Back contact solar cell

Abstract

The invention relates to a back contact solar cell which comprises a substrate. A first doping layer and a second doping layer which are arranged at intervals in an interdigital mode are arranged on the same surface of the substrate, and the first doping layer and the second doping layer have opposite doping types. The substrate is further provided with an isolation groove, the isolation groove is arranged between the first doping layer and the second doping layer, and the isolation groove is used for separating the first doping layer from the second doping layer. The first doped layer comprises a first main body part and a first finger part connected to the first main body part, and the second doped layer comprises a second main body part and a second finger part connected to the second main body part. The first finger part comprises a plurality of first sub-parts which are in contact with each other and extend towards the second main body part, and the extension lengths of the first sub-parts are different. The second finger part comprises a plurality of second sub-parts which are in contact with one another and extend towards the first main body part, and the extension lengths of the second sub-parts are different.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and in particular to a back-contact solar cell. Background Art

[0002] The back-contact cell is a solar cell structure used to improve cell efficiency. Its core design is to place 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. This can increase the area of ​​the cell that absorbs sunlight, reduce optical losses, and improve photoelectric conversion efficiency.

[0003] In order to avoid leakage problems in back-contact solar cells, isolation trenches are usually set between different doping regions to separate the different doping regions. As the width of the isolation trenches gradually narrows, the leakage risk in traditional back-contact solar cells will gradually increase. Summary of the invention

[0004] Based on this, it is necessary to provide a back-contact solar cell. The back-contact solar cell of the present application can achieve a better matching effect between the isolation groove, the doping region and the electrode, thereby reducing the risk of leakage.

[0005] The present application provides a back-contact solar cell, comprising: a substrate; a first doping layer and a second doping layer arranged in an interdigitated manner are arranged on the same surface of the substrate, and the first doping layer and the second doping layer have opposite doping types; an isolation groove is also arranged on the substrate, and the isolation groove is arranged between the first doping layer and the second doping layer, and the isolation groove is used to separate the first doping layer and the second doping layer;

[0006] The first doping layer includes a first main body and a first finger connected to the first main body, and the second doping layer includes a second main body and a second finger connected to the second main body;

[0007] The first finger portion includes a plurality of first sub-portions that are in contact with each other and extend toward the second main body portion, and each of the first sub-portions has a different extension length; the second finger portion includes a plurality of second sub-portions that are in contact with each other and extend toward the first main body portion, and each of the second sub-portions has a different extension length.

[0008] In some embodiments, in the first finger portion, the extension length of each of the first sub-portions decreases sequentially; and in the second finger portion, the extension length of each of the second sub-portions increases sequentially.

[0009] In some embodiments, in the first finger portion, the extension lengths of the first sub-portions decrease sequentially in geometric proportion; and in the second finger portion, the extension lengths of the second sub-portions increase sequentially in geometric proportion.

[0010] In some embodiments, the width of the isolation groove is less than 1 mm.

[0011] 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; and the first fingers and the second fingers are alternately arranged.

[0012] In some embodiments, in the first finger portion, the widths of the first sub-portions are equal; in the second finger portion, the widths of the second sub-portions are equal.

[0013] In some embodiments, in the first finger portion, the number of the first sub-portions is 2 to 4; in the second finger portion, the number of the second sub-portions is 2 to 4.

[0014] In some embodiments, the back contact solar cell further comprises a first main grid, a second main grid, a first fine grid and a second fine grid;

[0015] The first main grid is disposed on the surface of the first main portion; the first fine grid is connected to the first main grid, and there are a plurality of the first fine grids, each of which extends along an extension direction of one of the first sub-portions and is disposed on the surface of the first sub-portion;

[0016] The second main grid is arranged on the surface of the second main body; the second fine grid is connected to the second main grid, there are multiple second fine grids, each of which extends along the extension direction of a second sub-section and is arranged on the surface of the second sub-section.

[0017] In some embodiments, the back-contact solar cell also includes a first welding point and a second welding point; the first welding point is connected to the first main grid, and a plurality of first fine grids are connected to the first welding point; the second welding point is connected to the second main grid, and a plurality of second fine grids are connected to the second welding point.

