Back contact solar cell, cell assembly and photovoltaic system

Abstract

The utility model is suitable for the technical field of solar cells, and provides a back contact solar cell, a cell module and a photovoltaic system, in the back contact solar cell, a boss is arranged between a first groove and a second groove, a first doping layer is arranged at the first groove and is provided with a first extension part extending to the edge of the boss, and a second doping layer is arranged at the edge of the second groove. The second doping layer is arranged at the second groove and is provided with a second extension part extending to the edge of the boss, and insulating layers are arranged between the first extension part and the boss and between the second extension part and the boss. Thus, in the back contact solar cell, the first doping layer and the second doping layer are isolated through the boss, the isolation effect between the first doping layer and the second doping layer can be improved, and meanwhile, through the arrangement of the first extension part, the second extension part, the first insulating layer and the second insulating layer, the isolation effect between the first doping layer and the second doping layer can be improved. The passivation effect on the edge positions of the two grooves can be improved, so that the performance of the back contact solar cell is improved.

Description

Technical Field

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

[0002] A back-contact solar cell is a high-efficiency cell in which electrodes are arranged on the back of the cell. Specifically, in a back-contact solar cell, both the P-type electrode and the N-type electrode are arranged on the back, so that the front surface is not blocked by metal grid lines, thereby improving the efficiency of the cell.

[0003] In the related art, the P-type doped layer and the N-type doped layer in the back contact solar cell are directly located on the back of the silicon substrate, and the isolation of the P-type doped layer and the N-type doped layer is achieved by opening a groove between the two. However, the isolation effect of this method is poor, and the passivation effect is also poor. The matching design between the isolation effect and the passivation effect is not fully considered, so the performance of the current back contact solar cell is poor. Utility Model Content

[0004] The present application provides a back-contact solar cell, a cell module and a photovoltaic system.

[0005] The present application is implemented in this way. The back contact solar cell of the embodiment of the present application comprises:

[0006] A silicon substrate, wherein the silicon substrate has a front side and a back side opposite to each other, a plurality of first grooves and a plurality of second grooves arranged alternately in sequence are formed on the back side, and a boss is formed between adjacent first grooves and second grooves on the silicon substrate;

[0007] A first dielectric layer stacked in the first groove;

[0008] a first doping layer disposed at the first groove and stacked on the first dielectric layer, the first doping layer having a first extending portion extending to an edge of the boss, and a first insulating layer between the first extending portion and the boss;

[0009] A second dielectric layer stacked in the second groove; and

[0010] A second doping layer is disposed at the second groove and stacked on the second dielectric layer, wherein the second doping layer has a second extending portion extending to an edge of the boss, and a second insulating layer is provided between the second extending portion and the boss.

[0011] Furthermore, the surface of the boss is a non-suede structure; and / or

[0012] The surfaces of the first groove and the second groove are both non-suede structures.

[0013] Further, the surface roughness of the second groove is greater than that of the first groove.

[0014] Further, the surface of the boss includes a first region shielded by the first doping layer and the second doping layer and a second region not shielded by the first doping layer and the second doping layer, and the surface roughness of the second region is greater than that of the second groove.

[0015] Further, the surface roughness of the second region is greater than that of the first region.

[0016] Further, an indentation groove is formed in the region of the boss not covered by the first doping layer and the second doping layer.

[0017] Further, in the second groove, a partition groove is formed on the bottom of the second groove, and the second dielectric layer and the second doping layer are not provided at the partition groove.

[0018] Further, the depth of the first groove is 100 nm - 10 μm; and / or

[0019] the depth of the second groove is 100 nm - 10 μm.

[0020] Further, the depth of the second groove is greater than that of the first groove.

[0021] Further, the difference between the depth of the second groove and the depth of the first groove is 50 nm - 10 μm.

[0022] Further, the first doping layer is a phosphorus-doped layer, and the second doping layer is a boron-doped layer;

[0023] In the boss, the phosphorus doping concentration in the region close to the first groove is greater than the phosphorus doping concentration in the region close to the second groove; and / or

[0024] In the boss, the boron doping concentration in the region close to the second groove is greater than the boron doping concentration in the region close to the first groove.

[0025] Further, along the direction of the first groove towards the second groove, the phosphorus doping concentration in the boss gradually decreases;

[0026] Along the direction of the second groove towards the first groove, the boron doping concentration in the boss gradually decreases.

