Back-contact solar cell, cell module and photovoltaic system

Abstract

The present disclosure is applicable to the technical field of solar cells. Provided are a back-contact solar cell, a cell module and a photovoltaic system. In the back-contact solar cell, a boss is provided between a first groove and a second groove. A first doped layer is arranged at the first groove and has a first extension extending to an edge of the boss, and a second doped layer is arranged at the second groove and has a second extension extending to the edge of the boss. An insulating layer is provided between the boss and each of the first extension and the second extension. In this way, in the back-contact solar cell, the first doped layer and the second doped layer are isolated by means of the boss such that an isolation effect between the first doped layer and the second doped layer can be improved. Moreover, by means of the arrangement of the first extension, the second extension, a first insulating layer and a second insulating layer, the passivation effect at edge positions of the two grooves can be improved, thereby improving the performance of the back-contact solar cell.

Description

Back contact solar cell, cell assembly and photovoltaic system

[0001] Priority information

[0002] The present disclosure claims priority to and the benefit of the patent application No. 202411095320.X filed with the China National Intellectual Property Office on August 09, 2024, and incorporates it herein by reference in its entirety. TECHNICAL FIELD

[0003] The present disclosure relates to the technical field of solar cell, in particular to a back contact solar cell, a cell assembly and a photovoltaic system. BACKGROUND

[0004] The back contact solar cell is a high-efficiency cell in which electrodes are arranged on the back surface of the cell. Specifically, in the back contact solar cell, P-type electrodes and N-type electrodes are arranged on the back surface, so that the front surface is not shielded by metal grid lines, thereby improving the efficiency of the cell.

[0005] 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 surface of the silicon substrate, and isolation of the P-type doped layer and the N-type doped layer is achieved by opening a groove therebetween. However, the isolation effect is poor using such a way, and the passivation effect is also poor, and 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. SUMMARY

[0006] The present disclosure provides a back contact solar cell, a cell assembly and a photovoltaic system.

[0007] The present disclosure is implemented in this way. The back contact solar cell of the present disclosure embodiment comprises:

[0008] a silicon substrate having opposite front and back surfaces, the back surface having a plurality of first grooves and a plurality of second grooves arranged alternately and spaced apart in sequence, the silicon substrate having a boss between adjacent first grooves and second grooves;

[0009] a first dielectric layer located in the first groove and arranged on the surface of the first groove;

[0010] a first doped layer arranged in the first groove and stacked on the first dielectric layer, the first doped layer having a first extension part extending to the edge of the boss, the first extension part and the boss having a first insulating layer therebetween;

[0011] a second dielectric layer located in the second groove and arranged on the surface of the second groove;

[0012] A second doped layer is disposed in the second groove and stacked on the second dielectric layer, the second doped layer has a second extension part extending to the edge of the protrusion, and the second extension part and the protrusion have a second insulating layer therebetween.

[0013] Optionally, the back contact solar cell satisfies at least one of the following:

[0014] The surface of the protrusion is a non-textured structure.

[0015] The surface of the protrusion is a non-textured structure.

[0016] Optionally, the surface roughness of the second groove is greater than the surface roughness of the first groove.

[0017] Optionally, the surface of the protrusion includes a first region blocked by the first doped layer and the second doped layer and a second region not blocked by the first doped layer and the second doped layer, and the surface roughness of the second region is greater than the surface roughness of the second groove.

[0018] Optionally, the surface roughness of the second region is greater than the surface roughness of the first region.

[0019] Optionally, the protrusion has a recessed groove on a region not covered by the first doped layer and the second doped layer.

[0020] Optionally, in the second groove, the bottom of the second groove has a separation groove, and the separation groove is offset from the second dielectric layer and the second doped layer.

[0021] Optionally, the back contact solar cell satisfies at least one of the following:

[0022] The depth of the first groove is 100 nm-10 μm.

[0023] The depth of the second groove is 100 nm-10 μm.

[0024] Optionally, the depth of the second groove is greater than the depth of the first groove.

[0025] Optionally, the difference between the depth of the second groove and the depth of the first groove is 50 nm-10 μm.

[0026] Optionally, the first doped layer is a phosphorus-doped layer, and the second doped layer is a boron-doped layer; and the back contact solar cell satisfies at least one of the following:

[0027] In the protrusion, the phosphorus doping concentration in a region close to the first groove is greater than the phosphorus doping concentration in a region close to the second groove.

