be configured as a bent structure. The bent structure can be two opposite 90-degree bends. The bent structure first bends 90 degrees from the first side 20 toward the second side 30 and extends to a position that passes through the gap between adjacent cell 10 and is flush with the second welding ribbon 32 of the second cell 12. It then bends 90 degrees toward the second welding ribbon 32 and extends to a point where it can connect to the bus ribbon 50 located on the second side 30 of the second cell 12. The bus ribbon 50 can be located at one end of the second welding ribbon 32 near the bent structure of the first welding ribbon 22 and at least partially extend beyond the end of the second welding ribbon 32. The extended portion of the bus ribbon 50 is used to connect to the first welding ribbon 22. The embodiments of this application do not limit the specific location of the busbar 50 on the second side 30 of the second battery cell 12, nor the bending and extension method (such as the specific bending angle and the length of the bending extension) of the bending structure of the first welding ribbon 22 extending toward the second welding ribbon 32, in order to meet various needs. It should be noted that the busbar 50 can be arranged on the side of the second welding ribbon 32 of the second battery cell 12 that is close to the second side 30, or it can be arranged on the side of the second welding ribbon 32 that is away from the second side 30. The embodiments of this application do not limit the specific location of the busbar 50, in order to meet various needs.

[0101] Example 12

[0102] See also Figures 8 to 13 In some optional embodiments, the first welding ribbon 22 of the first battery cell 11 and the second welding ribbon 32 of the second battery cell 12 are connected to the same surface or opposite surfaces of the busbar 50 .

[0103] In this way, the welding ribbon can be connected to different surfaces of the bus ribbon 50 according to actual needs to meet various requirements.

[0104] For example, when the bus ribbon 50 is disposed on the second side 30 of the second cell 12, the following situations may occur. In one example, the first welding ribbon 22 of the first cell 11 and the second welding ribbon 32 of the second cell 12 are connected to the same side of the bus ribbon 50. In this case, the first welding ribbon 22 and the second welding ribbon 32 are both disposed on the side of the bus ribbon 50 away from the second side 30, or the first welding ribbon 22 and the second welding ribbon 32 are both disposed on the side of the bus ribbon 50 closer to the second side 30. In another example, the first welding ribbon 22 of the first cell 11 and the second welding ribbon 32 of the second cell 12 are connected to opposite sides of the bus ribbon 50. In this case, the first welding ribbon 22 is disposed on the side of the bus ribbon 50 away from the second side 30, and the second welding ribbon 32 is disposed on the side of the bus ribbon 50 closer to the second side 30; or the first welding ribbon 22 is disposed on the side of the bus ribbon 50 closer to the second side 30, and the second welding ribbon 32 is both disposed on the side of the bus ribbon 50 away from the second side 30.

[0105] In the embodiment of the present application, the relative positions of the first welding ribbon 22 and the second welding ribbon 32 connected to the bus ribbon 50 are not limited to meet various requirements.

[0106] Furthermore, when the bus ribbon 50 is disposed between two adjacent battery cells 10, the following situations may occur. In one example, the first welding ribbon 22 of the first battery cell 11 and the second welding ribbon 32 of the second battery cell 12 are connected to the same surface of the bus ribbon 50. In this case, the first welding ribbon 22 and the second welding ribbon 32 are both disposed on the side of the bus ribbon 50 close to the first battery cell 11, or the first welding ribbon 22 and the second welding ribbon 32 are both disposed on the side of the bus ribbon 50 close to the second battery cell 12. In another example, the first welding ribbon 22 of the first battery cell 11 and the second welding ribbon 32 of the second battery cell 12 are connected to opposite surfaces of the bus ribbon 50. In this case, the first welding ribbon 22 is disposed on the side of the bus ribbon 50 close to the first battery cell 11, and the second welding ribbon 32 is disposed on the side of the bus ribbon 50 close to the second battery cell 12; or the first welding ribbon 22 is disposed on the side of the bus ribbon 50 close to the second battery cell 12, and the second welding ribbon 32 are both disposed on the side of the bus ribbon 50 close to the first battery cell 11. In the embodiment of the present application, the relative positions of the first welding ribbon 22 and the second welding ribbon 32 connected to the bus ribbon 50 are not limited to meet various requirements.

[0107] Example 13

[0108] See also Figure 1 and Figure 2 In some optional embodiments, the first welding ribbon 22 of the first battery cell 11 and the second welding ribbon 32 of the second battery cell 12 are electrically connected to the bus ribbon 50 through conductive glue or welding points.

[0109] In this way, the first welding ribbon 22 and the second welding ribbon 32 can be firmly connected together through the bus ribbon 50 , and stable transmission of current can be ensured.

