Back contact solar cell, photovoltaic module and photovoltaic system

Abstract

The utility model is suitable for the technical field of solar cells, and provides a back contact solar cell, a photovoltaic assembly and a photovoltaic system, the back contact solar cell comprises a silicon substrate, the back surface of the silicon substrate is provided with a plurality of first doped regions and a plurality of second doped regions which are sequentially and alternately arranged along a first direction, the polarities of the first doped region and the second doped region are opposite, the adjacent first doped region and second doped region are electrically isolated through a groove, the groove comprises a side wall and a bottom surface, the side wall is provided with a plurality of first miniature pyramid structures, the bottom surface is provided with a plurality of second miniature pyramid structures, the first miniature pyramid structures correspond to a second direction, and the second direction corresponds to a third direction. The second micro pyramid structure corresponds to a third direction, and the third direction is perpendicular to the bottom face and intersects with the second direction. Through the arrangement, the light trapping effect between the first micro pyramid structure and the second micro pyramid structure is good, and the light reflectivity is reduced, so that the photoelectric conversion efficiency of the back contact solar cell is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of back-contact solar cells, and in particular relates to a back-contact solar cell, a photovoltaic component and a photovoltaic system. Background Art

[0002] Since back-contact solar cells have no main grid lines on the front, the positive and negative electrodes are both arranged on the back of the battery, which reduces shading and effectively increases the short-circuit circuit of the battery, thereby improving the energy conversion efficiency of the solar cell and thus having broad application prospects.

[0003] The backside of a back-contact solar cell features several p-regions and several n-regions, spaced apart and electrically isolated from each other by trenches. Between the backside and the trenches, a suede structure is applied. This suede structure features numerous micro-pyramids, which help absorb and utilize light striking the cell's surface after secondary or multiple reflections, thereby improving the solar cell's photoelectric conversion efficiency.

[0004] On this basis, how to further improve the photoelectric conversion efficiency of solar cells is a problem that needs to be solved. Utility Model Content

[0005] The embodiment of the present invention provides a back-contact solar cell, aiming to solve the problem of low photoelectric conversion efficiency of existing back-contact solar cells.

[0006] The embodiment of the present invention is implemented as follows: a back-contact solar cell, comprising:

[0007] A silicon substrate, wherein a plurality of first doping regions and a plurality of second doping regions are arranged alternately in sequence along a first direction on a back side of the silicon substrate, and the polarities of the first doping regions and the second doping regions are opposite;

[0008] Adjacent first doping regions and second doping regions are electrically isolated by trenches;

[0009] The groove includes a side wall and a bottom surface, the side wall is provided with a first velvet surface, the first velvet surface has a plurality of first micro-pyramid structures, the bottom surface is provided with a second velvet surface, the second velvet surface has a plurality of second micro-pyramid structures, the direction from the center point of the base of the first micro-pyramid structure to the top of the first micro-pyramid structure is the second direction, the direction from the center point of the base of the second micro-pyramid structure to the top of the second micro-pyramid structure is the third direction, the third direction is perpendicular to the bottom surface, and the third direction intersects with the second direction.

[0010] Furthermore, an angle between the third direction and the second direction is greater than or equal to 90°.

[0011] Furthermore, the first micro-pyramid structure and / or the second micro-pyramid structure is in a prism shape or a pyramid shape.

[0012] Furthermore, the side of the first micro-pyramid structure facing the second micro-pyramid structure is the first side, the side of the second micro-pyramid structure facing the first micro-pyramid structure is the second side, and the angle between the plane where the first side is located and the plane where the second side is located is less than or equal to 90°.

[0013] Furthermore, the ratio of the height of the first micro-pyramid structure and / or the second micro-pyramid structure to the side length of the base is (0.65 to 0.73):1.

[0014] Furthermore, at least one inclined surface of the first micro-pyramid structure and / or the second micro-pyramid structure is provided with a plurality of protrusions.

[0015] Furthermore, the ratio of the area of ​​the protrusion to the area of ​​the inclined surface is less than 50%.

[0016] In a second aspect, the present application also provides a photovoltaic module comprising the back-contact solar cell as described above.

[0017] In a third aspect, the present application also provides a photovoltaic system, comprising the photovoltaic assembly as described above.

