Cell, cell module, and photovoltaic system

Abstract

The present disclosure provides a cell, a cell module, and a photovoltaic system. The cell comprises: a front surface provided with a first textured surface, a P-type doped region provided with a second textured surface, and an N-type doped region provided with a third textured surface. The difference between an average base angle of first-type pyramid structures of the first textured surface and an average base angle of second-type pyramid structures of the second textured surface is greater than the difference between the average base angle of the first-type pyramid structures and an average base angle of third-type pyramid structures of the third textured surface.

Description

Batteries, modules and photovoltaic systems

[0001] Cross-references to related applications

[0002] This disclosure claims priority to Chinese patent application filed on January 17, 2025, with the application date 202520125053.X, entitled "A Back Contact Solar Cell, Battery Module and Photovoltaic System", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the field of solar cell technology, and in particular to a back-contact solar cell, a cell module, and a photovoltaic system. Background Technology

[0004] Interdigitated back contact (IBC) solar cells, also known as interdigitated back contact solar cells, have both positive and negative electrode grids located on the back of the cell. This completely eliminates the shading caused by the metal grids on the front surface, preventing optical losses. Furthermore, the electrode grids can be designed to be wider than existing types, reducing series resistance losses and significantly improving cell conversion efficiency. In addition, the absence of electrode grids on the front results in a more aesthetically pleasing product, making it suitable for various applications.

[0005] In existing technologies, back-contact solar cells typically only have a textured surface prepared on the front side of the silicon substrate, while the back side of the silicon substrate is usually prepared into a polished surface using alkaline polishing or acid polishing. This is done to increase the uniformity of the passivation contact structure and improve the overall passivation quality. However, this reduces the reflection of sunlight entering the silicon substrate from the back side. Sunlight entering the silicon substrate is more likely to be emitted directly from the back side, resulting in low sunlight utilization and low cell efficiency.

[0006] Public content

[0007] This disclosure provides a back-contact solar cell, which aims to solve the problem of low solar energy utilization and low cell efficiency in existing back-contact solar cells.

[0008] This disclosure is implemented as follows: a back-contact solar cell is provided, including a silicon substrate, the silicon substrate having a front side and a back side disposed opposite to each other, the back side including a P-type doped region and an N-type doped region, at least a portion of the front side having a first textured surface, at least a portion of the P-type doped region having a second textured surface, and at least a portion of the N-type doped region having a third textured surface.

[0009] The first velvet surface includes several first-type pyramidal structures, the second velvet surface includes several second-type pyramidal structures, and the third velvet surface includes several third-type pyramidal structures.

[0010] The average base angles of the second and third type pyramidal structures are smaller than the average base angle of the first type pyramidal structure; the average base angles of the first and second type pyramidal structures have a first angular difference, and the average base angles of the first and third type pyramidal structures have a second angular difference, and the first angular difference is greater than the second angular difference.

[0011] In some embodiments, both the first angle difference and the second angle difference are greater than 10°.

[0012] In some embodiments, both the first angle difference and the second angle difference are greater than 15°.

[0013] In some embodiments, both the first angle difference and the second angle difference are greater than 20°.

[0014] In some embodiments, the first angle difference is 20–30° and the second angle difference is 10–25°.

[0015] In some embodiments, the back surface also includes an isolation region disposed between the P-type doped region and the N-type doped region, and at least a portion of the isolation region is provided with a fourth textured surface.

[0016] In some embodiments, the fourth velvet surface includes a plurality of fourth-type pyramidal structures, wherein the average base angle of the fourth-type pyramidal structure is the same as the average base angle of the first-type pyramidal structure.

[0017] In some embodiments, the average base angle of the fourth type of pyramid structure is smaller than the average base angle of the first type of pyramid structure, and the average base angle of the first type of pyramid structure and the average base angle of the fourth type of pyramid structure have a third angle difference, and the second angle difference is greater than the third angle difference.

[0018] In some embodiments, the third angle difference is greater than 5°.

[0019] In some embodiments, the third angle difference is 5 to 10°.

[0020] In some embodiments, the average base angle of the first type of pyramidal structure is 30 to 85°; the average base angle of the second type of pyramidal structure is 15 to 45°; and the average base angle of the third type of pyramidal structure is 20 to 55°.

[0021] In some embodiments, the average base angle of the fourth type of pyramidal structure is 40 to 75°.

[0022] In some embodiments, the top of the second type of pyramidal structure is configured as a first arc surface, and the top of the third type of pyramidal structure is configured as a second arc surface.

[0023] In some embodiments, the curvature of the first arc surface is less than the curvature of the second arc surface.

[0024] In some embodiments, the connection between two adjacent second-type pyramidal structures is configured as a third arc surface, and the connection between two adjacent third-type pyramidal structures is configured as a fourth arc surface.

[0025] In some embodiments, the curvature of the third arc surface is less than the curvature of the fourth arc surface.

[0026] In some embodiments, the top of the fourth type pyramid structure is sharp, and the connection between two adjacent fourth type pyramid structures is sharp.

[0027] In some embodiments, the height of the second type of pyramidal structure is less than the height of the third type of pyramidal structure.

[0028] In some embodiments, the height of the third type of pyramid structure is less than the height of the fourth type of pyramid structure.

[0029] This disclosure also provides a battery assembly including the aforementioned back-contact solar cell.

[0030] This disclosure also provides a photovoltaic system including the aforementioned battery module.

[0031] The back-contact solar cell disclosed herein provides a first textured surface on the front side of a silicon substrate, a second textured surface in a P-type doped region, and a third textured surface in an N-type doped region. Sunlight enters the silicon substrate through the first textured surface. By utilizing the interaction of the first, second, and third textured surfaces, sunlight is reflected multiple times within the silicon substrate, increasing the reflection path of sunlight within the silicon substrate, reducing sunlight directly emitted from the back side, decreasing the transmittance of sunlight from the back side, increasing the absorption of sunlight by the back-contact solar cell, and improving the utilization rate of sunlight by the back-contact solar cell.

