Back contact solar cell, slice, assembly and photovoltaic system

Abstract

The utility model 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 utility model relates to the field of silicon solar cell, especially to a back contact solar cell, piece, assembly and photovoltaic system. BACKGROUND

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

[0003] The central GAP area and the edge GAP area occupy the effective area of the cell piece, and reduce the conversion efficiency. Specifically, the central GAP area and the edge GAP area are generally only provided with a passivation layer (AlOx, SiNx, etc.), that is, no carrier is generated in this area, and it is also impossible to collect, which reduces the conversion efficiency. SUMMARY

[0004] The utility model wants to solve the technical problem, provide a back contact solar cell, piece, assembly and photovoltaic system, it can promote the surface passivation effect, promote the conversion efficiency.

[0005] In order to solve the above problem, the utility model discloses a back contact solar cell, which comprises:

[0006] A silicon substrate comprising oppositely arranged light-receiving surface and back surface; the back surface comprises first preset area, second preset area and third preset area, the first preset area, third preset area, second preset area along the first direction arrangement, the third preset area is the area for cutting the back contact solar cell;

[0007] First doped layer, second doped layer and third doped layer, the first doped layer and the second doped layer along the first direction alternately arranged in the first preset area and the second preset area; The third doped layer is arranged in the third preset area, and the third doped layer at least partially covers the third preset area.

[0008] As an improvement of the above technical solution, the back surface further comprises at least one fourth preset area arranged close to the edge of the silicon substrate, the first preset area, the second preset area and the third preset area form a main base surface, and the fourth preset area is located at 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 and the second direction intersect;

[0010] The fourth preset area is at least partially covered by a passivation film layer, and no doped layer is arranged.

[0011] As an improvement of the above technical solution, the backlight surface further comprises 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 form a main base surface, and the fourth preset area is located at 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 and the second direction intersect.

[0013] The fourth preset area is sequentially stacked with a fourth doped layer and a passivation film layer.

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

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

[0016] As an improvement of the above technical solution, further comprising:

[0017] A fifth doped layer, the third doped layer and the fifth doped layer are arranged alternately in the third preset area along the first direction.

[0018] The third doped layer is in contact with the first doped layer, and the fifth doped layer is in contact with the second doped layer.

[0019] As an improvement of the above technical solution, further comprising:

[0020] A first sub-gate and a second sub-gate, the first sub-gate and the second sub-gate are arranged alternately 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 in contact with the first doped layer, and the second sub-gate is arranged above the second doped layer and in contact with the second doped layer.

[0021] As an improvement of the above technical solution, further comprising:

[0022] A third sub-gate, the third sub-gate is arranged in the third preset area and extends along the second direction, and the third sub-gate is in contact with the third doped layer.

[0023] As an improvement of the above technical solution, further comprising:

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

[0025] The third sub-grid is in contact with the third doped layer, and the fourth sub-grid is in contact with the fifth doped layer.

[0026] As an improvement of the above technical solution, further comprising:

[0027] A fifth sub-grid is arranged in the fourth preset area, and the fifth sub-grid is in contact with the fourth doped layer.

[0028] As an improvement of the above technical solution, further comprising:

[0029] The first main grid and the second main grid are arranged alternately along the second direction and extend along the first direction; the first sub-grid is connected with the first main grid and insulated from the second main grid; and the second sub-grid is connected with the second main grid and insulated from the first main grid.

[0030] As an improvement of the above technical solution, further comprising:

[0031] The first main grid and the second main grid are arranged alternately along the second direction and extend along the first direction; the first sub-grid is connected with the first main grid and insulated from the second main grid; and the second sub-grid is connected with the second main grid and insulated from the first main grid.

[0032] The first main grid and the second main grid are arranged only 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 with 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, further comprising:

[0036] The first main grid and the second main grid are arranged alternately along the second direction and extend along the first direction; the first sub-grid is connected with the first main grid and insulated from the second main grid; and the second sub-grid is connected with the second main grid and insulated from the first main grid.

