Solar cell, preparation method thereof and solar cell module

Abstract

The invention relates to the technical field of photovoltaic power generation, and discloses a solar cell, a preparation method thereof and a solar cell module. The solar cell comprises a substrate and at least one grid line structure located on the surface of the substrate, and each grid line structure comprises a plurality of sub-grid line structures sequentially arranged in the first direction, harpoon parts connected to the ends of every two adjacent sub-grid line structures, and connecting structures located between every two adjacent sub-grid line structures. The sub-grid line structure comprises a plurality of sub-grid lines arranged in the second direction, the harpoon part is connected with the adjacent sub-grid lines located at the end of the sub-grid line structure, and a plurality of first connecting grid lines are correspondingly arranged in the harpoon part. According to the solar cell, the preparation method thereof and the solar cell module provided by the invention, the reliability of the printed grid line pattern can be ensured, and the phenomenon of module welding grid breakage can be reduced.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic power generation technology, and in particular to a solar cell and a preparation method thereof, and a solar cell module. Background Art

[0002] With the continuous development of renewable energy power generation technologies, the proportion of renewable energy power generation is increasing. Renewable energy is widely accessible and environmentally friendly. Photovoltaic power generation is the process of generating electricity by harvesting the radiant energy of sunlight. This is achieved through solar cells, which utilize the photovoltaic effect, which generates an electric current when exposed to sunlight, thereby generating electricity.

[0003] Solar cells undergo a screen printing process during their manufacture. During this process, electrode paste is printed onto a screen to form the gridline structure. The gridline structure is a crucial component of solar cells, collecting and transmitting electrons. The screen is designed based on the gridline structure. The characteristics of the gridline structure formed during the screen printing process affect the subsequent soldering of components, leading to gridline breakage during soldering. Therefore, designing the gridline structure to ensure the reliability of the printed gridline pattern and reduce the occurrence of gridline breakage during component soldering is a critical issue. Summary of the Invention

[0004] The purpose of the embodiments of the present application is to provide a solar cell and a method for preparing the same, as well as a solar cell module, which can help ensure the reliability of the printed grid line pattern and reduce the phenomenon of grid breakage during module welding.

[0005] In order to solve the above technical problems, an embodiment of the present application provides a solar cell. The solar cell includes a substrate and at least one grid line structure located on the surface of the substrate, the grid line structure includes a plurality of sub-grid line structures arranged in sequence along a first direction, a harpoon portion connected to the ends of two adjacent sub-grid line structures, and a connecting structure located between the two adjacent sub-grid line structures. The sub-grid line structure includes a plurality of sub-grid lines arranged along a second direction, the harpoon portion connects a plurality of adjacent sub-grid lines located at the ends of the sub-grid line structure, and a plurality of first connecting grid lines are correspondingly arranged in the harpoon portion. The first connecting grid line includes a main body extending along the first direction, and a first connecting portion and a second connecting portion relatively arranged at two ends of the main body, the first connecting portion and the second connecting portion both extending along the second direction, the first connecting portion and the second connecting portion are connected to different sub-grid lines, and the first direction intersects with the second direction.

[0006] The embodiments of the present application further provide a method for preparing a solar cell, which is used to prepare the above-mentioned solar cell. The method for preparing a solar cell comprises:

[0007] providing a substrate;

[0008] A first screen is used to print and form the harpoon portion and the connecting structure on the surface of the substrate. The first screen is provided with a plurality of first printing areas spaced apart along a first direction. The first printing area is provided with a first opening slot and a second opening slot spaced apart along a second direction, and a plurality of third opening slots located between the first opening slots and the second opening slots. A plurality of fourth opening slots are provided corresponding to the first opening slots and the second opening slots.

[0009] A sub-grid structure is formed by printing on the surface of the substrate using a second screen, wherein the second screen is provided with a plurality of second printing areas spaced apart along a first direction, and the second printing areas are provided with a plurality of fifth opening slots spaced apart along the second direction, wherein the fifth opening slots extend along the first direction and are provided corresponding to the first printing area at a position between two adjacent second printing areas in the first direction;

[0010] The first direction intersects with the second direction.

[0011] The embodiments of the present application further provide a solar cell assembly, which includes a plurality of the aforementioned solar cells or a plurality of solar cells prepared by the aforementioned solar cell preparation method, wherein the plurality of solar cells are electrically connected.

[0012] The solar cell and its preparation method, and solar cell module provided by the embodiment of the present application are designed with a sub-grid line structure and a connection structure on the surface of the substrate. The sub-grid lines in the multiple sub-grid line structures are connected through the connection grid line or the first connection grid line in the connection structure to form a fine grid. In addition, the harpoon structure formed in the harpoon portion is provided with a first connection grid line, and the first connection grid line corresponding to the harpoon portion is provided in an I-shape. By adding an I-shaped grid line to the harpoon portion and connecting it with the fine grid, the stress effect during screen printing can be reduced and the shape of the screen can be stabilized. At the same time, the first connection grid line is provided in correspondence with the harpoon portion, so that the first connection grid line and the sub-grid line can be printed separately, reducing the load when the fine grid is printed on the full-opening steel plate screen, thereby reducing the printing breakage phenomenon of the fine grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings. These exemplifications do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements. Unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0014] Figure 1 is a schematic structural diagram of a solar cell provided in some embodiments of the present application;