[0018] The beneficial effects of the present application are as follows: The back-contact solar cell provided by the present application includes a silicon substrate, wherein a plurality of first doped regions and a plurality of second doped regions are arranged alternately along a first direction on the back side of the silicon substrate, wherein the first doped regions and the second doped regions have opposite polarities, and adjacent first doped regions and the second doped regions are electrically isolated by a trench, wherein the trench includes sidewalls and a bottom surface, wherein the sidewalls are provided with a first velvet surface, wherein the first velvet surface has a plurality of first micro-pyramid structures, and the bottom surface is provided with a second velvet surface, wherein the second velvet surface has a plurality of second micro-pyramid structures, wherein the direction from the center point of the base of the first micro-pyramid structure to the top of the first micro-pyramid structure is a second direction, and the direction from the center point of the base of the second micro-pyramid structure to the top of the second micro-pyramid structure is a third direction, wherein the third direction is perpendicular to the bottom surface and intersects the second direction. Through the above arrangement, due to the intersection of the third direction and the second direction, the light trapping effect between the first micro-pyramid structure and the second micro-pyramid structure is improved, thereby reducing light reflectivity, thereby improving the photoelectric conversion efficiency of the back-contact solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic structural diagram of an embodiment of a back-contact solar cell provided by the present application;

[0020] Figure 2 This is a schematic structural diagram of a groove in an embodiment of a back contact solar cell provided by the present application;

[0021] Figure 3 yes Figure 2 A magnified schematic diagram of part A1;

[0022] Figure 4 This is a schematic structural diagram of a groove of another embodiment of a back contact solar cell provided by the present application;

[0023] Figure 5 yes Figure 4 An enlarged schematic diagram of part A2;

[0024] Figure 6 This is a schematic structural diagram of a groove in another embodiment of a back-contact solar cell provided by the present application;

[0025] Figure 7 This is a schematic structural diagram of a groove in an embodiment of a back contact solar cell provided by the present application;

[0026] Figure 8 yes Figure 7 An enlarged schematic diagram of part A3.

[0027] Explanation of the reference numerals: 100, silicon substrate; 200, first doped region; 300, second doped region; 400, trench; 410, sidewall; 420, bottom surface; 500, first micro-pyramid structure; 600, second micro-pyramid structure. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. Examples of embodiments are shown in the accompanying drawings, in which the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and are not to be construed as limiting the present invention. In addition, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0029] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "left", "right", "horizontal", "top", "bottom", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features being referred to. Thus, features defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this utility model, "plurality" means two or more, unless otherwise specifically defined.

[0031] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections, or mutual communication; direct connections or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0032] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0033] The disclosure below provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference values ​​and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but a person of ordinary skill in the art will recognize the application of other processes and / or the use of other materials.

[0034] The back-contact solar cell provided in the present application includes a silicon substrate, wherein a back side of the silicon substrate is provided with a plurality of first doped regions and a plurality of second doped regions arranged alternately in sequence along a first direction, wherein the first doped regions and the second doped regions have opposite polarities, and adjacent first doped regions and the second doped regions are electrically isolated by a trench, wherein the trench includes sidewalls and a bottom surface, wherein the sidewalls are provided with a first velvet surface, wherein the first velvet surface has a plurality of first micro-pyramid structures, and the bottom surface is provided with a second velvet surface, wherein the second velvet surface has a plurality of second micro-pyramid structures, wherein the direction from the center point of the base of the first micro-pyramid structure to the top of the first micro-pyramid structure is a second direction, and the direction from the center point of the base of the second micro-pyramid structure to the top of the second micro-pyramid structure is a third direction, wherein the third direction is perpendicular to the bottom surface and intersects the second direction. Due to the above arrangement, since the third direction intersects the second direction, a light trapping effect between the first micro-pyramid structure and the second micro-pyramid structure is improved, light reflectivity is reduced, and the photoelectric conversion efficiency of the back-contact solar cell is improved.

