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EP-4432369-B1 - A BACK-CONTACT SOLAR CELL, BACK-CONTACT SOLAR CELL ASSEMBLY, AND PHOTOVOLTAIC SYSTEM

EP4432369B1EP 4432369 B1EP4432369 B1EP 4432369B1EP-4432369-B1

Inventors

  • WANG, YONGQIAN
  • LIU, Shengpu
  • CHEN, GANG

Dates

Publication Date
20260513
Application Date
20231128

Claims (18)

  1. A back-contact solar cell (100), including: a silicon wafer (10), wherein the silicon wafer has a light-receiving face (11) and a shady face (12) which are mutually opposed, and the shady face (12) includes a plurality of groove areas (121) and a plurality of non groove areas (122) spaced at intervals, and the non groove areas (122) and groove areas (121) are disposed alternately, wherein the groove area (121) and the non groove area (122) are formed through a plurality of slots that are disposed at intervals on the silicon wafer (10), and the formed slots correspond to the groove area (121) while the area between two adjacent slots corresponds to the non groove area (122); a first doped layer (20) that is stacked on the non groove area (122); and a second doped layer (30) that is stacked within the groove area (121) and has a polarity opposite to the first doped layer (20); characterized in that , at a predetermined position (123) in the groove area (121), the first doped layer (20) has an extending portion (21) extending above the groove area (121), and the extending portion (21) has a first surface (211) facing towards the groove area (121) and a second surface (212) facing away from the groove area (121); and, at the predetermined position (123), the second doped layer (30) has a wrapping portion (31) that extends along a side wall surface of the groove area (121) and covers the first surface (211) of the extending portion (21), and the wrapping portion (31) recombines with the first surface (211) of the extending portion (21), wherein one side of a recombination area between the wrapping portion (31) and the extending portion (21) is the groove area (121) without any part of silicon wafer.
  2. The back-contact solar cell (100) according to claim 1, wherein the back-contact solar cell further includes a first dielectric layer (70) stacked on the non groove area (122), and the first doped layer (20) is stacked on the first dielectric layer (70).
  3. The back-contact solar cell (100) according to claim 1, wherein the back-contact solar cell further includes a second dielectric layer (80) stacked on the first surface (211), and the wrapping portion covers the second dielectric layer (80) and recombines with the first surface (211) through the second dielectric layer (80).
  4. The back-contact solar cell (100) according to claim 3, wherein the second dielectric layer (80) has a thickness of 0.5nm-50nm.
  5. The back-contact solar cell (100) according to claim 3, wherein the first surface (211) has a first region (213) and a second region (214), which are adjacent and continuous, along the arrangement direction of the groove area (121) and the non groove area (122); the thickness of the second dielectric layer (80) at the second region (214) is greater than the thickness of the second dielectric layer (80) at the first region (213), and a part of the second dielectric layer (80) located in the first region (213) has tunneling function.
  6. The back-contact solar cell (100) according to claim 5, wherein at the first region (213), the second dielectric layer (80) is 0.5nm-6nm thick, and at the second region (214), the second dielectric layer (80) is 2nm-50nm thick.
  7. The back-contact solar cell (100) according to claim 6, wherein at the first region (213), the second dielectric layer (80) is 4nm-5nm thick, and at the second region (214), the second dielectric layer (80) is 15nm-45nm thick.
  8. The back-contact solar cell (100) according to claim 5, wherein along the arrangement direction of the groove area (121) and the non groove area (122), the length of the first region (213) is 0.05 µm-1 µm, and the length of the second region (214) is 0.1 µm-10 µm.
  9. The back-contact solar cell (100) according to claim 8, wherein along the arrangement direction of the groove area (121) and the non groove area (122), the length of the first region (213) is 0.05 µm -1 µm, and the length of the second region (214) is 0.5 µm-3 µm.
  10. The back-contact solar cell (100) according to claim 1, wherein the first surface (211) and the second surface (212) intersect at the end of the extending portion (21) to form a tip (32), and the wrapping portion wraps around the tip (32).
  11. The back-contact solar cell (100) according to claim 1, wherein the extending portion (21) is 0.15 µm-10 µm long in the arrangement direction of the groove area (121) and the non groove area (122).
  12. The back-contact solar cell (100) according to claim 1, wherein in the length direction of the groove area (121), the ratio of the total lengths of all the extending portions to the area of the shady face (12) is 0.003cm/cm 2 -0.6cm/cm 2 .
  13. The back-contact solar cell (100) according to claim 1, wherein in a single groove area (121), the number of predetermined positions is M, and the number of extended parts and wrapped parts is also M; in the length direction of the groove area (121), the ratio of the total length of M extending portions to the length of a single groove area is 0.005-0.5, and M is a positive integer greater than or equal to 1.
  14. The back-contact solar cell (100) according to claim 1, wherein the ratio of the total orthographic projection areas of all extending portions on the shady face (12) to the area of the shady face is 4.5*10 -8 -1.5*10 -5 .
  15. The back-contact solar cell (100) according to claim 1, wherein at the predetermined position (123), a third doped layer (110) stacked on the upper layer of the second surface (212) has the same polarity as that of the second doped layer (30), the third doped layer (110) covers the second surface (212), and an insulation layer (120) is provided between the third doped layer (110) and the second surface (212).
  16. The back-contact solar cell (100) according to claim 1, wherein the depth of the groove area (121) is 0.1 µm-15 µm.
  17. A back-contact solar cell assembly, including a back-contact solar cell as claimed in any one of claims 1-16.
  18. A photovoltaic system, including a back-contact solar cell assembly as claimed in claim 17.