[0015] Figure 2 is a schematic diagram of a grid line pattern in a solar cell provided by some embodiments of the present application;

[0016] Figure 3 yes Figure 2 Schematic diagram of the enlarged structure at A in the middle;

[0017] Figure 4 yes Figure 2 Schematic diagram of the enlarged structure at B in the middle;

[0018] Figure 5 is a schematic diagram of a sub-gridline structure of a gridline structure in a solar cell provided by some embodiments of the present application;

[0019] Figure 6 yes Figure 5 Schematic diagram of the enlarged structure at C in the middle;

[0020] Figure 7 Schematic diagram of the distribution of the harpoon portion and the connection structure of the grid line structure in the solar cell provided by some embodiments of the present application;

[0021] Figure 8 is a schematic diagram of the coordination structure between the harpoon portion and the connection structure in the solar cell provided in some embodiments of the present application;

[0022] Figure 9 is a schematic structural diagram of a first connecting grid line in a solar cell provided in some embodiments of the present application;

[0023] Figure 10 is a schematic structural diagram of a second connecting grid line in a solar cell provided in some embodiments of the present application;

[0024] Figure 11 is a flow chart of a method for preparing a solar cell provided in some embodiments of the present application;

[0025] Figure 12 It is a schematic structural diagram of a solar cell assembly provided in some embodiments of the present application. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, each embodiment of the present application will be described in detail below with reference to the accompanying drawings. However, it will be understood by those skilled in the art that in each embodiment of the present application, many technical details are proposed in order to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present application can be implemented. The division of the following embodiments is for convenience of description and should not constitute any limitation on the specific implementation of the present application. The various embodiments can be combined with each other and referenced to each other under the premise of no contradiction.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are for the purpose of describing specific embodiments only and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0028] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and they can refer to internal connectivity between two components or interaction between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0029] With the continuous development of solar cell manufacturing technology, the photoelectric conversion efficiency of solar cells is also constantly improving. During the preparation of solar cells, they will undergo a screen printing process. Through the screen printing process, grid line electrodes are formed on the surface of the solar cell. The grid lines can be divided into main grids and auxiliary grids, and the auxiliary grids are also called fine grids. According to the number of main grids, solar cells can be divided into super-multi-busbar cells, multi-busbar cells and no-busbar cells. The main grid usually intersects with the fine grid at right angles, and the grid line electrodes can be formed on one or both sides of the solar cell. Screen printing is carried out using a screen. The screen is designed with openings to allow metal paste to pass through during printing. The metal paste is usually silver paste. The metal paste is printed on the surface of the cell to form a main grid or fine grid. After sintering or drying and curing, the desired electrode pattern is obtained.

[0030] A fully-apertured steel plate screen is a screen with a 100% aperture ratio. The main body is no longer woven from steel wire, but is made of alloy steel sheets, with printing openings obtained by laser slotting. The aperture ratio of the screen printing working area reaches 100%, that is, the entire printed pattern is not blocked by steel wire or other similar structures. Since the fully-apertured steel plate screen has no mesh obstruction in the slotted area, the transmittance of the electrode slurry can be greatly improved, saving slurry consumption. At the same time, the use of a fully-apertured steel plate screen for screen printing can optimize the width of the grid line and significantly reduce the shading area on the battery surface. In addition, the height of the grid line after printing with a fully-apertured steel plate screen is uniform and flat, and the height fluctuation is significantly lower than that of traditional screen printing. It can significantly reduce the resistance of the grid line electrode and improve the fill factor of the solar cell.

[0031] However, since fully apertured stencils lack any support such as yarn in the openings, they can cause structural instability. Specifically, when using fully apertured stencils for screen printing, stress can cause deformation of the stencil structure away from the center of the squeegee. This deformation can easily lead to broken grid lines during screen printing.

[0032] In order to ensure the reliability of the grid line pattern printed by the full-opening steel plate screen and reduce the phenomenon of grid breakage during component welding, some embodiments of the present application provide a solar cell. The grid line form of the solar cell is optimized and the printing of the fine grid is optimized, and I-shaped grid lines are added to connect with the fine grid near the harpoon structure on both sides. By designing the I-shaped printing area, the regional tension of the full-opening steel plate screen is reduced, thereby making the shape of the screen stable and reducing the probability of deformation of the screen. When screen printing is performed, the I-shaped grid line connected to the fine grid can be printed synchronously with the harpoon structure, thereby reducing the load on the screen when printing the fine grid and reducing the phenomenon of grid breakage during printing on the fine grid. This ensures the reliability of the grid line pattern printed by the full-opening steel plate screen and reduces the phenomenon of grid breakage during component welding.

[0033] The following combination Figures 1 to 10 The structure of the solar cell provided by some embodiments of the present application is described.