[0035] Example 1

[0036] like Figures 1 to 8 As shown, one embodiment of the present application provides a back-contact solar cell, comprising:

[0037] A silicon substrate 100, wherein a plurality of first doping regions 200 and a plurality of second doping regions 300 are arranged alternately along a first direction on the back side of the silicon substrate 100, wherein the polarities of the first doping regions 200 and the second doping regions 300 are opposite;

[0038] The adjacent first doping regions 200 and second doping regions 300 are electrically isolated by the trench 400;

[0039] The sidewall 410 of the groove 400 is provided with a first velvet surface, and the first velvet surface has a plurality of first micro-pyramid structures 500. The first micro-pyramid structures 500 are perpendicular to the sidewall 410. The groove 400 includes a sidewall 410 and a bottom surface 420. The sidewall 410 is provided with a first velvet surface, and the first velvet surface has a plurality of first micro-pyramid structures 500. The bottom surface 420 is provided with a second velvet surface, and the second velvet surface has a plurality of second micro-pyramid structures 600. The direction from the center point of the base of the first micro-pyramid structure 500 to the top of the first micro-pyramid structure 500 is the second direction, and the direction from the center point of the base of the second micro-pyramid structure 600 to the top of the second micro-pyramid structure 600 is the third direction. The third direction is perpendicular to the bottom surface 420 and intersects with the second direction.

[0040] In practice, solar cells are also known as solar photovoltaics (abbreviated as PV). They are photoelectric semiconductor wafers that use sunlight to generate electricity directly. They are also called "solar chips" or "photocells". As long as the solar cell is illuminated by light that meets certain illumination conditions, it can instantly output voltage and generate current in the presence of a circuit.

[0041] Back-contact solar cells refer to solar cells in which the electrode grid lines are located on the back of the cell, thereby reducing or eliminating the shading loss of the front grid lines and improving cell efficiency.

[0042] During implementation, the silicon substrate 100 can be an N-type silicon wafer or a P-type silicon wafer, wherein the N-type silicon wafer is obtained by adding pentavalent elements (such as phosphorus or arsenic) to the silicon raw material, and these pentavalent elements provide additional free electrons; the P-type silicon wafer is obtained by adding trivalent elements (such as boron or gallium) to the silicon raw material, and these trivalent elements control the diffusion of electron holes, which will not be elaborated.

[0043] The silicon substrate 100 has a front side and a back side, wherein the front side of the silicon substrate 100 corresponds to the light-receiving side of the solar cell, and similarly, the back side of the silicon substrate 100 corresponds to the backlight side of the solar cell.

[0044] Optionally, the silicon substrate 100 may be a single crystal silicon wafer. A single crystal silicon wafer is a single crystal formed by slowly cooling a silicon raw material after melting. The crystal structure is compact and orderly, and it has high conversion efficiency, stability and lifespan.

[0045] Alternatively, the silicon substrate 100 may be a polycrystalline silicon wafer, which is a form of elemental silicon. When molten elemental silicon solidifies under supercooling conditions, silicon atoms are arranged in a diamond lattice to form numerous crystal nuclei. When these nuclei grow into grains with different crystal plane orientations, these grains combine to form polycrystalline silicon.

[0046] Optionally, the surface of the silicon substrate 100 can be a polished surface or a textured surface, without limitation. The textured surface is produced by performing a texturing process on the surface of the silicon substrate 100 to create an uneven pyramid structure on the surface of the silicon substrate 100. The uneven textured surface utilizes the light trapping effect to increase sunlight absorption, reduce reflectivity, increase short-circuit current, and improve the photoelectric conversion efficiency of the solar cell.

[0047] Optionally, the texturing process includes but is not limited to acid texturing, alkali texturing, mechanical texturing, electrochemical texturing, reactive ion etching texturing, laser texturing and mask texturing, etc., which will not be described in detail.

[0048] The first doping region 200 and the second doping region 300 are the positive and negative electrode regions of the solar cell. When the first doping region 200 is the positive electrode region, the second doping region 300 is the negative electrode region. Similarly, when the first doping region 200 is the negative electrode region, the second doping region 300 is the positive electrode region.

[0049] For example, taking an n-type silicon wafer as an example, a positive electrode region can be formed by doping a trivalent element such as boron on the n-type silicon wafer, and a negative electrode region can be formed by doping a pentavalent element such as phosphorus on the n-type silicon wafer, which will not be described in detail.

