Photovoltaic cell, substrate structure for a photovoltaic cell

Abstract

The utility model discloses a photovoltaic cell, a substrate structure for photovoltaic cell, the photovoltaic cell of the present application includes substrate main part, and the at least one first grid line of setting of the front surface of substrate main part near photovoltaic cell, the outer surface contour shape of first grid line is cylindrical, the outer surface of first grid line includes the first surface and the second surface along its axial direction extension, the interval of first surface and second surface gradually reduces in the direction along the back surface of photovoltaic cell away, the outer surface of first surface and second surface is smooth surface, and the light of first grid line outer surface reflection can be irradiated to photovoltaic cell. Thus, the photovoltaic cell of the present application can reduce the shading of grid line to sunlight to the greatest extent, and makes the sunlight be fully reflected under the action of first grid line and be absorbed and utilized by photovoltaic cell again, and the overall performance of photovoltaic cell is obviously improved.

Description

Technical Field

[0001] This utility model relates to the field of photovoltaic cell technology, and in particular to a photovoltaic cell and a substrate structure for a photovoltaic cell. Background Technology

[0002] Metal grid lines, serving as channels for collecting and conducting photocurrent, have a crucial impact on battery performance due to their design and fabrication process. Currently, the mainstream technology involves screen printing silver paste onto a textured surface, followed by sintering to form metal electrodes. However, this process has the following drawbacks: the printed silver grid lines have a rough surface and irregular shape, resulting in severe diffuse reflection when light shines on them, leading to a significant direct loss of light energy.

[0003] Furthermore, the reflected light energy from the grid lines of existing photovoltaic cells is not fully utilized by the photovoltaic cells. A schematic diagram of the shape of existing metal grid lines is shown below. Figure 1 As shown, this results in a significant waste of light energy. This is especially true given the large number of sub-grid lines on the battery surface, which cause substantial light energy loss. Utility Model Content

[0004] To address the aforementioned technical problems, this invention provides a photovoltaic cell and a substrate structure for the photovoltaic cell, which enables light to be reflected back into the photovoltaic cell by the grid lines when the light is irradiated at the location of the grid lines, and to be fully utilized, thereby comprehensively improving the photoelectric conversion efficiency of the photovoltaic cell.

[0005] To address the aforementioned technical problems, this application provides a photovoltaic cell, including a substrate body and at least one first grid line disposed on the front side of the substrate body near the photovoltaic cell. The outer surface profile of the first grid line is cylindrical, and the outer surface of the first grid line includes a first surface and a second surface extending along its axial direction. The distance between the first surface and the second surface gradually decreases along the direction away from the back side of the photovoltaic cell. The outer surfaces of the first surface and the second surface are smooth surfaces, and the light reflected from the outer surface of the first grid line can be irradiated onto the photovoltaic cell. Therefore, by setting the first grid line as cylindrical and setting the outer surfaces of the first surface and the second surface as smooth surfaces, the shading of sunlight by the grid line can be minimized, and the sunlight can be fully reflected by the first grid line and absorbed and utilized again by the photovoltaic cell.

[0006] Furthermore, at least one first textured surface is provided on the front side of the substrate body near the photovoltaic cell, and the first grid line is disposed on the outer surface of the first textured surface. The shape of the outer surface of the first textured surface is approximately the same as the shape of the outer surface of the first grid line. Therefore, the shape of the outer surface of the first textured surface can be utilized during the formation of the first grid line, facilitating the formation of the structure of the first grid line.

[0007] Furthermore, the first gate line is formed on the outer surface of the first textured surface through an electroplating process. Therefore, it is easy to achieve a smooth, mirror-like finish on the outer surface of the first gate line, and it also enables the fabrication of ultra-fine gate lines.

[0008] Furthermore, the distance between the first textured surface and the back of the photovoltaic cell is less than or equal to the distance between the area without the first textured surface and the back of the photovoltaic cell. When the distance between the first textured surface and the back of the photovoltaic cell is less than the distance between the area without the first textured surface and the back of the photovoltaic cell, the substrate body has at least one recessed area extending from the front to the back of the photovoltaic cell, and at least one first textured surface is provided in each recessed area. Therefore, light reflected from the outer surface of the first grid line is still irradiated onto the photovoltaic cell and absorbed by it, maximizing the utilization of light energy.