[0037] The first main grid and the second main grid are arranged only 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 auxiliary grid and the fourth auxiliary grid; or

[0039] 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 with the third auxiliary grid, and the first main grid is insulated from the fourth auxiliary grid; the second main grid is connected with the fourth auxiliary grid, and the second main grid is insulated from the third auxiliary grid.

[0040] As an improvement of the above technical solution, further comprising:

[0041] A sixth doped layer and a seventh doped layer, the sixth doped layer and the seventh doped layer are arranged alternately in the first preset area and the second preset area along a second direction, and extend along a first direction; the first direction intersects the second direction;

[0042] The sixth doped layer is in contact with the first doped layer, and the second doped layer is disconnected at the sixth doped layer;

[0043] The seventh doped layer is in contact with the second doped layer, and the first doped layer is disconnected at the seventh doped layer.

[0044] As an improvement of the above technical solution, further comprising:

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

[0046] As an improvement of the above technical solution, further comprising:

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

[0048] A first main grid and a second main grid; the first main grid and the second main grid are arranged alternately along a second direction, and extend along a first direction; the first main grid is arranged above the sixth doped layer; the second main grid is arranged above the seventh doped layer;

[0049] The first main grid is connected with the first auxiliary grid, and is insulated from the second auxiliary grid; the second main grid is connected with the second auxiliary grid, and is insulated from the first auxiliary grid.

[0050] As the improvement of the above technical scheme, further comprising:

[0051] The first main grid and the second main grid are arranged alternately in the second direction in the first preset area, the second preset area and the third preset area, and extend in the first direction; the first main grid in the first preset area and the second preset area is arranged above the sixth doped layer; the first main grid in the third preset area is arranged above the third doped layer;

[0052] The second main grid in the first preset area and the second preset area is arranged above the seventh doped layer; the second main grid in the third preset area is arranged above the fifth doped layer.

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

[0054] As the improvement of the above technical scheme, the third doped layer has the same doping polarity as the silicon substrate.

[0055] As the improvement of the above technical scheme, further comprising a contact layer, the contact layer is arranged between the adjacent first doped layer and the second doped layer, and the first doped layer and the second doped layer form a contact;

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

[0057] Correspondingly, the utility model discloses a kind of solar cell fragments, which is cut by the back contact solar cell described above along cutting line, and the cutting line is arranged in the third preset area and extends along the second direction.

[0058] Correspondingly, the utility model further discloses a kind of battery assembly, which includes the back contact solar cell described above or the solar cell fragment described above.

[0059] Correspondingly, the utility model further discloses a kind of photovoltaic system, which includes the battery assembly described above.

[0060] The utility model has the following beneficial effects:

[0061] The first preset area, the third preset area and the second preset area are arranged along a first direction in the back contact solar cell in the embodiment of the utility model; wherein, a plurality of first doped layers and second doped layers which are alternately arranged along the first direction are arranged in the first preset area and the second preset area, and a third doped layer is arranged in the third preset area, and the third doped layer at least partially covers the third preset area. The third doped layer is also arranged in the third preset area which is used to cut the silicon substrate in the embodiment, and the third doped layer can effectively improve the passivation effect and improve the conversion efficiency of the back contact solar cell. BRIEF DESCRIPTION OF DRAWINGS

[0062] Figure 1 It is the back surface structure schematic diagram of the back contact solar cell in the embodiment of the utility model;

[0063] Figure 2 It is the cross section structure schematic diagram of the back contact solar cell in the embodiment of the utility model;

[0064] Figure 3 It is the distribution schematic diagram of the doped layer of the back light surface of the silicon substrate in the embodiment of the utility model;

[0065] Figure 4 It is the distribution schematic diagram of each doped layer of the back light surface of the silicon substrate in another embodiment of the utility model;

[0066] Figure 5 It is the back surface structure schematic diagram of the back contact solar cell in another embodiment of the utility model;

[0067] Figure 6 It is the back surface structure schematic diagram of the back contact solar cell in another embodiment of the utility model;