[0050] It should be noted that the above-mentioned solar cell including the silicon substrate 100, the first doping region 200, and the second doping region 300 is an example of the embodiment of the present application, and is not a specific limitation of the present application. In some other embodiments, the solar cell may also include other structures, such as a passivation layer and an anti-reflection layer, etc., which are not limited.

[0051] The first doping region 200 and the second doping region 300 are alternately distributed along the first direction on the back side of the silicon substrate 100. For ease of understanding, the application uses the extending direction of the line segment L1 as the first direction. Figure 1 shown.

[0052] Since the polarities of the first doping region 200 and the second doping region 300 are opposite, electrical isolation needs to be set between the first doping region 200 and the second doping region 300. For example, the present application achieves electrical isolation between the first doping region 200 and the second doping region 300 by setting a trench 400 between the first doping region 200 and the second doping region 300.

[0053] During implementation, the extension direction of the groove 400 is perpendicular or substantially perpendicular to the first direction. For example, when the first direction is horizontal, the extension direction of the groove 400 is vertical. Similarly, when the first direction is vertical, the extension direction of the groove 400 is horizontal.

[0054] The groove 400 is composed of a bottom surface 420 and two side walls 410. In some embodiments, the side walls 410 and the bottom surface 420 are perpendicular or substantially perpendicular. Figure 2 As shown, the cross section of the groove 400 is U-shaped. In some possible embodiments, the bottom surface 420 gradually expands toward the opening of the groove 400, such as Figure 4 As shown, or the bottom surface 420 gradually shrinks toward the opening direction of the groove 400, as shown Figure 5 As a possible implementation, the side wall 410 may also be a regular or irregular curved surface, without limitation.

[0055] The bottom surface 420 of the groove 400 of the present application is provided with a second velvet surface, and the second velvet surface has a plurality of second micro-pyramid structures 600. The direction from the center point of the base of the second micro-pyramid structure 600 to the top of the second micro-pyramid structure 600 is the third direction. For ease of understanding, the center point of the base of the second micro-pyramid structure 600 is recorded as D21, and the top of the second micro-pyramid structure 600 is recorded as D22. The extending direction of the line between D21 and D22 is the third direction, and the third direction is recorded as L3. Figure 3 The third direction can be regarded as the growth direction of the second micro-pyramid structure 600 , and the third direction is perpendicular to the bottom surface 420 , that is, the growth direction of the second micro-pyramid structure 600 is perpendicular to the bottom surface 420 .

[0056] The sidewall 410 of the groove 400 is provided with a first velvet surface, which is made by adopting the above-mentioned velvet making process. The first velvet surface has a plurality of first micro-pyramid structures 500, that is, the first micro-pyramid structures 500 are grown on the sidewall 410 of the groove 400. The direction from the center point of the base of the first micro-pyramid structure 500 to the top of the first micro-pyramid structure 500 is the second direction. For ease of understanding, the center point of the base of the first micro-pyramid structure 500 is recorded as D11, and the top of the first micro-pyramid structure 500 is recorded as D12. The extension direction of the line between D11 and D12 is the second direction, and the second direction is recorded as L2. The third direction intersects with the second direction. For example, the angle between the third direction and the second direction can be designed to be an acute angle, that is, the angle b between L2 and L3 is an acute angle, such as Figure 3 The second direction can be regarded as the growth direction of the first micro-pyramid structure 500 , and the third direction intersects the second direction, that is, the growth direction of the first micro-pyramid structure 500 intersects the growth direction of the second micro-pyramid structure 600 .

[0057] In some possible embodiments, the angle between the third direction and the second direction is greater than or equal to 90°. Figure 7 and Figure 8 As shown, the angle b between L2 and L3 is an obtuse angle. For example, the angle b between the third direction and the second direction is 95°, 100°, 105°, 110°, 115°, 120°, 125°, 130°, 135°, or any angle greater than 90°, without specific limitation. By setting the angle between the third direction and the second direction to be greater than or equal to 90°, the light trapping effect between the first micro-pyramid structure 500 and the second micro-pyramid structure 600 is improved, reducing light reflectivity, thereby improving the photoelectric conversion efficiency of the back-contact solar cell.