[0028] In the protrusion, 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.

[0029] Optionally, the phosphorus doping concentration in the protrusion gradually decreases in the direction from the first groove to the second groove.

[0030] The boron doping concentration in the protrusion gradually decreases in the direction from the second groove to the first groove.

[0031] Optionally, the first groove and the second groove are arranged alternately and sequentially in a first direction and extend in a second direction, the protrusion extends in the second direction, the second direction intersects the first direction, and the protrusion is a continuous structure in the second direction.

[0032] In the protrusion, the first extension and the second extension are not in contact with each other at all positions.

[0033] In some regions of the protrusion, the first extension and the second extension are insulated and separated, and in other regions of the protrusion, the first extension and the second extension are conductively connected.

[0034] Optionally, when the first extension and the second extension are not in contact with each other at all positions, the length of the first extension is 5-60 μm and the length of the second extension is 5-60 μm in the arrangement direction of the first groove and the second groove.

[0035] Optionally, at least some regions of the surface of the protrusion have a first diffusion layer, and the first extension and the second extension are conductively connected through the first diffusion layer.

[0036] Optionally, the first groove and the second groove are arranged alternately and sequentially in a first direction and extend in a second direction, the second direction intersects the first direction, and the first diffusion layer extends in the second direction. In the second direction, the first diffusion layer has a plurality of diffusion regions with different doping concentrations.

[0037] Optionally, the first groove and the second groove are arranged alternately and sequentially in a first direction and extend in a second direction, the protrusion extends in the second direction, and the second direction intersects the first direction.

[0038] The protrusion is an intermittent structure in the second direction, and the protrusion includes a plurality of protrusion segments arranged alternately in the second direction, and an intermittent region between adjacent two protrusion segments.

[0039] wherein, on the boss segment, the first extension part and the second extension part are insulated and isolated, and at the discontinuous region, the first doped layer and the second doped layer are conductively connected.

[0040] Optionally, at the discontinuous region, there is a second diffusion layer, and the first doped layer and the second doped layer are conductively connected through the second diffusion layer.

[0041] Optionally, in the arrangement direction of the first groove and the second groove, the width of the boss is 10-700 μm.

[0042] The present disclosure also provides a battery assembly comprising a plurality of the back contact solar cell as described in any one of the above.

[0043] The present disclosure also provides a photovoltaic system comprising the battery assembly as described above.

[0044] In the back contact solar cell, the battery assembly and the photovoltaic system of the embodiments of the present disclosure, there is a boss between the first groove and the second groove, the first doped layer is arranged at the first groove and has a first extension part extending to the edge of the boss, the second doped layer is arranged at the second groove and has a second extension part extending to the edge of the boss, and the first extension part and the second extension part each have an insulating layer between the first extension part and the second extension part and the boss. In this way, in the back contact solar cell, the first doped layer and the second doped layer are isolated by the boss, which can improve the isolation effect between the first doped layer and the second doped layer. Meanwhile, through the arrangement of the first extension part, the second extension part and 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.

[0045] Additional aspects and advantages of the present disclosure will be made apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0046] Fig. 1 is a schematic diagram of a module of a photovoltaic system according to an embodiment of the present disclosure;

[0047] Fig. 2 is a schematic diagram of a planar structure of a back contact solar cell according to an embodiment of the present disclosure;

[0048] Fig. 3 is a schematic diagram of a cross-sectional structure of the back contact solar cell along line III-III in Fig. 2;

[0049] Fig. 4 is a schematic diagram of another cross-sectional structure of a back contact solar cell according to an embodiment of the present disclosure;

[0050] Fig. 5 is another schematic diagram of a planar structure of a back contact solar cell according to an embodiment of the present disclosure;

[0051] Fig. 6 is a schematic diagram of a cross-sectional structure of the back contact solar cell along line VI-VI in Fig. 5;

[0052] Fig. 7 is another schematic diagram of a planar structure of a back contact solar cell according to an embodiment of the present disclosure;

[0053] Fig. 8 is a schematic diagram of a cross-sectional structure of the back contact solar cell along line VIII-VIII in Fig. 7;

[0054] Fig. 9 is still another schematic diagram of a planar structure of a back contact solar cell according to an embodiment of the present disclosure;

[0055] Fig. 10 is a schematic diagram of a cross-sectional structure of the back contact solar cell along line X-X in Fig. 9;