[0032] Meanwhile, controlling the difference between the average base angle of the first type of pyramidal structure on the first textured surface and the average base angle of the second type of pyramidal structure on the second textured surface to be greater than the difference between the average base angle of the first type of pyramidal structure on the first textured surface and the average base angle of the third type of pyramidal structure in the N-type doped region is beneficial to reducing the surface recombination loss of the P-type doped region, and is also beneficial to the deposition of the back film layer in the P-type doped region and to improving the passivation performance of the back film layer in the P-type doped region. This achieves a good match between the optical performance of the back contact solar cell and the good passivation performance of the back side of the cell, thereby improving the cell efficiency. Attached Figure Description

[0033] Figure 1 is a schematic diagram of a back-contact solar cell provided in an embodiment of this disclosure;

[0034] Figure 2 is a schematic diagram of the structure of a silicon substrate for a back-contact solar cell provided in an embodiment of this disclosure;

[0035] Figure 3 is a partial structural diagram of the first textured surface of a back-contact solar cell provided in an embodiment of this disclosure;

[0036] Figure 4 is a partial structural diagram of the second textured surface of a back-contact solar cell provided in an embodiment of this disclosure;

[0037] Figure 5 is a partial structural diagram of the third textured surface of a back-contact solar cell provided in an embodiment of this disclosure;

[0038] Figure 6 is a partial structural diagram of the fourth textured surface of a back-contact solar cell provided in an embodiment of this disclosure;

[0039] Figure 7 is a schematic diagram of the silicon substrate structure of the second type of back-contact solar cell provided in this embodiment of the present disclosure;

[0040] Figure 8 is a partial structural schematic diagram of the second textured surface of the second type of back-contact solar cell provided in an embodiment of this disclosure;

[0041] Figure 9 is a partial structural diagram of the third textured surface of the second type of back-contact solar cell provided in the embodiments of this disclosure. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. Examples of embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this disclosure, and should not be construed as limiting this disclosure. Furthermore, it should be understood that the specific embodiments described herein are merely illustrative of this disclosure and are not intended to limit this disclosure.

[0043] In the description of this disclosure, it should be understood that the terms "upper", "lower", "back", "front", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this disclosure 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 disclosure.

[0044] In this disclosure, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0045] The following disclosure provides numerous different embodiments or examples for implementing various structures of this disclosure. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this disclosure. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this disclosure, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0046] The back-contact solar cell disclosed herein features a first textured surface on the front side of a silicon substrate, a second textured surface on a P-type doped region on the back side of the silicon substrate, and a third textured surface on an N-type doped region on the back side of the silicon substrate. By controlling a first angle difference greater than a second angle difference, and utilizing the interaction between the first, second, and third textured surfaces, sunlight entering the silicon substrate from the front side undergoes multiple reflections within the silicon substrate via the second and third textured surfaces on the back side. This increases the reflection path of sunlight within the silicon substrate, thereby increasing the absorption of sunlight by the back-contact solar cell and improving its utilization rate. Furthermore, controlling the difference between the average bottom angle of the first textured surface and the average bottom angle of the second textured surface in the P-type doped region to be greater than the difference between the average bottom angle of the first textured surface and the average bottom angle of the N-type doped region facilitates further optimization of the optical performance of the P-type and N-type doped regions. On the other hand, by controlling the first angle difference to be greater than the second angle difference, the difference between the average base angle of the first type of pyramidal structure on the first textured surface and the average base angle of the second type of pyramidal structure on the second textured surface is greater than the difference between the average base angle of the first type of pyramidal structure on the first textured surface and the average base angle of the third type of pyramidal structure in the N-type doped region. This makes the textured surface of the P-type doped region flatter than that of the N-type doped region, which is beneficial to reducing the surface recombination loss of the P-type doped region, and also beneficial to the deposition of the back film layer of the P-type doped region and to improving the passivation performance of the back film layer of the P-type doped region. This achieves a good match between the optical performance of the back contact solar cell and the good passivation performance of the back side of the cell, thereby improving the cell efficiency.

[0047] Referring to Figures 1-5, this disclosure provides a back-contact solar cell, including a silicon substrate 1. The silicon substrate 1 has a front side and a back side disposed opposite to each other. The back side includes a P-type doped region 31, an N-type doped region 32, and an isolation region 33 disposed between the P-type doped region 31 and the N-type doped region 32. At least a portion of the front side is provided with a first textured surface 20, at least a portion of the P-type doped region 31 is provided with a second textured surface 311, and at least a portion of the N-type doped region 32 is provided with a third textured surface 321.

[0048] The first velvet surface 20 includes a plurality of first-type pyramidal structures 201, the second velvet surface 311 includes a plurality of second-type pyramidal structures 312, and the third velvet surface 321 includes a plurality of third-type pyramidal structures 322.

[0049] The average base angles of the second type pyramid structure 312 and the third type pyramid structure 322 are smaller than the average base angle of the first type pyramid structure 201. The average base angles of the first type pyramid structure 201 and the second type pyramid structure 312 have a first angular difference, and the average base angles of the first type pyramid structure 201 and the third type pyramid structure 322 have a second angular difference, and the first angular difference is greater than the second angular difference.

[0050] In this embodiment, the front side of the silicon substrate 1 is the side facing sunlight when the back-contact solar cell is working, and the back side of the silicon substrate 1 is the side facing away from sunlight when the back-contact solar cell is working. P-type doped regions 31 are areas where P-type doped layers are formed, N-type doped regions 32 are areas where N-type doped layers are formed, and isolation regions 33 are located between adjacent P-type doped regions 31 and N-type doped regions 32 and are used to physically isolate the P-type doped regions 31 and N-type doped regions 32. The specific number of P-type doped regions 31 and N-type doped regions 32 is not limited. Optionally, there are multiple P-type doped regions 31 and multiple N-type doped regions 32, which are arranged alternately and sequentially, with an isolation region 33 between adjacent P-type doped regions 31 and N-type doped regions 32.