[0110] Specifically, both the first welding ribbon 22 and the second welding ribbon 32 can be connected to the bus ribbon 50 through a conductive adhesive; or, both the first welding ribbon 22 and the second welding ribbon 32 can be connected to the bus ribbon 50 through a solder joint; or, the first welding ribbon 22 can be connected to the bus ribbon 50 through a conductive adhesive, while the second welding ribbon 32 can be connected to the bus ribbon 50 through a solder joint; or, the first welding ribbon 22 can be connected to the bus ribbon 50 through a solder joint, while the second welding ribbon 32 can be connected to the bus ribbon 50 through a conductive adhesive. This application does not limit the electrical connection method between the welding ribbons and the bus ribbon 50 to meet various needs.

[0111] Example 14

[0112] See also Figure 1 and Figure 2 In some optional embodiments, the first welding strip 22 is a flat welding strip, a round welding strip, or a triangular welding strip, and the second welding strip 32 is a flat welding strip, a round welding strip, or a triangular welding strip.

[0113] In this way, the setting of different styles of welding strips can meet various needs.

[0114] In the embodiment of the present application, the specific shapes of the first and second welding strips 22, 32 are not limited to meet different needs. Preferably, the first and second welding strips 22, 32 can be circular or triangular to reduce light blocking and improve the bifaciality of the solar cell 100.

[0115] It should be noted that different soldering ribbons have different cross-sectional shapes, resulting in different ribbon widths for the same cross-sectional area. In other words, different ribbons have different widths for the same resistance. Flat ribbons have the largest width and provide the most light shielding for the same cross-sectional area. Therefore, round or triangular ribbons are preferably used for the first and second soldering ribbons 22, 32 to ensure the performance of the cell 10.

[0116] For example, in one embodiment, the first welding ribbon 22 and the second welding ribbon 32 can be the same type of welding ribbon, such as both flat welding ribbons, or both round welding ribbons, or both triangular welding ribbons. In another embodiment, the first welding ribbon 22 and the second welding ribbon 32 can be different types of welding ribbons. The first welding ribbon 22 can be a flat welding ribbon, while the second welding ribbon 32 can be a round welding ribbon or a triangular welding ribbon. Alternatively, the first welding ribbon 22 can be a round welding ribbon, while the second welding ribbon 32 can be a flat welding ribbon or a triangular welding ribbon. Alternatively, the first welding ribbon 22 can be a triangular welding ribbon, while the second welding ribbon 32 can be a flat welding ribbon or a round welding ribbon. The embodiments of the present application do not limit the specific shapes of the first welding ribbon 22 and the second welding ribbon 32 to meet various needs.

[0117] Example 15

[0118] See also Figure 1 and Figure 2 In some optional embodiments, the first surface 20 is a light-receiving surface, and when the first welding strip 22 is a round welding strip, the diameter of the round welding strip is 0.05 mm to 0.3 mm. For example, the diameter of the round welding strip can be 0.05 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, or 0.3 mm.

[0119] In this way, while ensuring the small resistance of the round welding ribbon, a welding ribbon with a smaller diameter can be selected to avoid waste of material. At the same time, it can avoid blocking the light and improve the light receiving rate of the battery.

[0120] For example, when the power of the battery cell 10 is low and the current generated is low, a circular welding ribbon with a narrower diameter along the second direction, for example, a circular welding ribbon with a diameter of 0.1 mm, can be selected to reduce production costs. In another case, when the power of the battery cell 10 is high and the current generated is high, a circular welding ribbon with a wider diameter along the second direction, for example, a circular welding ribbon with a diameter of 0.25 mm, can be selected to reduce the resistance loss of the battery cell 10 and ensure the performance of the battery cell 10.

[0121] Example 16

[0122] See also Figure 1 and Figure 2 In some optional embodiments, when the first surface 20 is a light-receiving surface and the first welding ribbon 22 is a round welding ribbon, the width of the flat welding ribbon along the second direction is 0.2 mm to 0.8 mm. For example, the width of the flat welding ribbon along the second direction can be 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, or 0.8 mm.

[0123] In this way, while ensuring the small resistance of the flat welding strip, a flat welding strip with a smaller width can be selected to avoid material waste.

[0124] For example, when the power of the battery cell 10 is low and the current generated is low, a flat solder ribbon with a narrower width along the second direction, for example, a flat solder ribbon with a width of 0.3 mm, can be selected to reduce production costs. In another case, when the power of the battery cell 10 is high and the current generated is high, a flat solder ribbon with a wider width along the second direction, for example, a flat solder ribbon with a width of 0.5 mm, can be selected to reduce the resistance loss of the battery cell 10 and ensure the performance of the battery cell 10.

