Back contact solar cell, cell module and photovoltaic system

Abstract

The utility model is applicable to the technical field of solar cells, and provides a back contact solar cell, a cell assembly and a photovoltaic system, the back contact solar cell comprises a silicon substrate, the back surface of the silicon substrate comprises a P-type doped region, an N-type doped region and an isolation region, the front surface of the silicon substrate is provided with a first suede, the P-type doped region is provided with a second suede, and the N-type doped region is provided with a second suede. The N-type doped region is provided with a third suede; the average base angle of the second pyramid-like structure of the second suede and the average base angle of the third pyramid-like structure of the third suede are smaller than the average base angle of the first pyramid-like structure of the first suede; the average base angle of the first pyramid structure and the average base angle of the second pyramid structure and the average base angle of the third pyramid structure respectively have a first angle difference and a second angle difference, and the first angle difference is larger than the second angle difference. The back contact solar cell provided by the utility model can realize the matching of good optical performance and good passivation performance of the back surface, thereby improving the cell efficiency.

Description

TECHNICAL FIELD

[0001] The utility model relates to solar cell technical field especially relates to a back contact solar cell, battery assembly and photovoltaic system. BACKGROUND

[0002] The back contact (Interdigitated back contact, IBC) solar cell, namely the interdigital back contact solar cell, the positive / negative electrode grid line is designed in the back of the cell, makes the front surface avoid the shelter of metal grid line completely, eliminates the optical loss brought by electrode grid line shelter, and the electrode grid line can be designed wider than the existing, reduces the series resistance loss, thereby greatly improves the cell conversion efficiency. In addition, due to the design of the electrode grid line on the front surface of the cell, the product appearance is more beautiful, suitable for a variety of application scenarios.

[0003] In the prior art, the back contact solar cell is usually prepared with a textured surface only on the front surface of the silicon substrate, and the back surface of the silicon substrate is usually polished by alkali or acid to form a polished surface, so as to increase the uniformity of the passivation contact structure and improve the overall passivation quality, but the reflection of the sunlight into the silicon substrate from the back surface is reduced, and the sunlight entering the silicon substrate is easily directly emitted from the back surface, resulting in low sunlight utilization rate and low battery efficiency. UTILITY MODEL CONTENTS

[0004] The utility model provides a back contact solar cell, aims at solving the problem of low sunlight utilization rate and low battery efficiency of the back contact solar cell in the prior art.

[0005] The utility model is realized in this way, and provides a back contact solar cell, which comprises a silicon substrate, the silicon substrate has a front surface and a back surface arranged oppositely, the back surface comprises a P-type doped region and an N-type doped region, a first textured surface is arranged on at least part of the front surface, a second textured surface is arranged on at least part of the P-type doped region, and a third textured surface is arranged on at least part of the N-type doped region.

[0006] The first textured surface comprises a plurality of first pyramidal structures, the second textured surface comprises a plurality of second pyramidal structures, and the third textured surface comprises a plurality of third pyramidal structures.

[0007] The average base angle of the second pyramidal structure and the average base angle of the third pyramidal structure are smaller than the average base angle of the first pyramidal structure; the average base angle of the first pyramidal structure has a first angle difference with the average base angle of the second pyramidal structure, the average base angle of the first pyramidal structure has a second angle difference with the average base angle of the third pyramidal structure, and the first angle difference is greater than the second angle difference.

[0008] Preferably, the first angle difference and the second angle difference are both greater than 10°.

[0009] Preferably, the first angle difference and the second angle difference are both greater than 15°.

[0010] Preferably, the first angle difference and the second angle difference are both greater than 20°.

[0011] Preferably, the first angle difference is 20-30° and the second angle difference is 10-25°.

[0012] Preferably, the back surface further comprises an isolation region arranged between the P-type doped region and the N-type doped region, and a fourth textured surface is arranged in at least a partial region of the isolation region.

[0013] Preferably, the fourth textured surface comprises a plurality of fourth pyramidal structures, and the average base angle of the fourth pyramidal structures is the same as the average base angle of the first pyramidal structures.

[0014] Preferably, the fourth textured surface comprises a plurality of fourth pyramidal structures, and the average base angle of the fourth pyramidal structures is smaller than the average base angle of the first pyramidal structures, the average base angle of the first pyramidal structures and the average base angle of the fourth pyramidal structures have a third angle difference, and the second angle difference is greater than the third angle difference.

[0015] Preferably, the third angle difference is greater than 5°.

[0016] Preferably, the third angle difference is 5-10°.

[0017] Preferably, the average base angle of the first pyramidal structures is 30-85°, the average base angle of the second pyramidal structures is 15-45°, and the average base angle of the third pyramidal structures is 20-55°.

[0018] Preferably, the average base angle of the fourth pyramidal structures is 40-75°.

[0019] Preferably, the top of the second pyramidal structures is arranged as a first circular arc surface, and the top of the third pyramidal structures is arranged as a second circular arc surface.

[0020] Preferably, the curvature of the first circular arc surface is smaller than the curvature of the second circular arc surface.

[0021] Preferably, the connection between two adjacent second pyramidal structures is arranged as a third circular arc surface, and the connection between two adjacent third pyramidal structures is arranged as a fourth circular arc surface.

[0022] Preferably, the curvature of the third circular arc surface is smaller than the curvature of the fourth circular arc surface.

[0023] Preferably, the top of the fourth type of pyramid structure is pointed, and the junction of two adjacent fourth type of pyramid structures is pointed.

[0024] Preferably, the height of the second type of pyramid structure is less than the height of the third type of pyramid structure.

[0025] Preferably, the height of the third type of pyramid structure is less than the height of the fourth type of pyramid structure.

[0026] The utility model also provides a battery assembly, including above-mentioned back contact solar cell.