[0051] In this embodiment of the present disclosure, the front surface of the silicon substrate 1 may have only a portion of the surface with the first textured surface 20, or the entire front surface of the silicon substrate 1 may have the first textured surface 20. Preferably, the entire front surface of the silicon substrate 1 may have the first textured surface 20.

[0052] In this embodiment of the disclosure, at least a portion of the P-type doped region 31 is provided with a second textured surface 311. This can be understood as either a portion of the P-type doped region 31 being provided with the second textured surface 311, or the entire P-type doped region 31 being provided with the second textured surface 311. When only a portion of the P-type doped region 31 is provided with the second textured surface 311, each P-type doped region 31 may be provided with the second textured surface 311, but at least one P-type doped region 31 may have a portion of a non-textured area, i.e., at least one P-type doped region 31 may have a portion of a polished surface; or (i.e., when the entire P-type doped region 31 is provided with the second textured surface 311), only a portion of the P-type doped regions 31 are provided with the second textured surface 311, while another portion of the P-type doped regions 31 are non-textured areas, i.e., the other portion of the P-type doped regions 31 are polished surfaces. Thus, the P-type doped region 31 is designed by combining the second textured surface 311 and the polished surface. The second textured surface 311 improves the utilization rate of sunlight by the P-type doped region 31, while the polished surface reduces the surface recombination loss of the P-type doped region 31 and helps to improve the passivation performance of the back film layer of the P-type doped region 31, which is beneficial to improving the battery efficiency.

[0053] In this embodiment of the disclosure, at least a portion of the N-type doped region 32 is provided with a third textured surface 321. This can be understood as either only a portion of the N-type doped region 32 being provided with the third textured surface 321, or the entire area of ​​all N-type doped regions 32 being provided with the third textured surface 321. When only a portion of the N-type doped region 32 is provided with the third textured surface 321, each N-type doped region 32 may be provided with the third textured surface 321, but at least one N-type doped region 32 may have a portion of a non-textured area, i.e., at least one N-type doped region 32 may have a portion of a polished surface; or (i.e., when the entire N-type doped region 32 is provided with the third textured surface 321), only a portion of the N-type doped regions 32 may be provided with the third textured surface 321, while another portion of the N-type doped regions 32 may be non-textured areas, i.e., another portion of the N-type doped regions 32 may be polished surfaces. Thus, the N-type doped region 32 utilizes a combination of the third textured surface 321 and the polished surface. The third textured surface 321 enhances the utilization rate of sunlight by the N-type doped region 32, while the polished surface reduces the surface recombination loss of the N-type doped region 32 and helps improve the passivation performance of the back film layer of the N-type doped region 32, thereby improving the battery efficiency.

[0054] As shown in Figure 3, in this embodiment of the present disclosure, the first textured surface 20 includes a plurality of first-type pyramidal structures 201. The base angle A of the first-type pyramidal structure 201 is the angle between the side surface and the base surface of the first-type pyramidal structure 201, and the base surface is a plane perpendicular to the thickness direction of the silicon substrate 1. The arrangement of the plurality of first-type pyramidal structures 201 is not limited; they can be arranged in a linear array or in an irregular arrangement, and adjacent first-type pyramidal structures 201 can also be stacked. As shown in Figure 4, the plurality of second-type pyramidal structures 312 of the second textured surface 311 can also be arranged in a linear array or in an irregular arrangement. The base angle B of the second-type pyramidal structure 312 is the angle between the side surface and the base surface of the second-type pyramidal structure 312, and the base surface is a plane perpendicular to the thickness direction of the silicon substrate 1. As shown in Figure 5, the plurality of third-type pyramidal structures 322 of the third textured surface 321 can also be arranged in a linear array or in an irregular arrangement. The base angle C of the third type pyramid structure 322 is the angle between the side surface of the third type pyramid structure 322 and the base surface of the third type pyramid structure 322, and the base surface is a plane perpendicular to the thickness direction of the silicon substrate 1.

[0055] The first type of pyramidal structure 201, the second type of pyramidal structure 312, and the third type of pyramidal structure 322 are all pyramidal structures with a apex or pyramidal structures with a truncated apex; wherein, the pyramidal structure can be a pyramidal structure with three sides and one base, or a pyramidal structure with four sides and one base; or a pyramidal structure with five sides and one base; or a pyramidal structure with six sides and one base; of course, the pyramidal structure can also be a pyramidal structure with more than one number of sides and one base.

[0056] When the angles between each side surface of a pyramidal structure and its base are equal, the base angle of the pyramidal structure is determined by measuring the angle between any one side surface and its base. However, the angles between the side surfaces and base of a pyramidal structure may not be equal. In this case, the average angle between the side surfaces and base is taken as the base angle of the pyramidal structure.

[0057] In this embodiment of the disclosure, the average base angle of the first type of pyramidal structure 201 is the average base angle of all the first type of pyramidal structures 201 on the first velvet surface 20; the average base angle of the second type of pyramidal structure 312 is the average base angle of a preset number of second type of pyramidal structures 312 in the target area of ​​the second velvet surface 311; and the average base angle of the third type of pyramidal structure 322 is the average base angle of all the third type of pyramidal structures 322 on the third velvet surface 321.

[0058] Alternatively, the average base angle of the first type of pyramidal structure 201 can be the average base angle of a first preset number of first type of pyramidal structures 201 in the first pile surface 20; the average base angle of the second type of pyramidal structure 312 can be the average base angle of a first preset number of second type of pyramidal structures 312 in the second pile surface 311; and the average base angle of the third type of pyramidal structure 322 can be the average base angle of a first preset number of third type of pyramidal structures 322 in the third pile surface 321. Preferably, the first preset number is 3 to 10, and the average base angle of 3 to 10 first type of pyramidal structures 201 in the first pile surface 20 is measured as the average base angle of the first type of pyramidal structure 201; the average base angle of 3 to 10 second type of pyramidal structures 312 in the second pile surface 311 is measured as the average base angle of the second type of pyramidal structure 312; and the average base angle of 3 to 10 third type of pyramidal structures 322 in the third pile surface 321 is measured as the average base angle of the third type of pyramidal structure 322.