[0027] Further, the first groove and the second groove are alternately arranged at intervals in a first direction and extend in a second direction, the boss also extends in the second direction, the second direction intersects with the first direction, and the boss is a continuous structure in the second direction;

[0028] Wherein, on the boss, the first extension portion and the second extension portion do not contact each other at all positions; or

[0029] On a partial area of the boss, the first extension portion and the second extension portion are insulated from each other, and on another partial area of the boss, the first extension portion and the second extension portion are conductively connected.

[0030] Further, in the case where the first extension portion and the second extension portion do not contact each other at all positions, in the arrangement direction of the first groove and the second groove, the length of the first extension portion is 5 μm - 60 μm, and the length of the second extension portion is 5 μm - 60 μm.

[0031] Further, a first diffusion layer is formed on at least a partial area of the surface of the boss, and the first extension portion and the second extension portion are conductively connected through the first diffusion layer.

[0032] Further, the first groove and the second groove are alternately arranged in sequence in a first direction and both extend in a second direction, the second direction intersects with the first direction, the first diffusion layer extends in the second direction, and in the second direction, the first diffusion layer has a plurality of diffusion regions with different doping concentrations.

[0033] Further, the first groove and the second groove are alternately arranged at intervals in a first direction and extend in a second direction, the boss also extends in the second direction, the second direction intersects with the first direction;

[0034] The boss is a discontinuous structure in the second direction, the boss includes a plurality of boss segments arranged at intervals in the second direction, and there is a discontinuous region between adjacent two boss segments;

[0035] Wherein, on the boss segment, the first extension portion and the second extension portion are insulated from each other, and at the discontinuous region, the first doping layer and the second doping layer are conductively connected.

[0036] Further, a second diffusion layer is formed at the discontinuous region, and the first doping layer and the second doping layer are conductively connected through the second diffusion layer.

[0037] Further, in the arrangement direction of the first groove and the second groove, the width of the boss is 10 μm - 700 μm.

[0038] The present application also provides a battery assembly, including a plurality of the back-contact solar cells described in any one of the above.

[0039] The present application also provides a photovoltaic system, which includes the battery assembly described above.

[0040] In the back-contact solar cell, the battery assembly and the photovoltaic system according to the embodiments of the present application, there is a boss between the first groove and the second groove. The first doping layer is disposed at the first groove and has a first extension portion extending to the edge of the boss. The second doping layer is disposed at the second groove and has a second extension portion extending to the edge of the boss. There are insulating layers between the first extension portion and the second extension portion and the boss respectively. Thus, in the back-contact solar cell, the first doping layer and the second doping layer are isolated by the boss, which can improve the isolation effect between the first doping layer and the second doping layer. At the same time, through the settings of the first extension portion, the second extension portion, the first insulating layer and the second insulating layer, the passivation effect on the edges of the two grooves (i.e., the two side edges of the boss) can be improved, thereby improving the performance of the back-contact solar cell.

[0041] Some of the additional aspects and advantages of the present application will be given in the following description, some will become apparent from the following description, or be learned through the practice of the present application. Description of the Drawings

[0042] Figure 1 is a schematic module diagram of the photovoltaic system provided by the embodiment of the present application;

[0043] Figure 2 is a schematic plan view of the back-contact solar cell provided by the embodiment of the present application;

[0044] Figure 3 is Figure 2 the cross-sectional structure diagram of the back-contact solar cell along line III-III in

[0045] Figure 4 is another cross-sectional structure diagram of the back-contact solar cell provided by the embodiment of the present application;

[0046] Figure 5 is another schematic plan view of the back-contact solar cell provided by the embodiment of the present application;

[0047] Figure 6 is Figure 5 the cross-sectional structure diagram of the back-contact solar cell along line VI-VI in

[0048] Figure 7 is another schematic plan view of the back-contact solar cell provided by an embodiment of the present application;

[0049] Figure 8 is Figure 7 a schematic cross-sectional view of the back-contact solar cell along line VIII-VIII in

[0050] Figure 9 is another schematic plan view of the back-contact solar cell provided by an embodiment of the present application;

[0051] Figure 10 is Figure 9 a schematic cross-sectional view of the back-contact solar cell along line X-X in

[0052] Figure 11 is Figure 9 a schematic cross-sectional view of the back-contact solar cell along line XI-XI in Detailed implementation manners

[0053] In order to make the objectives, technical solutions and advantages of the present application clearer and more understandable, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals indicate the same or similar elements or elements with the same or similar functions throughout. It should be noted that the embodiments described below with reference to the accompanying drawings are exemplary only for explaining the present application and cannot be construed as limiting the present application. In addition, it should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0054] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "top", "bottom", "side", "lateral", "longitudinal", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present application 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 construed as limiting the present application.