[0068] In the drawing, 1 is a silicon substrate, 11 is a light receiving surface, 12 is a back light 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 doped layer, 22 is a second doped layer, 23 is a third doped layer, 24 is a fourth doped layer, 25 is a fifth doped layer, 26 is a sixth doped layer, 27 is a seventh doped layer, 31 is a first vice grid, 32 is a second vice grid, 33 is a third vice grid, 34 is a fourth vice grid, 35 is a fifth vice grid, 41 is a first main grid, 42 is a second main grid, 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 scheme and advantages of the utility model more clear, the utility model is described in further detail below.

[0070] Referring to Figure 1 andFigure 2 The utility model discloses an embodiment of a back contact battery, which comprises a silicon substrate 1, a first doped layer 21, a second doped layer 22 and a third doped layer 23. The silicon substrate 1 comprises a light receiving surface 11 and a back surface 12 arranged oppositely. The back 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 for forming the first doped layer 21 and the second doped layer 22, and then a gate line (electrode) structure is formed subsequently. The third preset area 130 is used for cutting the silicon substrate 1 in the later stage. The first preset area 110, the third preset area 130 and the second preset area 120 are arranged in the first direction in sequence.

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

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

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

[0074] The third doped layer 23 can partially cover or completely cover the third preset area 130. Specifically, the improvement range of the conversion efficiency can be determined comprehensively according to the arrangement of the electrode of the third preset area 130. Specifically, the following several embodiments can be included:

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

[0076] Further, based on the embodiment, the third doped layer 23 can be in contact with the first doped layer 21 or the second doped layer 22 having the same doping polarity as the third doped layer 23 and arranged in the first preset area 110 and the second preset area 120. Based on the above arrangement, the carriers in the third preset area can be collected even if no electrode is arranged in the third preset area, and the light emitting efficiency is improved.

[0077] (1.2) The third doped layer 23 partially covers the third preset area 130, and only the third doped layer 23 having a single doping polarity is arranged in the third preset area 130. The doping polarity of the third doped layer 23 is the same as or different from the doping polarity of the silicon substrate 1. It should be noted that since laser cutting process is needed for later splitting, if the third doped layer 23 covers the laser cutting area, the doping elements of the third doped layer 23 can be pushed into the silicon substrate 1. If the doping polarity of the third doped layer 23 is the same as the doping polarity of the silicon substrate 1, a region 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 mode that the third doped layer 23 partially covers the third preset area 130 can be adopted. More specifically, in one embodiment, the covering area of the third doped layer 23 is arranged to be staggered with the laser splitting area in the first direction; in another embodiment, two or more third doped layers 23 are arranged in the third preset area 130 along the first direction, and the laser splitting area is arranged between adjacent third doped layers 23.

[0078] Further, based on the embodiment, the third doped layer 23 can be in contact with the first doped layer 21 or the second doped layer 22 having the same doping polarity as the third doped layer 23 and arranged in the first preset area 110 and the second preset area 120. Based on the above arrangement, the carriers in the third preset area can be collected even if no electrode is arranged in the third preset area, and the light emitting efficiency is improved.

[0079] (1.3) Referring to Figure 1 , the third doped layer 23 partially covers the third preset area 130, and the fifth doped layer 25 is further arranged in the third preset area 130. The fifth doped layer 25 has a different doping polarity from the third doped layer 23, and the third doped layer 23 and the fifth doped layer 25 are insulated by the gap arranged therebetween. Based on the above embodiment, different polarity grid lines can be formed in the third preset area 130 in the later stage, thereby collecting carriers of different polarities and improving the conversion efficiency of the solar cell.

[0080] The number of the third doped layer 23 and the fifth doped layer 25 is one or more, but is not limited to this. When the number of the two is more, the third doped layer 23 and the fifth doped layer 25 can be arranged alternately along the first direction or the second direction, but are not limited to this. Specifically, in one embodiment, the third doped layer 23 and the fifth doped layer 25 are arranged alternately along the first direction and extend along the second direction. Based on this embodiment, the later laser cutting area can be arranged between the third doped layer 23 and the fifth doped layer 25, so as to reduce the probability of the doped elements of the third doped layer 23 and the fifth doped layer 25 entering the silicon substrate 1.

