Back contact solar cell, slice, assembly and photovoltaic system

Abstract

The invention discloses a back contact solar cell, a fragment, an assembly and a photovoltaic system, and relates to the field of silicon solar cells. The back contact solar cell comprises a silicon substrate which comprises a light receiving surface and a backlight surface which are oppositely arranged; the backlight surface comprises a first preset area, a second preset area and a third preset area, and the first preset area, the third preset area and the second preset area are arranged in the first direction; a first doped layer, a second doped layer and a third doped layer, wherein the first doped layer and the second doped layer are alternately arranged in the first preset area and the second preset area along a first direction; the third doping layer is arranged in the third preset area, and the third doping layer completely or partially covers the third preset area. By implementing the embodiment, the passivation effect can be improved, and the conversion efficiency of the back contact solar cell is further improved.

Description

Technical Field

[0001] The present invention relates to the field of silicon solar cells, and in particular to a back-contact solar cell, a slice, a component and a photovoltaic system. Background Art

[0002] In existing back-contact cells, firstly, in order to facilitate subsequent cutting into slices (generally cut into 1 / 2 slices or 1 / 4 slices), a central GAP area is often set at the position to be cut, and the width of the central GAP area is generally 150-200μm. In addition, since the silicon wafer is prone to plating when forming the front structure, an edge GAP area is also set at its edge, and its width is 40-100μm.

[0003] The existence of the central GAP region and the edge GAP region occupies the effective area of ​​the cell and reduces its conversion efficiency. Specifically, the central GAP region and the edge GAP region are generally only provided with a passivation layer (AlOx, SiNx, etc.), that is, the region does not generate carriers and cannot collect them, which reduces the conversion efficiency. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a back-contact solar cell, slice, component and photovoltaic system, which can improve the surface passivation effect and improve the conversion efficiency.

[0005] In order to solve the above problems, the present invention discloses a back contact solar cell, which comprises:

[0006] A silicon substrate, comprising a light-receiving surface and a backlight surface arranged opposite to each other; the backlight surface comprises a first preset area, a second preset area and a third preset area, the first preset area, the third preset area and the second preset area are arranged along a first direction, and the third preset area is an area for cutting the back contact solar cell;

[0007] A first doping layer, a second doping layer and a third doping layer, wherein the first doping layer and the second doping layer are alternately arranged in the first preset area and the second preset area along a first direction; the third doping layer is arranged in the third preset area, and the third doping layer at least partially covers the third preset area.

[0008] As an improvement of the above technical solution, the backlight surface further includes at least one fourth preset area arranged near the edge of the silicon substrate, the first preset area, the second preset area, and the third preset area constitute a main base surface, and the fourth preset area is located on the side of the main base surface;

[0009] The fourth preset area extends along the first direction or the second direction, and the first direction intersects the second direction;

[0010] The fourth preset area is at least partially covered with a passivation film layer, and no doping layer is provided.

[0011] As an improvement of the above technical solution, the backlight surface is further provided with at least one fourth preset area arranged near the edge of the silicon substrate, the first preset area, the second preset area, and the third preset area constitute a main base surface, and the fourth preset area is located on the side of the main base surface;

[0012] The fourth preset area extends along the first direction or the second direction, and the first direction intersects the second direction;

[0013] A fourth doping layer and a passivation film layer are sequentially stacked in the fourth preset region;

[0014] The fourth doping layer at least partially covers the fourth preset area.

[0015] As an improvement of the above technical solution, the midline of the silicon substrate in the first direction falls into the third preset area.

[0016] As an improvement of the above technical solution, it also includes:

[0017] The third doping layer and the fifth doping layer are alternately arranged along the first direction and arranged in the third preset area;

[0018] The third doping layer contacts the first doping layer, and the fifth doping layer contacts the second doping layer.

[0019] As an improvement of the above technical solution, it also includes:

[0020] A first sub-gate and a second sub-gate; the first sub-gate and the second sub-gate are alternately arranged in the first preset area and the second preset area along the first direction, and extend along the second direction; the first sub-gate is arranged above the first doped layer and contacts the first doped layer, and the second sub-gate is arranged above the second doped layer and contacts the second doped layer.

[0021] As an improvement of the above technical solution, it also includes:

[0022] A third sub-gate is disposed in the third preset region and extends along the second direction, and the third sub-gate contacts the third doping layer.

[0023] As an improvement of the above technical solution, it also includes:

[0024] A third sub-grid and a fourth sub-grid, wherein the third sub-grid and the fourth sub-grid are alternately arranged along the first direction in the third preset area and extend along the second direction;

[0025] The third sub-gate contacts the third doped layer, and the fourth sub-gate contacts the fifth doped layer.

[0026] As an improvement of the above technical solution, it also includes:

[0027] A fifth sub-gate is disposed in the fourth preset region, and the fifth sub-gate is in contact with the fourth doping layer.

[0028] As an improvement of the above technical solution, it also includes:

[0029] A first main gate and a second main gate; the first main gate and the second main gate are alternately arranged along the second direction and extend along the first direction; the first sub-gate is connected to the first main gate and is insulated from the second main gate; the second sub-gate is connected to the second main gate and is insulated from the first main gate.

[0030] As an improvement of the above technical solution, it also includes:

[0031] A first main grid and a second main grid; the first main grid and the second main grid are alternately arranged along the second direction and extend along the first direction; the first auxiliary grid is connected to the first main grid and is insulated from the second main grid; the second auxiliary grid is connected to the second main grid and is insulated from the first main grid;

[0032] The first main grid and the second main grid are only arranged in the first preset area and the second preset area; or

[0033] The first main grid and the second main grid are arranged in the first preset area, the second preset area and the third preset area, and the first main grid and the second main grid are insulated from the third sub-grid; or

[0034] The first main grid and the second main grid are arranged in the first preset area, the second preset area and the third preset area, and the first main grid is connected to the third sub-grid, and the second main grid is insulated from the third sub-grid.

[0035] As an improvement of the above technical solution, it also includes:

[0036] A first main grid and a second main grid; the first main grid and the second main grid are alternately arranged along the second direction and extend along the first direction; the first auxiliary grid is connected to the first main grid and is insulated from the second main grid; the second auxiliary grid is connected to the second main grid and is insulated from the first main grid;

[0037] The first main grid and the second main grid are only arranged in the first preset area and the second preset area; or

[0038] The first main grid and the second main grid are arranged in the first preset area, the second preset area and the third preset area, and the first main grid and the second main grid are insulated from the third sub-grid and the fourth sub-grid; or

[0039] The first main gate and the second main gate are arranged in the first preset area, the second preset area and the third preset area, and the first main gate is connected to the third sub-gate, and the first main gate is insulated from the fourth sub-gate; the second main gate is connected to the fourth sub-gate, and the second main gate is insulated from the third sub-gate.