[0056] Fig. 11 is a schematic diagram of a cross-sectional structure of the back contact solar cell along line XI-XI in Fig. 9. DETAILED DESCRIPTION

[0057] In order to make the objectives, technical solutions and advantages of the present disclosure clearer, the present disclosure will be further described in detail below with reference to the accompanying drawings and embodiments. The examples of the embodiments are shown in the drawings, in which the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. It should be noted that the embodiments described below with reference to the drawings are exemplary and are only used to explain the present disclosure, and should not be understood as limiting the present disclosure. In addition, it should be understood that the specific embodiments described herein are only used to explain the present disclosure and should not be used to limit the present disclosure.

[0058] In the description of the present disclosure, it should be understood that the terms "upper", "lower", "left", "right", "top", "bottom", "side", "lateral", "longitudinal" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present disclosure and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present disclosure.

[0059] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present disclosure, the meaning of "several" is two or more, unless otherwise explicitly and specifically limited.

[0060] In the present disclosure, unless specifically defined and limited otherwise, a first feature "on" or "under" a second feature can include that the first and second features are directly in contact, or that the first and second features are not directly in contact but are in contact through another feature between them. Moreover, the first feature "over", "above" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or only means that the first feature is higher in horizontal height than the second feature. The first feature "under", "below" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or only means that the first feature is lower in horizontal height than the second feature.

[0061] The following disclosure provides many different embodiments, or examples, for implementing different structures of the present disclosure. For the purpose of simplifying the present disclosure, the components and arrangements of the specific examples described below are intended to be examples only. Of course, they are not meant to limit the present disclosure in any way. Furthermore, the present disclosure can repeat reference numerals and / or letters in different examples and / or drawings to indicate similar and / or identical elements. Also, the present disclosure provides various examples of the processes and materials, but one of ordinary skill in the art will recognize that other processes and / or materials can be used.

[0062] Referring to FIG. 1, a photovoltaic system 1000 in an embodiment of the present disclosure can include a cell assembly 200 in an embodiment of the present disclosure, the cell assembly 200 in an embodiment of the present disclosure can include a plurality of back contact solar cells 100 in an embodiment of the present disclosure, the plurality of back contact solar cells 100 can be connected together by a solder ribbon to form a plurality of cell strings, and each cell string can form the cell assembly 200 by series connection, parallel connection or series-parallel connection.

[0063] In combination with FIG. 2 and FIG. 3, the back contact solar cell 100 in an embodiment of the present disclosure can include a silicon substrate 10, a first dielectric layer 20, a first doped layer 30, a first insulating layer 40, a second dielectric layer 50, a second doped layer 60 and a second insulating layer 70.

[0064] As shown in FIG. 3, the silicon substrate 10 has opposite front surface 11 and back surface 12, the back surface 12 has a plurality of first grooves 121 and a plurality of second grooves 122, the plurality of first grooves 121 and the plurality of second grooves 122 are alternately and spacedly arranged, and the silicon substrate 10 has a plurality of bosses 123 between adjacent first grooves 121 and second grooves 122, that is, the first grooves 121 and the second grooves 122 are bosses 123, and the bosses 123 are regions between two grooves.

[0065] Specifically, as shown in FIG. 2 and FIG. 3, the first grooves 121 and the second grooves 122 are alternately arranged along a first direction and both extend along a second direction, which is perpendicular to the first direction. For example, as shown in FIG. 2, in some embodiments, the first direction can be a lateral direction of the back contact solar cell 100, and the second direction can be a longitudinal direction of the back contact solar cell 100, which are perpendicular to each other.

[0066] It can be understood that, in some embodiments, the first direction and the second direction can also be other directions, for example, the two directions can be two diagonal directions of the back contact solar cell 100, which are not limited herein.

[0067] As shown in FIG. 3, the first dielectric layer 20 can be arranged in the first grooves 121, specifically, the first dielectric layer 20 can cover the bottom and side surfaces of the first grooves 121, the first doped layer 30 is arranged in the first grooves 121 and is stacked on the first dielectric layer 20, the first doped layer 30 has a first extension part 31 extending to the edge of the mesa 123, and the first extension part 31 is insulated from the mesa 123 by the first insulating layer 40.