Description

Priority Information The present application requests the priority and interest of the patent applications No. 202310282218.X and 202320570099.3 submitted to the China National Intellectual Property Administration on March 16, 2023 and of the patent application No. 202321268949.0 and 202310583236.1 submitted to the China National Intellectual Property Administration on May 23, 2023. Technical Field The present application relates to the field of solar cell technology, in particular to a back-contact solar cell, a back-contact solar cell assembly and a photovoltaic system. Background Art Presently, among solar cells, back-contact solar cell is a type of cell with both the emitter and base contact electrodes disposed on its back (non light-receiving face). The cell's light-receiving face which is not obstructed by any metal electrodes effectively increases its short-circuit current. In traditional technical solutions, the back of the back-contact solar cell is usually a flat surface where P and N regions are alternately disposed, and at least a portion of the P and N regions intersect. In such cases, the severe edge recombination generated at the boundary of PIN region on the back of the back-contact solar cell has a wide impact range that affects the electrical performance of the cell, especially the filling factor, causing a decreased efficiency of the back-contact solar cell. Examples of related back contact solar cells in the prior art are described in JP 2015 191962 A, US 5 053 083 A, US 2016/087122 A1, US 2016/284922 A1 and JP 6 198813 B2. Summary of the Invention The invention is set out in the appended set of claims. The present application provides a back-contact solar cell, a back-contact solar cell assembly, and a photovoltaic system, and aims to address the technical issue of reducing the impact range of recombination at the boundary area of P/N region on the shady face of the back-contact solar cell, improving the filling factor of the cell and further the conversion efficiency. The present application is implemented as follows. The back-contact solar cell in the embodiment of the present application includes: a silicon wafer, wherein the silicon wafer has a light-receiving face and a shady face which are mutually opposed, and the shady face is provided with a plurality of groove areas and a plurality of non groove areas spaced at intervals, and the non groove areas and groove areas are disposed alternately;a first doped layer that is stacked on the non groove area, and at a predetermined position in the groove area, the first doped layer has an extending portion extending above the groove area, and the extending portion has a first surface facing towards the groove area and a second surface facing away from the groove area;a second doped layer that is stacked within the groove area and has a polarity opposite to the first doped layer, and at a predetermined position, the second doped layer has a wrapping portion that extends along the side wall surface of the groove area and covers the first surface, and the wrapping portion recombines with the first surface. Further, the present application also provides a back-contact solar cell, including: a silicon wafer, wherein the shady face of the silicon wafer includes a plurality of alternately disposed first region and second region, and slots are formed at the second region;a first doped layer located on the first region, and at a predetermined position at the slot, the first doped layer includes a first part located above the first region and a second part extending above the slot; anda second doped layer disposed at the slot, and at the predetermined position, the second doped layer covers the bottom and side faces of the slot and wraps around the surface facing the slot and the side faces of the second part, and the second doped layer recombines with the surface of the second part facing the slot. The present application also provides a back-contact solar cell assembly, including a back-contact solar cell as described in any of the above items. The present application also provides a photovoltaic system, including the back-contact solar cell assembly mentioned above. In the back-contact solar cell and its assembly and photovoltaic system of the present application, on the one hand, due to the presence of the groove area, the extending portion and the wrapping portion, the wrapping portion recombines with the first surface of the extending portion, and one side of the recombination area between the wrapping portion and extending portion is a groove area without any part of silicon wafer, and the edge recombination generated by the boundary region between the them only affects the silicon wafer on one side of the groove area, with a narrow range of impact, so that this can effectively reduce the number of affected carriers in the silicon wafer by narrowing the range of silicon wafer radiated by the boundary region, and improve the electrical perform