[0040] As an improvement of the above technical solution, it also includes:

[0041] a sixth doping layer and a seventh doping layer, wherein the sixth doping layer and the seventh doping layer are alternately arranged in the first preset region and the second preset region along the second direction and extend along the first direction; the first direction intersects the second direction;

[0042] The sixth doping layer contacts the first doping layer, and the second doping layer is disconnected at the sixth doping layer;

[0043] The seventh doping layer contacts the second doping layer, and the first doping layer is disconnected at the seventh doping layer.

[0044] As an improvement of the above technical solution, it also includes:

[0045] a fifth doping layer; the third doping layer and the fifth doping layer are alternately arranged along the second direction in the third preset area; the third doping layer is in contact with the sixth doping layer, and the fifth doping layer is in contact with the seventh doping layer.

[0046] As an improvement of the above technical solution, it also includes:

[0047] a first auxiliary gate and a second auxiliary gate; the first auxiliary gate and the second auxiliary gate are alternately arranged in the first preset area and the second preset area along the first direction, and extend along the second direction; the first auxiliary gate is arranged above the first doped layer and contacts the first doped layer, and the second auxiliary gate is arranged above the second doped layer and contacts the second doped layer; and

[0048] a first main gate and a second main gate; the first main gate and the second main gate are alternately arranged along the second direction and extend along the first direction; the first main gate is arranged above the sixth doping layer; the second main gate is arranged above the seventh doping layer;

[0049] The first main grid is connected to the first sub-grid and insulated from the second sub-grid; the second main grid is connected to the second sub-grid and insulated from the first sub-grid.

[0050] As an improvement of the above technical solution, it also includes:

[0051] A first main gate and a second main gate; the first main gate and the second main gate are alternately arranged in the first preset area, the second preset area and the third preset area along the second direction, and extend along the first direction; the first main gate located in the first preset area and the second preset area is arranged above the sixth doped layer; the first main gate located in the third preset area is arranged above the third doped layer;

[0052] The second main gate located in the first preset region and the second preset region is arranged above the seventh doping layer; the second main gate located in the third preset region is arranged above the fifth doping layer.

[0053] As an improvement of the above technical solution, along the first direction, the width of the third preset area is less than or equal to 5 mm.

[0054] As an improvement of the above technical solution, the third doping layer and the silicon substrate have the same doping polarity.

[0055] As an improvement of the above technical solution, it also includes a contact layer, which is arranged between adjacent first doping layers and second doping layers, and enables the first doping layers to form contact with the second doping layers;

[0056] The contact layer is arranged close to the edge of the silicon substrate.

[0057] Correspondingly, the present invention further discloses a solar cell slice, which is obtained by cutting the above-mentioned back-contact solar cell along a cutting line, wherein the cutting line is arranged in the third preset area and extends along the second direction.

[0058] Correspondingly, the present invention also discloses a battery assembly, which includes the above-mentioned back-contact solar cell or the above-mentioned solar cell slice.

[0059] Correspondingly, the present invention also discloses a photovoltaic system, which includes the above-mentioned battery assembly.

[0060] The implementation of the present invention has the following beneficial effects:

[0061] In a back-contact solar cell in an embodiment of the present invention, a first preset area, a second preset area and a third preset area are arranged on the backlight surface of the silicon substrate, and the first preset area, the third preset area and the second preset area are arranged along the first direction; wherein a plurality of first doping layers and second doping layers arranged alternately along the first direction are arranged in the first preset area and the second preset area, and a third doping layer is arranged in the third preset area, and the third doping layer at least partially covers the third preset area. In this embodiment, a third doping layer is also arranged in the third preset area for cutting the silicon substrate later, which can effectively improve the passivation effect and improve the conversion efficiency of the back-contact solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 is a schematic diagram of the back structure of a back-contact solar cell according to an embodiment of the present invention;

[0063] Figure 2 is a schematic cross-sectional structure diagram of a back contact solar cell in one embodiment of the present invention;

[0064] Figure 3 is a schematic diagram of the distribution of the doping layer on the backlight side of the silicon substrate in one embodiment of the present invention;

[0065] Figure 4 is a schematic diagram of the distribution of doping layers on the backlight surface of a silicon substrate in another embodiment of the present invention;

[0066] Figure 5 is a schematic diagram of the back structure of a back-contact solar cell in another embodiment of the present invention;

[0067] Figure 6 is a schematic diagram of the back structure of a back-contact solar cell in another embodiment of the present invention;

[0068] In the figure, 1 is a silicon substrate, 11 is a light-receiving surface, 12 is a backlight surface, 110 is a first preset area, 120 is a second preset area, 130 is a third preset area, 140 is a fourth preset area, 21 is a first doping layer, 22 is a second doping layer, 23 is a third doping layer, 24 is a fourth doping layer, 25 is a fifth doping layer, 26 is a sixth doping layer, 27 is a seventh doping layer, 31 is a first sub-gate, 32 is a second sub-gate, 33 is a third sub-gate, 34 is a fourth sub-gate, 35 is a fifth sub-gate, 41 is a first main gate, 42 is a second main gate, 5 is a passivation layer, 6 is a cutting line, and 7 is a contact layer. DETAILED DESCRIPTION

[0069] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in further detail below.

[0070] See also Figure 1 and Figure 2An embodiment of the present invention discloses a back contact battery, which includes a silicon substrate 1, a first doping layer 21, a second doping layer 22 and a third doping layer 23. The silicon substrate 1 includes a light-receiving surface 11 and a backlight surface 12 that are arranged opposite to each other. The backlight surface 12 is provided with a first preset area 110, a second preset area 120 and a third preset area 130. The first preset area 110 and the second preset area 120 are mainly used to form the first doping layer 21 and the second doping layer 22, and then form a gate line (electrode) structure later. The third preset area 130 is used to cut the silicon substrate 1 later. The first preset area 110, the third preset area 130 and the second preset area 120 are arranged in sequence along the first direction.

[0071] Specifically, in one embodiment, the width of the third preset area is less than or equal to 5 mm to improve the efficiency of light utilization. Preferably, the width of the third preset area is 100 μm to 300 μm.

[0072] It should be noted that the backlight surface 12 of the silicon substrate 1 in this embodiment can also receive incident light, that is, the back-contact cell in this embodiment can be a single-sided cell (receiving light only through the front side) or a double-sided cell (receiving light from both the front and back sides).

[0073] Among them, the number of the first doping layer 21 and the second doping layer 22 is multiple, and the multiple first doping layers 21 and the multiple second doping layers 22 are arranged alternately along the first direction in the first preset area 110 and the second preset area 120; and the first doping layer 21 and the second doping layer 22 extend along the second direction. The third doping layer 23 is arranged in the third preset area 130. In this embodiment, the third doping layer 23 is also arranged in the third preset area 130 used to cut the silicon substrate 1 in the later stage, which can effectively improve the passivation effect and improve the conversion efficiency of the back contact solar cell.