[0034] like Figures 1 to 10 As shown, the solar cell provided by some embodiments of the present application includes a substrate 10 and at least one grid line structure 100 located on the surface of the substrate 10, and the grid line structure 100 includes a first direction ( Figure 2 A plurality of sub-grid line structures 110 are sequentially arranged (in the direction indicated by the arrow X in the middle), a harpoon portion connecting the ends of two adjacent sub-grid line structures 110, and at least one connecting structure located between the two adjacent sub-grid line structures 110.

[0035] The sub-gate line structure 110 includes a Figure 2 The harpoon portion connects the adjacent sub-grid lines 111 at the end of the sub-grid line structure 110, and a plurality of first connecting grid lines 123 are correspondingly arranged in the harpoon portion.

[0036] The first connecting gate line 123 includes a main body 1231 extending along the first direction, and a first connecting portion 1232 and a second connecting portion 1233 relatively arranged at both ends of the main body 1231. The first connecting portion 1232 and the second connecting portion 1233 both extend along the second direction. The first connecting portion 1232 and the second connecting portion 1233 are connected to different sub-gate lines 111, and the first direction intersects with the second direction.

[0037] The substrate 10 is the basis for forming the gridline electrodes of the solar cell and is usually a silicon substrate. Metal paste can be printed on the front and back sides of the substrate 10 to form gridline electrodes with specific patterns. The gridline electrodes printed on the front side of the substrate 10 are front electrodes, and the gridline electrodes printed on the back side of the substrate 10 are back electrodes. Normally, the front side of the substrate 10 is the light-receiving side, which receives the solar energy brought by the directly incident light, and the back side of the substrate 10 is the backlight side, which receives the solar energy brought by the scattered and refracted light. The gridline electrodes can be printed on one side or both sides of the substrate 10 to form a single-sided cell or a double-sided cell. Figure 1 Take single-sided batteries as an example. Figure 2 Shows the gridline pattern on the surface of the solar cell.

[0038] The sub-gate line structure 110 and the connection structure in the gate line structure 100 are formed in different areas on the surface of the substrate 10. Figure 2 The sub-gate line structure 110 is shown. Figure 7 and Figure 8 The connection structure is shown. The sub-grid line structure 110 and the connection structure can be printed and formed using different screens to form a complete fine grid on the surface of the solar cell. A welding pad 101 can be designed in the connection structure to connect the welding strip. The sub-grid lines 111 at different positions are connected by the connecting grid lines in the connection structure to form the fine grid of the solar cell. The sub-grid lines 111 can pass through the welding pad 101 or not. The sub-grid lines 111 passing through the welding pad 101 can be connected to the adjacent sub-grid lines 111 with the help of the welding pad 101, and a path is formed by connecting through the welding pad 101. The fine grids are arranged at intervals on the surface of the substrate 10, and the extension direction of the fine grids, i.e., the first direction and the arrangement direction of the fine grids, i.e., the second direction, can be two directions perpendicular to each other, or can be two directions with other angles.

[0039] The harpoon portion includes a first harpoon portion 121 and a second harpoon portion 122 which are arranged at the head and tail ends of the sub-grid line structure 110, and different harpoon portions form a harpoon structure in the grid line pattern. In a battery with a main grid, the design of the harpoon structure can avoid the occurrence of hidden cracks and fragments caused by welding after the main grid passes through the head and tail pads 101. In a battery without a main grid, the design of the harpoon structure can play a role in confluence. The harpoon structure is formed at a position close to the edge of the substrate 10 or close to the position of the cutting line. The harpoon structure usually extends from the position of the pad 101 with a larger head and tail area toward the edge of the substrate 10 or the cutting line. The connecting grid line of the connecting structure is located between the first harpoon portion 121 and the second harpoon portion 122, and plays a connecting role for the sub-grid line 111 located in the middle position. The first connecting grid line 123 is arranged corresponding to the first harpoon portion 121 and the second harpoon portion 122, connecting at least part of the multiple sub-grid lines 111 crossed by the harpoon structure. The harpoon structure is simultaneously connected to a plurality of sub-grid lines 111 located at the ends of the head and tail ends of two adjacent sub-grid line structures 110 .

[0040] The connection grid line of connecting structure and the first connection grid line 123 keep a one-to-one or one-to-many corresponding relationship with the sub-grid lines 111 on both sides, that is, a connection grid line of connecting structure or a first connection grid line 123 can only be connected with a sub-grid line 111 at one end thereof, and also can be connected with a plurality of sub-grid lines 111.The connection grid line of connecting structure and the first connection grid line 123 are identical with the arrangement direction of sub-grid lines 111, and sub-grid lines 111 can be overlapped on the connection grid line of connecting structure or the first connection grid line 123 when printing.Thereby, by the connection grid line of connecting structure or the first connection grid line 123, the discontinuous sub-grid lines 111 are connected to form complete thin grid, guarantee to form the path that electron moves.In actual situation, the quantity of thin grid can be 45,50,55,60,65,70 or 75. In addition, the solar cells provided in some embodiments of the present application may be whole cells or constructed in the form of slice cells, where the slice cells are formed by cutting the whole cell into multiple parts along the extension direction parallel to the fine grid, such as two slices, three slices or four slices. When the solar cell is designed in the form of a slice cell, there may be multiple grid line structures 100, and there may be multiple connection structures in the same direction. For example, when the solar cell is designed in the form of two slices, two connection structures may be designed in the same direction, so that after the whole cell is cut, each slice cell has a complete connection structure between the two adjacent sub-grid line structures 110. When the solar cell is designed in the form of three slices, three connection structures may be designed in the same direction, so that after the whole cell is cut, each slice cell has a complete connection structure between the two adjacent sub-grid line structures 110.