[0068] That is, the first doped layer 30, in addition to the part arranged in the first grooves 121, also extends along the side surface of the first grooves 121 to the edge position of the mesa 123, thereby forming the first extension part 31, and the first extension part 31 is insulated from the silicon substrate 10 by the first insulating layer 40.

[0069] The second dielectric layer 50 can be arranged in the second grooves 122, specifically, the second dielectric layer 50 can cover the bottom and side surfaces of the second grooves 122, the second doped layer 60 is arranged in the second grooves 122 and is stacked on the second dielectric layer 50, the second doped layer 60 has a second extension part 61 extending to the edge of the mesa 123, and the second extension part 61 is insulated from the mesa 123 by the second insulating layer 70.

[0070] That is, the second doped layer 60, in addition to the part arranged in the second grooves 122, also extends along the side surface of the second grooves 122 to the edge position of the mesa 123, thereby forming the second extension part 61, and the second extension part 61 is insulated from the silicon substrate 10 by the second insulating layer 70.

[0071] In the present disclosure, the surface of the mesa 123 refers to the surface of the silicon substrate 10 between the first grooves 121 and the second grooves 122, and the edge of the mesa 123 refers to the two side edges of the surface of the mesa 123 facing away from the front surface 11, that is, the edge area of the mesa 123 close to the first grooves 121 and the edge area of the mesa 123 close to the second grooves 122.

[0072] In the back contact solar cell 100, the cell assembly 200 and the photovoltaic system 1000 in the embodiments of the present disclosure, the boss 123 is between the first groove 121 and the second groove 122, the first doped layer 30 is arranged at the first groove 121 and has the first extension 31 extending to the edge of the boss 123, the second doped layer 60 is arranged at the second groove 122 and has the second extension 61 extending to the edge of the boss 123, and the first extension 31 and the second extension 61 are both provided with the insulating layer between the boss 123. In this way, in the back contact solar cell 100, the first doped layer 30 and the second doped layer 60 are isolated by the boss 123, which can improve the isolation effect between the first doped layer 30 and the second doped layer 60. Meanwhile, by arranging the first extension 31, the second extension 61 and the first insulating layer 40 and the second insulating layer 70, the passivation effect of the edges of the two grooves (i.e. the edges of the boss 123) can be improved, thereby improving the performance of the back contact solar cell 100.

[0073] In addition, in the present disclosure, the two doped layers are isolated without using a groove, which can improve the strength of the silicon substrate 10 and reduce the probability of hidden cracks. Moreover, the insulating layer is arranged at the edge position of the boss 123, which can improve the reflectivity of light from the area of the front surface 11, thereby improving the utilization rate of light and further improving the performance of the back contact solar cell 100.

[0074] Specifically, in the embodiments of the present disclosure, the silicon substrate 10 can be a P-type silicon substrate or an N-type silicon substrate, which is not limited herein. One of the first doped layer 30 and the second doped layer 60 is a P-type doped layer, and the other can be an N-type doped layer. For example, in some embodiments, the first doped layer 30 can be a P-type doped polysilicon layer, a P-type doped microcrystalline silicon layer or the like, and the second doped layer 60 can be an N-type doped polysilicon layer, an N-type doped microcrystalline silicon layer or the like, which is not limited herein.

[0075] The first dielectric layer 20 and the second dielectric layer 50 can both be tunneling oxide layers, for example, both can be tunneling silicon oxide film layers. The first insulating layer 40 and the second insulating layer 70 can be silicon oxide layers, silicon nitride layers or the like with insulating function, which are not limited herein. Preferably, the first insulating layer 40 and the second insulating layer 70 are made of the same material, as long as they can realize the insulation between the first extension 31 and the second extension 61 and the silicon substrate 10.

[0076] In addition, it can also be understood that in the back contact solar cell 100, the back surface 12 can also be entirely covered by a passivation film layer (not shown in the figure), which 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 corresponding position of the first doped layer 30 (that is, at the first groove 121), which penetrates the passivation film layer and is in contact with the first doped layer 30. A second metal electrode (not shown in the figure) is provided at the corresponding position of the second doped layer 60 (that is, at the second groove 122), which penetrates the passivation film layer and is in contact with the second doped layer 60.

[0077] Referring to FIGS. 2 and 3, in the embodiments of the present disclosure, the width of the single protrusion 123 in the arrangement direction of the first groove 121 and the second groove 122 (that is, the first direction) is 10 μm-700 μm.