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

[0082] In one embodiment of the utility model, in order to optimize the passivation effect of the third preset area 130, the third preset area 130 is further covered with a passivation film layer 5, and the passivation film layer 5 is arranged above the third doped layer 23, the fifth doped layer 25 and the gap between the third doped layer 23 and the fifth doped layer 25.

[0083] In one embodiment of the utility model, referring to Figure 1 、 Figure 3 and Figure 4 , the back surface of the silicon substrate 1 further comprises at least one fourth preset area 140 arranged close to the edge of the silicon substrate 1. The first preset area 110, the second preset area 120 and the third preset area 130 form a main base surface 13, and the fourth preset area 140 is located at 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 this embodiment, the fourth preset area 140 can be covered with a passivation film layer 5, or the fourth preset area 140 is sequentially stacked with a fourth doped layer 24 and a passivation film layer 5. In this embodiment, the fourth doped 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 embodiment, the fourth doped layer 24 in the fourth preset area 140 can completely cover or partially cover the fourth preset area 140, and the specific implementation manner can be as follows:

[0085] (2.1) refer to Figure 1 and Figure 3 The fourth doping layer 24 completely covers the fourth preset area 140, and the doping polarity of the fourth doping layer 24 is the same as or different from that of the silicon substrate 1. Based on the embodiment, a gate line (electrode) can be arranged in the fourth preset area 140, thereby improving the carrier collection area and the conversion efficiency of the solar cell. Preferably, the doping polarity of the silicon substrate 1 is different from that of the fourth doping layer 24, which can further improve the area of the emitter and the conversion efficiency.

[0086] Further, based on the embodiment, the fourth doping layer 24 can be connected with the first doping layer 21 or the second doping layer 22 arranged in the first preset area 110 and the second preset area 120 and having the same doping polarity as the fourth doping layer 24. Based on the above arrangement, the carriers in the fourth preset area 140 can be collected without arranging an electrode in the fourth preset area 140, thereby improving the conversion efficiency.

[0087] (2.2) refer to Figure 4 The fourth doping layer 24 partially covers the fourth preset area 140, and only the fourth doping layer 24 is arranged in the fourth preset area 140. The doping polarity of the fourth doping layer 24 is the same as or different from that of the silicon substrate 1. Based on the arrangement, the area of laser scribing can be avoided, and the adverse effects of the laser on the silicon substrate 1 caused by the doping elements can be prevented. Specifically, in one embodiment, the fourth doping layer 24 is disconnected in the area of the laser line in the fourth preset area 140.

[0088] Further, based on the embodiment, the fourth doping layer 24 can be connected with the first doping layer 21 or the second doping layer 22 arranged in the first preset area 110 and the second preset area 120 and having the same doping polarity as the fourth doping layer 24, so that the carriers in the fourth preset area 140 can be collected without arranging an electrode in the fourth preset area 140, thereby improving the conversion efficiency.

[0089] In some embodiments of the utility model, the interval between the first doping layer 21 and the second doping layer 22 is 1-50 mu m, and is exemplarily 3 mu m, 8 mu m, 12 mu m, 20 mu m, 25 mu m, 30 mu m, 35 mu m, 40 mu m or 48 mu m, but is not limited to this. Preferably, it is 10-50 mu m.

[0090] In some embodiments of the utility model, the interval between the third doping layer 23 and the fifth doping layer 25 is 1-50 mu m, and is exemplarily 3 mu m, 8 mu m, 12 mu m, 20 mu m, 25 mu m, 30 mu m, 35 mu m, 40 mu m or 48 mu m, but is not limited to this. Preferably, it is 10-50 mu m.