[0125] Embodiment 17

[0126] See also Figure 1 and Figure 2 In some optional embodiments, when the first surface 20 is a light-receiving surface and the first welding strip 22 is a circular welding strip, the width of the bottom edge of the triangular welding strip along the second direction is 0.05 mm to 0.5 mm. For example, the width of the bottom edge of the triangular welding strip along the second direction can be 0.05 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, or 0.5 mm.

[0127] In this way, while ensuring the low resistance of the triangular welding strip, a triangular welding strip with a smaller bottom width can be selected to avoid material waste. At the same time, it can avoid blocking the light and improve the light receiving rate of the battery.

[0128] For example, when the power of the battery cell 10 is low and the current generated is low, a triangular welding strip with a narrower bottom edge along the second direction, for example, a triangular welding strip with a bottom width of 0.1 mm, can be selected to reduce production costs. In another case, when the power of the battery cell 10 is high and the current generated is high, a triangular welding strip with a wider bottom edge along the second direction, for example, a triangular welding strip with a bottom width of 0.25 mm, can be selected to reduce the resistance loss of the battery cell 10 and ensure the performance of the battery cell 10.

[0129] Embodiment 18

[0130] See also Figure 1 and Figure 14 The battery assembly 300 provided in the embodiment of the present application includes the battery string 200 of any of the above embodiments.

[0131] In this embodiment, the battery assembly 300 may further include a frame, a backplane, photovoltaic glass, and an adhesive film. The adhesive film may be placed between the front and back surfaces of the solar cells, the photovoltaic glass, and adjacent cells 10. As a filler, the adhesive film may be a transparent colloid with good light transmittance and aging resistance. For example, the adhesive film may be EVA film or POE film. The specific choice may be based on actual conditions and is not limited here.

[0132] Photovoltaic glass can cover the film on the front of the solar cell. This glass can be ultra-clear glass, which offers high light transmittance, high transparency, and superior physical, mechanical, and optical properties. For example, ultra-clear glass can have a light transmittance exceeding 92%, protecting the solar cell while minimizing its efficiency. The film also bonds the photovoltaic glass to the solar cell, providing a sealed, insulated, and moisture-proof seal.

[0133] The backsheet can be attached to the film on the back of the solar cell. The backsheet protects and supports the solar cell and has reliable insulation, water resistance, and aging resistance. Multiple backsheet options are available, typically including tempered glass, organic glass, aluminum alloy TPT composite film, etc. The specific configuration can be tailored to the specific situation and is not limited here. The entire assembly consisting of the backsheet, solar cell, film, and photovoltaic glass can be mounted on a frame. The frame serves as the primary external support structure for the entire battery assembly 300 and provides stable support and installation for the battery assembly 300. For example, the frame can be used to install the battery assembly 300 in the desired location.

[0134] Example 19

[0135] See also Figure 1 、 Figure 14 and Figure 15 The photovoltaic system 400 provided in the embodiment of the present application includes the battery assembly 300 of the above embodiment.

[0136] In the solar cell 100, cell string 200, cell assembly 300, and photovoltaic system 400 of the embodiments of the present application, the solar cell 100 includes a cell 10, the cell 10 including a first surface 20 and a second surface 30 opposite to each other; a plurality of first fine grids 21 on the first surface 20 of the cell 10 and a plurality of second fine grids 31 on the second surface 30, the first fine grids 21 extending in a first direction and spaced apart in a second direction; a plurality of first welding ribbons 22 on the first surface 20 of the cell 10 and a plurality of second welding ribbons 32 on the second surface 30, the first welding ribbons 22 extending in the first direction and spaced apart in the second direction, the first welding ribbons 22 being electrically connected to the first fine grids 21, and the second welding ribbons 32 being electrically connected to the second fine grids 31; wherein the extension direction of the second fine grids 31 is parallel or approximately parallel to the extension direction of the first fine grids 21; or the extension direction of the second fine grids 31 is arranged to intersect the extension direction of the first fine grids 21. In this way, the first welding strip 22 and the first fine grid 21 are almost overlapped, thereby reducing light shading loss and improving the photoelectric conversion efficiency of the solar cell 100 .

[0137] In this embodiment, the photovoltaic system 400 can be applied to photovoltaic power stations, such as ground power stations, rooftop power stations, water-surface power stations, etc., and can also be applied to equipment or devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars, solar buildings, etc. Of course, it is understandable that the application scenarios of the photovoltaic system 400 are not limited to this. In other words, the photovoltaic system 400 can be applied to all fields that require solar power generation. Taking the photovoltaic power generation system network as an example, the photovoltaic system 400 may include a photovoltaic array, a junction box, and an inverter. The photovoltaic array can be an array combination of multiple battery assemblies 300. For example, multiple battery assemblies 300 can form multiple photovoltaic arrays. The photovoltaic array is connected to a junction box, which can combine the current generated by the photovoltaic array. The combined current flows through the inverter to convert it into the alternating current required by the mains power grid and then connects to the mains power network to achieve solar power supply.