[0078] In this way, the width of the protrusion 123 in the first direction is set in this reasonable range, which can ensure the isolation effect of the first doped layer 30 and the second doped layer 60 while ensuring the efficiency of the back contact solar cell 100.

[0079] Specifically, in such embodiments, the width of the protrusion 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 and 700 μm.

[0080] In some embodiments, the surface of the protrusion 123 (the surface of the region between the first groove 121 and the second groove 122 of the silicon substrate 10) is a non-textured structure, that is, the lower surface of the protrusion 123 shown in the figure is a polished surface.

[0081] In this way, the surface reflectivity at the protrusion 123 is higher, which can enhance the reflection of the light rays that are incident from the front surface 11 and pass through the silicon substrate 10, so as to reflect more light rays 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 protrusion 123 as a non-textured structure can also improve the passivation effect when the passivation film layer is covered subsequently.

[0082] In some embodiments, the surfaces of the first groove 121 and the second groove 122 (the bottom surface and the side surface 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 polished surfaces.

[0083] In this way, the reflection of the light rays that enter the front surface 11 and pass through the silicon substrate 10 can be further enhanced, more light rays can be reflected back into the silicon substrate 10, and thus the efficiency of the back contact solar cell 100 can be improved.

[0084] Meanwhile, in the manufacturing process, after the first groove 121 and the second groove 122 are formed, the first groove 121 and the second groove 122 can be polished to remove the damage (e.g., laser damage caused by laser grooving) caused when the first groove 121 and the second groove 122 are formed.

[0085] In some embodiments, the surface roughness of the second groove 122 is greater than the surface roughness of the first groove 121.

[0086] In this way, by optimizing the matching of the surface roughness of the different grooves, the bifaciality of the back contact solar cell 100 can be improved.

[0087] Optionally, in some embodiments, the surface of the boss 123 can include a first region (i.e., the two side edge regions of the boss 123) that is shielded by the first doped layer 30 and the second doped layer 60 and a second region (i.e., the middle region of the boss 123) that is not shielded by the first doped layer 30 and the second doped layer 60, and the surface roughness of the second region is greater than the surface roughness of the second groove 122.

[0088] In this way, by optimizing the matching of the surface roughness of the boss 123 and the surface roughness of the grooves, the bifaciality of the back contact solar cell 100 can be further improved.

[0089] In some embodiments, the surface roughness of the second region can be greater than the surface roughness of the first region, i.e., in the boss 123, the surface roughness of the middle portion is greater than the surface roughness of the edge portion.

[0090] Referring to FIGS. 3 and 4, in some embodiments, the boss 123 has a recessed groove 1231 on the region that is not covered by the first doped layer 30 and the second doped layer 60, i.e., the second region described above has the recessed groove 1231.

[0091] In addition, referring to FIG. 4, in some embodiments, in the second groove 122, the bottom of the second groove 122 has a separation groove 1221, and the separation groove 1221 can not have the second dielectric layer 50 and the second doped layer 60, i.e., the separation groove 1221 is offset from the second dielectric layer 50 and the second doped layer 60.

[0092] In some embodiments, the depth of the first groove 121 (i.e., the depth of the recess in the silicon substrate 10) can be 100 nm-10 μm.

[0093] Thus, by setting the depth of the first recess 121 within this reasonable range, it can be avoided that the depth of the first recess 121 is too deep to cause the strength of the silicon substrate 10 to decrease, and it can also be avoided that the depth of the first recess 121 is too shallow to cause the height of the protrusion 123 to be too small to affect the isolation effect.

[0094] Specifically, in such embodiments, the depth of the first recess 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 and 10 μm.

[0095] In some embodiments, the depth of the second recess 122 (i.e. the depth of the second recess 122 inside the silicon substrate 10) can be 100 nm-10 μm.

[0096] Thus, by setting the depth of the second recess 122 within this reasonable range, it can be avoided that the depth of the second recess 122 is too deep to cause the strength of the silicon substrate 10 to decrease, and it can also be avoided that the depth of the second recess 122 is too shallow to cause the height of the protrusion 123 to be too small to affect the isolation effect.

[0097] Specifically, in such embodiments, the depth of the second recess 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 and 10 μm.

[0098] It should be noted that, in the present disclosure, the depth of a recess refers to the distance between any position on the bottom surface of the recess and the back surface 12.

