Back-contact solar cell

Abstract

The present application relates to a back-contact solar cell, comprising: a substrate. An isolation groove is provided on the substrate, and the isolation groove is disposed between a first doped layer and a second doped layer. The first doped layer comprises a first body portion and a first finger portion connected to the first body portion, and the second doped layer comprises a second body portion and a second finger portion connected to the second body portion. The first finger portion comprises a plurality of first sub-portions that are in contact with each other and extend toward the second body portion, the extension lengths of the first sub-portions being different. The second finger portion comprises a plurality of second sub-portions that are in contact with each other and extend toward the first body portion, the extension lengths of the second sub-portions being different.

Description

Back contact solar cell

[0001] This application claims priority to Chinese Patent Application No. 202411562781.3, filed on November 4, 2024, entitled “Back Contact Solar Cell”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of solar cell technology, and in particular to a back-contact solar cell. Background Technology

[0003] Back-contact solar cells are a type of solar cell structure used to improve cell efficiency. Their core design involves placing all the metal electrodes of the solar cell on the back of the cell, thereby ensuring that the front of the cell is not blocked by the metal grid lines. This increases the area of ​​the cell that absorbs sunlight, reduces optical losses, and improves photoelectric conversion efficiency.

[0004] In back-contact solar cells, to avoid leakage problems, isolation trenches are typically placed between different doped regions to separate them. As the width of the isolation trenches gradually narrows, the risk of leakage in traditional back-contact solar cells gradually increases.

[0005] Summary of the Invention

[0006] Therefore, it is necessary to provide a back-contact solar cell. The back-contact solar cell of this application can achieve a better matching effect between the isolation trench, the doped region and the electrode, thereby reducing the risk of leakage.

[0007] This application provides a back-contact solar cell, comprising: a substrate; a first doped layer and a second doped layer disposed on the same surface of the substrate in an interdigitated manner, the first doped layer and the second doped layer having opposite doping types; an isolation trench is also disposed on the substrate, the isolation trench being disposed between the first doped layer and the second doped layer, the isolation trench being used to separate the first doped layer and the second doped layer;

[0008] The first doped layer includes a first body portion and a first finger portion connected to the first body portion, and the second doped layer includes a second body portion and a second finger portion connected to the second body portion;

[0009] The first finger includes a plurality of first sub-parts that are in contact with each other and extend toward the second main body, each of the first sub-parts having a different extension length; the second finger includes a plurality of second sub-parts that are in contact with each other and extend toward the first main body, each of the second sub-parts having a different extension length.

[0010] In some embodiments, in the first finger portion, the extension length of each of the first sub-parts decreases sequentially; and in the second finger portion, the extension length of each of the second sub-parts increases sequentially.

[0011] In some embodiments, in the first finger portion, the extension length of each of the first sub-parts decreases proportionally in sequence; and in the second finger portion, the extension length of each of the second sub-parts increases proportionally in sequence.

[0012] In some embodiments, the width of the isolation groove is less than 1 mm.

[0013] In some embodiments, there are multiple first fingers, which are spaced apart along the extension direction of the first main body; there are multiple second fingers, which are spaced apart along the extension direction of the second main body; the first fingers and the second fingers are alternately arranged.

[0014] In some embodiments, the width of each of the first sub-parts in the first finger portion is equal; and the width of each of the second sub-parts in the second finger portion is equal.

[0015] In some embodiments, the number of first sub-parts in the first finger portion is 2 to 4; and the number of second sub-parts in the second finger portion is 2 to 4.

[0016] In some embodiments, the back-contact solar cell further includes a first main grid, a second main grid, a first fine grid, and a second fine grid;

[0017] The first main grid is disposed on the surface of the first main body; the first fine grid is connected to the first main grid, and there are multiple first fine grids, each of which extends along the extension direction of a first sub-part and is disposed on the surface of the first sub-part;

[0018] The second main grid is disposed on the surface of the second main body; the second fine grid is connected to the second main grid, and there are multiple second fine grids, each of which extends along the extension direction of a second sub-part and is disposed on the surface of the second sub-part.

[0019] In some embodiments, the back-contact solar cell further includes a first solder joint and a second solder joint; the first solder joint is connected to the first main grid, and a plurality of first fine grids are connected to the first solder joint; the second solder joint is connected to the second main grid, and a plurality of second fine grids are connected to the second solder joint.