[0059] Alternatively, the average base angle of the first type of pyramidal structure 201 can be the average base angle of a second preset number of first type of pyramidal structures 201 arranged along the first direction within the target area of ​​the first textured surface 20; the average base angle of the second type of pyramidal structure 312 can be the average base angle of a second preset number of second type of pyramidal structures 312 arranged along the first direction within the target area of ​​the second textured surface 311; and the average base angle of the third type of pyramidal structure 322 can be the average base angle of a second preset number of third type of pyramidal structures 322 arranged along the first direction within the target area of ​​the third textured surface 321. The target area can be a rectangular area of ​​20μm × 30μm, and the second preset number can be 2 to 10.

[0060] For example, when comparing the average base angles of the first type of pyramid structure 201, the second type of pyramid structure 312, and the third type of pyramid structure 322, rectangular areas of 20μm × 30μm are selected as target areas on the first surface 20, the second surface 311, and the third surface 321, respectively. Within the target area of ​​the first surface 20, the base angles of the three highest first type of pyramid structures 201 arranged along the first direction are measured, and the average base angle of the three first type of pyramid structures 201 is calculated as the first type of pyramid. The average base angle of structure 201; within the target area of ​​the second velvet surface 311, the base angles of the three tallest second-type pyramidal structures 312 arranged along the first direction are measured, and the average base angle of the three second-type pyramidal structures 312 is calculated as the average base angle of the second-type pyramidal structure 312; within the target area of ​​the third velvet surface 321, the base angles of the three tallest third-type pyramidal structures 322 arranged along the first direction are measured, and the average base angle of the three third-type pyramidal structures 322 is calculated as the average base angle of the third-type pyramidal structure 322. Of course, other areas can also be set as the target area and compared with the average base angles of other numbers of pyramidal structures.

[0061] In this embodiment, by providing a first textured surface 20 on the front side of the silicon substrate 1, a second textured surface 311 on the P-type doped region 31 on the back side of the silicon substrate 1, and a third textured surface 321 on the N-type doped region 32 on the back side of the silicon substrate 1, the first textured surface 20, the second textured surface 311, and the third textured surface 321 work together to effectively increase the reflection path of sunlight inside the silicon substrate 1, reduce the direct escape of sunlight from the back side, reduce the transmittance of sunlight from the back side, increase the absorption of sunlight by the solar cell, and greatly improve the utilization rate of sunlight by the back contact solar cell.

[0062] Simultaneously, by controlling the first angle difference to be greater than the second angle difference, the difference between the average bottom angle of the first textured surface 20 on the front side of the silicon substrate 1 and the average bottom angle of the second textured surface 311 of the P-type doped region 31 is made greater than the difference between the average bottom angle of the first textured surface 20 on the front side of the silicon substrate 1 and the average bottom angle of the third textured surface 321 of the N-type doped region 32. That is, by reducing the average bottom angle of the second pyramidal structure 312 of the second textured surface 311 of the P-type doped region 31, the average bottom angle of the second pyramidal structure 312 of the second textured surface 311 of the P-type doped region 31 is made smaller than the average bottom angle of the third textured surface 321 of the N-type doped region 32. The uniform bottom angle makes the second textured surface 311 of the P-type doped region 31 flatter than the third textured surface 321 of the N-type doped region 32. This helps reduce surface recombination loss of the P-type doped region 31, facilitates back-side film deposition of the P-type doped region 31, and improves the passivation performance of the back-side film of the P-type doped region 31. While increasing the light utilization rate of the battery, it also ensures good passivation performance of the P-type doped region 31, achieving a balance between good optical performance of the back contact battery and good passivation performance of the battery back side. This results in a good match between the battery's optical performance and passivation performance, thereby improving battery efficiency.

[0063] As one embodiment of this disclosure, both the first angle difference and the second angle difference are greater than 10°.

[0064] In this embodiment, the first angle difference and the second angle difference are greater than 10°, that is, the difference between the average base angle of the first type of pyramidal structure 201 of the first textured surface 20 and the average base angle of the second type of pyramidal structure 312 of the second textured surface 311, and the difference between the average base angle of the first type of pyramidal structure 201 of the first textured surface 20 and the average base angle of the third type of pyramidal structure 322 of the third textured surface 321 are both greater than 10°. This ensures that the difference between the average base angle of the first type of pyramidal structure 201 of the first textured surface 20 and the average base angle of the second type of pyramidal structure 312 of the second textured surface 311, and the difference between the average base angle of the first type of pyramidal structure 201 of the first textured surface 20 and the average base angle of the third type of pyramidal structure 322 of the third textured surface 321 meets the requirements of good optical performance, which is beneficial to further improve the reflection of light from the back side to the front side and improve battery efficiency.

[0065] As one embodiment of this disclosure, both the first angle difference and the second angle difference are greater than 15°.

[0066] In this embodiment, the first angle difference and the second angle difference are greater than 15°, which helps to further improve the reflection of light from the back side to the front side and improve battery efficiency.

[0067] As one embodiment of this disclosure, both the first angle difference and the second angle difference are greater than 20°.

[0068] In this embodiment, both the first angle difference and the second angle difference are greater than 20°. Further increasing the difference between the first angle and the second angle is beneficial to further enhance the reflection of light from the back side to the front side and improve battery efficiency.

[0069] As one embodiment of this disclosure, the first angle difference is 20 to 30°, and the second angle difference is 10 to 25°.