[0099] In some embodiments, the depth of the second recess 122 is greater than the depth of the first recess 121. Thus, by matching the depths of the two recesses differently, the efficiency of the back contact solar cell 100 can be ensured.

[0100] Specifically, in such embodiments, 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 and 10 μm.

[0101] In some embodiments, the first doped layer 30 can be a phosphorus-doped layer, and the second doped layer 60 can be a boron-doped layer. In the mesa 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; or, in the mesa 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; or, in the mesa 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 in the mesa 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.

[0102] In this way, by designing the phosphorus doping concentration and the boron doping concentration in different regions of the mesa 123 differently, the passivation effect of the surface layer of the mesa 123 can be better, surface recombination and edge recombination can be reduced, and the efficiency can be improved.

[0103] Optionally, in such embodiments, the phosphorus doping concentration in the mesa 123 gradually decreases in the direction from the first groove 121 to the second groove 122. The boron doping concentration in the mesa 123 gradually decreases in the direction from the second groove 122 to the first groove 121.

[0104] In this way, by designing the phosphorus doping concentration and the boron doping concentration in different regions of the mesa 123 specifically, the passivation effect of the surface layer of the mesa 123 can be improved, and surface recombination and edge recombination can be reduced.

[0105] Referring to FIGS. 2 and 3, in some embodiments, the first groove 121 and the second groove 122 are arranged alternately and spaced apart in the first direction and extend in the second direction, and the mesa 123 also extends in the second direction. The second direction is transverse to the first direction, and the mesa 123 is a continuous structure in the second direction.

[0106] In the mesa 123, the first extension 31 and the second extension 61 are not in contact with each other at all positions. In this way, the anti-creepage performance of the back contact solar cell 100 can be improved.

[0107] Specifically, in such embodiments, the first extension 31 and the second extension 61 not being in contact with each other means that they are insulated from each other on the protrusion 123, rather than being in direct contact to form an electrically conductive connection.

[0108] It is noted that, in the present disclosure, the protrusion 123 being a continuous structure in the second direction means that the protrusion 123 is a continuous and uninterrupted structure in the second direction.

[0109] Optionally, in such embodiments, in the case that the first extension 31 and the second extension 61 are insulated from each other at all locations, the length of the first extension 31 is 5-60 μm and the length of the second extension 61 is 5-60 μm in the arrangement direction of the first groove 121 and the second groove 122 (i.e. the first direction).

[0110] In this way, by setting the length of the first extension 31 and the second extension 61 within the above reasonable range, the passivation effect of the surface of the protrusion 123 can be improved to reduce surface recombination and edge recombination, while avoiding the length of the first extension 31 and the second extension 61 being too long to cause a significant decrease in the double-sided rate.

[0111] Specifically, in such embodiments, the length of the first extension 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 and 10 μm. The length of the second extension 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 and 60 μm.

[0112] Referring to FIGS. 5 and 6, in some embodiments, the first extension 31 and the second extension 61 are insulated from each other on a part of the protrusion 123, and the first extension 31 and the second extension 61 are in electrically conductive connection (i.e. the first extension 31 and the second extension 61 form a composite contact) on another part of the protrusion 123.

[0113] In this way, by forming a composite contact between the first extension 31 and the second extension 61 on a part of the protrusion 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 of the back contact solar cell 100.

[0114] Specifically, in such embodiments, the composite contact between the first extension 31 and the second extension 61 refers to that the two are directly in contact to realize the conductive connection therebetween, or a dielectric layer with a tunneling function is arranged between the first extension 31 and the second extension 61 to realize the conductive connection between the first extension 31 and the second extension 61 through the dielectric layer, which is not limited herein.

[0115] Referring to FIG. 7 and FIG. 8, in some embodiments, the first diffusion layer 80 is formed at at least a partial region of the surface of the bump 123, and the first extension 31 and the second extension 61 are conductively connected through the first diffusion layer 80.

[0116] In this way, the first diffusion layer 80 can enable the first doped layer 30 and the second doped layer 60 to form a conductive connection at at least a partial region of the bump 123, thereby reducing the hot spot risk of the back contact solar cell and improving the hot spot resistance.

[0117] Specifically, in such embodiments, the first diffusion layer 80 can be formed by diffusion on the silicon substrate 10, and the doping type of the first diffusion layer 80 can be the same as that of the first doped layer 30 or the second doped layer 60, which can be a phosphorus first diffusion layer or a boron first diffusion layer, which is not limited herein. The presence of the first diffusion layer 80 can enable the first doped layer 30 and the second doped layer 60 to realize conduction through the first diffusion layer 80, thereby improving the hot spot resistance.