[0074] The third doping layer 23 may partially cover or completely cover the third preset region 130. The degree of improvement in conversion efficiency may be determined comprehensively according to the arrangement of the electrodes in the third preset region 130. The following embodiments may be included:

[0075] (1.1) See Figure 3 , the third doping layer 23 completely covers the third preset area 130, and the third doping layer 23 has the same or different doping polarity as the silicon substrate 1. Based on this embodiment, the carrier collection area can be increased and the conversion efficiency of the solar cell can be improved. Preferably, the silicon substrate 1 has the same doping polarity as the third doping layer 23, which can further increase the carrier transmission rate and improve the conversion efficiency.

[0076] Furthermore, based on this embodiment, the third doping layer 23 can contact the first doping layer 21 or the second doping layer 22 arranged in the first preset area 110 or the second preset area 120 and having the same doping polarity as the third doping layer 23. Based on the above arrangement, when no electrode is arranged in the third preset area, carriers in the third preset area can still be collected, thereby improving the luminous efficiency.

[0077] (1.2) The third doping layer 23 partially covers the third preset area 130, and only the third doping layer 23 with a single doping polarity is arranged in the third preset area 130. The doping polarity of the third doping layer 23 is the same as or different from the doping polarity of the silicon substrate 1. It should be noted that since the laser cutting process is required for splitting in the later stage, if the third doping layer 23 is covered in the laser cutting area, the doping elements of the third doping layer 23 may be pushed into the silicon substrate 1. If the doping polarity of the third doping layer 23 is the same as the doping polarity of the silicon substrate 1, an area with extremely high doping concentration will be formed on the silicon substrate 1, forming a surface dead layer, which is not conducive to improving the light conversion efficiency. Therefore, the arrangement method in which the third doping layer 23 partially covers the third preset area 130 can be adopted. More specifically, in one embodiment, the covering area of ​​the third doping layer 23 and the laser splitting area are staggered in the first direction; in another embodiment, two or more third doping layers 23 are arranged in the third preset area 130 along the first direction, and the laser splitting area is arranged between adjacent third doping layers 23.

[0078] Furthermore, based on this embodiment, the third doping layer 23 can also be connected to the first doping layer 21 or the second doping layer 22 arranged in the first preset area 110 or the second preset area 120 and having the same doping polarity as the third doping layer 23 to improve the carrier collection efficiency and the conversion efficiency.

[0079] (1.3) See Figure 1 , the third doping layer 23 partially covers the third preset area 130, and a fifth doping layer 25 is also provided in the third preset area 130, the fifth doping layer 25 has a different doping polarity from the third doping layer 23, and the third doping layer 23 and the fifth doping layer 25 are insulated by a gap provided therebetween. Based on the above implementation, gate lines of different polarities can be formed in the third preset area 130 later, thereby collecting carriers of different polarities and improving the conversion efficiency of the solar cell.

[0080] Among them, the number of the third doping layer 23 and the fifth doping layer 25 is one or more, but not limited to this. When the number of both is more than one, the third doping layer 23 and the fifth doping layer 25 can be arranged alternately in the first direction or the second direction, but not limited to this. Specifically, in one embodiment, the third doping layer 23 and the fifth doping layer 25 are arranged alternately along the first direction and extend along the second direction. Based on this implementation, the subsequent laser cutting area can be set between the third doping layer 23 and the fifth doping layer 25 to reduce the probability of the doping elements of the third doping layer 23 and the fifth doping layer 25 entering the silicon substrate 1.

[0081] Further, based on this embodiment, the third doping layer 23 and the fifth doping layer 25 can be connected to the first doping layer 21 or the second doping layer 22 with the same doping polarity as the first preset region 110 and the second preset region 120, respectively. More specifically, the third doping layer 23 is connected to the first doping layer 21, and the fifth doping layer 25 is connected to the second doping layer 22, so that when no electrode is provided in the third preset region 130, the carriers of the third preset region can still be collected to improve the light emission efficiency.

[0082] In one embodiment of the present invention, in order to optimize the passivation effect of the third preset area 130, the third preset area 130 is also covered with a passivation film layer 5, which is arranged above the third doping layer 23, the fifth doping layer 25 and the gap therebetween.

[0083] Among them, in one embodiment of the present invention, see Figure 1 , Figure 3 and Figure 4 , the back side of the silicon substrate 1 also includes at least one fourth preset area 140 arranged near the edge of the silicon substrate 1. Among them, the first preset area 110, the second preset area 120, and the third preset area 130 constitute the main base surface 13, and the fourth preset area 140 is located on the side of the main base surface 13, that is, at least one fourth preset area 140 is arranged around the main base surface 13. The fourth preset area 140 extends along the first direction or the second direction. Specifically, in the present embodiment, the fourth preset area 140 may be covered with a passivation film layer 5, or the fourth preset area 140 may be sequentially stacked with a fourth doping layer 24 and a passivation film layer 5. In the present embodiment, a fourth doping layer 24 is also arranged in the fourth preset area 140 located at the edge of the silicon substrate 1, which can effectively improve the passivation effect and improve the conversion efficiency of the back contact solar cell.

[0084] Based on this implementation, the fourth doping layer 24 in the fourth preset region 140 may completely cover or partially cover the fourth preset region 140, and the specific implementations thereof may include the following:

[0085] (2.1) See Figure 1 and Figure 3 , the fourth doping layer 24 completely covers the fourth preset area 140, and the fourth doping layer 24 has the same or different doping polarity as the silicon substrate 1. Based on this embodiment, a gate line (electrode) can be set in the fourth preset area 140, thereby increasing the carrier collection area and improving the conversion efficiency of the solar cell. Preferably, the silicon substrate 1 and the fourth doping layer 24 have different doping polarities, which can further increase the emitter area and improve the conversion efficiency.

[0086] Furthermore, based on this embodiment, the fourth doping layer 24 can be connected to the first doping layer 21 or the second doping layer 22 arranged in the first preset area 110 or the second preset area 120 and having the same doping polarity as the fourth doping layer 24. Based on the above setting, when no electrode is set in the fourth preset area 140, the carriers in this area can still be collected, thereby improving the conversion efficiency.

[0087] (2.2) See Figure 4 , the fourth doping layer 24 partially covers the fourth preset area 140, and only the fourth doping layer 24 is set in the fourth preset area 140. The doping polarity of the fourth doping layer 24 is the same as or different from the doping polarity of the silicon substrate 1. Based on this setting scheme, the area of ​​laser cracking can be avoided to prevent the laser from possibly promoting the adverse effects of the doping elements on the silicon substrate 1. Specifically, in one embodiment, in the fourth preset area 140 where the laser line passes, the fourth doping layer 24 is set to be disconnected in the laser line area.