[0055] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the described features. In the description of the present application, "a number of" means two or more, unless otherwise specifically defined.

[0056] In this application, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may include direct contact between the first and second features, or may include indirect contact between the first and second features through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the horizontal height of the first feature is lower than that of the second feature.

[0057] The following disclosure provides many different embodiments or examples for implementing different structures of this application. To simplify the disclosure of this application, components and arrangements of specific examples are described below. Of course, they are merely examples and are not intended to limit this application. In addition, this application may repeat reference numerals and / or reference letters in different examples. This repetition is for the purpose of simplification and clarity, and in itself does not indicate the relationship between various embodiments and / or arrangements discussed. In addition, this application provides examples of various specific processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use scenarios of other materials.

[0058] Please refer to Figure 1 , the photovoltaic system 1000 in the embodiment of this application may include the battery assembly 200 in the embodiment of this application. The battery assembly 200 in the embodiment of this application may include several back-contact solar cells 100 in the embodiment of this application. Several back-contact solar cells 100 may be connected in series through solder strips to form several cell strings, and each cell string may form the battery assembly 200 in a series, parallel or series-parallel manner.

[0059] Please combine Figure 2 and Figure 3 , the back-contact solar cell 100 in the embodiment of this application may include a silicon substrate 10, a first dielectric layer 20, a first doping layer 30, a first insulating layer 40, a second dielectric layer 50, a second doping layer 60 and a second insulating layer 70.

[0060] As Figure 3 shown, the silicon substrate 10 has opposite front surface 11 and back surface 12. A plurality of first grooves 121 and a plurality of second grooves 122 are formed on the back surface 12. The plurality of first grooves 121 and the plurality of second grooves 122 are alternately arranged at intervals in sequence. The silicon substrate 10 forms a boss 123 between adjacent first grooves 121 and second grooves 122, that is, the boss 123 is between the first groove 121 and the second groove 122, and the boss region is between the two grooves.

[0061] Specifically, asFigure 2 and Figure 3 As shown, a plurality of first grooves 121 and a plurality of second grooves 122 may be alternately arranged at intervals in sequence along a first direction, and both extend along a second direction, and the second direction intersects the first direction. For example, as Figure 2 shown, in some embodiments, the first direction may be the lateral direction of the back-contact solar cell 100, and the second direction may be the longitudinal direction of the back-contact solar cell 100, and the two are perpendicular to each other.

[0062] Of course, it can be understood that in some embodiments, the first direction and the second direction may also be other directions. For example, the two directions may be the directions of two diagonals of the back-contact solar cell 100 respectively, and specific limitations are not made here.

[0063] As Figure 3 shown, the first dielectric layer 20 may be stacked in the first groove 121. Specifically, the first dielectric layer 20 may cover the bottom surface and the side surface of the first groove 121. The first doping layer 30 is disposed at the first groove 121 and stacked on the first dielectric layer 20. The first doping layer 30 has a first extension portion 31 extending to the edge of the boss 123, and there is a first insulating layer 40 between the first extension portion 31 and the boss 123.

[0064] That is to say, in addition to the part disposed in the first groove 121, the first doping layer 30 also extends along the side surface of the first groove 121 to the edge position of the boss 123, so as to form the first extension portion 31, and the first extension portion 31 is insulated and isolated from the silicon substrate 10 through the first insulating layer 40.

[0065] The second dielectric layer 50 may be stacked in the second groove 122. Specifically, the second dielectric layer 50 may cover the bottom surface and the side surface of the second groove 122. The second doping layer 60 is disposed at the second groove 122 and stacked on the second dielectric layer 50. The second doping layer 60 has a second extension portion 61 extending to the edge of the boss 123, and there is a second insulating layer 70 between the second extension portion 61 and the boss 123.

[0066] That is to say, in addition to the part disposed in the second groove 122, the second doping layer 60 also extends along the side surface of the second groove 122 to the edge position of the boss 123, so as to form the second extension portion 61, and the second extension portion 61 is insulated and isolated from the silicon substrate 10 through the second insulating layer 70.

[0067] In the present application, the surface of the boss 123 refers to the surface of the silicon substrate 10 located between the first groove 121 and the second groove 122. The "edge of the boss 123" refers to the two side edges of the surface of the boss 123 facing away from the front surface 11, that is, the edge region of the boss 123 near the first groove 121 and the edge region of the boss 123 near the second groove 122.