[0091] In some embodiments of the utility model, the interval between the third doping layer 23 and the fifth doping layer 25 is 1-50 mu m, and is exemplarily 3 mu m, 8 mu m, 12 mu m, 20 mu m, 25 mu m, 30 mu m, 35 mu m, 40 mu m or 48 mu m, but is not limited to this. Preferably, it is 10-50 mu m.Figure 1 、 Figure 2 The back contact solar cell further comprises a first sub-grid 31 and a second sub-grid 32, the first sub-grid 31 and the second sub-grid 32 are arranged in the first direction in the first preset area 110 and the second preset area 120 alternately and extend in the second direction. The first sub-grid 31 is arranged above the first doped layer 21 and in contact with the first doped layer 21, and the second sub-grid 32 is arranged above the second doped layer 22 and in contact with the second doped layer 22. Specifically, a passivation film layer 5 is arranged between the first sub-grid 31 and the first doped layer 21 and between the second sub-grid 32 and the second doped layer 22, the first sub-grid 31 is connected with the first doped layer 21 through a plurality of openings arranged on the first passivation film layer 5, and the second sub-grid 32 is connected with the second doped layer 22 through a plurality of openings arranged 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 burning, etc., but are not limited thereto.

[0092] Preferably, in some embodiments of the utility model, a sub-grid is also arranged in the third preset area 130, and the specific arrangement mode can include the following cases:

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

[0094] Specifically, the number of the third sub-grid 33 can be one or more. Specifically, when the number of the third sub-grid 33 is more, the third sub-grid 33 can be arranged correspondingly with a plurality of third doped layers 23 arranged in the third preset area 130.

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

[0096] Specifically, the number of the third auxiliary grid 33 and the fourth auxiliary grid 34 is one or more, which can be arranged alternately along the first direction or the second direction. The specific arrangement direction and the extension direction can be determined according to the arrangement direction and the extension direction of the third doped layer 23 and the fifth doped layer 25. For example, in one embodiment, the third auxiliary grid 33 and the fourth auxiliary 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 auxiliary grid 33 and the fourth auxiliary grid 34 are parallel to the first auxiliary grid 31 and the second auxiliary grid 32. In another embodiment, the third auxiliary grid 33 and the fourth auxiliary 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 auxiliary grid 33 and the fourth auxiliary grid 34 can be distributed in the area used for forming the main grid and / or the solder tape later, so as to facilitate the current collection.

[0097] In one embodiment of the utility model, a fifth auxiliary grid 35 corresponding to the doping polarity of the fourth doped layer 24 can also be arranged in the fourth preset area 140 to collect the current carriers in the area. The fifth auxiliary grid 35 can be connected with the fourth doped layer 24 through the opening arranged on the passivation film layer 5.

[0098] The back contact battery of the embodiment can be applied to the back contact battery with a main grid or the back contact battery without a main grid, but is not limited thereto.

[0099] In one embodiment of the utility model, referring to Figure 1 、 Figure 2 The back contact battery further comprises a first main grid 41 and a second main grid 42, the first main grid 41 and the second main grid 42 are arranged alternately along the second direction and extend along the first direction, the first main grid 41 is connected with the first auxiliary grid 31 and is insulated from the second auxiliary grid 32, so as to realize the current collection of the first auxiliary grid 31; the second main grid 42 is connected with the second auxiliary grid 32 and is insulated from the first auxiliary grid 31, so as to realize the current collection of the second auxiliary grid 32. The first auxiliary grid 31 can be disconnected at the position of the second main grid 42, or an insulating glue, an insulating layer or the like can be formed on the first auxiliary grid 31, so as to realize the insulation between the first auxiliary grid 31 and the second main grid 42. Correspondingly, the second auxiliary grid 32 can also be insulated from the first main grid 41 by means of disconnection, insulating glue or insulating layer.