[0027] The utility model also provides a photovoltaic system, including above-mentioned battery assembly.

[0028] The back contact solar cell provided by the utility model is provided with the first rough surface on the front surface of the silicon substrate, the second rough surface on the P-type doped area and the third rough surface on the N-type doped area, the sunlight enters the silicon substrate through the first rough surface, the sunlight is reflected in the silicon substrate through the first rough surface, the second rough surface and the third rough surface by the cooperation of the first rough surface, the second rough surface and the third rough surface, the reflection path of the sunlight in the silicon substrate is increased, the sunlight directly emitted from the back surface is reduced, the transmittance of the sunlight from the back surface is reduced, the absorption of the back contact solar cell to the sunlight is increased, and the utilization rate of the back contact solar cell to the sunlight is improved.

[0029] Meanwhile, the difference between the average base angle of the first type of pyramid structure of the first rough surface and the average base angle of the second type of pyramid structure of the second rough surface is greater than the difference between the average base angle of the first type of pyramid structure of the first rough surface and the average base angle of the third type of pyramid structure of the N-type doped area, which is beneficial to reducing the surface recombination loss of the P-type doped area, facilitating the deposition of the back film layer of the P-type doped area and improving the passivation performance of the back film layer of the P-type doped area, matching the good optical performance of the back contact solar cell with the good passivation performance of the back of the cell, and further improving the cell efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 A structure schematic view of a back contact solar cell provided by the utility model embodiment is shown in the figure;

[0031] Figure 2 A structure schematic view of a silicon substrate of a back contact solar cell provided by the utility model embodiment is shown in the figure;

[0032] Figure 3 A partial structure schematic view of a first rough surface of a back contact solar cell provided by the utility model embodiment is shown in the figure;

[0033] Figure 4Part structure diagram of the second textured surface of the back contact solar cell is provided for the embodiment of the utility model;

[0034] Figure 5 Part structure diagram of the third textured surface of the back contact solar cell is provided for the embodiment of the utility model;

[0035] Figure 6 Part structure diagram of the fourth textured surface of the back contact solar cell is provided for the embodiment of the utility model;

[0036] Figure 7 Structure diagram of the silicon substrate of the second back contact solar cell is provided for the embodiment of the utility model;

[0037] Figure 8 Part structure diagram of the second textured surface of the second back contact solar cell is provided for the embodiment of the utility model;

[0038] Figure 9 Part structure diagram of the third textured surface of the second back contact solar cell is provided for the embodiment of the utility model. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical scheme and advantages of the utility model more clear, the following will be further detailed by combining with the drawings and embodiments. The examples of the embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the utility model, and cannot be understood as limiting the utility model. In addition, it should be understood that the specific embodiments described herein are only used to explain the utility model, and cannot be used to limit the utility model.

[0040] In the description of the utility model, it should be understood that the orientation or position relationship indicated by the terms "upper", "lower", "back", "front" and the like is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore it cannot be understood as limiting the utility model.

[0041] In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature can include the first and second features directly contact, or can include the first and second features are not directly contact but through the other features between them contact. Moreover, the first feature is "on", "above" and "above" the second feature includes the first feature is directly above and obliquely above the second feature, or just indicates the first feature horizontal height is higher than the second feature. The first feature is "under", "below" and "below" the second feature includes the first feature is directly below and obliquely below the second feature, or just indicates the first feature horizontal height is less than the second feature.

[0042] The disclosure below provides many different embodiments or examples for implementing the different structures of the present application. In order to simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeatedly refer to numbers and / or letters in different examples, and such repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides various specific examples of processes and materials, but those skilled in the art can realize the application of other processes and / or the use of other materials.

[0043] The back contact solar cell provided by the utility model increases the reflection path of sunlight in the silicon substrate, increases the absorption of sunlight by the back contact solar cell, improves the utilization rate of sunlight by the back contact solar cell, and controls the difference between the average base angle of the first texture and the average base angle of the second texture of the P-type doped area to be greater than the difference between the average base angle of the first texture and the average base angle of the N-type doped area, thereby further optimizing the optical performance of the P-type doped area and the N-type doped area.

[0044] Please refer to Figures 1-5 The utility model provides a kind of back contact solar cell, including silicon substrate 1, silicon substrate 1 has oppositely arranged front and back, back includes P-type doped area 31, N-type doped area 32 and the isolation area 33 between P-type doped area 31 and N-type doped area 32, front is provided with first texture 20 at least partial area, P-type doped area 31 is provided with second texture 311 at least partial area, N-type doped area 32 is provided with third texture 321 at least partial area;

[0045] First texture 20 includes several first pyramidal structure 201, second texture 311 includes several second pyramidal structure 312, and third texture 321 includes several third pyramidal structure 322;

[0046] The average base angle of second pyramidal structure 312 and the average base angle of third pyramidal structure 322 are less than the average base angle of first pyramidal structure 201, the average base angle of first pyramidal structure 201 and the average base angle of second pyramidal structure 312 have first angle difference, the average base angle of first pyramidal structure 201 and the average base angle of third pyramidal structure 322 have second angle difference, and first angle difference is greater than second angle difference.

[0047] In the embodiment of the utility model, the front surface of the silicon substrate 1 is the surface facing the sunlight when the back contact solar cell is working, and the back surface of the silicon substrate 1 is the surface away from the sunlight when the back contact solar cell is working. The P-type doped region 31 is a region provided with a P-type doped layer, the N-type doped region 32 is a region provided with an N-type doped layer, and the isolation region 33 is located between the adjacent two P-type doped regions 31 and N-type doped regions 32 for physically isolating the P-type doped region 31 and the N-type doped region 32. The specific number of the P-type doped region 31 and the N-type doped region 32 is not limited. Optionally, the P-type doped region 31 and the N-type doped region 32 are both multiple, the multiple P-type doped regions 31 and N-type doped regions 32 are sequentially and alternately spaced, and the isolation region 33 is arranged between the adjacent two P-type doped regions 31 and N-type doped regions 32.