[0041] In addition, the solar cell can be a busbar-less cell or a busbar-equipped cell, and the busbar-equipped cell includes a multi-busbar cell and an ultra-multi-busbar cell.

[0042] The solar cells provided in some embodiments of the present application are designed with a sub-grid line structure 110 and a connecting structure on the surface of the substrate 10. The sub-grid lines 111 in the multiple sub-grid line structures 110 are connected to form a fine grid through a connecting grid line or a first connecting grid line 123 in the connecting structure. In addition, the harpoon structure formed in the harpoon portion is provided with a first connecting grid line 123 corresponding to the harpoon portion, and the first connecting grid line 123 corresponding to the harpoon portion is provided in an I-shape. By adding an I-shaped grid line to the harpoon portion to connect with the fine grid, the stress effect during screen printing can be reduced and the shape of the screen can be stabilized. At the same time, the first connecting grid line 123 is provided in correspondence with the harpoon portion, so that the first connecting grid line 123 and the sub-grid line 111 can be printed separately, reducing the load when the fine grid is printed on the full-opening steel plate screen, thereby reducing the printing breakage phenomenon of the fine grid.

[0043] It should be noted that the first connecting grid line 123 includes a plurality of parts, each of which plays a different role. The main body 1231 is the longer part of the first connecting grid line 123, forming the main structure of the first connecting grid line 123. The main body 1231 can ensure the overall length of the first connecting grid line 123, and ensure that the two adjacent sub-grids 111 in the fine grid can still be connected to form a whole via the first connecting grid line 123 when they are spaced a certain distance apart. The extension direction of the main body 1231 is the same as the extension direction of the sub-grid 111, and can play a connecting role between the two adjacent sub-grids 111. While ensuring the connection effect, the main body 1231 can be set to a smaller width to form a narrower strip to reduce the shading area and ensure the smooth flow of the electron transmission path.

[0044] The first connecting portion 1232 and the second connecting portion 1233 are parts that provide a basis for overlapping different sub-grid lines 111. The first connecting portion 1232 and the second connecting portion 1233 are located at the two ends of the main body 1231, and are arranged at the intervals of two adjacent sub-grid lines 111 corresponding to the first direction. In actual situations, in order to ensure the connection effect between the sub-grid line 111 and the first connecting grid line 123, the two connecting portions of the first connecting grid line 123 can be made to exceed the two side edges of the sub-grid line 111 distributed along the width direction. This allows the sub-grid line 111 to completely overlap within the area where the connecting portion of the first connecting grid line 123 is located when printing.

[0045] That is, the two connecting portions of the first connecting grid line 123 can extend along the width direction of the sub-grid line 111. Moreover, the length of the two connecting portions in the second direction is greater than the width of the main portion 1231 in the second direction. By making the length of the first connecting portion 1232 and the second connecting portion 1233 in the second direction greater than the width of the main portion 1231 in the second direction, the two connecting portions can extend beyond the edge of the main portion 1231 in the width direction of the sub-grid line 111. This provides favorable conditions for the sub-grid line 111 to overlap the end of the first connecting grid line 123, ensuring the connection effect between the sub-grid line 111 and the first connecting grid line 123.

[0046] It's important to note that when designing a fully open steel screen, since the slots are designed to have a 100% aperture ratio, discontinuities are added between the slots at different locations to ensure that the screen's structural strength isn't compromised by excessive slot lengths. This means that discontinuities are reserved for the slotted printing area. The discontinuities in the fine grid during printing correspond to the locations of the connecting structures in the gridline structure 100.

[0047] In some embodiments, the harpoon portion connects the 1st to the Mth sub-grid lines, where M is a positive integer less than or equal to 7.

[0048] That is, the harpoon portion is provided corresponding to the edge fine grid of the whole cell or the sliced ​​cell, and the edge fine grid is the fine grid of the whole cell close to the edge of the substrate 10, or the fine grid of the sliced ​​cell close to the edge or cut edge of the substrate 10. By controlling the range of the sub-grid lines 111 connected by the harpoon structure, it is possible to avoid the harpoon structure affecting the welding of the solder ribbon due to its large distribution range, and to avoid forming a large light-shielding area.

[0049] That is, in actual circumstances, the first harpoon portion 121 can be connected to the 1st to M sub-grid lines 111 in a direction away from the second harpoon portion 122, and the second harpoon portion 122 can be connected to the 1st to M sub-grid lines 111 in a direction away from the first harpoon portion 121, where M is a positive integer less than or equal to 7.

[0050] In addition, the plurality of first connection gate lines 123 corresponding to the harpoon portion can be connected to the first to M sub-gate lines 111 connected to the harpoon portion in a one-to-one correspondence 123 .