[0088] Furthermore, based on this embodiment, the fourth doping layer 24 can also be connected to the first doping layer 21 or the second doping layer 22 arranged in the first preset area 110 or the second preset area 120 and having the same doping polarity as the fourth doping layer 24, so as to still collect carriers in the area when no electrode is set in the fourth preset area 140, thereby improving the conversion efficiency.

[0089] In some embodiments of the present invention, the spacing between the first doping layer 21 and the second doping layer 22 is 1 μm to 50 μm, exemplarily 3 μm, 8 μm, 12 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm or 48 μm, but not limited thereto, preferably 10 μm to 50 μm.

[0090] In some embodiments of the present invention, the spacing between the third doping layer 23 and the fifth doping layer 25 is 1 μm to 50 μm, exemplarily 3 μm, 8 μm, 12 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm or 48 μm, but not limited thereto, preferably 10 μm to 50 μm.

[0091] Among them, see Figure 1 , Figure 2 The back contact solar cell further includes a first auxiliary grid 31 and a second auxiliary grid 32, which are alternately arranged in the first preset area 110 and the second preset area 120 along the first direction and extend along the second direction. The first auxiliary grid 31 is arranged above the first doping layer 21 and contacts the first doping layer 21, and the second auxiliary grid 32 is arranged above the second doping layer 22 and contacts the second doping layer 22. Specifically, a passivation film layer 5 is provided between the first auxiliary grid 31 and the first doping layer 21, and between the second auxiliary grid 32 and the second doping layer 22. The first auxiliary grid 31 can be connected to the first doping layer 21 through a plurality of openings provided on the first passivation film layer 5, and the second auxiliary grid 32 can be connected to the second doping layer 22 through a plurality of openings provided on the passivation film layer 5. It should be noted that the openings can be openings formed by wet etching, dry etching, laser ablation, slurry burn-through and other processes, but are not limited thereto.

[0092] Preferably, in some embodiments of the present invention, a secondary grid is also arranged in the third preset area 130, and its specific arrangement may include the following situations:

[0093] (3.1) Only the third sub-grid 33 of the same polarity is arranged in the third preset region 130, and the third sub-grid 33 is arranged above the third doped layer 23, and is connected to the third doped layer 23 through the opening arranged on the passivation film layer 5. Based on the third sub-grid 33, the carriers in the third preset region 130 can be collected to improve the conversion efficiency of the back contact solar cell.

[0094] Specifically, the number of the third sub-gates 33 may be one or more. Specifically, when the number of the third sub-gates 33 is more than one, they may be respectively disposed corresponding to the plurality of third doping layers 23 disposed in the third preset region 130 .

[0095] (3.2) See Figure 1 , a third sub-gate 33 and a fourth sub-gate 34 of different polarities are arranged in the third preset area 130. The third sub-gate 33 is arranged above the third doped layer 23, and is connected to the third doped layer 23 through an opening arranged on the passivation film layer 5, and the fourth sub-gate 34 is arranged above the fifth doped layer 25, and is connected to the fifth doped layer 25 through an opening arranged on the passivation film layer 5. Based on this embodiment, the carriers of the third doped layer 23 and the fifth doped layer 25 can be collected respectively, thereby improving the carrier collection efficiency.

[0096] Specifically, the number of the third sub-grid 33 and the fourth sub-grid 34 is one or more, and they can be arranged alternately along the first direction or the second direction. The specific arrangement direction and extension direction can be determined according to the arrangement direction and extension direction of the third doping layer 23 and the fifth doping layer 25. Exemplarily, in one embodiment, the third sub-grid 33 and the fourth sub-grid 34 are arranged alternately along the first direction in the third preset area 130, and extend along the second direction. That is, the third sub-grid 33 and the fourth sub-grid 34 are parallel to the first sub-grid 31 and the second sub-grid 32. In another embodiment, the third sub-grid 33 and the fourth sub-grid 34 are arranged alternately along the second direction in the third preset area 130, and extend along the first direction. Based on this embodiment, the third sub-grid 33 and the fourth sub-grid 34 can be distributed in the area for forming the main grid and / or the welding strip later to facilitate carrier convergence.

[0097] In one embodiment of the present invention, a fifth sub-gate 35 corresponding to the doping polarity of the fourth doping layer 24 may be provided in the fourth preset region 140 to collect carriers in the region. The fifth sub-gate 35 may be connected to the fourth doping layer 24 through an opening provided on the passivation film layer 5.

[0098] The back contact cell of this embodiment may be applicable to a conventional back contact cell with a main grid, or a back contact cell without a main grid, but is not limited thereto.

[0099] Among them, in one embodiment of the present invention, see Figure 1 , Figure 2 The back contact cell further includes a first main grid 41 and a second main grid 42, which are alternately arranged along the second direction and extend along the first direction. The first main grid 41 is connected to the first sub-grid 31 and insulated from the second sub-grid 32 to achieve carrier convergence of the first sub-grid 31; the second main grid 42 is connected to the second sub-grid 32 and insulated from the first sub-grid 31 to achieve carrier convergence of the second sub-grid 32. The first sub-grid 31 can be disconnected at the position of the second main grid 42, or an insulating glue, an insulating layer, etc. can be formed on the first sub-grid 31 to achieve insulation between the first sub-grid 31 and the second main grid 42. Correspondingly, the second sub-grid 32 can also be insulated from the first main grid 41 by disconnection, insulating glue, an insulating layer, etc.

[0100] The first main grid 41 and the second main grid 42 may be continuous structures or discontinuous structures, but are not limited thereto.

[0101] Preferably, according to the need to collect carriers, the main grid distribution mode can adopt the following implementation methods:

[0102] (4.1) The first main gate 41 and the second main gate 42 are only arranged in the first preset area 110 and the second preset area 120, that is, no main gate is arranged in the third preset area 130. Based on this method, solder joints can be formed on the third sub-gate 33 and the fifth sub-gate 35 when the components are formed later to collect the carriers of the third sub-gate 33 and the fifth sub-gate 35. The third doping layer 23 and the fifth doping layer 25 can also be arranged to contact the first doping layer 21 and the second doping layer 22 respectively, so as to collect carriers through the first sub-gate 31 and the second sub-gate 32 arranged above the first doping layer 21 and the second doping layer 22, but it is not limited thereto.

[0103] (4.2) The first main gate 41 and the second main gate 42 are arranged in the first preset area 110, the second preset area 120 and the third preset area 130, but the first main gate 41 and the second main gate 42 in the third preset area 130 are insulated from the third sub-gate 33 and the fourth sub-gate 34. Based on this method, welding points can also be formed on the third sub-gate 33 and the fifth sub-gate 35 when the components are formed later to collect the carriers of the third sub-gate 33 and the fifth sub-gate 35. The third doping layer 23 and the fifth doping layer 25 can also be arranged to contact the first doping layer 21 and the second doping layer 22 respectively, so as to collect the carriers through the first sub-gate 31 and the second sub-gate 32 arranged above the first doping layer 21 and the second doping layer 22, but it is not limited thereto.