[0068] In the back-contact solar cell 100, the battery module 200, and the photovoltaic system 1000 according to the embodiments of the present application, there is a boss 123 between the first groove 121 and the second groove 122. The first doping layer 30 is disposed at the first groove 121 and has a first extension portion 31 extending to the edge of the boss 123. The second doping layer 60 is disposed at the second groove 122 and has a second extension portion 61 extending to the edge of the boss 123. An insulating layer is provided between each of the first extension portion 31 and the second extension portion 61 and the boss 123. In this way, in the back-contact solar cell 100, the first doping layer 30 and the second doping layer 60 are isolated by the boss 123, which can improve the isolation effect between the first doping layer 30 and the second doping layer 60. At the same time, by providing the first extension portion 31, the second extension portion 61, the first insulating layer 40, and the second insulating layer 70, the passivation effect on the edges of the two grooves (i.e., the two side edges of the boss 123) can be improved, thereby improving the performance of the back-contact solar cell 100.

[0069] In addition, in the present application, there is no need to use trenches to isolate the two doping layers, which can improve the strength of the silicon substrate 10 and reduce the probability of hidden cracks. Moreover, an insulating layer is provided at the edge position of the boss 123, which can improve the reflectivity of light from the front surface 11 region, thereby improving the utilization rate of light and further improving the performance of the back-contact solar cell 100.

[0070] Specifically, in the embodiments of the present application, the silicon substrate 10 may be a P-type silicon substrate or an N-type silicon substrate, which is not specifically limited herein. One of the first doping layer 30 and the second doping layer 60 is a P-type doping layer, and the other may be an N-type doping layer. Exemplarily, in some embodiments, the first doping layer 30 may be a P-type doped polysilicon layer, a P-type doped microcrystalline silicon layer, etc., and the second doping layer 60 may be an N-type doped polysilicon layer, an N-type doped microcrystalline silicon layer, etc., which is not specifically limited herein.

[0071] The first dielectric layer 20 and the second dielectric layer 50 may both be tunneling oxide layers. For example, both of them may be tunneling silicon oxide film layers. The first insulating layer 40 and the second insulating layer 70 may be film layers such as silicon oxide layers and silicon nitride layers having an insulating function, which is not specifically limited herein. The two may preferably be made of the same material, as long as the two can achieve insulation between the first extension portion 31 and the second extension portion 61 and the silicon substrate 10.

[0072] In addition, it can also be understood that in the back-contact solar cell 100, a passivation film layer (not shown in the figure) may also be integrally covered on the back surface 12. The passivation film layer covers the entire back surface 12, that is, the passivation film layer covers the entire back surface area of the back-contact solar cell 100. A first metal electrode (not shown in the figure) is provided at the position corresponding to the first doping layer 30 (i.e., at the first groove 121), and the first metal electrode penetrates the passivation film layer to contact the first doping layer 30. A second metal electrode (not shown in the figure) is provided at the position corresponding to the second doping layer 60 (i.e., at the first groove 121), and the second metal electrode penetrates the passivation film layer to contact the second doping layer 60.

[0073] Please refer to Figure 2 and Figure 3 , in the embodiment of the present application, in the arrangement direction of the first groove 121 and the second groove 122 (i.e., the first direction), the width of a single boss 123 is 10 μm - 700 μm.

[0074] In this way, setting the width of the boss 123 in this reasonable range in the first direction can ensure the isolation effect between the first doping layer 30 and the second doping layer 60 while ensuring the efficiency of the back-contact solar cell 100.

[0075] Specifically, in such an embodiment, the width of the boss 123 can be, for example, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, 550 μm, 600 μm, 650 μm, 700 μm or any value between 50 μm - 700 μm.

[0076] In some embodiments, the surface of the boss 123 (the surface of the region of the silicon substrate 10 between the first groove 121 and the second groove 122) is a non-textured structure, that is, the lower surface of the boss 123 shown in the figure is a polished surface.

[0077] In this way, the surface reflectivity at the boss 123 is relatively high, which can enhance the reflection of the light incident from the front surface 11 and passing through the silicon substrate 10, so as to reflect more light back into the silicon substrate 10, thereby improving the efficiency of the back-contact solar cell 100. At the same time, setting the surface of the boss 123 as a non-textured structure can also improve the passivation effect during the subsequent coverage of the passivation film layer.

[0078] In some embodiments, the surfaces of the first groove 121 and the second groove 122 (the bottom and side surfaces of the first groove 121 and the second groove 122) can also be non-textured structures, that is, the surfaces of the first groove 121 and the second groove 122 are both polished surfaces.