[0051] By maintaining corresponding connections between the first connecting grid lines 123 and the seven or fewer sub-grid lines 111 crossed by the harpoon portion, the distribution position of the first connecting grid lines 123 can cover the deformation area of ​​the screen, thereby alleviating the stress at the fine grid positions at the corresponding edge of the screen and stabilizing the shape of the screen-printed grid line electrodes.

[0052] like Figure 3As shown, the multiple first connecting gate lines 123 corresponding to the first harpoon portion 121 can be connected one-to-one with the 1st to M sub-gate lines 111 connected to the first harpoon portion 121, and the multiple second connecting gate lines 123 corresponding to the second harpoon portion 122 can be connected one-to-one with the 1st to M sub-gate lines 111 connected to the second harpoon portion 122.

[0053] In some embodiments, the length L1 of the first connection portion 1232 and the second connection portion 1233 of the first connection gate line 123 in the second direction is greater than or equal to 70 microns and less than or equal to 150 microns, and the width W1 of the first connection portion 1232 and the second connection portion 1233 of the first connection gate line 123 in the first direction is greater than or equal to 10 microns and less than or equal to 20 microns.

[0054] By configuring the two connecting portions to be strip-shaped, the light shielding area can be reduced while the area where the connecting portions are located can completely cover the end paste printing area of ​​the sub-grid line 111, thereby ensuring the connection between the sub-grid line 111 and the first connecting grid line 123.

[0055] By designing the connection portion size within a smaller range, the size is reduced, and while saving slurry material, the shading area is reduced. The connection portion size can also be designed within a larger range to ensure a good overlap effect with the second sub-grid line 111. For example, the length L1 of the first connection portion 1232 and the second connection portion 1233 in the second direction can be 70 microns, 90 microns, 110 microns, 130 microns or 150 microns, and the width W1 of the first connection portion 1232 and the second connection portion 1233 in the first direction can be 10 microns, 12 microns, 14 microns, 16 microns, 18 microns or 20 microns.

[0056] In some embodiments, a width W2 of the main portion 1231 of the first connection gate line 123 in the second direction may be smaller than a width of the sub-gate line 111 in the second direction.

[0057] The main portion 1231 is located in the middle of the first connecting gate line 123 and can only function as a current conductor. The first connecting gate line 123 can be connected to different sub-gate lines 111 through the connecting portions at both ends. By reducing the width of the main portion 1231, the slurry consumption can be reduced, and the light shielding area can be reduced.

[0058] In practice, the width W2 of the main portion 1231 of the first connecting gate line 123 in the second direction is less than or equal to 40 micrometers. That is, the width W2 of the main portion 1231 in the second direction can be controlled within a range of 30 micrometers to 40 micrometers. For example, the width W2 of the main portion 1231 in the second direction can be 30 micrometers, 32 micrometers, 34 micrometers, 36 micrometers, 38 micrometers, or 40 micrometers.

[0059] In an optional example, the length L2 of the main portion 1231 of the first connecting gate line 123 is 500 micrometers, and the width W2 of the main portion 1231 of the first connecting gate line 123 is 20 micrometers. The length L1 of the first connecting portion 1232 and the second connecting portion 1233 of the first connecting gate line 123 is 200 micrometers, and the width W1 of the first connecting portion 1232 and the second connecting portion 1233 of the first connecting gate line 123 is 20 micrometers.

[0060] In some embodiments, the connection structure may include a plurality of second connection gate lines 124 arranged in sequence along the second direction, the second connection gate lines 124 extend along the first direction, and an extension portion 1241 is respectively provided at both ends of the second connection gate line 124, the extension portion 1241 extends along the second direction, and the second connection gate line 124 is connected to the sub-gate line 111 via the extension portion 1241.

[0061] In other words, the second connecting grid lines 124 can also be configured as I-shaped grid lines. The overlapping foundation formed by the I-shaped grid lines can optimize the printing effect of the fine grid, ensuring the connection and conductivity between the sub-grid lines 111. At the same time, by making the first connecting grid lines 123 and the second connecting grid lines 124 both present an I-shape, the opening groove structure of the screen corresponding to different connecting grid lines maintains a basically consistent shape, which can facilitate the production of a full-opening steel plate screen.

[0062] In addition, the length L3 of the extension portion 1241 in the second direction can be greater than the width of the sub-gate line 111 in the second direction, and the length L3 of the extension portion 1241 in the second direction is greater than or equal to 70 micrometers and less than or equal to 150 micrometers.

[0063] By controlling the length range of the extension portion 1241, it is possible to avoid the extension portion 1241 being too long, which would lead to increased slurry consumption and an increase in the shading area. It is also possible to avoid the extension portion 1241 being too short, which would prevent it from failing to provide a good connection and affecting the current conduction effect of the extension portion 1241.

[0064] In practice, the length L3 of the extension portion 1241 in the second direction may be 70 micrometers, 90 micrometers, 110 micrometers, 130 micrometers or 150 micrometers.