[0018] In some embodiments, the back-contact solar cell further includes a first passivation anti-reflection layer and a second passivation anti-reflection layer; the first passivation anti-reflection layer is disposed on the surface of the first doped layer and the second doped layer away from the substrate; the second passivation anti-reflection layer is disposed on the surface opposite to the surface of the substrate on which the first doped layer and the second doped layer are disposed.

[0019] Compared with traditional back-contact solar cells, when the width of the isolation grooves is the same, the structure of the above-mentioned back-contact solar cell has fewer isolation grooves. Generally, the more isolation grooves there are, the new challenges will be brought to the matching of the front-end and back-end processes, resulting in a higher risk of leakage. However, the back-contact solar cell of the present application has fewer isolation grooves parallel to the fine gate direction, which makes it easier to achieve a better matching effect between the isolation grooves, the doping area and the electrode, thereby reducing the risk of leakage. Furthermore, in the above-mentioned back-contact solar cell, the area of ​​the isolation groove is smaller, which can make the battery have a higher utilization rate, thereby achieving a higher current density. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG1 is a schematic diagram of the structure of the isolation groove and the doping layer in a conventional back contact solar cell;

[0021] FIG2 is a schematic diagram of the structure of a first doping layer and a second doping layer of a back contact solar cell provided in one embodiment of the present application;

[0022] FIG3 is a schematic diagram of a grid line structure of a back-contact solar cell provided in one embodiment of the present application;

[0023] FIG. 4 is a schematic diagram of the structure of a back-contact solar cell provided in one embodiment of the present application.

[0024] Description of Reference Numerals

[0025] 1. First doping layer; 2. Second doping layer; 3. Isolation groove; 4. First main body; 5. First finger; 6. First sub-part; 7. Second main body; 8. Second finger; 9. Second sub-part; 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 anti-reflection layer; 18. Second passivation anti-reflection layer. DETAILED DESCRIPTION

[0026] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0028] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0029] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0030] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0031] Referring to FIG. 1 , FIG. 1 is a schematic diagram of the structure of the isolation groove 3 and the doping layer in a conventional back contact solar cell. It can be seen that the first doping layer 1 and the second doping layer 2 are separated by the isolation groove 3 and are arranged in a forked finger shape. Among them, the fingers of the first doping layer 1 and the second doping layer 2 are both rectangular. When the width of the isolation groove 3 is small, the risk of leakage will increase.

[0032] An embodiment of the present application provides a back-contact solar cell, comprising: a substrate 16. A first doping layer 1 and a second doping layer 2 are arranged in a forked-finger-shaped interval on the same surface of the substrate 16, and the first doping layer 1 and the second doping layer 2 have opposite doping types. An isolation groove 3 is also provided on the substrate 16, and the isolation groove 3 is arranged between the first doping layer 1 and the second doping layer 2, and the isolation groove 3 is used to separate the first doping layer 1 and the second doping layer 2. The first doping layer 1 includes a first main body 4 and a first finger 5 connected to the first main body 4, and the second doping layer 2 includes a second main body 7 and a second finger 8 connected to the second main body 7. The first finger 5 includes a plurality of first sub-portions 6 that are in contact with each other and extend toward the second main body 7, and the extension lengths of each first sub-portion 6 are different. The second finger 8 includes a plurality of second sub-portions 9 that are in contact with each other and extend toward the first main body 4, and the extension lengths of each second sub-portion 9 are different.

[0033] Compared with traditional back-contact solar cells, when the width of the isolation groove 3 is the same, the structure of the above-mentioned back-contact solar cell has fewer isolation grooves 3. Generally, the more isolation grooves there are, the new challenges will be brought to the matching of the front-end and back-end processes, resulting in a higher risk of leakage. However, the back-contact solar cell of the present application has fewer isolation grooves 3 parallel to the fine gate direction, which makes it easier to achieve a better matching effect between the isolation groove 3, the doping region and the electrode, thereby reducing the risk of leakage. Furthermore, in the above-mentioned back-contact solar cell, the area of ​​the isolation groove 3 is smaller, which can make the battery have a higher utilization rate, thereby achieving a higher current density.