[0048] In the embodiment of the utility model, the front surface of the silicon substrate 1 can have only a part of the region provided with the first rough surface 20, and the front surface of the silicon substrate 1 can also have the entire region provided with the first rough surface 20. Preferably, the front surface of the silicon substrate 1 has the entire region provided with the first rough surface 20.

[0049] In the embodiment of the utility model, the P-type doped region 31 has at least a part of the region provided with the second rough surface 311. It can be understood that the P-type doped region 31 can have only a part of the region provided with the second rough surface 311, or the P-type doped region 31 can have the entire region provided with the second rough surface 311. When the P-type doped region 31 has only a part of the region provided with the second rough surface 311, each P-type doped region 31 can be provided with the second rough surface 311, but at least one P-type doped region 31 has a part of the region provided with a non-rough surface region, that is, at least one P-type doped region 31 has a part of the region provided with a polishing surface; or only a part of the P-type doped regions 31 are provided with the second rough surface 311, and the other part of the P-type doped regions 31 are non-rough surface regions, that is, the other part of the P-type doped regions 31 are provided with polishing surfaces. In this way, the P-type doped region 31 is designed in combination of the second rough surface 311 and the polishing surface, the utilization rate of the P-type doped region 31 to the sunlight is improved by using the second rough surface 311, the surface recombination loss of the P-type doped region 31 is reduced by using the polishing surface, and the passivation performance of the back film layer of the P-type doped region 31 is improved, which is beneficial to improving the battery efficiency.

[0050] In the embodiment of the utility model, the third rough surface 321 is arranged in at least part of the N-type doped region 32, that is, the N-type doped region 32 can be provided with the third rough surface 321 in part of the region, or the N-type doped region 32 can be provided with the third rough surface 321 in all of the region. When the N-type doped region 32 is provided with the third rough surface 321 in part of the region, each N-type doped region 32 is provided with the third rough surface 321, but at least one N-type doped region 32 is provided with a non-rough surface region in part of the region, that is, at least one N-type doped region 32 is provided with a polishing surface in part of the region; or only part of the N-type doped regions 32 are provided with the third rough surface 321, and the other part of the N-type doped regions 32 are non-rough surface regions, that is, the other part of the N-type doped regions 32 are polishing surfaces. In this way, the N-type doped region 32 is designed in combination of the third rough surface 321 and the polishing surface, the utilization rate of sunlight of the N-type doped region 32 is improved by the third rough surface 321, the surface recombination loss of the N-type doped region 32 is reduced by the polishing surface, and the passivation performance of the back film layer of the N-type doped region 32 is improved, thereby improving the battery efficiency.

[0051] As shown in Figure 3 the embodiment of the utility model, the first rough surface 20 includes a plurality of first pyramidal structures 201, the bottom angle A of the first pyramidal structure 201 is the included angle between the side surface of the first pyramidal structure 201 and the bottom surface of the first pyramidal structure 201, and the bottom surface is a plane perpendicular to the thickness direction of the silicon substrate 1. The arrangement mode of the plurality of first pyramidal structures 201 is not limited, which can be arranged in a linear array, or can be arranged irregularly, and the adjacent first pyramidal structures 201 can also be stacked. Figure 4 As shown in Figure 5 the embodiment of the utility model, the plurality of second pyramidal structures 312 of the second rough surface 311 can also be arranged in a linear array, or can be arranged irregularly. The bottom angle B of the second pyramidal structure 312 is the included angle between the side surface of the second pyramidal structure 312 and the bottom surface of the second pyramidal structure 312, and the bottom surface is a plane perpendicular to the thickness direction of the silicon substrate 1. The plurality of third pyramidal structures 322 of the third rough surface 321 can also be arranged in a linear array, or can be arranged irregularly. As shown in Figure 5 the embodiment of the utility model, the bottom angle C of the third pyramidal structure 322 is the included angle between the side surface of the third pyramidal structure 322 and the bottom surface of the third pyramidal structure 322, and the bottom surface is a plane perpendicular to the thickness direction of the silicon substrate 1.

[0052] The first type of pyramid structure 201, the second type of pyramid structure 312 and the third type of pyramid structure 322 are all pyramid-like structures with a top or truncated pyramid-like structures; wherein, the pyramid-like structure can be a pyramid-like structure with three side surfaces and one bottom surface, or the pyramid-like structure can be a pyramid-like structure with four side surfaces and one bottom surface, or the pyramid-like structure can be a pyramid-like structure with five side surfaces and one bottom surface, or the pyramid-like structure can be a pyramid-like structure with six side surfaces and one bottom surface, or of course, the pyramid-like structure can be a pyramid-like structure with more side surfaces and one bottom surface.

[0053] When the angles between the side surfaces of each pyramid-like structure and the bottom surface of the pyramid-like structure are equal, only the angle between any side surface of the pyramid-like structure and the bottom surface of the pyramid-like structure needs to be measured as the base angle of the pyramid-like structure. Of course, the angles between the side surfaces of each pyramid-like structure and the bottom surface of the pyramid-like structure can also be unequal, in which case the average of the angles between the side surfaces of the pyramid-like structure and the bottom surface of the pyramid-like structure is measured as the base angle of the pyramid-like structure.

[0054] In the embodiments of the utility model, the average base angle of the first type of pyramid structure 201 is the average of the base angles of all the first type of pyramid structures 201 in the first pile surface 20, the average base angle of the second type of pyramid structure 312 is the average of the base angles of the preset number of second type of pyramid structures 312 in the target area of the second pile surface 311, and the average base angle of the third type of pyramid structure 322 is the average of the base angles of all the third type of pyramid structures 322 in the third pile surface 321.