[0065] In addition, while controlling the length L3 of the extension portion 1241 in the second direction, the width W3 of the extension portion 1241 in the first direction can also be controlled, such that the width W3 of the extension portion 1241 in the first direction is greater than or equal to 10 microns and less than or equal to 20 microns. For example, the width W3 of the extension portion 1241 in the first direction can be 10 microns, 12 microns, 14 microns, 16 microns, 18 microns, or 20 microns.

[0066] like Figure 8 As shown, at least part of the connection structure may further include a third connection line 125 , which extends along the second direction and connects the plurality of second connection lines 124 together.

[0067] That is, in the connection structure, a third connection grid line 125 can be designed to pass through multiple second connection grid lines 124, and the third connection grid line 125 extends along the distribution direction of the multiple second connection grid lines 124. Through the connecting function of the third connection grid line 125, multiple second connection grid lines 124 can be connected to form a current path. This ensures the current conduction effect. It should be noted that the third connection grid line 125 can be a grid line that forms a connection loop in a battery without a main grid, or it can be a main grid line in a battery with a main grid. In a battery without a main grid, the third connection grid line 125 can be set only in some positions, or a third connection grid line 125 can be designed in each connection structure to connect multiple second connection grid lines 124. In actual situations, of course, the third connection grid line 125 can also be not set.

[0068] In addition, the third connection gate line 125 may include a first segment 1251 , a second segment 1252 and a third segment 1253 sequentially arranged along the second direction, and the widths of the first segment 1251 and the third segment 1253 in the first direction are greater than the width of the second segment 1252 in the first direction.

[0069] First section 1251 and third section 1253 are located at opposite ends of second section 1252, near the edge grid lines. Connecting grid lines near the edge grid lines are susceptible to high temperatures and can fail. By widening first section 1251 and third section 1253 near the edge grid lines, the ability of the photovoltaic module formed by the solar cell package to adapt to high-temperature and high-humidity environments can be improved, reducing the risk of damage to the photovoltaic module during use.

[0070] In practice, the first segment 1251 and the third segment 1253 may be portions of the third connection gate line 125 located between the first pad 101 and the second pad 101 near the edge of the substrate 10 or the cutting line.

[0071] In some embodiments, the width of the first segment 1251 and the third segment 1253 in the first direction can be greater than or equal to 20 micrometers and less than or equal to 50 micrometers, and the width of the second segment 1252 in the first direction can be greater than or equal to 5 micrometers and less than or equal to 20 micrometers.

[0072] That is, the first segment 1251 and the third segment 1253 may be somewhat wider than the second segment 1252. The width of the second segment 1252 in the first direction is maintained within a range of 5 to 20 microns, such as 5 to 10 microns, 10 to 15 microns, or 15 to 20 microns. Specifically, the width of the second segment 1252 in the first direction may be 5 microns, 7 microns, 9 microns, 11 microns, 13 microns, 15 microns, 17 microns, or 20 microns. The width of the first segment 1251 and the third segment 1253 in the first direction may be maintained within a range of 20 to 50 microns, such as 20 to 30 microns, 30 to 40 microns, or 40 to 50 microns. Specifically, the width of the first segment 1251 and the third segment 1253 in the first direction may be 20 microns, 25 microns, 30 microns, 35 microns, 40 microns, 45 microns, or 50 microns.

[0073] By controlling the width of the widened first section 1251 and the third section 1253 within the range of 20 microns to 50 microns, it is possible to avoid the inability to improve the adaptability to high temperature and high humidity environments due to too small a width, avoid the increase in electrode slurry consumption due to too large a width, avoid the resulting cost increase, and avoid the increase in shading area due to a larger grid line width, avoid affecting the efficiency of the solar cell.

[0074] In some embodiments, the first harpoon portion 121 and the second harpoon portion 122 can be connected to the end of the third connecting gate line 125, and the first harpoon portion 121 and the second harpoon portion 122 include a first gate line 1201 and a second gate line 1202 that are spaced apart. The first gate line 1201 and the second gate line 1202 are located on both sides of the third connecting gate line 125 and are connected to different sub-gate lines 111. The distance between the first gate line 1201 and the second gate line 1202 gradually increases in the direction away from the third connecting gate line 125.

[0075] Utilize the first gate line 1201 and the second gate line 1202 that the distance between each other increases gradually to form harpoon structure, can help connect edge gate line, guarantee the connection conduction effect of edge gate line.The first connection gate line 123 is positioned between the first gate line 1201 and the second gate line 1202.Simultaneously, harpoon structure is positioned at the end of the 3rd connection gate line 125, can be provided with the larger pad 101 of area at the end of the 3rd connection gate line 125, for example pad 101 can be arranged to rectangle, the length of rectangular pad 101 can be set to 1.2 millimeters, and width can be set to 0.8 millimeter.Two gate lines of harpoon structure are closer one end can be connected on the pad 101, and the larger one end of distance is towards substrate 10 edge or cutting line position.

[0076] In addition, a plurality of first connection gate lines 123 corresponding to the harpoon portion are connected to the first to N sub-gate lines 111 connected to the harpoon portion in a one-to-one correspondence 123 , where N is a positive integer less than or equal to 4.