[0070] In this embodiment, the first angle difference is 20-30°, that is, the difference between the average base angle of the first type pyramidal structure 201 on the front side of the silicon substrate 1 and the average base angle of the second type pyramidal structure 312 of the P-type doped region 31 is 20-30°; the second angle difference is 10-25°, that is, the difference between the average base angle of the first type pyramidal structure 201 on the front side of the silicon substrate 1 and the average base angle of the third type pyramidal structure 322 of the N-type doped region 32 is 10-25°.

[0071] Thus, by controlling the first angle difference to be 20–30° and the second angle difference to be 10–25°, the solar energy utilization rate of the P-type doped region 31 and the N-type doped region 32 is improved. At the same time, the back side of the P-type doped region 31 and the N-type doped region 32 and the isolation region 33 have low surface recombination loss and good surface passivation performance, thereby achieving a good balance between the optical performance and passivation performance of the P-type doped region 31 and the N-type doped region 32.

[0072] As an embodiment of this disclosure, the average base angle of the first type of pyramid structure 201 is 30 to 85°; the average base angle of the second type of pyramid structure 312 is 15 to 45°; and the average base angle of the third type of pyramid structure 322 is 20 to 55°.

[0073] In this embodiment, the average base angle of the first type of pyramidal structure 201 is set to 30-85°, which allows more sunlight to enter the silicon substrate 1, reduces the reflection of sunlight on the front of the battery, increases sunlight absorption, and helps improve battery efficiency.

[0074] Wherein, the average base angle of the first type of pyramid structure 201 can be any value between 30° and 85°, the average base angle of the second type of pyramid structure 312 can be any value between 15° and 45°, and the average base angle of the third type of pyramid structure 322 can be any value between 20° and 55°. It is only necessary to satisfy that the average base angle of the second type of pyramid structure 312 and the average base angle of the third type of pyramid structure 322 are both less than the average base angle of the first type of pyramid structure 201, the average base angle of the second type of pyramid structure 312 and the average base angle of the first type of pyramid structure 201 have a first angular difference, the base angle of the third type of pyramid structure 322 and the average base angle of the first type of pyramid structure 201 have a second angular difference, and the first angular difference is greater than the second angular difference, and both the first angular difference and the second angular difference are greater than 10°.

[0075] For example, the average base angle of the first type of pyramidal structure 201 can be any value among 50°, 52°, 54°, 55°, 56°, 58°, 60°, 61°, 62°, 63°, 64°, 65°, 66°, 67°, 68°, 69°, 70°, 72°, 73°, 75°, 80°, and 85°.

[0076] For example, the average base angle of the second type of pyramidal structure 312 can be any value among 15°, 16°, 17°, 18°, 20°, 22°, 24°, 25°, 28°, 30°, 32°, 35°, 38°, 40°, 42°, and 45°.

[0077] For example, the average base angle of the third type pyramid structure 322 can be any value among 20°, 21°, 22°, 23°, 25°, 27°, 29°, 30°, 35°, 38°, 40°, 42°, 45°, 48°, 49°, 50°, 52°, 54°, and 55°.

[0078] Please refer to Figures 1 and 6. As an embodiment of this disclosure, the back side also includes an isolation region 33 disposed between the P-type doped region and the N-type doped region. At least a portion of the isolation region 33 is provided with a fourth textured surface 331.

[0079] In this embodiment, a textured surface is provided in the P-type doped region 31, the N-type doped region 32, and the isolation region 33, which can further improve the utilization rate of sunlight by the battery.

[0080] As an embodiment of this disclosure, the fourth velvet surface 331 includes a plurality of fourth-type pyramidal structures 332, the average base angle of the fourth-type pyramidal structures 332 being the same as the average base angle of the first-type pyramidal structure 201.

[0081] In this embodiment, the fourth type of pyramidal structure 332 of the fourth velvet surface 331 can be the same as the first type of pyramidal structure 201 of the first velvet surface, which can make the average base angle of the fourth type of pyramidal structure 332 larger, so as to have good reflection performance of sunlight with front transmission.

[0082] In another embodiment of this disclosure, the average base angle of the fourth type of pyramid structure 332 is smaller than the average base angle of the first type of pyramid structure 201, and the average base angle of the first type of pyramid structure 201 and the average base angle of the fourth type of pyramid structure 332 have a third angle difference, and the second angle difference is greater than the third angle difference.

[0083] As shown in Figure 6, the base angle D of the fourth type of pyramid structure 332 is the angle between the side surface and the base surface of the fourth type of pyramid structure 332, where the base surface is a plane perpendicular to the thickness direction of the silicon substrate 1. The average base angle of the fourth type of pyramid structure 332 is calculated in the same way as the average base angles of the first type of pyramid structure 201, the second type of pyramid structure 312, and the third type of pyramid structure 322. The average base angle of the fourth type of pyramid structure 332 is the average base angle of all the fourth type of pyramid structures 332 on the fourth textured surface 331, or, the average base angle of the fourth type of pyramid structure 332 is the average base angle of a first preset number of fourth type of pyramid structures 332 in the fourth textured surface 331, or, the average base angle of the fourth type of pyramid structure 332 is the average base angle of a second preset number of fourth type of pyramid structures 332 arranged along the first direction within the target area of ​​the fourth textured surface 331.

[0084] In this embodiment, under the premise of setting a textured surface in the isolation region 33 to further improve the utilization rate of sunlight, the second angle difference is controlled to be greater than the third angle difference, and the average base angle of the fourth type pyramidal structure 332 is reduced. This makes the optical performance of the P-type doped region 31, N-type doped region 32, and isolation region 33 increase sequentially, while the passivation performance of the P-type doped region 31, N-type doped region 32, and isolation region 33 decreases sequentially, thus achieving a good match between the optical performance and passivation performance of the P-type doped region 31, N-type doped region 32, and isolation region 33.

[0085] As one embodiment of this disclosure, the third angle difference is greater than 5°.