[0009] Furthermore, a plurality of third textured surfaces are provided in the recessed area. The third textured surfaces are located on both sides of the first textured surface, and the distance between the third textured surface and the back of the photovoltaic cell is equal to the distance between the first textured surface and the back of the photovoltaic cell.

[0010] Furthermore, when the distance between the first textured surface and the back of the photovoltaic cell is less than the distance between the area where the first textured surface is not provided and the back of the photovoltaic cell, a plurality of second textured surfaces are provided in the area of ​​the substrate body outside the recessed area, and the distance between the location of the second textured surface and the back of the photovoltaic cell is greater than the distance between the first textured surface and the back of the photovoltaic cell. When the distance between the first textured surface and the back of the photovoltaic cell is equal to the distance between the area where the first textured surface is not provided and the back of the photovoltaic cell, a plurality of second textured surfaces are provided in the area of ​​the substrate body where the first textured surface is not provided.

[0011] Furthermore, the first and second surfaces intersect directly or indirectly at one end away from the back of the photovoltaic cell.

[0012] Furthermore, the first grid line is a sub-grid line of the photovoltaic cell. However, the first grid line is not limited to being a sub-grid line; it can also be a main grid line, or the frame of the cell can also be set in the shape of the first grid line and correspondingly set to have a smooth outer surface.

[0013] This application also provides a substrate structure for a photovoltaic cell, including a substrate body portion. A first textured surface and a second textured surface are provided on one side of the substrate body portion corresponding to the front side of the photovoltaic cell. The outer surface contour of the first textured surface is cylindrical. The outer surface of the first textured surface includes a third surface and a fourth surface extending along its axial direction. The distance between the third surface and the fourth surface gradually decreases in the direction away from the back side of the photovoltaic cell. The distance between the first textured surface and the back side of the photovoltaic cell is less than or equal to the distance between the second textured surface and the back side of the photovoltaic cell.

[0014] This application also provides a photovoltaic cell comprising the aforementioned substrate structure, wherein grid lines are disposed on the outer surface of a first textured surface of the substrate structure, the grid lines being formed on the outer surface of the first textured surface by electroplating. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the external shape of metal grid lines in the prior art; Figure 2 This is a schematic diagram showing the shape of the electrode layer and the substrate body according to an embodiment of the present invention; Figure 3 This is a three-dimensional structural diagram of the substrate body and the first textured surface according to an embodiment of the present invention.

[0016] In the picture: 1. Substrate body; 2. First gate line; 21. First surface; 22. Second surface; 11. First textured surface; 111. Third surface; 112. Fourth surface; 12. Recessed area; 13. Second textured surface; 14. Third textured surface; 3. Electrode layer; 4. Second gate line. Detailed Implementation

[0017] The embodiments of this utility model will now be described in detail with reference to the accompanying drawings, so that the advantages and features of this utility model can be more easily understood by those skilled in the art, thereby making a clearer and more explicit definition of the scope of protection of this utility model.

[0018] Example 1: See appendix Figure 2-3As shown, this embodiment is a photovoltaic cell, including a substrate body 1 and at least one first grid line 2 disposed on the front side of the substrate body 1 near the photovoltaic cell. The outer surface contour of the first grid line 2 is cylindrical. The outer surface of the first grid line 2 includes a first surface 21 and a second surface 22 extending along the axial direction of the first grid line 2. The distance between the first surface 21 and the second surface 22 gradually decreases along the direction away from the back side of the photovoltaic cell. The outer surfaces of the first surface 21 and the second surface 22 are smooth surfaces. The light reflected from the outer surface of the first grid line 2 can be irradiated onto the photovoltaic cell.

[0019] This application minimizes the shading of sunlight by setting the first grid line 2 as a column and setting the first surface 21 and the second surface 22 as smooth surfaces, and ensures that sunlight is fully reflected by the first grid line 2 and absorbed and utilized again by the photovoltaic cell. The structure of this application results in a large contact area between the first grid line 2 and the first textured surface 11, with multiple stress points, thereby increasing the pull-out force.

[0020] In some embodiments, the axial direction of the first grid line 2 may be along a direction parallel to the edge of the substrate body 1 of the photovoltaic cell. In other possible embodiments, the axial direction of the first grid line 2 may also be in a direction that is not parallel to the outer edge of the substrate body 1.