[0055] In addition, the average base angle of the first type of pyramid structure 201 can be the average of the base angles of the first preset number of first type of pyramid structures 201 in the first pile surface 20, the average base angle of the second type of pyramid structure 312 can be the average of the base angles of the first preset number of second type of pyramid structures 312 in the second pile surface 311, and the average base angle of the third type of pyramid structure 322 can be the average of the base angles of the first preset number of third type of pyramid structures 322 in the third pile surface 321. Preferably, the first preset number is 3-10, the average base angle of the first type of pyramid structure 201 is measured by measuring the average of the base angles of 3-10 first type of pyramid structures 201 in the first pile surface 20, the average base angle of the second type of pyramid structure 312 is measured by measuring the average of the base angles of 3-10 second type of pyramid structures 312 in the second pile surface 311, and the average base angle of the third type of pyramid structure 322 is measured by measuring the average of the base angles of 3-10 third type of pyramid structures 322 in the third pile surface 321.

[0056] The average base angle of the first type of pyramid structure 201 can be an average value of base angles of a second preset number of the first type of pyramid structure 201 arranged along the first direction in a target region of the first surface 20; the average base angle of the second type of pyramid structure 312 can be an average value of base angles of a second preset number of the second type of pyramid structure 312 arranged along the first direction in a target region of the second surface 311; and the average base angle of the third type of pyramid structure 322 can be an average value of base angles of a second preset number of the third type of pyramid structure 322 arranged along the first direction in a target region of the third surface 321. The target region can be a rectangular region of 20 μm*30 μm, and the second preset number can be 2-10.

[0057] 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, a rectangular region of 20 μm*30 μm is taken as a target region in the first surface 20, the second surface 311 and the third surface 321 respectively, the base angles of three first type of pyramid structures 201 arranged along the first direction and having the highest height in the target region of the first surface 20 are measured, and an average value of the base angles of the three first type of pyramid structures 201 is calculated as the average base angle of the first type of pyramid structure 201; the base angles of three second type of pyramid structures 312 arranged along the first direction and having the highest height in the target region of the second surface 311 are measured, and an average value of the base angles of the three second type of pyramid structures 312 is calculated as the average base angle of the second type of pyramid structure 312; and the base angles of three third type of pyramid structures 322 arranged along the first direction and having the highest height in the target region of the third surface 321 are measured, and an average value of the base angles of the three third type of pyramid structures 322 is calculated as the average base angle of the third type of pyramid structure 322. Of course, other areas can be taken as target regions, and other numbers of pyramid structures can be compared in terms of average base angles.

[0058] In the embodiment of the utility model, through setting the first surface 20 on the front surface of the silicon substrate 1, setting the second surface 311 on the P type doped area 31 of the back surface of the silicon substrate 1 and setting the third surface 321 on the N type doped area 32 of the back surface of the silicon substrate 1, the first surface 20, the second surface 311 and the third surface 321 can cooperate with each other to increase the reflection path of sunlight in the silicon substrate 1, reduce the escape of sunlight directly from the back surface, reduce the transmittance of sunlight from the back surface, increase the absorption of sunlight by the solar cell and greatly improve the utilization rate of sunlight by the back contact solar cell.

[0059] Meanwhile, the first angle difference is greater than the second angle difference, so that the average base angle of the first textured surface 20 on the front surface of the silicon substrate 1 is greater than the average base angle of the second textured surface 311 of the P-type doped region 31, and the average base angle of the first textured surface 20 on the front surface of the silicon substrate 1 is greater than the average base angle of the third textured surface 321 of the N-type doped region 32, that is, by reducing the average base angle of the second type of pyramid structure 312 of the second textured surface 311 of the P-type doped region 31, the average base angle of the second type of pyramid structure 312 of the second textured surface 311 of the P-type doped region 31 is smaller than the average base angle of the third textured surface 321 of the N-type doped region 32, so that the second textured surface 311 of the P-type doped region 31 is more flat than the third textured surface 321 of the N-type doped region 32, which is beneficial to reducing the surface recombination loss of the P-type doped region 31, and is beneficial to the deposition of the back surface film layer of the P-type doped region 31 and is beneficial to improving the passivation performance of the back surface film layer of the P-type doped region 31, which ensures the good passivation performance of the P-type doped region 31 under the premise of increasing the light utilization rate of the cell, realizes the balance of the good optical performance of the back contact cell and the good passivation performance of the back surface of the cell, and thus realizes the good matching of the optical performance and the passivation performance of the cell, and further improves the cell efficiency.

[0060] As an embodiment of the present application, the first angle difference and the second angle difference are both greater than 10°.

[0061] In the 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 pyramid structure 201 of the first textured surface 20 and the average base angle of the second type of pyramid structure 312 of the second textured surface 311 and the difference between the average base angle of the first type of pyramid structure 201 of the first textured surface 20 and the average base angle of the third type of pyramid structure 322 of the third textured surface 321 are both greater than 10°, so that the difference between the average base angle of the first type of pyramid structure 201 of the first textured surface 20 and the average base angle of the second type of pyramid structure 312 of the second textured surface 311 and the difference between the average base angle of the first type of pyramid structure 201 of the first textured surface 20 and the average base angle of the third type of pyramid structure 322 of the third textured surface 321 satisfy good optical performance, which is beneficial to further improving the reflection of the back surface to the front surface light and improving the cell efficiency.

[0062] As an embodiment of the present application, the first angle difference and the second angle difference are both greater than 15°.

[0063] In the embodiment, the first angle difference and the second angle difference are greater than 15°, which is beneficial to further improving the reflection of the back surface to the front surface light and improving the cell efficiency.