[0020] In some embodiments, the back-contact solar cell further includes a first passivation antireflection layer and a second passivation antireflection layer; the first passivation antireflection layer is disposed on the surface of the first doped layer and the second doped layer away from the substrate; the second passivation antireflection layer is disposed on the opposite surface of the substrate on which the first doped layer and the second doped layer are disposed.

[0021] Compared to traditional back-contact solar cells, the aforementioned back-contact solar cell structure has fewer isolation trenches while maintaining the same trench width. Generally, a higher number of isolation trenches presents new challenges to the matching of front-end and back-end processes, leading to a higher risk of leakage. However, the back-contact solar cell of this application has fewer isolation trenches parallel to the grid direction, making it easier to achieve a better matching effect between the isolation trenches, doped regions, and electrodes, thereby reducing the risk of leakage. Furthermore, the smaller area of ​​the isolation trenches in the aforementioned back-contact solar cell allows for higher cell utilization, resulting in a higher current density. Attached Figure Description

[0022] Figure 1 is a schematic diagram of the isolation trench and doped layer in a traditional back-contact solar cell;

[0023] Figure 2 is a schematic diagram of the structure of the first doped layer and the second doped layer of a back contact solar cell provided in an embodiment of this application;

[0024] Figure 3 is a schematic diagram of the grid structure of a back-contact solar cell provided in an embodiment of this application;

[0025] Figure 4 is a schematic diagram of the structure of a back-contact solar cell provided in an embodiment of this application.

[0026] Explanation of reference numerals in the attached figures

[0027] 1. First doped layer; 2. Second doped layer; 3. Isolation trench; 4. First main body portion; 5. First finger portion; 6. First sub-portion; 7. Second main body portion; 8. Second finger portion; 9. Second sub-portion; 10. First main gate; 11. First fine gate; 12. Second main gate; 13. Second fine gate; 14. First solder joint; 15. Second solder joint; 16. Substrate; 17. First passivation antireflection layer; 18. Second passivation antireflection layer. Detailed Implementation

[0028] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, a detailed description of specific embodiments of this application is provided below. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0030] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, 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, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0031] 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 technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0032] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0033] Referring to Figure 1, which is a schematic diagram of the isolation trench 3 and doped layers in a conventional back-contact solar cell, it can be seen that the first doped layer 1 and the second doped layer 2 are separated by the isolation trench 3 and arranged in an interdigitated shape. The "finger" portions of both the first doped layer 1 and the second doped layer 2 are rectangular. When the width of the isolation trench 3 is small, the risk of leakage increases.

[0034] One embodiment of this application provides a back-contact solar cell, including a substrate 16. A first doped layer 1 and a second doped layer 2, arranged in an interdigitated pattern, are disposed on the same surface of the substrate 16, with the first doped layer 1 and the second doped layer 2 having opposite doping types. An isolation trench 3 is also disposed on the substrate 16, between the first doped layer 1 and the second doped layer 2, and serves to separate the first doped layer 1 and the second doped layer 2. The first doped layer 1 includes a first body portion 4 and first finger portions 5 connected to the first body portion 4. The second doped layer 2 includes a second body portion 7 and second finger portions 8 connected to the second body portion 7. The first finger portions 5 include a plurality of contacting first sub-portions 6 extending toward the second body portion 7, each first sub-portion 6 having a different extension length. The second finger portions 8 include a plurality of contacting second sub-portions 9 extending toward the first body portion 4, each second sub-portion 9 having a different extension length.

[0035] Compared to traditional back-contact solar cells, the aforementioned back-contact solar cell has fewer isolation trenches 3 of the same width. Generally, a higher number of isolation trenches presents new challenges to the matching of front-end and back-end processes, leading to a higher risk of leakage. However, the back-contact solar cell of this application has fewer isolation trenches 3 parallel to the grid direction, making it easier to achieve a better matching effect between the isolation trenches 3, the doped region, and the electrodes, thereby reducing the risk of leakage. Furthermore, in the aforementioned back-contact solar cell, the area of ​​the isolation trenches 3 is smaller, enabling the cell to have higher utilization and thus achieve a higher current density.

[0036] In some embodiments, in the first finger portion 5, the extension length of each first sub-part 6 decreases sequentially. In the second finger portion 8, the extension length of each second sub-part 9 increases sequentially.