[0021] In some embodiments, the first surface 21 and the second surface 22 intersect directly or indirectly at the end away from the back of the photovoltaic cell. For example, if the outer contour of the first grid line 2 is triangular prism, it is the case that the first surface 21 and the second surface 22 intersect directly at the end away from the back of the photovoltaic cell; if the outer contour of the first grid line 2 is trapezoidal prism, it is the case that the first surface 21 and the second surface 22 intersect indirectly at the end away from the back of the photovoltaic cell.

[0022] In some embodiments, the outer surface contour shape of the first grid line 2 may also be a trapezoidal prism. Alternatively, the outer surface of the first grid line 2 may further include a fifth surface, which is connected to the first surface 21 and the second surface 22 respectively. The fifth surface may be a plane, an arc surface, a curved surface, or an irregular surface. Thus, the outer surface contour shape of the first grid line 2 may also be trapezoidal or other irregular geometric shapes.

[0023] In some embodiments, at least one first textured surface 11 is provided on the front side of the substrate body 1 near the photovoltaic cell, and a first grid line 2 is provided on the outer surface of the first textured surface 11. The shape of the outer surface of the first textured surface 11 is approximately consistent with the shape of the outer surface of the first grid line 2. The first textured surface 11 is arranged in a direction that is generally parallel to the first grid line 2. Therefore, the first grid line 2 can utilize the shape of the outer surface of the first textured surface 11 during its formation process, and the structure of the first grid line 2 can be naturally formed on the outer surface of the first textured surface 11 according to its shape. This makes the outer contour shape of the first grid line 2 consistent with the first textured surface 11 (the term "approaching consistency" here means that the outer contour shape of the first grid line 2 is not exactly the same as the outer contour shape of the first textured surface 11; it is only necessary to ensure that their approximate shapes are similar).

[0024] In some embodiments, the first grid line 2 is formed on the outer surface of the first textured surface 11 by an electroplating process. The electroplating process can employ seed-layer electroplating or seedless electroplating, and can use rack plating, horizontal electroplating, tank plating, etc., without limitation here. Therefore, by cleverly utilizing the original outer contour shape of the first textured surface 11 and forming a plating layer on its outer surface, a smooth mirror-like effect can be easily achieved on the outer surface of the first grid line 2, and the fabrication effect of ultra-fine grid lines can be realized. See Appendix. Figure 2 In some embodiments, the thickness of the coating is y, which ranges from 3 to 12 μm.

[0025] In some embodiments, the battery substrate also includes a second grid line 4 that intersects with the first grid line 2. The second grid line 4 can also be formed by electroplating and electroplating simultaneously with the first grid line 2. Alternatively, the main body of the second grid line 4 can be prepared by screen printing, and the structure of the second grid line 4 can be formed by electroplating on the outside of the main body of the second grid line 4 during the formation of the first grid line 4.

[0026] In some embodiments, the substrate body 1 has at least one recessed region 12 that is recessed from the front side of the photovoltaic cell to the back side, and each recessed region 12 is provided with at least one first textured surface 11. That is, the bottom surface P of the first textured surface 11 is located at a smaller distance from the back side of the photovoltaic cell than the surface of the substrate body 1 near the front side of the photovoltaic cell. Taking the side of the substrate body 1 corresponding to the front side of the photovoltaic cell as surface A and the other side as surface B, the recessed region 12 is recessed from surface A towards surface B. The distance between the area where the recessed region 12 is located and the back side of the photovoltaic cell is smaller than the distance between other areas of the substrate body 1 and the back side of the photovoltaic cell. Therefore, in actual use, the light reflected at the outer surface of the first grid line 2 is still irradiated onto the photovoltaic cell and absorbed by it, maximizing the utilization of light energy and achieving the light trapping effect.

[0027] In some embodiments, a plurality of second textured surfaces 13 are provided on the outer surface of the substrate body 1 in the area outside the recessed region 12. The distance between the bottom surface of the second textured surface 13 and the back surface of the photovoltaic cell is greater than the distance between the bottom surface of the first textured surface 11 and the back surface of the photovoltaic cell.