[0058] Optionally, the first micro-pyramid structure 500 and / or the second micro-pyramid structure 600 is in a prism shape or a pyramid shape. Optionally, the ratio of the height of the first micro-pyramid structure 500 and / or the second micro-pyramid structure 600 to the side length of the base is (0.65 to 0.73):1.

[0059] The first micro-pyramid structure 500 and / or the second micro-pyramid structure 600 may be pyramidal in shape. That is, the first micro-pyramid structure 500 is a convex tip grown on the sidewall 410 , and the second micro-pyramid structure 600 is a convex tip grown on the bottom surface 420 .

[0060] Optionally, when the pyramid structure is in the shape of a pyramid, the height of the pyramid structure is the distance from the top to the base, and when the pyramid structure is in the shape of a prism, the height of the pyramid structure is the distance from the upper surface of the prism to the base.

[0061] The ratio of the height of the pyramid structure to the side length of the base can be set to any value among 0.66:1, 0.067:1, 0.68:1, 0.69:1, 0.70:1, 0.71:1, 0.72:1, or (0.65 to 0.73):1, without limitation. The above setting makes the inclined surface of the pyramid structure steeper, thereby improving the light reflection effect and further improving the photoelectric conversion efficiency of the solar cell.

[0062] Furthermore, if Figure 5 As shown, the side of the first micro-pyramid structure 500 facing the second micro-pyramid structure 600 is a first side surface C1, and the side of the second micro-pyramid structure 600 facing the first micro-pyramid structure 500 is a second side surface C2. The angle between the plane where the first side surface C1 is located and the plane where the second side surface C2 is located is less than or equal to 90°.

[0063] When implementing, Figure 5 As shown, the angle a between the plane where the first side surface C1 and the plane where the second side surface C2 are located is less than or equal to 90°. For example, the angle a can be set to 88°, 85°, 80°, 75°, 70°, 65°, 60°, 55°, or any other angle less than or equal to 90°, without specific limitation. By setting the angle between the plane where the first side surface C1 and the plane where the second side surface C2 are located to less than or equal to 90°, light is trapped between the first side surface C1 and the second side surface C2. That is, the light is reflected multiple times between the first micro-pyramid structure 500 and the second micro-pyramid structure 600, thereby improving the light absorption rate of the solar cell and the photoelectric conversion efficiency of the solar cell.

[0064] In some optional embodiments, at least one inclined surface of the first micro-pyramid structure 500 and / or the second micro-pyramid structure 600 is provided with a plurality of protrusions.

[0065] During implementation, the first micro-pyramid structure 500 and / or the second micro-pyramid structure 600 are formed by etching. During the etching process, some of the pyramid structures' inclined surfaces are flat, inclined planes, while others have protrusions. Optionally, the ratio of the area of ​​the protrusions to the area of ​​the inclined surfaces is less than 50%. For example, the ratio of the area of ​​the protrusions to the area of ​​the inclined surfaces is 10%, 15%, 20%, 25%, 30%, 35%, 40%, or any value less than 50%, without limitation. Through this arrangement, the protrusions can increase the surface area of ​​the pyramid structures, further improving the light reflection effect, thereby further improving the photoelectric conversion efficiency of the solar cell.

[0066] Example 2

[0067] In some optional embodiments, the present application provides a photovoltaic module comprising the back-contact solar cell as described above.

[0068] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the structure and implementation principle of the photovoltaic assembly described above can refer to the corresponding structure and implementation principle in the aforementioned embodiment 1, and will not be repeated here.

[0069] The back-contact solar cell provided in the present application includes a silicon substrate 100. The back side of the silicon substrate 100 is provided with a plurality of first doped regions 200 and a plurality of second doped regions 300 arranged alternately in sequence along a first direction. The first doped regions 200 and the second doped regions 300 have opposite polarities. Adjacent first doped regions 200 and second doped regions 300 are electrically isolated by a trench 400. The trench 400 includes sidewalls 410 and a bottom surface 420. The sidewalls 410 are provided with a first velvet surface having a plurality of first micro-pyramid structures 500. The bottom surface 420 is provided with a second velvet surface having a plurality of second micro-pyramid structures 600. The direction from the center point of the base of the first micro-pyramid structure 500 to the top of the first micro-pyramid structure 500 is the second direction, and the direction from the center point of the base of the second micro-pyramid structure 600 to the top of the second micro-pyramid structure 600 is the third direction. The third direction is perpendicular to the bottom surface 420 and intersects with the second direction. With the above arrangement, since the third direction intersects the second direction, the light trapping effect between the first micro-pyramid structure 500 and the second micro-pyramid structure 600 is good, and the light reflectivity is reduced, thereby improving the photoelectric conversion efficiency of the back contact solar cell.