[0104] (4.3) See Figure 1 The first main grid 41 and the second main grid 42 are arranged in the first preset area 110, the second preset area 120 and the third preset area 130. The first main grid 41 and the second main grid 42 in the third preset area 130 are respectively connected to the third sub-grid 33 or the fourth sub-grid 34 with the same polarity, and are insulated from the sub-grid of the other polarity, so as to realize the convergence of current on the third sub-grid 33 and the fourth sub-grid 34 through the first main grid 41 and the second main grid 42.

[0105] Preferably, reference Figure 4 In one embodiment, the back contact cell is further provided with a contact layer 7, which is provided between the adjacent first doping layer 21 and the second doping layer 22, and makes the first doping layer 21 and the second doping layer 22 form contact; based on this structure, a leakage composite contact structure can be formed to improve the reverse leakage characteristics and the ability to resist the risk of hot spots. Preferably, in one embodiment, the contact layer 7 is provided close to the edge of the silicon substrate.

[0106] Preferably, in an embodiment, the third doping layer 23 has the same doping polarity as the silicon substrate 1 . Based on this implementation, surface recombination can be reduced and conversion efficiency can be improved.

[0107] Among them, see Figure 5In some embodiments of the present invention, the back-contact solar cell further includes a sixth doping layer 26 and a seventh doping layer 27, which are alternately arranged in the first preset area 110 and the second preset area 120 along the second direction and extend along the first direction; the sixth doping layer 26 is in contact with the first doping layer 21, and the second doping layer 22 is disconnected at the sixth doping layer 26; the seventh doping layer 27 is in contact with the second doping layer 22, and the first doping layer 21 is disconnected at the seventh doping layer 27. Based on this embodiment, the doping layers on the surface of the silicon substrate 1 are arranged in a "F" shape. Based on this arrangement, the arrangement of the doping layers, the auxiliary grid, and the main grid in the third preset area 130 needs to be adaptively adjusted. Specifically as follows:

[0108] The doping layer of the third preset region 130 may be specifically implemented as follows:

[0109] (5.1) The third doping layer 23 completely covers the third preset area 130, and the third doping layer 23 has the same or different doping polarity as the silicon substrate 1. Based on this embodiment, the carrier collection area can be increased and the conversion efficiency of the solar cell can be improved. Preferably, the silicon substrate 1 and the third doping layer 23 have different doping polarities, which can further increase the emitter area and improve the conversion efficiency.

[0110] Furthermore, based on this embodiment, the third doping layer 23 can be connected to the sixth doping layer 26 or the seventh doping layer 27 which is arranged in the first preset area 110 or the second preset area 120 and has the same doping polarity as the third doping layer 23. Based on the above arrangement, carrier collection in the third preset area 130 can be achieved when no electrode is arranged in the third preset area 130, thereby improving the conversion efficiency.

[0111] (5.2) The third doping layer 23 partially covers the third preset area 130, and only the third doping layer 23 with a single doping polarity is arranged in the third preset area 130. The doping polarity of the third doping layer 23 is the same as or different from the doping polarity of the silicon substrate 1. It should be noted that since the laser cutting process is required for splitting in the later stage, if the third doping layer 23 is covered in the laser cutting area, the doping elements of the third doping layer 23 may be pushed into the silicon substrate 1. If the doping polarity of the third doping layer 23 is the same as the doping polarity of the silicon substrate 1, an area with extremely high doping concentration may be formed on the silicon substrate 1, forming a surface dead layer, which is not conducive to improving the light conversion efficiency. Therefore, the arrangement method in which the third doping layer 23 partially covers the third preset area 130 can be adopted. More specifically, in one embodiment, the covering area of ​​the third doping layer 23 and the laser splitting area are staggered in the first direction; in another embodiment, two or more third doping layers 23 are arranged in the third preset area 130 along the first direction, and the laser splitting area is arranged between adjacent third doping layers 23.

[0112] Furthermore, based on this embodiment, the third doping layer 23 can also be connected to the sixth doping layer 26 or the seventh doping layer 27 arranged in the first preset area 110 or the second preset area 120 and having the same doping polarity as the third doping layer 23, so as to simplify the etching process of the doping layer and improve the printing accuracy of the subsequent gate lines.

[0113] (5.3) See Figure 5 , Figure 6 , the third doping layer 23 partially covers the third preset area 130, and a fifth doping layer 25 is also provided in the third preset area 130, the fifth doping layer 25 has a different doping polarity from the third doping layer 23, and the third doping layer 23 and the fifth doping layer 25 are insulated by a gap provided therebetween. Based on the above implementation, gate lines of different polarities can be formed in the third preset area 130 later, thereby collecting carriers of different polarities and improving the conversion efficiency of the solar cell.

[0114] The number of the third doping layer 23 and the number of the fifth doping layer 25 are one or more, but not limited thereto. The plurality of third doping layers 23 and the plurality of fifth doping layers 25 can be arranged alternately in sequence along the first direction or the second direction, but not limited thereto. Preferably, in one embodiment, see Figure 5, the third doping layer 23 and the fifth doping layer 25 are arranged alternately in the third preset area 130 along the second direction; the third doping layer 23 is in contact with or not in contact with the sixth doping layer 26, and the fifth doping layer 25 is in contact with or not in contact with the seventh doping layer 27; based on this embodiment, a plurality of gate lines overlapping with the main gates corresponding to the sixth doping layer 26 and the seventh doping layer 27 can be formed in the third preset area 130, greatly simplifying the printing process of the gate lines. In another embodiment, see Figure 6 The third doping layer 23 and the fifth doping layer 25 are alternately arranged along the first direction in the third preset area 130. The third doping layer 23 is in contact with or not in contact with the sixth doping layer 26, and the fifth doping layer 25 is in contact with or not in contact with the seventh doping layer 27.

[0115] For the auxiliary gates in the first preset area 110 and the second preset area 120, in this embodiment, the first auxiliary gate 31 and the second auxiliary gate 32 are arranged alternately along the first direction and extend along the second direction. The first auxiliary gate 31 is arranged above the first doping layer 21 and contacts the first doping layer 21 through the openings arranged on the passivation film layer 5. The first auxiliary gate 31 is disconnected in the area corresponding to the seventh doping layer 27. Correspondingly, the second auxiliary gate 32 is arranged above the second doping layer 22 and contacts the second doping layer 22 through the openings arranged on the passivation film layer 5. The second auxiliary gate 32 is disconnected in the area corresponding to the sixth doping layer 26.

[0116] Regarding the secondary gate in the third preset area 130, in this embodiment, it can have the following implementation modes:

[0117] (6.1) Only the third sub-grid 33 of the same polarity is arranged in the third preset region 130, and the third sub-grid 33 is arranged above the third doped layer 23, and is connected to the third doped layer 23 through the opening arranged on the passivation film layer 5. Based on the third sub-grid 33, the carriers in the third preset region 130 can be collected to improve the conversion efficiency of the back contact solar cell.