[0079] In this way, the reflection of the light incident from the front surface 11 and passing through the silicon substrate 10 can be further enhanced, and more light can be reflected back into the silicon substrate 10, thereby improving the efficiency of the back-contact solar cell 100.

[0080] Meanwhile, during the preparation process, after the first groove 121 and the second groove 122 are formed, by polishing the first groove 121 and the second groove 122, the damage caused during the formation of the first groove 121 and the second groove 122 (such as laser damage caused by laser grooving) can be removed.

[0081] In some embodiments, the surface roughness of the second groove 122 is greater than that of the first groove 121.

[0082] In this way, by optimizing the matching design of different roughnesses for different grooves, the bifaciality of the back-contact solar cell 100 can be improved.

[0083] Furthermore, in some embodiments, the surface of the boss 123 may include a first region (i.e., the two side edge regions of the boss 123) covered by the first doping layer 30 and the second doping layer 60 and a second region (i.e., the middle region of the boss 123) not covered by the first doping layer 30 and the second doping layer 60, and the surface roughness of the second region is greater than that of the second groove 122.

[0084] In this way, by optimizing the matching design of different roughnesses for the surface roughness of the boss 123 and the surface roughness of the groove, the bifaciality of the back-contact solar cell 100 can be further improved.

[0085] In some embodiments, the surface roughness of the second region may be greater than that of the first region, that is, in the boss 123, the surface roughness of the middle part is greater than that of the edge part.

[0086] Please refer to Figure 3 and Figure 4 , in some embodiments, an indentation groove 1231 is formed on the region of the boss 123 not covered by the first doping layer 30 and the second doping layer 60, that is, the indentation groove 1231 is provided at the second region described above.

[0087] In addition, please refer to Figure 4 , in some embodiments, in the second groove 122, a partition groove 1221 is formed at the bottom of the second groove 122, and the second dielectric layer 50 and the second doping layer 60 may not be provided at the partition groove 1221.

[0088] In some embodiments, the depth of the first groove 121 (i.e., the recessed depth of the first groove 121 within the silicon substrate 10) can be 100 nm - 10 μm.

[0089] Thus, by setting the depth of the first groove 121 within this reasonable range, it is possible to avoid a decrease in the strength of the silicon substrate 10 due to an overly deep first groove 121, and it is also possible to avoid an overly shallow depth of the first groove 121 resulting in a too small height of the boss 123 and affecting the isolation effect.

[0090] Specifically, in such an embodiment, the depth of the first groove 121 can be, for example, 100 nm, 150 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, or any value between 100 nm - 10 μm.

[0091] In some embodiments, the depth of the second groove 122 (i.e., the recessed depth of the second groove 122 within the silicon substrate 10) can be 100 nm - 10 μm.

[0092] Thus, by setting the depth of the second groove 122 within this reasonable range, it is possible to avoid a decrease in the strength of the silicon substrate 10 due to an overly deep second groove 122, and it is also possible to avoid an overly shallow depth of the second groove 122 resulting in a too small height of the boss 123 and affecting the isolation effect.

[0093] Specifically, in such an embodiment, the depth of the second groove 122 can be, for example, 100 nm, 150 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, or any value between 100 nm - 10 μm.

[0094] It should be noted that in this application, the depth of the groove refers to the distance between any position on the bottom surface of the groove and the back surface 12.

[0095] In some embodiments, the depth of the second groove 122 is greater than the depth of the first groove 121. Thus, by performing different matching designs on the depths of the two grooves, the efficiency of the back - contact solar cell 100 can be ensured.

[0096] Specifically, in such an embodiment, the difference between the depth of the second groove 122 and the depth of the first groove 121 is 50 nm - 10 μm. For example, 50 nm, 100 nm, 150 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, or any value between 50 nm - 10 μm

[0097] In some embodiments, the first doping layer 30 may be a phosphorus-doped layer, and the second doping layer 60 may be a boron-doped layer. In the boss 123, the phosphorus doping concentration in the region close to the first groove 121 is greater than the phosphorus doping concentration in the region close to the second groove 122; and / or, in the boss 123, the boron doping concentration in the region close to the second groove 122 is greater than the boron doping concentration in the region close to the first groove 121.

[0098] Thus, by designing the phosphorus doping concentration and boron doping concentration in different regions of the boss 123 differently, the passivation effect on the surface of the boss 123 can be better, surface recombination and edge recombination can be reduced, and the efficiency can be improved.