[0064] As an embodiment of the present application, the first angle difference and the second angle difference are both greater than 20°.

[0065] In the embodiment, the first angle difference and the second angle difference are both greater than 20°, further increasing the difference between the first angle and the second angle, which is beneficial to further improve the reflection of the back surface to the front surface light and improve the battery efficiency.

[0066] As an embodiment of the utility model, the first angle difference is 20-30°, and the second angle difference is 10-25°.

[0067] In the embodiment, the first angle difference is 20-30°, that is, the difference between the average base angle of the first type of pyramid structure 201 on the front surface of the silicon substrate 1 and the average base angle of the second type of pyramid 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 of pyramid structure 201 on the front surface of the silicon substrate 1 and the average base angle of the third type of pyramid structure 322 of the N-type doped region 32 is 10-25°.

[0068] In this way, the first angle difference is controlled to be 20-30°, and the second angle difference is controlled to be 10-25°, which improves the solar light utilization rate of the P-type doped region 31 and the N-type doped region 32, and at the same time, the back surface of the P-type doped region 31 and the N-type doped region 32 and the isolation region 33 all have a relatively low surface recombination loss and have good surface passivation performance, thereby well balancing the optical performance and passivation performance of the P-type doped region 31 and the N-type doped region 32.

[0069] As an embodiment of the utility model, the average base angle of the first type of pyramid structure 201 is 30-85°; the average base angle of the second type of pyramid structure 312 is 15-45°; and the average base angle of the third type of pyramid structure 322 is 20-55°.

[0070] In the embodiment, the average base angle of the first type of pyramid structure 201 is set to 30-85°, which can make more sunlight enter the inside of the silicon substrate 1, reduce the reflection of the solar light on the front surface of the battery, increase the solar light absorption, and be beneficial to improving the battery efficiency.

[0071] The average base angle of the first type of pyramid structure 201 can be any value in 30-85°, the average base angle of the second type of pyramid structure 312 can be any value in 15-45°, and the average base angle of the third type of pyramid structure 322 can be any value in 20-55°, as long as 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 smaller 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 has the first angle difference with the average base angle of the first type of pyramid structure 201, the average base angle of the third type of pyramid structure 322 has the second angle difference with the average base angle of the first type of pyramid structure 201, the first angle difference is greater than the second angle difference, and the first angle difference and the second angle difference are both greater than 10°.

[0072] For example, the average base angle of the first type of pyramid structure 201 can be any value in 50°, 52°, 54°, 55°, 56°, 58°, 60°, 61°, 62°, 63°, 64°, 65°, 66°, 67°, 68°, 69°, 70°, 72°, 73°, 75°, 80°, 85°.

[0073] For example, the average base angle of the second type of pyramid structure 312 can be any value in 15°, 16°, 17°, 18°, 20°, 22°, 24°, 25°, 28°, 30°, 32°, 35°, 38°, 40°, 42°, 45°.

[0074] For example, the average base angle of the third type of pyramid structure 322 can be any value in 20°, 21°, 22°, 23°, 25°, 27°, 29°, 30°, 35°, 38°, 40°, 42°, 45°, 48°, 49°, 50°, 52°, 54°, 55°.

[0075] Please refer to Figure 1 and Figure 6 As an embodiment of the present application, the back surface further comprises an isolation region 33 arranged between the P-type doped region and the N-type doped region, and the fourth textured surface 331 is arranged at least in part of the isolation region 33.

[0076] In this embodiment, the textured surface is arranged on 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 solar light by the solar cell.

[0077] As an embodiment of the present application, the fourth textured surface 331 comprises a plurality of fourth type of pyramid structures 332, and the average base angle of the fourth type of pyramid structure 332 is the same as that of the first type of pyramid structure 201.

[0078] In this embodiment, the fourth type of pyramid structure 332 of the fourth textured surface 331 can be the same as the first type of pyramid structure 201 of the first textured surface, which can make the average base angle of the fourth type of pyramid structure 332 larger, and make the solar light with front transmission have good reflection performance.

[0079] As another embodiment of the present application, the average base angle of the fourth type of pyramid structure 332 is smaller than that of the first type of pyramid structure 201, 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 larger than the third angle difference.

[0080] In this embodiment, the fourth type of pyramid structure 332 is arranged on the fourth textured surface 331, and the average base angle of the fourth type of pyramid structure 332 is smaller than that of the first type of pyramid structure 201. Figure 6As shown, the bottom angle D of the fourth type of pyramid structure 332 is the included angle between the side surface of the fourth type of pyramid structure 332 and the bottom surface of the fourth type of pyramid structure 332, and the bottom surface is a plane perpendicular to the thickness direction of the silicon substrate 1. The average bottom angle of the fourth type of pyramid structure 332 is calculated in the same way as the average bottom angle 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 bottom angle of the fourth type of pyramid structure 332 is the average value of the bottom angles of all the fourth type of pyramid structures 332 in the fourth surface 331, or the average value of the bottom angles of the first preset number of the fourth type of pyramid structures 332 in the fourth surface 331, or the average value of the bottom angles of the second preset number of the fourth type of pyramid structures 332 arranged in the first direction in the target area of the fourth surface 331.

[0081] In the embodiment, under the premise that the surface is arranged in the isolation area 33 to further improve the utilization rate of sunlight, the second angle difference is controlled to be greater than the third angle difference, the average bottom angle of the fourth type of pyramid structure 332 is reduced, the optical performance of the P-type doped region 31, the N-type doped region 32, and the isolation area 33 is sequentially increased, and the passivation performance of the P-type doped region 31, the N-type doped region 32, and the isolation area 33 is sequentially decreased, thereby realizing good matching of the optical performance and the passivation performance of the P-type doped region 31, the N-type doped region 32, and the isolation area 33.