[0118] Specifically, the number of the third sub-gates 33 may be one or more. Specifically, when the number of the third sub-gates 33 is more than one, they may be respectively disposed corresponding to the plurality of third doping layers 23 disposed in the third preset region 130 .

[0119] The third auxiliary grid 33 may be continuous or discontinuous, but is not limited thereto.

[0120] (6.2) See Figure 6, a third sub-gate 33 and a fourth sub-gate 34 of different polarities are arranged in the third preset area 130. The third sub-gate 33 is arranged above the third doped layer 23, and is connected to the third doped layer 23 through an opening arranged on the passivation film layer 5, and the fourth sub-gate 34 is arranged above the fifth doped layer 25, and is connected to the fifth doped layer 25 through an opening arranged on the passivation film layer 5. Based on this embodiment, the carriers of the third doped layer 23 and the fifth doped layer 25 can be collected respectively, thereby improving the carrier collection efficiency.

[0121] Specifically, in this embodiment, the number of the third sub-grid 33 and the fourth sub-grid 34 can be one or more, but not limited thereto. The third sub-grid 33 and the fourth sub-grid 34 can be continuous or discontinuous, but not limited thereto.

[0122] (6.3) See Figure 5 No auxiliary gate is provided in the third preset region 130 , and the first main gate 41 and the second main gate 42 are directly extended to the third preset region 130 to collect carriers.

[0123] Regarding the main grid, in this embodiment, there are the following specific implementation methods:

[0124] (7.1) The first main gate 41 and the second main gate 42 are only arranged in the first preset area 110 and the second preset area 120, that is, no main gate is arranged in the third preset area 130. Among them, the first main gate 41 in the first preset area 110 and the second preset area 120 is arranged above the sixth doping layer 26. The second main gate 42 in the first preset area 110 and the second preset area 120 is arranged above the seventh doping layer 27. The first main gate 41 is connected to the first sub-gate 31 and is insulated from the second sub-gate 32. The second main gate 42 is connected to the second sub-gate 32 and is insulated from the first sub-gate 31. Based on this method, solder joints can be formed on the third sub-gate 33 and the fifth sub-gate 35 when the components are formed later to collect the carriers of the third sub-gate 33 and the fifth sub-gate 35. The third doping layer 23 and the fifth doping layer 25 may be respectively provided to contact the first doping layer 21 and the second doping layer 22 so as to collect carriers through the first sub-gate 31 and the second sub-gate 32 provided above the first doping layer 21 and the second doping layer 22, but the present invention is not limited thereto.

[0125] (7.2) The first main gate 41 and the second main gate 42 are arranged in the first preset area 110, the second preset area 120 and the third preset area 130, wherein the first main gate 41 in the first preset area 110 and the second preset area 120 is arranged above the sixth doping layer 26. The second main gate 42 in the first preset area 110 and the second preset area 120 is arranged above the seventh doping layer 27 and contacts the seventh doping layer 27 through the openings arranged on the passivation film layer 5. The first main gate 41 is connected to the first sub-gate 31 and is insulated from the second sub-gate 32. The second main gate 42 is connected to the second sub-gate 32 and is insulated from the first sub-gate 31.

[0126] The first main gate 41 and the second main gate 42 in the third preset area 130 are insulated from the third sub-gate 33 and the fourth sub-gate 34. Based on this method, solder joints can be formed on the third sub-gate 33 and the fifth sub-gate 35 when forming components later to collect carriers of the third sub-gate 33 and the fifth sub-gate 35. The third doping layer 23 and the fifth doping layer 25 can also be arranged to contact the first doping layer 21 and the second doping layer 22 respectively, so as to collect carriers through the first sub-gate 31 and the second sub-gate 32 arranged above the first doping layer 21 and the second doping layer 22, but it is not limited thereto.

[0127] (7.3) See Figure 6 , the first main gate 41 and the second main gate 42 are arranged in the first preset area 110, the second preset area 120 and the third preset area 130. Among them, the first main gate 41 in the first preset area 110 and the second preset area 120 is arranged above the sixth doping layer 26. The second main gate 42 in the first preset area 110 and the second preset area 120 is arranged above the seventh doping layer 27. The first main gate 41 is connected to the first sub-gate 31 and is insulated from the second sub-gate 32. The second main gate 42 is connected to the second sub-gate 32 and is insulated from the first sub-gate 31.

[0128] The first main grid 41 in the third preset region 130 is connected to the third sub-grid 33 and insulated from the fourth sub-grid 34; the second main grid 42 in the third preset region 130 is connected to the fourth sub-grid 34 and insulated from the third sub-grid 33. Based on this method, the carriers in the third preset region 130 collected by the third sub-grid 33 and the fourth sub-grid 34 can be converged by forming the first main grid 41 and the second main grid 42 later.

[0129] (7.4) See Figure 6, the first main gate 41 and the second main gate 42 are arranged in the first preset area 110, the second preset area 120 and the third preset area 130. Among them, the first main gate 41 in the first preset area 110 and the second preset area 120 is arranged above the sixth doping layer 26. The second main gate 42 in the first preset area 110 and the second preset area 120 is arranged above the seventh doping layer 27. The first main gate 41 is connected to the first sub-gate 31 and is insulated from the second sub-gate 32. The second main gate 42 is connected to the second sub-gate 32 and is insulated from the first sub-gate 31.

[0130] The first main gate 41 in the third preset region 130 is disposed above the third doped layer 23, and is connected to the third doped layer 23 through an opening disposed on the passivation film layer 5. The second main gate 42 in the third preset region 130 is disposed above the fifth doped layer 25, and is connected to the fifth doped layer 25 through an opening disposed on the passivation film layer 5. Based on this embodiment, the carriers generated in the third preset region 130 can be directly collected through the first main gate 41 and the second main gate 42, without the need to dispose other sub-gates in the third preset region 130, thereby simplifying the printing process.

[0131] It should be noted that the doping polarity in this embodiment refers to the doping polarity of the silicon substrate 1 or the doping layer. For example, when the silicon substrate 1 is doped with VA group elements (such as P, As, Sb, etc.), it is N-type doping; when the silicon substrate 1 is doped with IVA group elements (such as B, Al, Ga, etc.), it is P-type doping. The polarity in this embodiment refers to the polarity of the gate line (main gate, auxiliary gate). For example, the gate line used to collect the current of the N-type doped layer is the N-type gate line, and the gate line used to collect the current of the P-type doped layer is the P-type gate line. In this embodiment, the first direction may be a horizontal direction, and the second direction may be a vertical direction, but is not limited thereto.