[0099] Further, in such an embodiment, along the direction from the first groove 121 towards the second groove 122, the phosphorus doping concentration in the boss 123 gradually decreases. Along the direction from the second groove 122 towards the first groove 121, the boron doping concentration in the boss 123 gradually decreases.

[0100] Thus, by specifically designing the phosphorus doping concentration and boron doping concentration in each region of the boss 123, the passivation effect on the surface of the boss 123 can be improved, and surface recombination and edge recombination can be reduced.

[0101] Please refer to Figure 2 and Figure 3 , in some embodiments, the first groove 121 and the second groove 122 are arranged alternately at intervals in sequence along the first direction and extend along the second direction. The boss 123 also extends along the second direction. The second direction intersects with the first direction, and the boss 123 is a continuous structure in the second direction.

[0102] Among them, on the boss 123, the first extension part 31 and the second extension part 61 do not contact each other at all positions. In this way, the anti-leakage performance of the back-contact solar cell 100 can be improved.

[0103] Specifically, in such an embodiment, that the first extension part 31 and the second extension part 61 do not contact each other means that they are separated and insulated from each other on the boss 123, rather than directly contacting to form an electrical connection.

[0104] It should be noted that in the present application, the boss 123 being a continuous structure in the second direction means that the boss 123 is a continuous and unbroken structure in the second direction.

[0105] Furthermore, in such an embodiment, when the first extension part 31 and the second extension part 61 are insulated from each other at all positions, in the arrangement direction (i.e., the first direction) of the first groove 121 and the second groove 122, the length of the first extension part 31 is 5 μm - 60 μm, and the length of the second extension part 61 is 5 μm - 60 μm.

[0106] In this way, by setting the lengths of the first extension part 31 and the second extension part 61 within the above - reasonable range, while improving the passivation effect on the surface of the boss 123 to reduce surface recombination and edge recombination, it is possible to avoid a significant decrease in the bifaciality rate due to the excessive lengths of the first extension part 31 and the second extension part 61.

[0107] Specifically, in such an embodiment, the length of the first extension part 31 can be, for example, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm or any value between 10 μm - 10 μm. The length of the second extension part 61 can also be, for example, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm or any value between 5 μm - 60 μm.

[0108] Of course, referring to Figure 5 and Figure 6 , in some embodiments, in some regions of the boss 123, the first extension part 31 is insulated from the second extension part 61, and in other regions of the boss 123, the first extension part 31 is conductively connected to the second extension part 61 (that is, the first extension part 31 and the second extension part 61 form a composite contact).

[0109] In this way, by forming a composite contact between the first extension part 31 and the second extension part 61 in some regions on the boss 123, the reverse breakdown voltage and the hot - spot risk of the back - contact solar cell 100 can be reduced, thereby improving the hot - spot resistance performance of the back - contact solar cell 100.

[0110] Specifically, in such an embodiment, the compound contact between the first extension portion 31 and the second extension portion 61 refers to that the two are in direct contact to achieve the electrical connection between the two, or a dielectric layer with tunneling function is provided between the first extension portion 31 and the second extension portion 61, so as to achieve the electrical connection between the first extension portion 31 and the second extension portion 61 through the dielectric layer. Specifically, no limitation is made here.

[0111] Please refer to Figure 7 and Figure 8 , further, in some embodiments, a first diffusion layer 80 is formed at least in part of the surface of the boss 123, and the first extension portion 31 and the second extension portion 61 are electrically connected through the first diffusion layer 81.

[0112] In this way, the first diffusion layer 80 can enable the first doping layer 30 and the second doping layer 60 to form an electrical connection at least in part of the region of the boss 123, thereby reducing the hot spot risk of the back contact solar energy and improving the anti-hot spot performance.

[0113] Specifically, in such an embodiment, the first diffusion layer 80 can be formed by diffusion on the silicon substrate 10. The doping type of the first diffusion layer 80 can be the same as that of the first doping layer 30 or the second doping layer 60. It can be a phosphorus first diffusion layer or a boron first diffusion layer. Specifically, no limitation is made here. The existence of the first diffusion layer 80 can enable the first doping layer 30 and the second doping layer 60 to be conducted through the first diffusion layer 80, thereby improving the anti-hot spot performance.

[0114] In such an embodiment, the first diffusion layer 80 can be in contact with the first dielectric layer 20 and the second dielectric layer 50 to achieve the electrical connection between the first extension portion 31 and the second extension portion 61, or the first diffusion layer 80 can be directly in contact with the first extension portion 31 and the second extension portion 61 to achieve the electrical connection.