[0082] As an embodiment of the utility model, the third angle difference is greater than 5°.

[0083] In this way, the average bottom angle of the first type of pyramid structure 201 and the average bottom angle of the fourth type of pyramid structure 332 are controlled to be greater than 5°, the optical performance and the passivation performance of the isolation area 33 are considered, and good matching of the optical performance and the passivation performance of the isolation area 33 is realized.

[0084] As an embodiment of the utility model, the third angle difference is 5-10°.

[0085] In this way, the difference between the average bottom angle of the first type of pyramid structure 201 and the average bottom angle of the fourth type of pyramid structure 332 is controlled to be greater than 5°, the difference between the average bottom angle of the first type of pyramid structure 201 and the average bottom angle of the fourth type of pyramid structure 332 is further optimized, and more optimal matching of the optical performance and the passivation performance of the isolation area 33 is further realized.

[0086] As an embodiment of the utility model, the average bottom angle of the fourth type of pyramid structure 332 is 40-75°.

[0087] In this way, the isolation area 33 has good optical performance, low surface recombination loss, and good surface passivation performance, thereby balancing the optical performance and the passivation performance of the isolation area 33.

[0088] In the embodiment, the average base angle of the fourth type of pyramid structure 332 is set to 40-75°, so that the base angle difference between the isolation area 33 and the front surface texture is smaller, and the optical performance is good, and the utilization rate of sunlight is improved. The average base angle of the fourth type of pyramid structure 332 can be any value in 40-75°, as long as 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.

[0089] For example, the average base angle of the fourth type of pyramid structure 332 can be any value in 40°, 42°, 45°, 48°, 50°, 52°, 55°, 57°, 58°, 60°, 61°, 63°, 65°, 70°, 75°.

[0090] Please refer to Figures 7-9 As an embodiment of the utility model, the top of the second type of pyramid structure 312 is set to a first circular arc surface 313, and the top of the third type of pyramid structure 322 is set to a second circular arc surface 323.

[0091] In the embodiment, the top of the second type of pyramid structure 312 of the P-type doped region 31 is set to a first circular arc surface 313, and the top of the third type of pyramid structure 322 of the N-type doped region 32 is set to a second circular arc surface 323, that is, the top of the second type of pyramid structure 312 and the top of the third type of pyramid structure 322 are both smooth circular 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.

[0092] As an embodiment of the utility model, the curvature of the first circular arc surface 313 is smaller than the curvature of the second circular arc surface 323.

[0093] In the embodiment, the curvature of the first circular arc surface 313 is smaller than the curvature of the second circular arc surface 323, that is, the radius of the first circular arc surface 313 is larger than the radius of the second circular arc surface 323, and the top of the second type of pyramid structure 312 of the P-type doped region 31 is flatter than the top of the third type of pyramid 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.

[0094] As an embodiment of the utility model, the connection between the two adjacent second type of pyramid structures 312 is set to a third circular arc surface 314, and the connection between the two adjacent third type of pyramid structures 322 is set to a fourth circular arc surface 324.

[0095] In the embodiment, the junctions of the adjacent second-type pyramid structures 312 of the P-type doped region 31 and the junctions of the adjacent third-type pyramid structures 322 of the N-type doped region 32 are both arranged as circular arc surfaces, so that the surface recombination loss caused by texturing of the P-type doped region 31 and the N-type doped region 32 can be further reduced, and the deposition of the back film layer of the P-type doped region 31 and the N-type doped region 32 is facilitated, so that the passivation performance of the back passivation layer of the P-type doped region 31 and the N-type doped region 32 can be improved.

[0096] As an embodiment of the utility model, the curvature of the third circular arc surface 314 is smaller than the curvature of the fourth circular arc surface 324.

[0097] In the embodiment, the curvature of the third circular arc surface 314 is smaller than the curvature of the fourth circular arc surface 324, that is, the radius of the third circular arc surface 314 is larger than the radius of the fourth circular arc surface 324, and the junctions of the adjacent second-type pyramid structures 312 of the P-type doped region 31 are flatter than the junctions of the adjacent third-type pyramid structures 322 of the N-type doped region 32, so that the passivation effect of the P-type doped region 31 can be further improved, and the battery efficiency can be improved.

[0098] As an embodiment of the utility model, the top of the fourth-type pyramid structure 332 is arranged as sharp, and the junctions of the adjacent two fourth-type pyramid structures 332 are arranged as sharp.

[0099] In the embodiment, the top of the fourth-type pyramid structure 332 in the isolation region 33 is arranged as sharp, and the junctions of the adjacent fourth-type pyramid structures 332 are also arranged as sharp, so that the good optical performance of the isolation region 33 is ensured, the good optical performance of the isolation region 33 and the good passivation performance of the P-type doped region 31 and the N-type doped region 32 are matched, and the battery efficiency can be further improved.

[0100] As an embodiment of the utility model, the height of the second-type pyramid structure 312 is smaller than the height of the third-type pyramid structure 322.

[0101] The height of the second-type pyramid structure 312 is the distance from the bottom surface of the second-type pyramid structure 312 to the top end thereof, and the height of the third-type pyramid structure 322 is the distance from the bottom surface of the third-type pyramid structure 322 to the top end thereof. Since the height of the second-type pyramid structure 312 is smaller than the height of the third-type pyramid structure 322, the surface of the P-type doped region 31 can be flatter than the surface of the N-type doped region 32, and the passivation performance of the P-type doped region 31 can be improved.

[0102] As an embodiment of the utility model, the height of the third-type pyramid structure 322 is smaller than the height of the fourth-type pyramid structure 332.