[0037] Back-contact solar cells with the above structure can achieve a better matching effect between the isolation trench 3, the doped region and the electrode, thereby reducing the risk of leakage.

[0038] In some embodiments, in the first finger portion 5, the extension lengths of each first sub-part 6 decrease proportionally in sequence. In the second finger portion 8, the extension lengths of each second sub-part 9 increase proportionally in sequence.

[0039] Back-contact solar cells with the above structure can achieve a better matching effect between the isolation trench 3, the doped region and the electrode, thereby reducing the risk of leakage.

[0040] In some embodiments, the width of the isolation groove 3 is less than 1 mm.

[0041] When the width of the isolation trench 3 is small, the leakage risk of traditional back-contact solar cells increases. However, the back-contact solar cell of this application can achieve a better matching effect between the isolation trench 3, the doped region, and the electrode, thereby reducing the risk of leakage. Optionally, the width of the isolation trench 3 is 0.01mm, 0.02mm, 0.05mm, 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, or 1mm, or the width of the isolation trench 3 can be within any two of the above widths.

[0042] In some embodiments, there are multiple first fingers 5, which are spaced apart along the extending direction of the first main body 4. There are also multiple second fingers 8, which are spaced apart along the extending direction of the second main body 7. The first fingers 5 and the second fingers 8 are alternately arranged.

[0043] In some embodiments, in the first finger portion 5, each of the first sub-parts 6 has an equal width. In the second finger portion 8, each of the second sub-parts 9 has an equal width.

[0044] In some embodiments, the number of first sub-parts 6 in the first finger portion 5 is 2 to 4. The number of second sub-parts 9 in the second finger portion 8 is 2 to 4.

[0045] Optionally, the number of the first sub-part 6 is 2, 3, or 4. The number of the second sub-part 9 is 2, 3, or 4.

[0046] Referring to FIG3, in some embodiments, the back-contact solar cell further includes a first main grid 10, a second main grid 12, a first fine grid 11, and a second fine grid 13. The first main grid 10 is disposed on the surface of the first main body portion 4. Multiple first fine grids 11 are connected to the first main grid 10, each extending along the extending direction of a first sub-part 6 and disposed on the surface of the first sub-part 6. The second main grid 12 is disposed on the surface of the second main body portion 7. Multiple second fine grids 13 are connected to the second main grid 12, each extending along the extending direction of a second sub-part 9 and disposed on the surface of the second sub-part 9.

[0047] Furthermore, in the structure of conventional back-contact solar cells, the fine grid is disposed on the fingers. Therefore, the fine grid extends close to the doped region on the other side, resulting in an excessively long transmission path. Consequently, the current at the end of the fine grid is difficult to collect by the main grid, leading to high series resistance. In the grid structure described above in this application, compared with conventional back-contact solar cells, the back-contact solar cell of this application has a significantly shorter transmission path, thereby reducing series resistance. Simultaneously, near each fine grid doped region (i.e., each sub-region), there are still heterogeneous doped regions with opposite doping types, thus having a smaller impact on the open-circuit voltage of the back-contact solar cell. In other words, the back-contact solar cell with the above-described grid structure can have a lower leakage risk, lower series resistance, and higher current density.

[0048] In some embodiments, the back-contact solar cell further includes a first solder joint 14 and a second solder joint 15. The first solder joint 14 is connected to a first main grid 10, and a plurality of first fine grids 11 are connected to the first solder joint 14. The second solder joint 15 is connected to a second main grid 12, and a plurality of second fine grids 13 are connected to the second solder joint 15.

[0049] Referring to FIG4, in some embodiments, the back-contact solar cell further includes a first passivation antireflection layer 17 and a second passivation antireflection layer 18. The first passivation antireflection layer 17 is disposed on the surface of the first doped layer 1 and the second doped layer 2 away from the substrate 16. The second passivation antireflection layer 18 is disposed on the opposite surface of the substrate 16 on the surface where the first doped layer 1 and the second doped layer 2 are disposed.