[0132] Correspondingly, the present embodiment also discloses a solar cell slice, which is obtained by cutting the above-mentioned back-contact solar cell. Specifically, the cutting may be cleavage, laser cutting, etc., but is not limited thereto. During cutting, cutting is performed along a cutting line 6 set in the third preset area 130, and the cutting line 6 may be set at any position in the third preset area 130. Preferably, in one embodiment, the cutting line is set at the edge of the third preset area 130. Based on this implementation, among the cell slices obtained after cutting, at least one cell slice may not be set with the third preset area 130, thereby further improving the conversion efficiency.

[0133] Correspondingly, this embodiment further discloses a battery assembly, which may include the above-mentioned back-contact solar cell or solar cell slices obtained by cutting the back-contact solar cell.

[0134] Correspondingly, this embodiment also discloses a photovoltaic system, which includes the above-mentioned battery assembly.

[0135] The present invention will be further described below with specific embodiments:

[0136] Example 1

[0137] This embodiment provides a solar cell slice, which is obtained by cutting a back contact solar cell along a cutting line.

[0138] The back contact solar cell includes a silicon substrate, which includes a light receiving surface and a backlight surface arranged opposite to each other; the backlight surface includes a first preset area, a second preset area and a third preset area with a width of 200 μm, the first preset area, the third preset area and the second preset area are arranged along a first direction, and the center line of the silicon substrate in the first direction falls into the third preset area. The first preset area, the second preset area and the third preset area constitute a main base surface, and four fourth preset areas with a width of 200 μm are arranged around the main base surface.

[0139] Wherein, a plurality of first doped layers and second doped layers are arranged in the first preset region and the second preset region, and the first doped layers and the second doped layers are arranged alternately along the first direction. A first auxiliary gate is arranged above the first doped layer, which contacts the first doped layer through an opening arranged on the passivation film layer, and a second auxiliary gate is arranged above the second doped layer, which contacts the second doped layer through an opening arranged on the passivation film layer. A plurality of first main gates and second main gates are also arranged in the second preset region, wherein the first main gate and the second main gate are arranged alternately along the second direction and extend along the first direction; the first auxiliary gate is connected to the first main gate and is insulated from the second main gate; the second auxiliary gate is connected to the second main gate and is insulated from the first main gate.

[0140] A third doping layer covering the entire surface of the third preset region is provided in the third preset region, and the doping polarity is the same as that of the first doping layer. A passivation film layer and a third auxiliary gate are provided on the third doping layer in sequence, and the third auxiliary gate contacts the third doping layer through an opening on the passivation film layer. The first main gate extends to the third preset region and is connected to the third auxiliary gate. The fourth preset region is only fully covered with a passivation film layer.

[0141] In this embodiment, one side of the solar cell slice obtained by cutting is not provided with a GAP region, and the other three sides are provided with GAP regions. It should be noted that in this embodiment, the GAP region refers to a region that only covers the passivation film layer but not the doping layer.

[0142] Example 2

[0143] This embodiment provides a solar cell segment, which is different from the embodiment 1 in that:

[0144] Among the four fourth preset areas, any fourth preset area close to the two edges of the silicon substrate in the first direction is entirely covered with a fourth doped layer, and a passivation film layer and a fifth sub-gate are sequentially arranged on the fourth doped layer, and the fifth sub-gate is in contact with the fourth doped layer through an opening arranged on the passivation film layer.

[0145] The two sides of the solar cell slices obtained by cutting in this embodiment do not have a GAP area. It should be noted that in this embodiment, the GAP area refers to a region that only covers the passivation film layer but does not cover the doping layer.

[0146] Example 3

[0147] This embodiment provides a solar cell segment, which is different from the embodiment 1 in that:

[0148] Among the four fourth preset areas, the entire surface of the fourth preset area close to the two edges of the silicon substrate in the first direction is covered with a fourth doped layer, and a passivation film layer and a fifth sub-gate are sequentially arranged on the fourth doped layer, and the fifth sub-gate is in contact with the fourth doped layer through an opening arranged on the passivation film layer.

[0149] The three sides of the solar cell slices obtained by cutting in this embodiment do not have a GAP area. It should be noted that in this embodiment, the GAP area refers to an area that only covers the passivation film layer but does not cover the doping layer.

[0150] Example 4

[0151] This embodiment provides a solar cell segment, which is different from the embodiment 1 in that:

[0152] Three or four of the four fourth preset areas (two fourth preset areas close to the two edges of the silicon substrate in the first direction and one to two fourth preset areas close to the two edges of the silicon substrate in the second direction) are entirely covered with a fourth doped layer, and a passivation film layer and a fifth sub-gate are sequentially arranged on the fourth doped layer, and the fifth sub-gate is in contact with the fourth doped layer through an opening arranged on the passivation film layer.

[0153] In this embodiment, the four sides of at least one solar cell slice obtained by cutting do not have a GAP region. It should be noted that in this embodiment, the GAP region refers to a region that only covers the passivation film layer but does not cover the doping layer.

[0154] Comparative Example 1

[0155] This comparative example provides a solar cell segment, which differs from Example 1 in that:

[0156] The third preset area is only covered with a passivation film layer, that is, the solar cell slices obtained by cutting in this comparative example are all surrounded by GAP areas.

[0157] The solar cell slices obtained in Examples 1 to 4 and Comparative Example 1 were tested, and the specific results are shown in the following table:

[0158] Open circuit voltage Short circuit current Fill Factor Conversion efficiency Example 1 0.747 0.429 0.850 27.24％ Example 2 0.749 0.43 0.852 27.44％ Example 3 0.751 0.429 0.853 27.48％ Example 4 0.753 0.43 0.853 27.62％ Comparative Example 1 0.743 0.426 0.848 26.84％

[0159] It can be seen from the table that when the back contact solar cell structure of this embodiment is adopted, the open circuit voltage and fill factor can be effectively improved, thereby improving the conversion efficiency of the solar cell.

[0160] The above is a preferred embodiment of the invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the invention. These improvements and modifications are also considered to be within the scope of protection of the invention.

Claims

1. A back contact solar cell, characterized in that: include: A silicon substrate, comprising a light-receiving surface and a backlight surface that are arranged opposite to each other; The backlight surface includes a first preset area, a second preset area and a third preset area, the first preset area, the third preset area and the second preset area are arranged along a first direction, and the third preset area is an area for cutting the back contact solar cell; A first doping layer, a second doping layer and a third doping layer, wherein the first doping layer and the second doping layer are alternately arranged in the first preset region and the second preset region along a first direction; The third doping layer is disposed in the third preset region, and the third doping layer at least partially covers the third preset region.

2. The back contact solar cell according to claim 1, characterized in that The backlight surface further includes at least one fourth preset area arranged near the edge of the silicon substrate, the first preset area, the second preset area, and the third preset area constitute a main base surface, and the fourth preset area is located on the side of the main base surface; The fourth preset area extends along the first direction or the second direction, and the first direction intersects the second direction; The fourth preset area is at least partially covered with a passivation film layer, and no doping layer is provided.