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

[0101] Preferably, according to the need of collecting current carriers, the distribution mode of the main grid can adopt the following embodiments:

[0102] (4.1) The first main grid 41 and the second main grid 42 are only arranged in the first preset area 110 and the second preset area 120, i.e. no main grid is arranged in the third preset area 130. Based on this mode, the solder points can be formed on the third auxiliary grid 33 and the fifth auxiliary grid 35 when the component is formed later to collect the carriers of the third auxiliary grid 33 and the fifth auxiliary grid 35. Alternatively, the third doped layer 23 and the fifth doped layer 25 can be arranged in contact with the first doped layer 21 and the second doped layer 22 respectively to collect the carriers through the first auxiliary grid 31 and the second auxiliary grid 32 arranged above the first doped layer 21 and the second doped layer 22, but the present application is not limited thereto.

[0103] (4.2) 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, but the first main grid 41 and the second main grid 42 in the third preset area 130 are insulated from the third auxiliary grid 33 and the fourth auxiliary grid 34. Based on this mode, the solder points can be formed on the third auxiliary grid 33 and the fifth auxiliary grid 35 when the component is formed later to collect the carriers of the third auxiliary grid 33 and the fifth auxiliary grid 35. Alternatively, the third doped layer 23 and the fifth doped layer 25 can be arranged in contact with the first doped layer 21 and the second doped layer 22 respectively to collect the carriers through the first auxiliary grid 31 and the second auxiliary grid 32 arranged above the first doped layer 21 and the second doped layer 22, but the present application is not limited thereto.

[0104] (4.3) Referring to 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, and the first main grid 41 and the second main grid 42 in the third preset area 130 are connected with the third auxiliary grid 33 or the fourth auxiliary grid 34 having the same polarity as them respectively, and are insulated from the auxiliary grid having the opposite polarity, so as to realize the convergence of the current on the third auxiliary grid 33 and the fourth auxiliary grid 34 through the first main grid 41 and the second main grid 42.

[0105] Preferably, referring to Figure 4 , in an embodiment, the back contact cell is further provided with a contact layer 7 arranged between the adjacent first doped layer 21 and second doped layer 22 and making the first doped layer 21 and the second doped layer 22 form a contact; based on this structure, a leakage composite contact structure can be formed to improve the reverse leakage characteristics and the ability to resist hot spot risks. Preferably, in an embodiment, the contact layer 7 is arranged close to the edge of the silicon substrate.

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

[0107] , referring to 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. The sixth doping layer 26 and the seventh doping layer 27 are alternately arranged along the second direction within the first preset area 110 and the second preset area 120, and extend along the first direction; the sixth doping layer 26 contacts the first doping layer 21, and the second doping layer 22 is disconnected at the sixth doping layer 26; the seventh doping layer 27 contacts 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, auxiliary gates, and main gates in the third preset area 130 needs to be adaptively adjusted. Specifically as follows:

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

[0109] (5.1) The third doped layer 23 completely covers the third predetermined area 130, and the third doped layer 23 and the silicon substrate 1 have the same or different doping polarity. Based on this embodiment, the carrier collection area can be increased, thereby improving the conversion efficiency of the solar cell. Preferably, the silicon substrate 1 and the third doped layer 23 have different doping polarities, which can further increase the emitter area and improve 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 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, carrier collection in the third preset area 130 can be achieved even when no electrode is arranged in the third preset area 130, thereby improving conversion efficiency.

[0111] (5.2) The third doped layer 23 partially covers the third preset area 130, and only the third doped layer 23 with a single doping polarity is arranged in the third preset area 130. The doping polarity of the third doped layer 23 is the same as or different from the doping polarity of the silicon substrate 1. It should be noted that since laser cutting process is required in the later stage, if the third doped layer 23 covers the laser cutting area, the doping elements of the third doped layer 23 may advance into the silicon substrate 1, and if the doping polarity of the third doped layer 23 is the same as the doping polarity of the silicon substrate 1, a region 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 mode that the third doped layer 23 partially covers the third preset area 130 can be adopted. More specifically, in one embodiment, the covering area of the third doped layer 23 is arranged to be staggered with the laser cleaving area in the first direction; in another embodiment, two or more third doped layers 23 are arranged in the third preset area 130 along the first direction, and the laser cleaving area is arranged between adjacent third doped layers 23.