[0034] In some embodiments, in the first finger portion 5, the extension lengths of the first sub-portions 6 decrease in sequence. In the second finger portion 8, the extension lengths of the second sub-portions 9 increase in sequence.

[0035] The back-contact solar cell with the above structure can achieve a better matching effect between the isolation groove 3, the doping region and the electrode, thereby reducing the risk of leakage.

[0036] In some embodiments, in the first finger portion 5, the extension lengths of the first sub-portions 6 decrease in a geometrical ratio. In the second finger portion 8, the extension lengths of the second sub-portions 9 increase in a geometrical ratio.

[0037] The back-contact solar cell with the above structure can achieve a better matching effect between the isolation groove 3, the doping region and the electrode, thereby reducing the risk of leakage.

[0038] In some embodiments, the width of the isolation groove 3 is less than 1 mm.

[0039] When the width of the isolation groove 3 is small, the leakage risk of the traditional back contact solar cell will increase, while the back contact solar cell of the present application can achieve a better matching effect between the isolation groove 3, the doping region and the electrode, thereby reducing the risk of leakage. Optionally, the width of the isolation groove 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 groove 3 can also be within the range between any two of the above widths.

[0040] In some embodiments, there are multiple first fingers 5, which are spaced apart along the extension direction of the first main body 4. There are multiple second fingers 8, which are spaced apart along the extension direction of the second main body 7. The first fingers 5 and the second fingers 8 are arranged alternately.

[0041] In some embodiments, in the first finger portion 5, the widths of the first sub-portions 6 are equal. In the second finger portion 8, the widths of the second sub-portions 9 are equal.

[0042] In some embodiments, in the first finger portion 5, the number of the first sub-portions 6 is 2 to 4. In the second finger portion 8, the number of the second sub-portions 9 is 2 to 4.

[0043] Optionally, the number of the first subsections 6 is 2, 3 or 4. The number of the second subsections 9 is 2, 3 or 4.

[0044] As shown in 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 portion 4. The first fine grid 11 is connected to the first main grid 10, and there are a plurality of first fine grids 11, each of which extends along the extension direction of a first sub-portion 6 and is disposed on the surface of the first sub-portion 6. The second main grid 12 is disposed on the surface of the second main portion 7. The second fine grid 13 is connected to the second main grid 12, and there are a plurality of second fine grids 13, each of which extends along the extension direction of a second sub-portion 9 and is disposed on the surface of the second sub-portion 9.

[0045] Furthermore, in the structure of a traditional back-contact solar cell, the fine gate is arranged on the finger portion, so the fine gate will extend to the doped region near the other side, resulting in an excessively long transmission path, which makes it difficult for the current at the end of the fine gate to be collected by the main gate, resulting in a higher series resistance. In the above-mentioned gate line structure of the present application, compared with the traditional back-contact solar cell, the back-contact solar cell of the present application obviously has a shorter transmission path, thereby being able to reduce the series resistance. At the same time, near each fine gate doping region, i.e., each sub-portion, there is still an oppositely doped region with the opposite doping type, so the impact on the open circuit voltage of the back-contact solar cell is small. That is, the back-contact solar cell with the above-mentioned gate line structure can have a lower leakage risk, a smaller series resistance and a higher current density.

[0046] In some embodiments, the back contact solar cell further includes a first welding point 14 and a second welding point 15. The first welding point 14 is connected to the first main grid 10, and a plurality of first fine grids 11 are connected to the first welding point 14. The second welding point 15 is connected to the second main grid 12, and a plurality of second fine grids 13 are connected to the second welding point 15.

[0047] 4, in some embodiments, the back contact solar cell further includes a first passivation anti-reflection layer 17 and a second passivation anti-reflection layer 18. The first passivation anti-reflection 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 anti-reflection layer 18 is disposed on the surface of the substrate 16 opposite to the surface on which the first doped layer 1 and the second doped layer 2 are disposed.