[0050] Referring again to Figures 2, 3, and 4, in some embodiments, the back-contact solar cell includes a substrate 16, which has a front side and a back side disposed opposite to each other. A first doped layer 1 and a second doped layer 2, arranged in an interdigitated pattern, are disposed on the back side of the substrate 16, having opposite doping types. An isolation trench 3 is also disposed on the substrate 16, positioned between the first doped layer 1 and the second doped layer 2, serving to separate the first doped layer 1 and the second doped layer 2. The first doped layer 1 includes a first body portion 4 and first finger portions 5 connected to the first body portion 4. The second doped layer 2 includes a second body portion 7 and second finger portions 8 connected to the second body portion 7. The first finger portion 5 includes a plurality of contacting first sub-parts 6 extending toward the second body portion 7, each first sub-part 6 having a different extension length. The second finger portion 8 includes a plurality of contacting second sub-parts 9 extending toward the first body portion 4, each second sub-part 9 having a different extension length. In the first finger portion 5, the extension lengths of each first sub-part 6 decrease sequentially. In the second finger portion 8, the extension length of each second sub-part 9 increases sequentially. In the first finger portion 5, the extension length of each first sub-part 6 decreases sequentially in a proportional manner. In the second finger portion 8, the extension length of each second sub-part 9 increases sequentially in a proportional manner. There are multiple first finger portions 5, which are spaced apart along the extension direction of the first main body portion 4. There are multiple second finger portions 8, which are spaced apart along the extension direction of the second main body portion 7. The first finger portions 5 and second finger portions 8 are alternately arranged. In the first finger portion 5, the width of each first sub-part 6 is equal. In the second finger portion 8, the width of each second sub-part 9 is equal. The back contact solar cell also includes a first main grid 10, a second main grid 12, a first fine grid 11, and a second fine grid 13. The first main grid 10 is disposed on the surface of the first main body portion 4. The first fine grid 11 is connected to the first main grid 10, and there are multiple first fine grids 11, each of which extends along the extension direction of a first sub-part 6 and is disposed on the surface of the first sub-part 6. The second main gate 12 is disposed on the surface of the second main body portion 7. Multiple second fine gates 13 are connected to the second main gate 12, each extending along the extension direction of a second sub-portion 9 and disposed on the surface of the second sub-portion 9. The back contact solar cell also includes a first solder joint 14 and a second solder joint 15. The first solder joint 14 is connected to the first main gate 10, and multiple first fine gates 11 are connected to the first solder joint 14. The second solder joint 15 is connected to the second main gate 12, and multiple second fine gates 13 are connected to the second solder joint 15. The back contact solar cell also includes a first passivation antireflection layer 17 and a second passivation antireflection layer 18. The first passivation antireflection layer 17 covers the surfaces of the first doped layer 1 and the second doped layer 2 away from the substrate 16. The second passivation antireflection layer 18 covers the front side of the substrate 16.

[0051] The following are specific embodiments.

[0052] Example 1

[0053] Referring again to Figures 2-4, the back-contact solar cell in Embodiment 1 includes a substrate 16, which has a front side and a back side disposed opposite to each other. An N-type doped layer and a P-type doped layer are disposed on the back side of the substrate 16 in an interdigitated manner. An isolation trench 3 is also disposed on the substrate 16, between the first doped layer 1 and the second doped layer 2, and serves to separate the N-type and P-type doped layers. The N-type doped layer includes a first body portion 4 and a first finger portion 5 connected to the first body portion 4. The P-type doped layer includes a second body portion 7 and a second finger portion 8 connected to the second body portion 7. In this embodiment, the first finger portion 5 includes two contacting first sub-parts 6 of equal width extending toward the second body portion 7, wherein the shorter first sub-part 6 has a length that is half the length of the longer first sub-part 6. The second finger portion 8 includes two contacting second sub-parts 9 of equal width extending toward the first body portion 4, wherein the shorter second sub-part 9 has a length that is half the length of the longer second sub-part 9. The shorter first sub-section 6 and the shorter second sub-section 9 are arranged opposite each other.

[0054] The back-contact solar cell also includes a first main grid 10, a second main grid 12, a first fine grid 11, and a second fine grid 13. The first main grid 10 is disposed on the surface of the first main body portion 4. Multiple first fine grids 11 are connected to the first main grid 10, each extending along the extension direction of a first sub-part 6 and disposed on the surface of the first sub-part 6. The second main grid 12 is disposed on the surface of the second main body portion 7. Multiple second fine grids 13 are connected to the second main grid 12, each extending along the extension direction of a second sub-part 9 and disposed on the surface of the second sub-part 9. The back-contact solar cell also includes a first solder joint 14 and a second solder joint 15. The first solder joint 14 is connected to the first main grid 10, and multiple first fine grids 11 are connected to the first solder joint 14. The second solder joint 15 is connected to the second main grid 12, and multiple second fine grids 13 are connected to the second solder joint 15. The back-contact solar cell also includes a first passivation antireflection layer 17 and a second passivation antireflection layer 18. The first passivation antireflection layer 17 covers the surfaces of the first doped layer 1 and the second doped layer 2 away from the substrate 16. The second passivation antireflection layer 18 covers the front side of the substrate 16.