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

[0113] (5.3) Referring to Figure 5 , Figure 6 , the third doped layer 23 partially covers the third preset area 130, and the fifth doped layer 25 is further arranged in the third preset area 130, the fifth doped layer 25 has a different doping polarity from the third doped layer 23, and the third doped layer 23 and the fifth doped layer 25 are insulated by the gap arranged therebetween. Based on the above-mentioned embodiment, different-polarity gate lines can be formed in the third preset area 130 in the later stage, so as to collect different-polarity carriers and improve the conversion efficiency of the solar cell.

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

[0115] For the sub-gates in the first preset area 110 and the second preset area 120, in the embodiment, the first sub-gate 31 and the second sub-gate 32 are arranged in the first direction and extend in the second direction. The first sub-gate 31 is arranged above the first doped layer 21 and is in contact with the first doped layer 21 through the opening in the passivation film layer 5. The first sub-gate 31 is disconnected in the region corresponding to the seventh doped layer 27. Correspondingly, the second sub-gate 32 is arranged above the second doped layer 22 and is in contact with the second doped layer 22 through the opening in the passivation film layer 5. The second sub-gate 32 is disconnected in the region corresponding to the sixth doped layer 26.

[0116] For the sub-gates in the third preset area 130, in the embodiment, the following embodiments can be used:

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

[0118] Specifically, the number of the third sub-gate 33 can be one or more. Specifically, when the number of the third sub-gate 33 is more, the third sub-gate 33 can be arranged corresponding to the plurality of third doped layers 23 arranged in the third preset area 130.

[0119] The third sub-gate 33 can be continuous or discontinuous, but is not limited thereto.

[0120] (6.2) Referring to Figure 6In the third preset area 130, a third auxiliary gate 33 and a fourth auxiliary gate 34 with different polarities are arranged. The third auxiliary gate 33 is arranged above the third doped layer 23 and is connected with the third doped layer 23 through an opening in the passivation film layer 5. The fourth auxiliary gate 34 is arranged above the fifth doped layer 25 and is connected with the fifth doped layer 25 through an opening in 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, and the carrier collection efficiency is improved.

[0121] Specifically, in this embodiment, the number of the third auxiliary gate 33 and the fourth auxiliary gate 34 can be one or more, but is not limited to this. The third auxiliary gate 33 and the fourth auxiliary gate 34 can be continuous or discontinuous, but are not limited to this.

[0122] (6.3) Referring to Figure 5 In the third preset area 130, no auxiliary gate is arranged, and the first main gate 41 and the second main gate 42 are directly extended to the third preset area 130 to collect carriers.

[0123] For the main gate, in this embodiment, the following embodiments can be specifically implemented:

[0124] (7.1) The first main gate 41 and the second main gate 42 are arranged only 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. The first main gate 41 in the first preset area 110 and the second preset area 120 is arranged above the sixth doped layer 26. The second main gate 42 in the first preset area 110 and the second preset area 120 is arranged above the seventh doped layer 27. The first main gate 41 is connected with the first auxiliary gate 31 and is insulated from the second auxiliary gate 32. The second main gate 42 is connected with the second auxiliary gate 32 and is insulated from the first auxiliary gate 31. Based on this mode, the solder joints can be formed on the third auxiliary gate 33 and the fifth auxiliary gate 35 when the assembly is formed later, so as to collect the carriers of the third auxiliary gate 33 and the fifth auxiliary gate 35. The third doped layer 23 and the fifth doped layer 25 can also be arranged to be in contact with the first doped layer 21 and the second doped layer 22 respectively, so as to collect the carriers through the first auxiliary gate 31 and the second auxiliary gate 32 arranged above the first doped layer 21 and the second doped layer 22, but are not limited to this.