[0103] The height of the fourth type of pyramid structure 332 is the distance from the bottom surface of the fourth type of pyramid structure 332 to the top end. Since the height of the third type of pyramid structure 322 is less than the height of the fourth type of pyramid structure 332, the passivation performance of the N-type doped region 32 can be improved, the passivation performance of the P-type doped region 31, the N-type doped region 32 and the isolation region 33 decreases in turn, the optical performance of the P-type doped region 31, the N-type doped region 32 and the isolation region 33 increases in turn, the optical performance and the passivation performance of the P-type doped region 31, the N-type doped region 32 and the isolation region 33 are well matched, and the cell efficiency is further improved.

[0104] As an embodiment of the present application, the roughness of the side surface of the fourth type of pyramid structure 332 is greater than the roughness of the side surface of the third type of pyramid structure 322, and the roughness of the side surface of the third type of pyramid structure 322 is greater than the roughness of the side surface of the second type of pyramid structure 312, which can further realize that the optical performance of the P-type doped region 31, the N-type doped region 32 and the isolation region 33 increases in turn, and the passivation performance of the P-type doped region 31, the N-type doped region 32 and the isolation region 33 decreases in turn, thereby further realizing the good matching of the optical performance and the passivation performance of the P-type doped region 31, the N-type doped region 32 and the isolation region 33.

[0105] Please refer to Figure 1 As an embodiment of the present application, the back contact solar cell further comprises:

[0106] The P-type doped layer 4 is arranged on the P-type doped region 31.

[0107] The N-type doped layer 5 is arranged on the N-type doped region 32.

[0108] In the 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.

[0109] As an embodiment of the present application, the back contact solar cell further comprises:

[0110] The first passivation layer 6 is arranged between the P-type doped layer 4 and the back surface of the silicon substrate 1.

[0111] The second passivation layer 7 is arranged between the N-type doped layer 5 and the back surface of the silicon substrate 1.

[0112] The first passivation layer 6 and the second passivation layer 7 can be a silicon oxide layer. The first passivation layer 6 and the second passivation layer 7 passivate the back surface of the silicon substrate 1, and further improve the passivation effect of the P-type doped region 31 and the N-type doped region 32.

[0113] As an embodiment of the utility model, still include:

[0114] The first electrode 8 is arranged on the side, away from the silicon substrate 1, of the P-type doped layer 4, and the first electrode 8 is in contact with the P-type doped layer 4.

[0115] The second electrode 9 is arranged on the side, away from the silicon substrate 1, of the N-type doped layer 4, and the second electrode 9 is in contact with the N-type doped layer 4.

[0116] As an embodiment of the utility model, the distribution density of the second type of pyramid structure 312 in the region of the P-type doped region 31 corresponding to the first electrode 8 is greater than the distribution density of the second type of pyramid structure 312 in the region of the P-type doped region 31 not corresponding to the first electrode 8, which is conducive to improving the bonding tensile force of the first electrode 8. Similarly, the distribution density of the third type of pyramid structure 322 in the region of the N-type doped region 32 corresponding to the second electrode 9 is greater than the distribution density of the third type of pyramid structure 322 in the region of the N-type doped region 32 not corresponding to the second electrode 9, which is conducive to improving the bonding tensile force of the second electrode 9.

[0117] As an embodiment of the utility model, still include:

[0118] The back passivation layer 13 covers the P-type doped layer 4, the N-type doped layer 5, and the isolation region 33.

[0119] In the embodiment, the first electrode 8 passes through the back passivation layer 13 and is in contact with the P-type doped layer 4, and the second electrode 9 passes through the back passivation layer 13 and is in contact with the N-type doped layer 4. The back passivation layer 13 can further improve the passivation effect of the battery and improve the efficiency of the battery. The back passivation layer 13 is at least one of an aluminum oxide film layer, a silicon oxide film layer, a silicon nitride film layer, a silicon carbide film layer, and a silicon oxynitride film layer, or a combination of multiple thereof, for example, in some embodiments, the back passivation layer 13 can include an aluminum oxide film layer and a silicon nitride film layer stacked in sequence, which is not limited in particular herein.

[0120] The utility model embodiment further provides a battery assembly, the battery assembly includes the back contact solar cell of above-mentioned embodiment. It needs to explain, this battery assembly and above-mentioned back contact solar cell have same or similar beneficial effect, and the related place between both can be mutually referred to, in order to avoid repetition, here will not be repeated.

[0121] In the embodiment, the plurality of back contact solar cells in the battery assembly can be sequentially connected together to form a battery string, thereby realizing series connection of the current, for example, the connection of the battery pieces can be realized by means of welding strip (bus bar, interconnecting strip), conductive back plate, etc.

[0122] It can be understood that in such an embodiment, the battery assembly can further include a metal frame, a back plate, photovoltaic glass and a film. The film can be filled between the front and back surfaces of the back contact solar cell and the photovoltaic glass, adjacent cell pieces, etc. as a filler, which can be a transparent gel with good light transmission performance and aging resistance, for example, the film can use EVA film or POE film, which can be selected according to actual conditions, and is not limited here.

[0123] The photovoltaic glass can be covered on the film on the front surface of the back contact solar cell. The photovoltaic glass can be super white glass, which has high light transmittance, high transparency, and superior physical, mechanical and optical properties. For example, the light transmittance of super white glass can be more than 92%, which can protect the back contact solar cell as much as possible without affecting the efficiency of the back contact solar cell. At the same time, the film can bond the photovoltaic glass and the back contact solar cell together, and the presence of the film can seal and insulate the back contact solar cell and prevent water and moisture.

[0124] The back plate can be attached to the film on the back surface of the back contact solar cell. The back plate can protect and support the back contact solar cell, has reliable insulation, water resistance and aging resistance, and can have multiple choices, which can be tempered glass, organic glass, aluminum alloy TPT composite film, etc. The specific setting can be made according to the specific situation, and is not limited here. The whole of the back plate, the back contact solar cell, the film and the photovoltaic glass can be arranged on the metal frame. The metal frame serves as the main external support structure of the entire back contact solar cell assembly, and can stably support and install the back contact solar cell assembly, for example, the metal frame can be used to install the back contact solar cell assembly at the desired installation position.