[0118] In such embodiments, the first diffusion layer 80 can be in contact with the first dielectric layer 20 and the second dielectric layer 50 to realize the conductive connection between the first extension 31 and the second extension 61, or the first diffusion layer 80 can be directly in contact with the first extension 31 and the second extension 61 to realize the conductive connection.

[0119] Optionally, referring to FIG. 7 and FIG. 8, in such embodiments, the first recess 121 and the second recess 122 are arranged alternately 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, and in the second direction, the first diffusion layer 80 has a plurality of diffusion regions 81 with different doping concentrations.

[0120] Therefore, 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, and the risk resistance of the back contact solar cell 100 to hot spots can be improved. The diffusion region 81 with a lower doping concentration does not cause a large decrease in the reverse breakdown voltage, so that the diffusion region 81 corresponding to the low doping concentration does not cause a large leakage current, and the function of improving the risk resistance to hot spots is realized only by the diffusion region 81 with a higher doping concentration. That is to say, the risk resistance to hot spots can be improved while avoiding a large decrease in the efficiency caused by a large leakage current of the back contact solar cell 100.

[0121] Specifically, in such an embodiment, the first extension part 31 and the second extension part 61 can be conductively connected between each other by the diffusion region 81 with a higher doping concentration to improve the anti-hot spot performance, and the diffusion region 81 with a lower doping concentration does not cause a large leakage current, avoiding a large decrease in the efficiency.

[0122] 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 the first direction, and the first diffusion layer 80 extends along the second direction.

[0123] As shown in FIGS. 9-11, the boss 123 is a discontinuous structure in the second direction, and the boss 123 can include a plurality of boss segments 1232 arranged at intervals along the second direction, and the adjacent two boss segments 1232 have an interruption region 1233 therebetween.

[0124] In the boss segment 1232, the first extension part 31 and the second extension part 61 are insulated and separated, and in the interruption region 1233, the first doped layer 30 and the second doped layer 60 are conductively connected.

[0125] In the present disclosure, the boss 123 being a discontinuous structure in the second direction means that the boss 123 has a plurality of interruption regions 1233 in the second direction, thereby dividing the boss 123 into a plurality of boss segments 1232, and in the interruption region 1233, the first doped layer 30 and the second doped layer 60 do not have a boss structure therebetween.

[0126] Therefore, by setting the boss 123 as a discontinuous structure and conductively connecting the first doped layer 30 and the second doped layer 60 in the interruption region 1233, the risk of hot spots of the back contact solar cell can be reduced, and the anti-hot spot performance can be improved.

[0127] Specifically, in such an embodiment, the electrically conductive connection between the first doped layer 30 and the second doped layer 60 at the discontinuity 1233 can be either a direct contact between the two at the discontinuity 1233, or an electrically conductive connection between the two through another electrically conductive layer, without limitation.

[0128] Optionally, referring to FIGS. 9-11, in such an embodiment, there is a second diffusion layer 90 at the discontinuity 1233, and the first doped layer 30 and the second doped layer 60 are electrically conductively connected through the second diffusion layer 90. The second diffusion layer 90 can be obtained by phosphorus diffusion or boron diffusion on the silicon substrate 10 at the discontinuity 1233.

[0129] In this way, the second diffusion layer 90 can cause the first doped layer 30 and the second doped layer 60 to form an electrically conductive connection at the discontinuity 1233, thereby reducing the hot spot risk of the back contact solar cell and improving the hot spot resistance.

[0130] In the description of the present specification, the description of 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 disclosure. 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.

[0131] In addition, the above only describes the preferred embodiments of the present disclosure and does not limit the present disclosure. Any modification, equivalent replacement and improvement made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A back contact solar cell, wherein, The back contact solar cell comprises: a silicon substrate having opposite front and back surfaces, the back surface having a plurality of first grooves and a plurality of second grooves arranged alternately and spaced apart in sequence, the silicon substrate having a mesa between adjacent first and second grooves; a first dielectric layer disposed in the first grooves and on the surface of the first grooves; a first doped layer disposed in the first grooves and stacked on the first dielectric layer, the first doped layer having a first extension portion extending to the edge of the mesa, the first extension portion and the mesa being separated by a first insulating layer; a second dielectric layer disposed in the second grooves and on the surface of the second grooves; a second doped layer disposed in the second grooves and stacked on the second dielectric layer, the second doped layer having a second extension portion extending to the edge of the mesa, the second extension portion and the mesa being separated by a second insulating layer.