[0048] Referring again to FIG. 2 , FIG. 3 , and FIG. 4 , in some embodiments, the back contact solar cell includes a substrate 16, and the substrate 16 has a front side and a back side arranged oppositely. A first doping layer 1 and a second doping layer 2 are arranged in a forked finger-like interval on the back side of the substrate 16, and the first doping layer 1 and the second doping layer 2 have opposite doping types. An isolation groove 3 is also provided on the substrate 16, and the isolation groove 3 is arranged between the first doping layer 1 and the second doping layer 2, and the isolation groove 3 is used to separate the first doping layer 1 and the second doping layer 2. The first doping layer 1 includes a first main body 4 and a first finger 5 connected to the first main body 4, and the second doping layer 2 includes a second main body 7 and a second finger 8 connected to the second main body 7. The first finger 5 includes a plurality of first sub-portions 6 that are in contact and extend toward the second main body 7, and the extension lengths of each first sub-portion 6 are different. The second finger 8 includes a plurality of second sub-portions 9 that are in contact and extend toward the first main body 4, and the extension lengths of each second sub-portion 9 are different. In the first finger 5, the extension lengths of each first sub-portion 6 decrease successively. In the second finger 8, the extension length of each second sub-portion 9 increases in sequence. In the first finger 5, the extension length of each first sub-portion 6 decreases in geometric proportion. In the second finger 8, the extension length of each second sub-portion 9 increases in geometric proportion. There are multiple first fingers 5, and the multiple first fingers 5 are spaced along the extension direction of the first main body 4. There are multiple second fingers 8, and the multiple second fingers 8 are spaced along the extension direction of the second main body 7. The first fingers 5 and the second fingers 8 are arranged alternately. In the first finger 5, the width of each first sub-portion 6 is equal. In the second finger 8, the width of each second sub-portion 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 arranged on the surface of the first main body 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-portion 6 and is arranged on the surface of the first sub-portion 6. The second main grid 12 is arranged on the surface of the second main body 7. The second fine grid 13 is connected to the second main grid 12, and there are multiple second fine grids 13. Each second fine grid 13 extends along the extension direction of a second sub-section 9 and is arranged on the surface of the second sub-section 9. The back contact solar cell also includes a first welding point 14 and a second welding point 15. The first welding point 14 is connected to the first main grid 10, and multiple first fine grids 11 are connected to the first welding point 14. The second welding point 15 is connected to the second main grid 12, and multiple second fine grids 13 are connected to the second welding point 15. The back contact solar cell also includes a first passivation anti-reflection layer 17 and a second passivation anti-reflection layer 18. The first passivation anti-reflection layer 17 covers the surface of the first doped layer 1 and the second doped layer 2 away from the substrate 16. The second passivation anti-reflection layer 18 covers the front side of the substrate 16.

[0049] The following are specific embodiments

[0050] Example 1

[0051] Referring again to FIGS. 2 to 4 , the back-contact solar cell in Embodiment 1 includes a substrate 16, which has a front side and a back side arranged opposite to each other. An N-type doped layer and a P-type doped layer arranged in a forked-finger-like manner are arranged on the back side of the substrate 16. An isolation groove 3 is also arranged on the substrate 16, and the isolation groove 3 is arranged between the first doped layer 1 and the second doped layer 2, and the isolation groove 3 is used to separate the N-type doped layer and the P-type doped layer. The N-type doped layer includes a first main body 4 and a first finger 5 connected to the first main body 4, and the P-type doped layer includes a second main body 7 and a second finger 8 connected to the second main body 7. In this embodiment, the first finger 5 includes two first sub-portions 6 of equal width in contact and extending toward the second main body 7, wherein the length of the shorter first sub-portion 6 is half the length of the longer first sub-portion 6. The second finger 8 includes two second sub-portions 9 of equal width in contact and extending toward the first main body 4, wherein the length of the shorter second sub-portion 9 is half the length of the longer second sub-portion 9. The shorter first sub-portion 6 and the shorter second sub-portion 9 are arranged opposite to each other.