[0125] The utility model embodiment further provides a photovoltaic system, the photovoltaic system includes the battery assembly of above-mentioned embodiment. It needs to be explained that the photovoltaic system has same or similar beneficial effects with the above-mentioned back contact solar cell, and the related places between the two can be mutually referred to, in order to avoid repetition, which will not be repeated here.

[0126] In the embodiment, the photovoltaic system can be applied in a photovoltaic power station, such as a ground power station, a roof power station, a water surface power station, etc., and can also be applied in a device or apparatus using solar energy to generate power, such as a user solar power source, a solar street lamp, a solar car, a solar building, etc. Of course, it can be understood that the application scenarios of the photovoltaic system are not limited to this, that is, the photovoltaic system can be applied in all fields requiring solar energy to generate power. Taking a photovoltaic power generation system network as an example, the photovoltaic system can include a photovoltaic array, a combiner box and an inverter, the photovoltaic array can be an array combination of a plurality of back contact solar cell modules, for example, a plurality of back contact solar cell modules can form a plurality of photovoltaic arrays, the photovoltaic arrays are connected to the combiner box, the combiner box can combine the current generated by the photovoltaic arrays, the combined current flows through the inverter to convert into alternating current required by a power grid, and then is connected to a power network to realize solar power supply.

[0127] In the description of the present specification, the description referring to the terms "some embodiments", "exemplary embodiments", "examples", "specific examples", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0128] The above is only a preferred embodiment of the present application, and is not intended to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A back contact solar cell, characterized by, The back contact solar cell comprises a silicon substrate having opposite front and back surfaces, the back surface comprising a P-type doped region, an N-type doped region, and the front surface being provided with a first textured surface in at least a partial region, the P-type doped region being provided with a second textured surface in at least a partial region, and the N-type doped region being provided with a third textured surface in at least a partial region. The first textured surface comprises a plurality of first pyramidal structures, the second textured surface comprises a plurality of second pyramidal structures, and the third textured surface comprises a plurality of third pyramidal structures. The average base angle of the second pyramidal structures and the average base angle of the third pyramidal structures are smaller than the average base angle of the first pyramidal structures; the average base angle of the first pyramidal structures and the average base angle of the second pyramidal structures have a first angle difference, the average base angle of the first pyramidal structures and the average base angle of the third pyramidal structures have a second angle difference, and the first angle difference is larger than the second angle difference.

2. The back contact solar cell of claim 1, wherein, The first angle difference and the second angle difference are both larger than 10°.

3. The back contact solar cell of claim 1, wherein, The first angle difference and the second angle difference are both larger than 15°.

4. The back contact solar cell of claim 1, wherein, The first angle difference and the second angle difference are both larger than 20°.

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

6. The back contact solar cell of claim 1, wherein, The back surface further comprises an isolation region provided between the P-type doped region and the N-type doped region, and the isolation region is provided with a fourth textured surface in at least a partial region.

7. The back contact solar cell of claim 6, wherein, The fourth textured surface comprises a plurality of fourth pyramidal structures, and the average base angle of the fourth pyramidal structures is the same as the average base angle of the first pyramidal structures.

8. The back contact solar cell of claim 6, wherein, The fourth textured surface comprises a plurality of fourth pyramidal structures, the average base angle of the fourth pyramidal structures is smaller than the average base angle of the first pyramidal structures, the average base angle of the first pyramidal structures and the average base angle of the fourth pyramidal structures have a third angle difference, and the second angle difference is larger than the third angle difference.

9. The back contact solar cell of claim 8, wherein, The third angle difference is larger than 5°.

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

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

12. The back contact solar cell of claim 8, wherein, The average base angle of the fourth pyramidal structures is 40-75°.

13. The back contact solar cell of claim 1 wherein, The top of the second pyramidal structures is provided as a first circular arc surface, and the top of the third pyramidal structures is provided as a second circular arc surface.

14. The back contact solar cell of claim 13, wherein, The curvature of the first circular arc surface is smaller than the curvature of the second circular arc surface.

15. The back contact solar cell of claim 11, wherein, The connection between adjacent two second pyramidal structures is provided as a third circular arc surface, and the connection between adjacent two third pyramidal structures is provided as a fourth circular arc surface.

16. The back contact solar cell of claim 15, wherein, The curvature of the third circular arc surface is smaller than the curvature of the fourth circular arc surface.

17. The back contact solar cell of claim 8, wherein, The top of the fourth pyramidal structures is provided as a sharp structure, and the connection between adjacent two fourth pyramidal structures is provided as a sharp structure.

18. The back contact solar cell of claim 1 wherein, The height of the second pyramidal structures is smaller than the height of the third pyramidal structures.

19. The back contact solar cell of claim 8, wherein, The height of the third pyramidal structures is smaller than the height of the fourth pyramidal structures.

20. A battery assembly comprising: The back contact solar cell comprises a silicon substrate having opposite front and back surfaces, the back surface comprising a P-type doped region, an N-type doped region, and the front surface being provided with a first textured surface in at least a partial region, the P-type doped region being provided with a second textured surface in at least a partial region, and the N-type doped region being provided with a third textured surface in at least a partial region.

21. A photovoltaic system characterized by, The back contact solar cell comprises a silicon substrate having opposite front and back surfaces, the back surface comprising a P-type doped region, an N-type doped region, and the front surface being provided with a first textured surface in at least a partial region, the P-type doped region being provided with a second textured surface in at least a partial region, and the N-type doped region being provided with a third textured surface in at least a partial region.

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