[0028] See appendix for details. Figure 2-3 In some embodiments, the bottom surface of the first velvet surface 11 ( Figure 3 A plane (marked as P) located on the side of the first textured surface 11 near the back of the photovoltaic cell is disposed on the upper surface of the recessed area 12, and the bottom surface of the first textured surface 11 is located closer to the back of the photovoltaic cell than the bottom surface of the second textured surface 13. In some embodiments, the difference m between the height of the top of the second textured surface 13 and the height of the top of the first textured surface 11 is greater than or equal to 0 (that is, the distance between the top of the first textured surface 11 and the back of the photovoltaic cell is less than or equal to the distance between the top of the second textured surface 13 and the back of the photovoltaic cell). Therefore, light reflected by the first textured surface 11 can re-enter the photovoltaic cell, achieving full utilization of the light energy incident on the front of the photovoltaic cell with extremely low light loss.

[0029] In some embodiments, the distance W between the outer edge of the first textured surface 11 and the bottom edge of the recessed area 12 is defined as W, the width X of the bottom of the first textured surface 11 is defined as X, where W ≥ 0 μm and X is 5-20 μm, and the width (or diameter) d of the bottom of the second textured surface 13 is defined as d, where d is 1-3 μm. This dimensional setting of the first textured surface 11 and the second textured surface 13 facilitates the processing of the battery substrate. In some embodiments, the second textured surface 13 can be pyramidal in shape.

[0030] In some embodiments, third textured surfaces 14 are also provided on both sides of the first textured surface 11, and the distance between the bottom surface of the third textured surface 14 and the back surface of the photovoltaic cell is the same as the distance between the bottom surface of the first textured surface 11 and the back surface of the photovoltaic cell. By providing the third textured surface 14, the electrode layer 3 and the first textured surface 11 can form a more stable stress-bearing structure.

[0031] In other possible implementations, when the distance between the top of the first textured surface 11 and the back of the photovoltaic cell is set to be equal to the distance between the area without the first textured surface 11 and the back of the photovoltaic cell, the distance between the bottom surface of the first textured surface 11 and the back of the photovoltaic cell is still less than the distance between the area without the first textured surface 11 and the back of the photovoltaic cell. For example, the cross-section of the first textured surface 11 can be set to a trapezoid. Under the premise that the distance between the top of the first textured surface 11 and the back of the photovoltaic cell is equal to the distance between the area without the first textured surface 11 and the back of the photovoltaic cell, the area of ​​the top surface of the first textured surface 11 can be set as small as possible, thus ensuring that the light reflected by the first textured surface 11 is basically irradiated into the photovoltaic cell.

[0032] In other possible implementations, the distance between the top of the first textured surface 11 and the back of the photovoltaic cell can be set to be less than the distance between the area without the first textured surface 11 and the back of the photovoltaic cell. In this case, the first textured surface 11 can be set as a triangular prism, and the bottom surface of the first textured surface 11 can be set at... Figure 3 The recessed area 12 in the first textured surface 11 is designed so that the light reflected from the outer surface of the first grid line 2 formed on the surface of the first textured surface 11 can be irradiated onto the photovoltaic cell to the greatest extent.

[0033] In some embodiments, the first grid line 2 is a sub-grid line of the photovoltaic cell. Since the shading problem of the main grid line of the photovoltaic cell is unavoidable, overcoming the light loss problem in the area of ​​the sub-grid line directly determines the utilization efficiency of the photovoltaic cell for solar energy. This application forms the sub-grid line on the first textured surface 11 and sets the sub-grid line to the aforementioned structure and position of the first grid line 2, so that the photovoltaic cell does not suffer any light loss due to the setting of the sub-grid line, which greatly improves the overall power generation performance of the photovoltaic cell.

[0034] The performance of the photovoltaic cell used in this embodiment is compared with that of conventional HJT cells and conventional (electroplated) cells. The cell measures 210*105mm (220.48cm² after chamfering). 2 The HJT solar cells are fabricated using conventional HJT processes, while conventional cells (screen-coated) are fabricated using electroplating processes instead of screen-coating processes. The silicon wafer structure remains unchanged, and the fabricated cells are used for light injection and testing.