[0070] Example 3

[0071] In some optional embodiments, the present application provides a photovoltaic system including the photovoltaic assembly as described above.

[0072] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the structure and implementation principle of the photovoltaic system described above can refer to the corresponding structures and implementation principles in the aforementioned embodiments one and two, and will not be repeated here.

[0073] The back-contact solar cell provided in the present application includes a silicon substrate 100. The back side of the silicon substrate 100 is provided with a plurality of first doped regions 200 and a plurality of second doped regions 300 arranged alternately in sequence along a first direction. The first doped regions 200 and the second doped regions 300 have opposite polarities. Adjacent first doped regions 200 and second doped regions 300 are electrically isolated by a trench 400. The trench 400 includes sidewalls 410 and a bottom surface 420. The sidewalls 410 are provided with a first velvet surface having a plurality of first micro-pyramid structures 500. The bottom surface 420 is provided with a second velvet surface having a plurality of second micro-pyramid structures 600. The direction from the center point of the base of the first micro-pyramid structure 500 to the top of the first micro-pyramid structure 500 is the second direction, and the direction from the center point of the base of the second micro-pyramid structure 600 to the top of the second micro-pyramid structure 600 is the third direction. The third direction is perpendicular to the bottom surface 420 and intersects with the second direction. With the above arrangement, since the third direction intersects the second direction, the light trapping effect between the first micro-pyramid structure 500 and the second micro-pyramid structure 600 is good, and the light reflectivity is reduced, thereby improving the photoelectric conversion efficiency of the back contact solar cell.

[0074] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A back contact solar cell, characterized in that: include: A silicon substrate, wherein a plurality of first doping regions and a plurality of second doping regions are arranged alternately in sequence along a first direction on a back side of the silicon substrate, wherein the first doping regions and the second doping regions have opposite polarities; The adjacent first doping regions and the second doping regions are electrically isolated by a trench; The groove includes a side wall and a bottom surface, the side wall is provided with a first velvet surface, the first velvet surface has a plurality of first micro-pyramid structures, the bottom surface is provided with a second velvet surface, the second velvet surface has a plurality of second micro-pyramid structures, the direction from the center point of the base of the first micro-pyramid structure to the top of the first micro-pyramid structure is a second direction, the direction from the center point of the base of the second micro-pyramid structure to the top of the second micro-pyramid structure is a third direction, the third direction is perpendicular to the bottom surface, and the third direction intersects with the second direction.

2. The back contact solar cell according to claim 1, wherein An included angle between the third direction and the second direction is greater than or equal to 90°.

3. The back contact solar cell according to claim 2, wherein: The first micro-pyramid structure and / or the second micro-pyramid structure is in a prism shape or a pyramid shape.

4. The back contact solar cell according to claim 3, wherein: The side of the first micro-pyramid structure facing the second micro-pyramid structure is a first side, and the side of the second micro-pyramid structure facing the first micro-pyramid structure is a second side. The angle between the plane where the first side lies and the plane where the second side lies is less than or equal to 90°.

5. The back contact solar cell according to claim 3, wherein: The ratio of the height of the first micro-pyramid structure and / or the second micro-pyramid structure to the side length of the base is (0.65 to 0.73):

1.

6. The back contact solar cell according to claim 3, wherein: At least one inclined surface of the first micro-pyramid structure and / or the second micro-pyramid structure is provided with a plurality of protrusions.

7. The back contact solar cell according to claim 6, wherein: The ratio of the area of ​​the protrusion to the area of ​​the inclined surface is less than 50%.

8. A photovoltaic module, characterized in that: A back-contact solar cell comprising the method according to any one of claims 1 to 7.

9. A photovoltaic system, characterized in that: Comprising the photovoltaic module according to claim 8.

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