[0077] In other words, the I-shaped grid lines corresponding to the harpoon structure can be arranged near the end of the third connecting grid line 125, and some edge fine grid lines are connected via the first connecting grid lines 123. Sub-grid lines 111 near the edge of the substrate 10 or the cutting line can be connected and conducted via the harpoon structure. This reduces the number of first connecting grid lines 123, reduces the use of electrode paste, and reduces light obstruction.

[0078] In actual situations, the multiple first connecting gate lines 123 corresponding to the first harpoon portion 121 are connected one-to-one with the 1st to N sub-gate lines 111 connected to the first harpoon portion 121, and the multiple first connecting gate lines 123 corresponding to the second harpoon portion 122 are connected one-to-one with the 1st to N sub-gate lines 111 connected to the second harpoon portion 122, where N is a positive integer less than or equal to 4.

[0079] In some embodiments, the electrode paste used to form the sub-gate lines 111 is different from the electrode paste used to form the connection structures.

[0080] In other words, different connecting grid lines can be printed using the same electrode paste as the harpoon portion, and can be screen-printed using the same fully open stencil. Furthermore, the printing of the first connecting grid line 123, the second connecting grid line 124, and the harpoon portion can be completed simultaneously, simplifying the printing process for the different connecting grid lines. Sub-grid lines 111 can be printed using a fine grid electrode paste.

[0081] The solar cells provided in some embodiments of this application utilize the characteristics of a fully apertured steel screen to improve the gridline pattern. By designing an I-shaped gridline structure within the harpoon structure, the probability of deformation of the screen itself during printing is reduced. This improves the reliability of the gridline pattern, enabling more precise display and alignment of the gridline pattern.

[0082] In addition, the area where the middle I-shaped grid line is located can be connected by connecting grid lines to form a whole. The current forms a loop through the connecting grid lines, thereby ensuring the current conduction effect. In addition, the connecting grid line from the first large pad on the edge to the area where the adjacent small pad is located can be designed to be thickened. Because the solder ribbons near the edges of the battery cells are prone to falling off in high temperature and high humidity environments, widening the connecting grid lines near the edges of both ends can improve TC (high and low temperature environment) failure and enhance the adaptability of the module in high temperature and high humidity environments.

[0083] Some embodiments of the present application also provide a method for preparing a solar cell, which is used to prepare the above-mentioned solar cell.

[0084] like Figure 11 As shown, the method for preparing a solar cell includes the following steps:

[0085] Step S110: providing a substrate.

[0086] The substrate is the foundation for screen printing, the process used to create gate electrodes. Typically made of silicon, it exhibits the photovoltaic effect, generating electricity when exposed to sunlight.

[0087] Step S120: Use a first screen to print on the surface of the substrate to form a harpoon portion and a connecting structure, the first screen is provided with a plurality of first printing areas arranged at intervals along a first direction, the first printing area is provided with a first opening groove and a second opening groove arranged at intervals along a second direction, and a plurality of third opening grooves located between the first opening grooves and the second opening grooves, and a plurality of fourth opening grooves are provided corresponding to the first opening grooves and the second opening grooves.

[0088] The first screen uses a fully open steel plate screen with a 100% aperture ratio. There's no mesh obstructing the openings, ensuring the transmittance of the electrode paste. The first and second openings of the first screen correspond to the printing of different harpoon sections. The third opening corresponds to the printing of the first connecting grid lines, and the fourth opening corresponds to the printing of the second connecting grid lines. The printing of the harpoon structure and the connecting grid lines can be completed simultaneously or in separate steps.

[0089] Step S130: Use a second screen to print on the surface of the substrate to form a sub-gate line structure, the second screen is provided with a plurality of second printing areas arranged at intervals along the first direction, the second printing areas are provided with a plurality of fifth opening grooves arranged at intervals along the second direction, the fifth opening grooves extend along the first direction, and are provided corresponding to the first printing area at the intervals between two adjacent second printing areas in the first direction; wherein the first direction intersects the second direction.

[0090] The second screen uses a fully open steel plate screen with a 100% aperture ratio. There is no mesh obstruction in the opening slots, ensuring the transmittance of the electrode paste. The fifth opening slot of the second screen corresponds to the printing of sub-grid lines. Multiple sub-grid lines located in a straight line are overlapped on multiple first connecting grid lines or second connecting grid lines to form a fine grid.

[0091] In practice, solar cells can be printed on both sides to form grid electrodes. When printing the grid electrodes, a step-by-step printing process is employed. When preparing the front electrode, the front sub-grids are connected via different connecting grid lines to form a front fine grid. Then, the front sub-grids of the back electrode are printed, so that the back sub-grids are connected via different connecting grid lines to form a back fine grid. Furthermore, after printing the grid electrodes, the solar cell can be cut into multiple pieces along the extension direction of the fine grid to form a sliced ​​cell.

[0092] like Figure 12 As shown, some embodiments of the present application further provide a solar cell assembly, which includes a plurality of the above-mentioned solar cells or a plurality of solar cells prepared by the above-mentioned solar cell preparation method, wherein the plurality of solar cells are electrically connected.