[0115] Further, please refer to Figure 7 and Figure 8 , in such an embodiment, the first groove 121 and the second groove 122 are arranged alternately in sequence along the first direction and extend along the second direction. The second direction intersects the first direction. The first diffusion layer 80 extends along the second direction. In the second direction, the first diffusion layer 80 has a plurality of diffusion regions 81 with different doping concentrations.

[0116] Thus, by controlling the doping concentration of the first diffusion layer 80 in different diffusion regions 81, the reverse breakdown voltage at the diffusion region 81 with a higher doping concentration is lower, which can improve the ability of the back-contact solar cell 100 to resist thermal runaway risk; at the diffusion region 81 with a lower doping concentration, it will not cause a significant decrease in the reverse breakdown voltage, so that the diffusion region 81 corresponding to the low doping concentration will not cause a large leakage current, and only the diffusion region 81 with a higher doping concentration is used to achieve the function of improving the thermal runaway resistance. That is to say, this can improve the thermal runaway resistance while avoiding a significant decrease in efficiency due to excessive leakage current in the back-contact solar cell 100.

[0117] Specifically, in such an embodiment, the first extension portion 31 and the second extension portion 61 can be electrically connected through the diffusion region 81 with a higher doping concentration to improve the thermal runaway resistance performance, while the diffusion region 81 with a lower doping concentration will not cause a large leakage current and avoid a significant decrease in efficiency.

[0118] Please refer to Figures 9 - 11 , in some embodiments, the first groove 121 and the second groove 122 are alternately arranged in sequence along the first direction and extend along the second direction, the boss 123 also extends along the second direction, the second direction intersects with the first direction, and the first diffusion layer 80 extends along the second direction.

[0119] Among them, the boss 123 is a discontinuous structure in the second direction, and the boss 123 may include a plurality of boss segments 1232 arranged at intervals in the second direction, and there is a discontinuous region 1233 between two adjacent boss segments 1232;

[0120] Among them, on the boss segment 1233, the first extension portion 31 and the second extension portion 61 are insulated from each other, and at the discontinuous region 1233, the first doping layer 30 and the second doping layer 60 are electrically connected.

[0121] In the present application, the fact that the boss 123 is a discontinuous structure in the second direction means that the boss 123 has several discontinuous regions 1233 in the second direction, so that the boss 123 is divided into a plurality of boss segments 1232. At the interval region 1233, there is no boss structure between the first doping layer 30 and the second doping layer 60.

[0122] Thus, by setting the boss 123 as a discontinuous structure and setting the first doping layer 30 and the second doping layer 60 to be electrically connected at the discontinuous region 1233, the thermal runaway risk of the back-contact solar cell can be reduced and the thermal runaway resistance performance can be improved.

[0123] Specifically, in such an embodiment, the first doped layer 30 and the second doped layer 60 may be electrically connected at the discontinuous region 1233 either by directly contacting each other at the discontinuous region 1233 or by other conductive layers to achieve electrical conduction therebetween, and no specific limitation is made herein.

[0124] Further, please continue to refer to Figures 9 - 11 , in such an embodiment, a second diffusion layer 90 is formed at the discontinuous region 1233, and the first doped layer 30 and the second doped layer 60 are electrically connected through the second diffusion layer 90. The second diffusion layer 90 can be obtained by performing phosphorus diffusion or boron diffusion on the silicon substrate 10 at the discontinuous region 1233.

[0125] In this way, the second diffusion layer 90 can enable the first doped layer 30 and the second doped layer 60 to form an electrical connection at the discontinuous region 1233, thereby reducing the hot spot risk of the back-contact solar cell and improving the anti-hot spot performance.

[0126] In the description of this specification, the descriptions with reference to terms such as "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" etc. mean 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 this specification, the schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0127] In addition, the above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements 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 in that: include: A silicon substrate, wherein the silicon substrate has a front side and a back side opposite to each other, a plurality of first grooves and a plurality of second grooves arranged alternately in sequence are formed on the back side, and a boss is formed between adjacent first grooves and second grooves on the silicon substrate; A first dielectric layer stacked in the first groove; a first doping layer disposed at the first groove and stacked on the first dielectric layer, the first doping layer having a first extending portion extending to an edge of the boss, and a first insulating layer between the first extending portion and the boss; A second dielectric layer stacked in the second groove; and A second doping layer is disposed at the second groove and stacked on the second dielectric layer, wherein the second doping layer has a second extending portion extending to an edge of the boss, and a second insulating layer is disposed between the second extending portion and the boss.