[0138] Throughout this specification, reference to terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with an embodiment or example is included in at least one embodiment or example of the present application. In this specification, the illustrative use of the above terms does not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0139] In addition, the above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A solar cell, characterized in that: include: A battery cell, the battery cell comprising a first surface and a second surface opposite to each other; A plurality of first fine grids are provided on the first surface of the cell and a plurality of second fine grids are provided on the second surface, wherein the first fine grids extend along a first direction and are arranged at intervals along a second direction; a plurality of first welding strips provided on the first surface of the battery cell and a plurality of second welding strips provided on the second surface, the first welding strips extending along a first direction and arranged at intervals along the second direction, the first welding strips being electrically connected to the first fine grid, and the second welding strips being electrically connected to the second fine grid; wherein the extension direction of the second fine grid is parallel or approximately parallel to the extension direction of the first fine grid; or An extension direction of the second fine grid intersects with an extension direction of the first fine grid.

2. The solar cell according to claim 1, characterized in that The second welding strip is electrically connected to the second fine grid in a cross-connection manner.

3. The solar cell according to claim 2, characterized in that The solar cell further includes a main grid arranged on the second surface, the main grid and the second fine grid are arranged to cross and be electrically connected, and the second welding strip and the second fine grid are connected together through the main grid.

4. A battery string, characterized in that: Comprising the solar cell according to any one of claims 1 to 3, the cell string comprises a plurality of cells, the plurality of cells are distributed along a first direction, the plurality of cells include a first cell and an adjacent second cell, and the first welding ribbon of the first cell is electrically connected to the second welding ribbon of the second cell.

5. The battery string according to claim 4, characterized in that: The first welding strip on the first side of the first battery cell and the second welding strip on the second side of the adjacent second battery cell are an integral continuous structure.

6. The battery string according to claim 5, characterized in that: The second fine grid of the second battery cell extends along a third direction, the second welding strip extends along a fourth direction, and the second welding strip is cross-electrically connected to the second fine grid.

7. The battery string according to claim 6, characterized in that: An angle β between the third direction and the fourth direction is an acute angle.

8. The battery string according to claim 5, characterized in that: A plurality of main grids are provided on the second surface of the second battery cell, and a second welding strip on the second surface of the second battery cell is cross-electrically connected to the main grids.

9. The battery string according to claim 4, characterized in that: The first welding strip on the first side of the first battery cell and the second welding strip on the second side of the adjacent second battery cell are non-integrated continuous structures, and the first welding strip and the second welding strip are electrically connected through a busbar.

10. The battery string according to claim 9, characterized in that: A busbar connecting the first welding ribbon of the first battery cell and the second welding ribbon of the adjacent second battery cell is located between the first battery cell and the second battery cell.

11. The battery string according to claim 9, characterized in that: The busbar connecting the first welding ribbon of the first battery cell and the second welding ribbon of the adjacent second battery cell is located on the second surface of the second battery cell.

12. The battery string according to claim 9, characterized in that: The first welding ribbon of the first battery cell and the second welding ribbon of the second battery cell are connected to the same surface or opposite surfaces of the busbar.

13. The battery string according to claim 9, characterized in that The first welding strip of the first battery cell and the second welding strip of the second battery cell are electrically connected to the busbar through conductive glue or welding points.

14. The battery string according to claim 6, characterized in that The first welding strip is a flat welding strip, a round welding strip, or a triangular welding strip, and the second welding strip is a flat welding strip, a round welding strip, or a triangular welding strip.

15. The battery string according to claim 14, characterized in that: The first surface is a light-receiving surface. When the first welding strip is a round welding strip, the diameter of the round welding strip is 0.05 mm-0.3 mm.

16. The battery string according to claim 14, characterized in that The first surface is a light-receiving surface. When the first welding strip is a flat welding strip, the width of the flat welding strip along the third direction is 0.2 mm-0.8 mm.

17. The battery string according to claim 14, characterized in that The first surface is a light-receiving surface. When the first welding strip is a triangular welding strip, the width of the bottom edge of the triangular welding strip along the third direction is 0.05 mm-0.5 mm.

18. A battery assembly, characterized in that: Comprising the battery string according to any one of claims 4 to 17.

19. A photovoltaic system, characterized in that: Comprising the battery assembly as claimed in claim 18.

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