[0093] Multiple solar cells are electrically connected to form a cell string 1. This cell string 1 is then encapsulated, with encapsulation material applied to both sides of the cell string 1. The encapsulation material includes an encapsulation film 2, a cover sheet 3, and a back sheet 4. The solar cells are connected to the cover sheet 3 and back sheet 4 via the encapsulation film 2.

[0094] Those skilled in the art will appreciate that the above-mentioned embodiments are specific examples for implementing the present application, and that in actual applications, various changes may be made thereto in form and detail without departing from the spirit and scope of the present application.

Claims

1. A solar cell, characterized in that: The invention comprises a substrate and at least one grid line structure located on a surface of the substrate, wherein the grid line structure comprises a plurality of sub-grid line structures arranged in sequence along a first direction, a harpoon portion connected to ends of two adjacent sub-grid line structures, and a connecting structure located between the two adjacent sub-grid line structures; The sub-grid structure includes a plurality of sub-grids arranged in sequence along the second direction, the harpoon portion connects a plurality of adjacent sub-grids located at ends of the sub-grid structure, and a plurality of first connecting grid lines are correspondingly arranged in the harpoon portion; The first connecting gate line includes a main body extending along the first direction, and a first connecting portion and a second connecting portion relatively arranged at two ends of the main body, the first connecting portion and the second connecting portion both extend along the second direction, the first connecting portion and the second connecting portion are connected to different sub-gate lines, and the first direction intersects with the second direction.

2. The solar cell according to claim 1, wherein The harpoon portion connects the 1st to Mth sub-grid lines, where M is a positive integer less than or equal to 7.

3. The solar cell according to claim 2, wherein The plurality of first connecting gate lines corresponding to the harpoon portion are connected to the first to M sub-gate lines connected to the harpoon portion in a one-to-one correspondence.

4. The solar cell according to claim 1, wherein The length of the first connection portion and the second connection portion of the first connection gate line in the second direction is greater than or equal to 70 micrometers and less than or equal to 150 micrometers, and the width of the first connection portion and the second connection portion of the first connection gate line in the first direction is greater than or equal to 10 micrometers and less than or equal to 20 micrometers.

5. The solar cell according to claim 1, wherein A width of the main portion of the first connecting gate line in the second direction is smaller than a width of the sub-gate line in the second direction.

6. The solar cell according to claim 5, characterized in that A width of the main portion of the first connecting gate line in the second direction is less than or equal to 40 micrometers.

7. The solar cell according to any one of claims 1 to 6, characterized in that The connection structure includes a plurality of second connection gate lines arranged in sequence along the second direction, the second connection gate lines extend along the first direction, and an extension portion is provided at both ends of the second connection gate lines, the extension portion extends along the second direction, and the second connection gate lines are connected to the sub-gate lines via the extension portion.

8. The solar cell according to claim 7, characterized in that The length of the extension portion in the second direction is greater than the width of the sub-gate line in the second direction, and the length of the extension portion in the second direction is greater than or equal to 70 micrometers and less than or equal to 150 micrometers.

9. The solar cell according to claim 7, wherein: At least part of the connection structure further includes a third connection line extending along the second direction, and the third connection line connects a plurality of the second connection lines together.

10. The solar cell according to claim 9, characterized in that The third connecting gate line includes a first segment, a second segment, and a third segment sequentially arranged along the second direction. The widths of the first segment and the third segment in the first direction are greater than the width of the second segment in the first direction.

11. The solar cell according to claim 10, characterized in that The width of the first segment and the third segment in the first direction is greater than or equal to 20 micrometers and less than or equal to 50 micrometers, and the width of the second segment in the first direction is greater than or equal to 5 micrometers and less than or equal to 20 micrometers.

12. The solar cell according to claim 1, wherein The plurality of first connecting gate lines corresponding to the harpoon portion are connected to the first to Nth sub-gate lines connected to the harpoon portion in a one-to-one correspondence, where N is a positive integer less than or equal to 4.

13. The solar cell according to claim 1, wherein The electrode paste used to form the sub-gate lines is different from the electrode paste used to form the connection structures.

14. A method for preparing a solar cell, for preparing the solar cell according to any one of claims 1 to 13, characterized in that: include: providing a substrate; A first screen is used to print and form the harpoon portion and the connecting structure on the surface of the substrate, wherein the first screen is provided with a plurality of first printing areas spaced apart along a first direction, the first printing area is provided with a first opening slot and a second opening slot spaced apart along a second direction, and a plurality of third opening slots located between the first opening slots and the second opening slots, and a plurality of fourth opening slots are provided corresponding to the first opening slots and the second opening slots; A sub-grid structure is formed by printing on the surface of the substrate using a second screen, wherein the second screen is provided with a plurality of second printing areas spaced apart along the first direction, and the second printing areas are provided with a plurality of fifth opening slots spaced apart along the second direction, wherein the fifth opening slots extend along the first direction and are provided corresponding to the first printing area at a position between two adjacent second printing areas in the first direction; The first direction intersects with the second direction.

15. A solar cell module, characterized in that: The invention comprises a plurality of solar cells according to any one of claims 1 to 13 or a plurality of solar cells prepared by the method for preparing a solar cell according to claim 14, wherein the plurality of solar cells are electrically connected.

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