[0055] Comparative Example 1

[0056] Referring to Figure 1, the only difference between the back-contact solar cell structure in Comparative Example 1 and that in Example 1 is that each finger of the doped layer in the back-contact solar cell of Comparative Example 1 is rectangular, and the width of each finger is the same as the width of the sub-part in Example 1. The width of the isolation trench 3 in Example 2 is also the same as that in Example 1.

[0057] The back contact batteries in Example 1 and Comparative Example 1 were tested, and the test results are shown in the table below:

[0058] As can be seen from the test results in the table above, the back-contact solar cell in Example 1 has a lower series resistance and a higher current density than the back-contact solar cell in Comparative Example 1, thus achieving a higher conversion efficiency.

[0059] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0060] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. A back-contact solar cell, comprising: Substrate; On the same surface of the substrate, a first doped layer and a second doped layer are disposed in an interdigitated manner, the first doped layer and the second doped layer having opposite doping types; an isolation trench is also disposed on the substrate, the isolation trench being disposed between the first doped layer and the second doped layer, the isolation trench being used to separate the first doped layer and the second doped layer. The first doped layer includes a first body portion and a first finger portion connected to the first body portion, and the second doped layer includes a second body portion and a second finger portion connected to the second body portion; The first finger includes a plurality of first sub-parts that are in contact with each other and extend toward the second main body, each of the first sub-parts having a different extension length; the second finger includes a plurality of second sub-parts that are in contact with each other and extend toward the first main body, each of the second sub-parts having a different extension length.

2. The back-contact solar cell according to claim 1, wherein, In the first finger portion, the extension length of each of the first sub-parts decreases sequentially; in the second finger portion, the extension length of each of the second sub-parts increases sequentially.

3. The back-contact solar cell according to claim 2, wherein, In the first finger portion, the extension length of each of the first sub-parts decreases proportionally in sequence; in the second finger portion, the extension length of each of the second sub-parts increases proportionally in sequence.

4. The back-contact solar cell according to claim 1, wherein, The width of the isolation groove is less than 1 mm.

5. The back-contact solar cell according to claim 1, wherein, There are multiple first fingers, which are spaced apart along the extension direction of the first main body; there are multiple second fingers, which are spaced apart along the extension direction of the second main body; the first fingers and the second fingers are alternately arranged.

6. The back-contact solar cell according to claim 1, wherein, In the first finger portion, the width of each of the first sub-parts is equal; in the second finger portion, the width of each of the second sub-parts is equal.

7. The back-contact solar cell according to claim 1, wherein, In the first finger portion, the number of the first sub-parts is 2 to 4; in the second finger portion, the number of the second sub-parts is 2 to 4.

8. The back-contact solar cell according to any one of claims 1 to 7, wherein, The back-contact solar cell further includes a first main grid, a second main grid, a first fine grid, and a second fine grid; The first main grid is disposed on the surface of the first main body; the first fine grid is connected to the first main grid, and there are multiple first fine grids, each of which extends along the extension direction of a first sub-part and is disposed on the surface of the first sub-part; The second main grid is disposed on the surface of the second main body; the second fine grid is connected to the second main grid, and there are multiple second fine grids, each of which extends along the extension direction of a second sub-part and is disposed on the surface of the second sub-part.

9. The back-contact solar cell according to claim 8, wherein, The back-contact solar cell further includes a first solder joint and a second solder joint; the first solder joint is connected to the first main grid, and a plurality of first fine grids are connected to the first solder joint; the second solder joint is connected to the second main grid, and a plurality of second fine grids are connected to the second solder joint.

10. The back-contact solar cell according to any one of claims 1 to 7, wherein, The back-contact solar cell further includes a first passivation antireflection layer and a second passivation antireflection layer; the first passivation antireflection layer is disposed on the surface of the first doped layer and the second doped layer away from the substrate; the second passivation antireflection layer is disposed on the opposite surface of the substrate on which the first doped layer and the second doped layer are disposed.

Images