[0035] The difference between this embodiment and conventional photovoltaic cells is that the aforementioned first textured surface 11 structure is created during the cleaning and texturing stage. Then, an electrode layer 3 is formed on the outer surface of the first textured surface 11 using an electroplating process. The resulting solar cell is then used for light injection and testing. The comparison results are shown in Table 1. Table 1 Performance comparison of the photovoltaic cells in this application with conventional photovoltaic cells

[0036] As shown in Table 1, the Jsc (short-circuit current) of the photovoltaic cell of this application is significantly increased, while the Rs (series resistance) is significantly reduced. Compared with conventional HJT cells that use electroplating to form electrodes, the performance of the cell of this application is further improved. This is due to the use of the first textured surface 11 structure of this application, on which a first grid line 2 with a smooth mirror surface is electroplated and recessed into the silicon substrate, effectively reducing the shading of light caused by the grid line itself in the first grid line 2 region, thus maximizing the utilization of solar energy.

[0037] The battery substrate of this application may include substrates of common crystalline silicon solar cells such as PERC, HJT and TOPCon.

[0038] In other possible implementations, the first grid line 2 is not necessarily limited to being a sub-grid line; it can also be a main grid line, or the battery frame can also be set in the shape of the first grid line and correspondingly set to have a smooth outer surface.

[0039] Example 2: See appendix Figure 3 As shown, this embodiment is a substrate structure for a photovoltaic cell, including a substrate body 1. A first textured surface 11 and a second textured surface 13 are provided on one side of the substrate body 1 corresponding to the front side of the photovoltaic cell. The outer surface of the first textured surface 11 includes a third surface 111 and a fourth surface 112 extending along a first direction. The third surface 111 and the fourth surface 112 are parallel to the first surface 21 and the second surface 22, respectively, and the third surface 111 and the fourth surface 112 are located on the side of the first surface 21 and the second surface 22 closer to the back side of the photovoltaic cell. The distance between the third surface 111 and the fourth surface 112 gradually decreases in the direction away from the back side of the photovoltaic cell. The distance between the first textured surface 11 and the back side of the photovoltaic cell is less than or equal to the distance between the second textured surface 13 and the back side of the photovoltaic cell.

[0040] In some embodiments, when the distance between the first textured surface 11 and the back surface of the photovoltaic cell is less than the distance between the area where the first textured surface 11 is not provided and the back surface of the photovoltaic cell, the substrate body 1 has at least one recessed area 12 that is recessed from the front surface of the photovoltaic cell to the back surface, and at least one first textured surface 11 is provided in each recessed area 12. The recessed area 12 can be formed by directly trenching on the surface of the substrate body 1 (including but not limited to laser or etching methods), or it can be formed naturally when the first textured surface 11 is prepared.

[0041] In some embodiments, W is defined as the distance between the outer edge of the first textured surface 11 and the bottom edge of the recessed area 12, X is defined as the width of the bottom of the first textured surface 11, and d is defined as the width (or diameter) of the bottom of the second textured surface 13, where W ≥ 0 μm, X is 5-20 μm, and d is 1-3 μm. This application, by setting the dimensions of the first textured surface 11 and the second textured surface 13, facilitates the processing of the battery substrate, requiring only an additional processing step for the first textured surface 11 in the traditional battery substrate processing technology.

[0042] The difference m between the height of the top of the first textured surface 11 and the height of the top of the second textured surface 13 of the present application is ≥ 0. Thus, the light reflected by the first grid line 2 can be irradiated into the photovoltaic cell again. Meanwhile, the second textured surfaces 13 of the present application are located in other regions of the outer surfaces on both sides of the substrate main body 1 outside the recessed region 12, and the second textured surfaces 13 may be textured structures formed by a conventional texturing process. The recessed region 12 and the substrate main body 1 located on both sides thereof form a shape similar to the Chinese character "ao" (concave). By providing the second textured surface 13 structure in all other regions of the outer surface of the substrate main body 1 outside the recessed region 12, the reflected light of the electrode layer 3 formed on the third surface 111 and the fourth surface 112 of the first textured surface 11 can be completely irradiated into the photovoltaic cell and absorbed by the photovoltaic cell.

[0043] When W is greater than 0, on both sides of the first textured surface 11, a third textured surface 14 is further provided on the bottom wall of the recessed region 12. By providing the third textured surface 14, a more stable force-bearing structure can be formed between the electrode 3 and the first textured surface 11 when the electrode layer 3 is electroplated.