3. The back contact solar cell according to claim 1, characterized in that The backlight surface is further provided with at least one fourth preset area arranged near the edge of the silicon substrate, the first preset area, the second preset area, and the third preset area constitute a main base surface, and the fourth preset area is located at the side of the main base surface; The fourth preset area extends along the first direction or the second direction, and the first direction intersects the second direction; A fourth doping layer and a passivation film layer are sequentially stacked in the fourth preset region; The fourth doping layer at least partially covers the fourth preset area.

4. The back contact solar cell according to claim 1, characterized in that: The center line of the silicon substrate in the first direction falls into the third preset area.

5. The back contact solar cell according to any one of claims 1 to 4, characterized in that: Also includes: a fifth doping layer; The third doping layer and the fifth doping layer are alternately arranged in the first direction and arranged in the third preset area; The third doping layer contacts the first doping layer, and the fifth doping layer contacts the second doping layer.

6. The back contact solar cell according to claim 1, characterized in that: Also includes: a first sub-grid and a second sub-grid; The first sub-gate and the second sub-gate are alternately arranged in the first preset area and the second preset area along the first direction, and extend along the second direction; the first sub-gate is arranged above the first doped layer and contacts the first doped layer, and the second sub-gate is arranged above the second doped layer and contacts the second doped layer.

7. The back contact solar cell according to claim 1, characterized in that: Also includes: A third sub-gate is disposed in the third preset region and extends along the second direction, and the third sub-gate contacts the third doping layer.

8. The back contact solar cell according to claim 5, characterized in that: Also includes: A third sub-grid and a fourth sub-grid, wherein the third sub-grid and the fourth sub-grid are alternately arranged along the first direction in the third preset area and extend along the second direction; The third sub-gate contacts the third doped layer, and the fourth sub-gate contacts the fifth doped layer.

9. The back contact solar cell according to claim 3, characterized in that: Also includes: A fifth sub-gate is disposed in the fourth preset region, and the fifth sub-gate is in contact with the fourth doping layer.

10. The back contact solar cell according to claim 6, characterized in that: Also includes: A first main grid and a second main grid; the first main grid and the second main grid are alternately arranged along the second direction and extend along the first direction; The first sub-grid is connected to the first main grid and insulated from the second main grid; the second sub-grid is connected to the second main grid and insulated from the first main grid.

11. The back contact solar cell according to claim 7, characterized in that: Also includes: A first main grid and a second main grid; the first main grid and the second main grid are alternately arranged along the second direction and extend along the first direction; The first auxiliary grid is connected to the first main grid and insulated from the second main grid; the second auxiliary grid is connected to the second main grid and insulated from the first main grid; The first main grid and the second main grid are only arranged in the first preset area and the second preset area; or The first main grid and the second main grid are arranged in the first preset area, the second preset area and the third preset area, and the first main grid and the second main grid are insulated from the third sub-grid; or The first main grid and the second main grid are arranged in the first preset area, the second preset area and the third preset area, and the first main grid is connected to the third sub-grid, and the second main grid is insulated from the third sub-grid.

12. The back contact solar cell according to claim 8, characterized in that: Also includes: A first main grid and a second main grid; the first main grid and the second main grid are alternately arranged along the second direction and extend along the first direction; The first auxiliary grid is connected to the first main grid and insulated from the second main grid; the second auxiliary grid is connected to the second main grid and insulated from the first main grid; The first main grid and the second main grid are only arranged in the first preset area and the second preset area; or The first main grid and the second main grid are arranged in the first preset area, the second preset area and the third preset area, and the first main grid and the second main grid are insulated from the third sub-grid and the fourth sub-grid; or The first main gate and the second main gate are arranged in the first preset area, the second preset area and the third preset area, and the first main gate is connected to the third sub-gate, and the first main gate is insulated from the fourth sub-gate; the second main gate is connected to the fourth sub-gate, and the second main gate is insulated from the third sub-gate.

13. The back contact solar cell according to any one of claims 1 to 3, characterized in that: Also includes: a sixth doping layer and a seventh doping layer, wherein the sixth doping layer and the seventh doping layer are alternately arranged in the first preset region and the second preset region along the second direction and extend along the first direction; The first direction intersects the second direction; The sixth doping layer contacts the first doping layer, and the second doping layer is disconnected at the sixth doping layer; The seventh doping layer contacts the second doping layer, and the first doping layer is disconnected at the seventh doping layer.

14. The back contact solar cell according to claim 13, characterized in that Also includes: a fifth doping layer; The third doping layer and the fifth doping layer are alternately arranged in the second direction and disposed in the third preset area; The third doping layer contacts the sixth doping layer, and the fifth doping layer contacts the seventh doping layer.

15. The back contact solar cell according to claim 13, characterized in that Also includes: a first sub-grid and a second sub-grid; The first auxiliary gate and the second auxiliary gate are alternately arranged in the first preset area and the second preset area along the first direction, and extend along the second direction; the first auxiliary gate is arranged above the first doped layer and contacts the first doped layer, and the second auxiliary gate is arranged above the second doped layer and contacts the second doped layer; and A first main grid and a second main grid; the first main grid and the second main grid are alternately arranged along the second direction and extend along the first direction; The first main gate is disposed above the sixth doping layer; the second main gate is disposed above the seventh doping layer; The first main grid is connected to the first sub-grid and insulated from the second sub-grid; the second main grid is connected to the second sub-grid and insulated from the first sub-grid.

16. The back contact solar cell according to claim 14, characterized in that Also includes: A first main grid and a second main grid; the first main grid and the second main grid are alternately arranged in the first preset area, the second preset area and the third preset area along the second direction, and extend along the first direction; A first main gate located in the first preset area and the second preset area is arranged above the sixth doping layer; The first main gate located in the third preset area is arranged above the third doping layer; The second main gate located in the first preset area and the second preset area is arranged above the seventh doping layer; The second main gate located in the third preset area is arranged above the fifth doping layer.

17. The back contact solar cell according to claim 1, wherein: Along the first direction, the width of the third preset area is less than or equal to 5 mm.

18. The back contact solar cell according to claim 1, wherein: The third doping layer has the same doping polarity as the silicon substrate.

19. The back contact solar cell according to any one of claims 1 to 3, characterized in that: It also includes a contact layer, which is disposed between adjacent first doping layers and second doping layers and enables the first doping layers to form contact with the second doping layers; The contact layer is arranged close to the edge of the silicon substrate.

20. A solar cell slice, characterized in that: The solar cell is obtained by cutting the back-contact solar cell according to any one of claims 1 to 19 along a cutting line, wherein the cutting line is arranged in the third preset area and extends along the second direction.

21. A battery assembly, characterized in that: It comprises the back-contact solar cell according to any one of claims 1 to 19 or the solar cell slice according to claim 20.

22. A photovoltaic system, characterized in that: Comprising a battery assembly as claimed in claim 21.

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