[0086] Thus, by controlling the average base angle of the first type of pyramid structure 201 and the average base angle of the fourth type of pyramid structure 332 to be greater than 5°, the optical performance and passivation performance of the isolation region 33 are balanced, achieving a good match between the optical performance and passivation performance of the isolation region 33.

[0087] As one embodiment of this disclosure, the third angle difference is 5 to 10°.

[0088] Thus, by controlling the difference between the average base angle of the first type of pyramid structure 201 and the average base angle of the fourth type of pyramid structure 332 to be greater than 5°, the difference between the average base angle of the first type of pyramid structure 201 and the average base angle of the fourth type of pyramid structure 332 is further optimized, thereby achieving a better match between the optical performance and passivation performance of the isolation region 33.

[0089] As one embodiment of this disclosure, the average base angle of the fourth type of pyramidal structure 332 is 40 to 75°.

[0090] In this way, the isolation region 33 has good optical performance, low surface recombination loss and good surface passivation performance, thus achieving a good balance between the optical performance and passivation performance of the isolation region 33.

[0091] In this embodiment, the average base angle of the fourth type of pyramid structure 332 is set to 40-75°, which makes the difference between the base angle of the isolation area 33 and the velvet structure on the front side smaller, resulting in good optical performance and improved sunlight utilization. The average base angle of the fourth type of pyramid structure 332 can be any value between 40-75°, as long as the average base angle of the fourth type of pyramid structure 332 is less than the average base angle of the first type of pyramid structure 201.

[0092] For example, the average base angle of the fourth type pyramid structure 332 can be any value among 40°, 42°, 45°, 48°, 50°, 52°, 55°, 57°, 58°, 60°, 61°, 63°, 65°, 70°, and 75°.

[0093] Please refer to Figures 7-9. As an embodiment of this disclosure, the second velvet surface 311 includes a plurality of second-type pyramidal structures 312, and the third velvet surface 321 includes a plurality of third-type pyramidal structures 322. The top of the second-type pyramidal structure 312 is configured as a first arc surface 313 (as shown in Figure 8), and the top of the third-type pyramidal structure 322 is configured as a second arc surface 323 (as shown in Figure 9).

[0094] In this embodiment, the top of the second type pyramidal structure 312 of the P-type doped region 31 is set as a first arc surface 313, and the top of the third type pyramidal structure 322 of the N-type doped region 32 is set as a second arc surface 323. That is, the tops of the second type pyramidal structure 312 and the tops of the third type pyramidal structure 322 are both smooth arc surfaces, which can reduce the surface recombination loss caused by texturing of the P-type doped region 31 and the N-type doped region 32, and facilitate the deposition of the back film layer of the P-type doped region 31 and the N-type doped region 32, thereby improving the passivation performance of the back film layer of the P-type doped region 31 and the N-type doped region 32.

[0095] As an embodiment of this disclosure, the curvature of the first arc surface 313 is less than the curvature of the second arc surface 323.

[0096] In this embodiment, the curvature of the first arc surface 313 is less than that of the second arc surface 323, that is, the radius of the first arc surface 313 is larger than that of the second arc surface 323. The top of the second type pyramidal structure 312 of the P-type doped region 31 is flatter than the top of the third type pyramidal structure 322 of the N-type doped region 32, which is more conducive to improving the passivation effect of the P-type doped region 31 and improving the battery efficiency.

[0097] As an embodiment of this disclosure, the connection between two adjacent second-type pyramidal structures 312 is provided as a third arc surface 314 (as shown in FIG8), and the connection between two adjacent third-type pyramidal structures 322 is provided as a fourth arc surface 324 (as shown in FIG9).

[0098] In this embodiment, the connection points of adjacent second-type pyramidal structures 312 of P-type doped region 31 and adjacent third-type pyramidal structures 322 of N-type doped region 32 are both set as arc surfaces. This can further reduce the surface recombination loss caused by texturing of P-type doped region 31 and N-type doped region 32, and facilitate the deposition of back film layers of P-type doped region 31 and N-type doped region 32, thereby improving the passivation performance of the back passivation layer of P-type doped region 31 and N-type doped region 32.

[0099] As an embodiment of this disclosure, the curvature of the third arc surface 314 is less than the curvature 324 of the fourth arc surface 324.

[0100] In this embodiment, the curvature of the third arc surface 314 is less than that of the fourth arc surface 324, that is, the radius of the third arc surface 314 is larger than that of the fourth arc surface 324. The connection between the adjacent second type pyramidal structure 312 of the P-type doped region 31 is flatter than the connection between the adjacent third type pyramidal structure 322 of the N-type doped region 32, which is more conducive to further improving the passivation effect of the P-type doped region 31 and improving the battery efficiency.

[0101] As an embodiment of this disclosure, as shown in Figures 6 and 7, the fourth velvet surface 331 includes a plurality of fourth pyramidal structures 332, the top of the fourth pyramidal structures 332 being sharp, and the connection between two adjacent fourth pyramidal structures 332 being sharp.

[0102] In this embodiment, the top of the fourth type pyramidal structure 332 in the isolation region 33 is pointed, and the connection point of adjacent fourth type pyramidal structures 332 is also pointed, which ensures the good optical performance of the isolation region 33, achieves good optical performance of the isolation region 33 and good passivation performance of the P-type doped region 31 and N-type doped region 32, and further improves the battery efficiency.

[0103] As an embodiment of this disclosure, the height of the second type of pyramid structure 312 is less than the height of the third type of pyramid structure 322.

[0104] In this design, the height of the second type of pyramidal structure 312 is the distance from its base to its apex, and the height of the third type of pyramidal structure 322 is the distance from its base to its apex. Because the height of the second type of pyramidal structure 312 is less than the height of the third type of pyramidal structure 322, the textured surface of the P-type doped region 31 is flatter than that of the N-type doped region 32, thus improving the passivation performance of the P-type doped region 31.