[0044] Third Embodiment: This embodiment relates to a photovoltaic cell, grid lines are provided on the outer surface of the first textured surface 11 of the substrate structure in the second embodiment, and the grid lines are formed on the outer surface of the first textured surface 11 by electroplating.

[0045] The above embodiments are only intended to illustrate the technical concept and features of the present utility model, and their purpose is to enable those skilled in the art to understand the content of the present utility model and implement it accordingly, and shall not be construed as limiting the protection scope of the present utility model. All equivalent changes or modifications made according to the spirit and essence of the present utility model shall be covered within the protection scope of the present utility model.

Claims

1. A photovoltaic cell, comprising a substrate body portion (1) and at least one first grid line (2) disposed on the front side of the substrate body portion (1) near the photovoltaic cell, characterized in that, The outer surface contour of the first grid line (2) is cylindrical. The outer surface of the first grid line (2) includes a first surface (21) and a second surface (22) extending along its axial direction. The distance between the first surface (21) and the second surface (22) gradually decreases along the direction away from the back of the photovoltaic cell. The outer surfaces of the first surface (21) and the second surface (22) are smooth surfaces. The light reflected from the outer surface of the first grid line (2) can be irradiated onto the photovoltaic cell.

2. The photovoltaic cell according to claim 1, characterized in that, The substrate body (1) has at least one first textured surface (11) on the front side near the photovoltaic cell. The first grid line (2) is disposed on the outer surface of the first textured surface (11). The shape of the outer surface of the first textured surface (11) is close to the shape of the outer surface of the first grid line (2).

3. The photovoltaic cell according to claim 2, characterized in that, The first grid line (2) is formed on the outer surface of the first textured surface (11) by an electroplating process.

4. The photovoltaic cell according to claim 3, characterized in that, The distance between the top of the first textured surface (11) and the back of the photovoltaic cell is less than or equal to the distance between the area where the first textured surface (11) is not provided and the back of the photovoltaic cell, and the distance between the bottom surface of the first textured surface (11) and the back of the photovoltaic cell is less than the distance between the area where the first textured surface (11) is not provided and the back of the photovoltaic cell. The substrate body (1) has at least one recessed area (12) that is recessed from the front to the back of the photovoltaic cell, and at least one first textured surface (11) is provided in each recessed area (12).

5. The photovoltaic cell according to claim 4, characterized in that, A plurality of third textured surfaces (14) are also provided in the recessed area (12). The third textured surfaces (14) are located on both sides of the first textured surface (11), and the distance between the third textured surface (14) and the back of the photovoltaic cell is equal to the distance between the first textured surface (11) and the back of the photovoltaic cell.

6. The photovoltaic cell according to claim 4, characterized in that, A plurality of second textured surfaces (13) are provided on the outer surface of the substrate body (1) in the area outside the recessed area (12). The distance between the bottom surface of the second textured surface (13) and the back surface of the photovoltaic cell is greater than the distance between the bottom surface of the first textured surface (11) and the back surface of the photovoltaic cell.

7. The photovoltaic cell according to any one of claims 1-6, characterized in that, The first surface (21) and the second surface (22) intersect directly or indirectly at one end away from the back of the photovoltaic cell.

8. The photovoltaic cell according to any one of claims 1-6, characterized in that, The first grid line (2) is the sub-grid line of the photovoltaic cell.

9. A substrate structure for photovoltaic cells, comprising a substrate body (1), characterized in that, A first textured surface (11) and a second textured surface (13) are provided on one side of the substrate body (1) corresponding to the front side of the photovoltaic cell. The outer surface contour of the first textured surface (11) is cylindrical. The outer surface of the first textured surface (11) includes a third surface (111) and a fourth surface (112) extending along its axial direction. The distance between the third surface (111) and the fourth surface (112) gradually decreases in the direction away from the back of the photovoltaic cell, and the distance between the first textured surface (11) and the back of the photovoltaic cell is less than or equal to the distance between the second textured surface (13) and the back of the photovoltaic cell.

10. A photovoltaic cell, characterized in that, The substrate structure includes the substrate structure of claim 9, wherein a grid line is provided on the outer surface of the first textured surface (11) of the substrate structure, and the grid line is formed on the outer surface of the first textured surface (11) by electroplating.

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