2. The back contact solar cell of claim 1, wherein, The back contact solar cell satisfies at least one of the following conditions: the surface of the mesa is a non-textured structure; the surface of the first grooves and the surface of the second grooves are non-textured structures.

3. The back contact solar cell of claim 1, wherein, The surface roughness of the second grooves is greater than the surface roughness of the first grooves.

4. The back contact solar cell of claim 3, wherein, The surface of the mesa includes a first region blocked by the first doped layer and the second doped layer and a second region not blocked by the first doped layer and the second doped layer, the surface roughness of the second region being greater than the surface roughness of the second grooves.

5. The back contact solar cell of claim 4, wherein, The surface roughness of the second region is greater than the surface roughness of the first region.

6. The back contact solar cell of claim 1, wherein, The region of the mesa not covered by the first doped layer and the second doped layer has an inwardly recessed groove.

7. The back contact solar cell of claim 1, wherein, In the second grooves, the bottom of the second grooves has a separation groove that is offset from the second dielectric layer and the second doped layer.

8. The back contact solar cell of claim 1, wherein, The back contact solar cell satisfies at least one of the following conditions: the depth of the first grooves is 100 nm-10 μm; the depth of the second grooves is 100 nm-10 μm.

9. The back contact solar cell of claim 1, wherein, The depth of the second grooves is greater than the depth of the first grooves.

10. The back contact solar cell of claim 9, wherein, The difference between the depth of the second grooves and the depth of the first grooves is 50 nm-10 μm.

11. The back contact solar cell of claim 1, wherein, The first doped layer is a phosphorus-doped layer and the second doped layer is a boron-doped layer, and the back contact solar cell satisfies at least one of the following conditions: in the mesa, the phosphorus doping concentration in the region close to the first grooves is greater than the phosphorus doping concentration in the region close to the second grooves; in the mesa, the boron doping concentration in the region close to the second grooves is greater than the boron doping concentration in the region close to the first grooves.

12. The back contact solar cell of claim 11, wherein, The phosphorus doping concentration in the mesa gradually decreases in the direction of the first grooves towards the second grooves; The boron doping concentration in the mesa gradually decreases in the direction of the second grooves towards the first grooves.

13. The back contact solar cell of claim 1, wherein, The first grooves and the second grooves are arranged alternately and spaced apart in a first direction and extend in a second direction, the mesa extends in the second direction, the second direction intersects the first direction, and the mesa is a continuous structure in the second direction; Wherein, on the protrusion, the first extension and the second extension are not in contact with each other at all positions; or, On a part of the protrusion, the first extension and the second extension are insulated from each other, and on another part of the protrusion, the first extension and the second extension are electrically connected.

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

15. The back contact solar cell of claim 1, wherein, At least a part of the protrusion surface has a first diffusion layer, and the first extension and the second extension are electrically connected through the first diffusion layer.

16. The back contact solar cell of claim 15, wherein, The first groove and the second groove are arranged alternately along a first direction and extend along a second direction, the second direction is perpendicular to the first direction, the first diffusion layer extends along the second direction, and the first diffusion layer has a plurality of diffusion regions with different doping concentrations in the second direction.

17. The back contact solar cell of claim 1, wherein, The first groove and the second groove are arranged alternately along a first direction and extend along a second direction, the protrusion extends along the second direction, and the second direction is perpendicular to the first direction. The protrusion is an intermittent structure in the second direction, and the protrusion includes a plurality of protrusion segments arranged alternately along the second direction, and an intermittent region between adjacent two protrusion segments. Wherein, on the protrusion segment, the first extension and the second extension are insulated from each other, and on the intermittent region, the first doping layer and the second doping layer are electrically connected.

18. The back contact solar cell of claim 17, wherein, The first doping layer and the second doping layer are electrically connected through a second diffusion layer at the intermittent region.

19. The back contact solar cell of any of claims 1-18, wherein, The width of the protrusion is 10-700 μm.

20. A battery assembly, wherein, The back contact solar cell of any one of claims 1-19.

21. A photovoltaic system, wherein, The battery assembly of claim 20.

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