[0105] As an embodiment of this disclosure, the height of the third type of pyramid structure 322 is less than the height of the fourth type of pyramid structure 332.

[0106] In this design, the height of the fourth type pyramidal structure 332 is the distance from its base to its apex. Since the height of the third type pyramidal structure 322 is less than that of the fourth type pyramidal structure 332, the passivation performance of the N-type doped region 32 can be improved. This results in the passivation performance of the P-type doped region 31, N-type doped region 32, and isolation region 33 decreasing sequentially, while the optical performance of the P-type doped region 31, N-type doped region 32, and isolation region 33 increases sequentially. This achieves a good match between the optical performance and passivation performance of the P-type doped region 31, N-type doped region 32, and isolation region 33, which is beneficial for further improving battery efficiency.

[0107] As an embodiment of this disclosure, the roughness of the side surface of the fourth type pyramidal structure 332 is greater than the roughness of the side surface of the third type pyramidal structure 322, and the roughness of the side surface of the third type pyramidal structure 322 is greater than the roughness of the side surface of the second type pyramidal structure 312. This can further achieve an increase in the optical performance of the P-type doped region 31, the N-type doped region 32, and the isolation region 33, and an decrease in the passivation performance of the P-type doped region 31, the N-type doped region 32, and the isolation region 33, thereby further achieving a good match between the optical performance and passivation performance of the P-type doped region 31, the N-type doped region 32, and the isolation region 33.

[0108] Referring to Figure 1, as an embodiment of this disclosure, the back-contact solar cell further includes:

[0109] A P-type doped layer 4 is provided in the P-type doped region 31;

[0110] An N-type doped layer 5 is provided in the N-type doped region 32.

[0111] In this embodiment, the P-type doped layer 4 is one or a combination of P-type polycrystalline silicon, P-type microcrystalline silicon, P-type nanocrystalline silicon, and P-type amorphous silicon, and the N-type doped layer 5 is one or a combination of N-type polycrystalline silicon, N-type microcrystalline silicon, N-type nanocrystalline silicon, and N-type amorphous silicon.

[0112] As one embodiment of this disclosure, the back-contact solar cell further includes:

[0113] A first passivation layer 6 is disposed between the p-type doped layer 4 and the back side of the silicon substrate 1;

[0114] A second passivation layer 7 is disposed between the N-type doped layer 5 and the back side of the silicon substrate 1.

[0115] Specifically, the first passivation layer 6 and the second passivation layer 7 can be silicon oxide layers. The first passivation layer 6 and the second passivation layer 7 are used to passivate the back side of the silicon substrate 1, further improving the passivation effect of the P-type doped region 31 and the N-type doped region 32.

[0116] As one embodiment of this disclosure, it also includes:

[0117] A first electrode 8 is disposed on the side of the P-type doped layer 4 away from the silicon substrate 1, and the first electrode 8 is in contact with the P-type doped layer 4.

[0118] A second electrode 9 is disposed on the side of the N-type doped layer 5 away from the silicon substrate 1, and the second electrode 9 is in contact with the N-type doped layer 5.

[0119] As an embodiment of this disclosure, the distribution density of the second type pyramidal structure 312 in the region corresponding to the first electrode 8 of the P-type doped region 31 is greater than the distribution density of the second type pyramidal structure 312 in the region not corresponding to the first electrode 8 of the P-type doped region 31, which is beneficial to improving the bonding pull of the first electrode 8; similarly, the distribution density of the third type pyramidal structure 322 in the region corresponding to the second electrode 9 of the N-type doped region 32 is greater than the distribution density of the third type pyramidal structure 322 in the region not corresponding to the second electrode 9 of the N-type doped region 32, which is beneficial to improving the bonding pull of the second electrode 9.

[0120] As one embodiment of this disclosure, it also includes:

[0121] The back passivation layer 13 covers the P-type doped layer 4, the N-type doped layer 5, and the isolation region 33.

[0122] In this embodiment, the first electrode 8 passes through the back passivation layer 13 and contacts the P-type doped layer 4; the second electrode 9 passes through the back passivation layer 13 and contacts the N-type doped layer 5. The back passivation layer 13 can further improve the battery passivation effect and increase battery efficiency. The back passivation layer 13 is at least one or a combination of aluminum oxide, silicon oxide, silicon nitride, silicon carbide, and silicon oxynitride films. For example, in some embodiments, the back passivation layer 13 may include sequentially stacked aluminum oxide and silicon nitride films; specific details are not limited here.

[0123] This disclosure also provides a battery assembly including the back-contact solar cell described in the above embodiments. It should be noted that this battery assembly has the same or similar beneficial effects as the back-contact solar cell, and the related aspects between the two can be referred to each other; to avoid repetition, they will not be repeated here.

[0124] In this embodiment, multiple back-contact solar cells in the battery module can be connected in series to form a battery string, thereby achieving series current output. For example, the battery cells can be connected in series by setting solder strips (busbars, interconnecting strips), conductive backplates, etc.

[0125] It is understood that in such embodiments, the battery assembly may also include a metal frame, a backsheet, photovoltaic glass, and an encapsulating film. The encapsulating film may be filled between the front and back of the back-contact solar cell, the photovoltaic glass, adjacent cells, etc. As a filler, it may be a transparent colloid with good light transmittance and aging resistance. For example, the encapsulating film may be an EVA film or a POE film, and the specific choice can be made according to the actual situation, without limitation.

[0126] Photovoltaic glass can be applied to the encapsulating film on the front side of the back-contact solar cell. This photovoltaic glass can be ultra-clear glass, possessing high light transmittance, high transparency, and superior physical, mechanical, and optical properties. For example, ultra-clear glass can achieve a light transmittance of over 92%. It can protect the back-contact solar cell while minimizing impact on its efficiency. Simultaneously, the encapsulating film bonds the photovoltaic glass and the back-contact solar cell together, providing sealing, insulation, and waterproofing / moisture protection for the back-contact solar cell.