2. The back contact solar cell according to claim 1, characterized in that: The surface of the boss is a non-suede structure; and / or The surfaces of the first groove and the second groove are both non-suede structures.

3. The back contact solar cell according to claim 1, characterized in that: The surface roughness of the second groove is greater than the surface roughness of the first groove.

4. The back contact solar cell according to claim 3, characterized in that: The surface of the boss includes a first region blocked by the first doping layer and the second doping layer and a second region not blocked by the first doping layer and the second doping layer, and the surface roughness of the second region is greater than the surface roughness of the second groove.

5. The back contact solar cell according to claim 4, characterized in that: The surface roughness of the second region is greater than the surface roughness of the first region.

6. The back contact solar cell according to claim 1, characterized in that: A sunken groove is formed on a region of the boss that is not covered by the first doping layer and the second doping layer.

7. The back contact solar cell according to claim 1, characterized in that: In the second groove, a separation groove is formed on the bottom of the second groove, and the second dielectric layer and the second doping layer are not provided at the separation groove.

8. The back contact solar cell according to claim 1, characterized in that: The depth of the first groove is 100 nm-10 μm; and / or The second groove has a depth of 100 nm-10 μm.

9. The back contact solar cell according to claim 1, characterized in that: The depth of the second groove is greater than the depth of the first groove.

10. The back contact solar cell according to claim 9, characterized in that: The difference between the depth of the second groove and the depth of the first groove is 50 nm-10 μm.

11. The back contact solar cell according to claim 1, characterized in that: The first doped layer is a phosphorus doped layer, and the second doped layer is a boron doped layer; In the boss, a phosphorus doping concentration in a region close to the first groove is greater than a phosphorus doping concentration in a region close to the second groove; and / or In the mesa, a boron doping concentration in a region close to the second groove is greater than a boron doping concentration in a region close to the first groove.

12. The back contact solar cell according to claim 11, characterized in that: Along the direction from the first groove to the second groove, the phosphorus doping concentration in the boss gradually decreases; Along the direction from the second groove to the first groove, the boron doping concentration in the boss gradually decreases.

13. The back contact solar cell according to claim 1, characterized in that: The first grooves and the second grooves are alternately arranged in sequence along the first direction and extend along the second direction, the bosses also extend along the second direction, the second direction intersects the first direction, and the bosses are continuous structures in the second direction; wherein, on the boss, the first extension portion and the second extension portion do not contact each other at all positions; or In a partial area of ​​the boss, the first extension portion is insulated and isolated from the second extension portion, and in another partial area of ​​the boss, the first extension portion is conductively connected to the second extension portion.

14. The back contact solar cell according to claim 13, characterized in that: When the first extension portion and the second extension portion are not in contact with each other at all positions, in the arrangement direction of the first groove and the second groove, the length of the first extension portion is 5 μm-60 μm, and the length of the second extension portion is 5 μm-60 μm.

15. The back contact solar cell according to claim 1, characterized in that: A first diffusion layer is formed at least partially on a surface of the boss, and the first extension portion and the second extension portion are conductively connected via the first diffusion layer.

16. The back contact solar cell according to claim 15, characterized in that: The first grooves and the second grooves are alternately arranged in sequence along a first direction and extend along a second direction, the second direction intersects the first direction, the first diffusion layer extends along the second direction, and in the second direction, the first diffusion layer has a plurality of diffusion regions with different doping concentrations.

17. The back contact solar cell according to claim 1, characterized in that: The first grooves and the second grooves are alternately arranged in sequence along the first direction and extend along the second direction, the bosses also extend along the second direction, and the second direction intersects the first direction; The boss is a discontinuous structure in the second direction, and the boss includes a plurality of boss segments arranged at intervals along the second direction, and a discontinuity zone is provided between two adjacent boss segments; Wherein, on the boss segment, the first extension portion is insulated and isolated from the second extension portion, and at the discontinuity region, the first doped layer and the second doped layer are conductively connected.

18. The back contact solar cell according to claim 17, characterized in that: A second diffusion layer is formed at the discontinuous region, and the first doping layer and the second doping layer are conductively connected via the second diffusion layer.

19. The back contact solar cell according to any one of claims 1 to 18, characterized in that: In the arrangement direction of the first groove and the second groove, the width of the boss is 10 μm-700 μm.

20. A battery assembly, characterized in that: A back-contact solar cell comprising the steps of any one of claims 1 to 19.

21. A photovoltaic system, characterized in that: A battery assembly comprising the battery assembly of claim 20.

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