[0052] 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 arranged on the surface of the first main portion 4. The first fine grid 11 is connected to the first main grid 10, and there are multiple first fine grids 11. Each first fine grid 11 extends along the extension direction of a first sub-portion 6 and is arranged on the surface of the first sub-portion 6. The second main grid 12 is arranged on the surface of the second main portion 7. The second fine grid 13 is connected to the second main grid 12. There are multiple second fine grids 13. Each second fine grid 13 extends along the extension direction of a second sub-portion 9 and is arranged on the surface of the second sub-portion 9. The back-contact solar cell further includes a first welding point 14 and a second welding point 15. The first welding point 14 is connected to the first main grid 10, and multiple first fine grids 11 are connected to the first welding point 14. The second welding point 15 is connected to the second main grid 12, and multiple second fine grids 13 are connected to the second welding point 15. The back contact solar cell further comprises a first passivation anti-reflection layer 17 and a second passivation anti-reflection layer 18. The first passivation anti-reflection layer 17 covers the surface of the first doped layer 1 and the second doped layer 2 away from the substrate 16. The second passivation anti-reflection layer 18 covers the front surface of the substrate 16.

[0053] Comparative Example 1

[0054] 1 , the structure of the back contact solar cell in Comparative Example 1 is different from that in Example 1 only in that each finger of the doping layer of the back contact solar cell in Comparative Example 1 is rectangular, and the width of each finger is the same as the width of the sub-portion in Example 1. The width of the isolation groove 3 in Example 2 is also the same as that in Example 1.

[0055] The back contact cells in Example 1 and Comparative Example 1 were tested, and the test results are shown in the following table:

[0056]

[0057] It can be seen from the test results in the above table that 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, thereby being able to obtain a higher conversion efficiency.

[0058] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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.

[0059] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims, and the description and drawings may be used to interpret the contents of the claims.

Claims

1. A back contact solar cell, characterized in that: include: substrate; A first doping layer and a second doping layer are arranged in an interdigitated manner on the same surface of the substrate, and the first doping layer and the second doping layer have opposite doping types; an isolation groove is also arranged on the substrate, and the isolation groove is arranged between the first doping layer and the second doping layer, and the isolation groove is used to separate the first doping layer and the second doping layer; The first doping layer includes a first main body and a first finger connected to the first main body, and the second doping layer includes a second main body and a second finger connected to the second main body; The first finger portion includes a plurality of first sub-portions that are in contact with each other and extend toward the second main body portion, and each of the first sub-portions has a different extension length; the second finger portion includes a plurality of second sub-portions that are in contact with each other and extend toward the first main body portion, and each of the second sub-portions has a different extension length.

2. The back contact solar cell according to claim 1, characterized in that: In the first finger portion, the extension lengths of the first sub-portions decrease in sequence; and in the second finger portion, the extension lengths of the second sub-portions increase in sequence.

3. The back contact solar cell according to claim 2, characterized in that: In the first finger portion, the extension lengths of the first sub-portions decrease in sequence in a geometric ratio; in the second finger portion, the extension lengths of the second sub-portions increase in sequence in a geometric ratio.

4. The back contact solar cell according to claim 1, characterized in that: The width of the isolation groove is less than 1 mm.

5. The back contact solar cell according to claim 1, characterized in that: 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, characterized in that: In the first finger portion, the widths of the first sub-portions are equal; in the second finger portion, the widths of the second sub-portions are equal.

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

8. The back contact solar cell according to any one of claims 1 to 7, characterized in that: The back contact solar cell further comprises 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 portion; the first fine grid is connected to the first main grid, and there are a plurality of the first fine grids, each of which extends along an extension direction of one of the first sub-portions and is disposed on the surface of the first sub-portion; The second main grid is arranged on the surface of the second main body; the second fine grid is connected to the second main grid, there are multiple second fine grids, each of which extends along the extension direction of a second sub-section and is arranged on the surface of the second sub-section.

9. The back contact solar cell according to claim 8, characterized in that: The back-contact solar cell also includes a first welding point and a second welding point; the first welding point is connected to the first main grid, and a plurality of first fine grids are connected to the first welding point; the second welding point is connected to the second main grid, and a plurality of second fine grids are connected to the second welding point.

10. The back contact solar cell according to any one of claims 1 to 7, characterized in that: The back-contact solar cell also includes a first passivation anti-reflection layer and a second passivation anti-reflection layer; the first passivation anti-reflection layer is arranged on the surface of the first doped layer and the second doped layer away from the substrate; the second passivation anti-reflection layer is arranged on the surface opposite to the surface of the substrate where the first doped layer and the second doped layer are arranged.

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