[0127] The backsheet can be attached to the adhesive film on the back of the back-contact solar cell. The backsheet protects and supports the solar cell, providing reliable insulation, water resistance, and aging resistance. Multiple backsheet options are available, typically including tempered glass, acrylic glass, and aluminum alloy TPT composite adhesive film, etc. The specific choice depends on the specific circumstances and is not limited here. The backsheet, back-contact solar cell, adhesive film, and photovoltaic glass can be mounted on a metal frame. The metal frame serves as the main external support structure for the entire back-contact solar cell module, providing stable support and installation. For example, the back-contact solar cell module can be installed at the desired location using the metal frame.

[0128] This disclosure also provides a photovoltaic system including the battery module described above. It should be noted that this photovoltaic system has the same or similar beneficial effects as the back-contact solar cell described above, and the related aspects between the two can be referred to each other; to avoid repetition, they will not be repeated here.

[0129] In this embodiment, the photovoltaic system can be applied in photovoltaic power plants, such as ground-mounted power plants, rooftop power plants, and floating power plants. It can also be applied to equipment or devices that utilize solar energy to generate electricity, such as user solar power supplies, solar streetlights, solar cars, and solar buildings. Of course, it is understood that the application scenarios of the photovoltaic system are not limited to these; that is, the photovoltaic system can be applied in all fields that require solar energy to generate electricity. Taking a photovoltaic power generation system grid as an example, the photovoltaic system may include a photovoltaic array, a combiner box, and an inverter. The photovoltaic array may be an array combination of multiple back-contact solar cell modules. For example, multiple back-contact solar cell modules can form multiple photovoltaic arrays. The photovoltaic array is connected to the combiner box, which can collect the current generated by the photovoltaic array. The collected current flows through the inverter and is converted into AC power required by the mains power grid before being connected to the mains power grid to achieve solar power supply.

[0130] In the description of this specification, references to terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0131] The above are merely preferred embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A back-contact solar cell, comprising a silicon substrate having a front side and a back side disposed opposite to each other, the back side including a P-type doped region and an N-type doped region, the front side having at least a portion having a first textured surface, the P-type doped region having at least a portion having a second textured surface, and the N-type doped region having at least a portion having a third textured surface; The first pile surface includes a plurality of first-type pyramidal structures, the second pile surface includes a plurality of second-type pyramidal structures, and the third pile surface includes a plurality of third-type pyramidal structures; The average base angle of the second type of pyramid structure and the average base angle of the third type of pyramid structure are smaller than the average base angle of the first type of pyramid structure; the average base angle of the first type of pyramid structure and the average base angle of the second type of pyramid structure have a first angular difference, the average base angle of the first type of pyramid structure and the average base angle of the third type of pyramid structure have a second angular difference, and the first angular difference is greater than the second angular difference.

2. The back-contact solar cell according to claim 1, wherein, Both the first angle difference and the second angle difference are greater than 10°.

3. The back-contact solar cell according to claim 1, wherein, Both the first angle difference and the second angle difference are greater than 15°.

4. The back-contact solar cell according to claim 1, wherein, Both the first angle difference and the second angle difference are greater than 20°.

5. The back-contact solar cell according to claim 1, wherein, The first angle difference is 20-30°, and the second angle difference is 10-25°.

6. The back-contact solar cell according to claim 1, wherein, The back side also includes an isolation region disposed between the P-type doped region and the N-type doped region, and at least a portion of the isolation region is provided with a fourth textured surface.

7. The back-contact solar cell according to claim 6, wherein, The fourth velvet surface includes several fourth-type pyramidal structures, and the average base angle of the fourth-type pyramidal structure is the same as the average base angle of the first-type pyramidal structure.

8. The back-contact solar cell according to claim 7, wherein, The average base angle of the fourth type of pyramid structure is smaller than the average base angle of the first type of pyramid structure. The average base angle of the first type of pyramid structure and the average base angle of the fourth type of pyramid structure have a third angle difference, and the second angle difference is greater than the third angle difference.

9. The back-contact solar cell according to claim 8, wherein, The third angle difference is greater than 5°.

10. The back-contact solar cell according to claim 9, wherein, The third angle difference is 5 to 10°.

11. The back-contact solar cell according to claim 1, wherein, The average base angle of the first type of pyramidal structure is 30-85°; the average base angle of the second type of pyramidal structure is 15-45°; and the average base angle of the third type of pyramidal structure is 20-55°.

12. The back-contact solar cell according to claim 8, wherein, The average base angle of the fourth type of pyramidal structure is 40–75°.

13. The back-contact solar cell according to claim 1, wherein, The top of the second type of pyramidal structure is set as a first arc surface, and the top of the third type of pyramidal structure is set as a second arc surface.

14. The back-contact solar cell according to claim 13, wherein, The curvature of the first arc surface is less than the curvature of the second arc surface.

15. The back-contact solar cell according to claim 11, wherein, The connection between two adjacent second-type pyramidal structures is set as a third arc surface, and the connection between two adjacent third-type pyramidal structures is set as a fourth arc surface.

16. The back-contact solar cell according to claim 15, wherein, The curvature of the third arc surface is less than the curvature of the fourth arc surface.

17. The back-contact solar cell according to claim 8, wherein, The top of the fourth type of pyramidal structure is sharp, and the connection between two adjacent fourth type pyramidal structures is also sharp.

18. The back-contact solar cell according to claim 1, wherein, The height of the second type of pyramidal structure is less than the height of the third type of pyramidal structure.

19. The back-contact solar cell according to claim 8, wherein, The height of the third type of pyramidal structure is less than the height of the fourth type of pyramidal structure.

20. A battery assembly comprising a back-contact solar cell as described in any one of claims 1 to 19.

21. A photovoltaic system comprising the battery module as described in claim 20.

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