[0125] (7.2) 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 in the first preset area 110 and the second preset area 120 is arranged above the sixth doped layer 26. The second main grid 42 in the first preset area 110 and the second preset area 120 is arranged above the seventh doped layer 27 and contacts the seventh doped layer 27 through the opening arranged on the passivation layer 5. The first main grid 41 is connected with the first auxiliary grid 31 and is insulated from the second auxiliary grid 32. The second main grid 42 is connected with the second auxiliary grid 32 and is insulated from the first auxiliary grid 31.

[0126] The first main grid 41 and the second main grid 42 in the third preset area 130 are insulated from the third auxiliary grid 33 and the fourth auxiliary grid 34. In this way, the soldering points can be formed on the third auxiliary grid 33 and the fifth auxiliary grid 35 to collect the carriers of the third auxiliary grid 33 and the fifth auxiliary grid 35 when the component is formed later. The third doped layer 23 and the fifth doped layer 25 can also be arranged to contact the first doped layer 21 and the second doped layer 22 respectively to collect the carriers through the first auxiliary grid 31 and the second auxiliary grid 32 arranged above the first doped layer 21 and the second doped layer 22, but are not limited thereto.

[0127] (7.3) Referring to Figure 6 , 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 in the first preset area 110 and the second preset area 120 is arranged above the sixth doped layer 26. The second main grid 42 in the first preset area 110 and the second preset area 120 is arranged above the seventh doped layer 27. The first main grid 41 is connected with the first auxiliary grid 31 and is insulated from the second auxiliary grid 32. The second main grid 42 is connected with the second auxiliary grid 32 and is insulated from the first auxiliary grid 31.

[0128] The first main grid 41 in the third preset area 130 is connected with the third auxiliary grid 33 and is insulated from the fourth auxiliary grid 34. The second main grid 42 in the third preset area 130 is connected with the fourth auxiliary grid 34 and is insulated from the third auxiliary grid 33. In this way, the first main grid 41 and the second main grid 42 can be formed later to collect the carriers of the third preset area 130 collected by the third auxiliary grid 33 and the fourth auxiliary grid 34.

[0129] (7.4) Referring to Figure 6The 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 in the first preset area 110 and the second preset area 120 is arranged above the sixth doped layer 26. The second main grid 42 in the first preset area 110 and the second preset area 120 is arranged above the seventh doped layer 27. The first main grid 41 is connected with the first auxiliary grid 31 and is insulated from the second auxiliary grid 32. The second main grid 42 is connected with the second auxiliary grid 32 and is insulated from the first auxiliary grid 31.

[0130] The first main grid 41 in the third preset area 130 is arranged above the third doped layer 23 and is connected with the third doped layer 23 through the opening arranged on the passivation film layer 5. The second main grid 42 in the third preset area 130 is arranged above the fifth doped layer 25 and is connected with the fifth doped layer 25 through the opening arranged on the passivation film layer 5. According to the embodiment, the carriers generated in the third preset area 130 can be directly collected by the first main grid 41 and the second main grid 42, and no other auxiliary grid needs to be arranged in the third preset area 130, thereby simplifying the printing process.

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

[0132] Correspondingly, the embodiment also discloses a solar cell piece cut from the back contact solar cell. Specifically, the cutting can be splitting, laser cutting, etc., but is not limited thereto. When cutting, the cutting is performed along the cutting line 6 arranged in the third preset area 130. The cutting line 6 can be arranged at any position of the third preset area 130. Preferably, in one embodiment, the cutting line is arranged at the edge of the third preset area 130. According to the embodiment, after cutting, at least one of the cell pieces can not be provided with the third preset area 130, thereby further improving the conversion efficiency.

[0133] Correspondingly, the embodiment also discloses a cell module which can include the back contact solar cell or the solar cell piece cut from the back contact solar cell.

[0134] Correspondingly, the embodiment also discloses a photovoltaic system which includes the cell module.

[0135] The utility model will be further described below with specific examples:

[0136] Example 1

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

[0138] The back contact solar cell comprises a silicon substrate, which comprises oppositely arranged light-receiving surfaces and back surfaces; the back surface comprises one first preset area, one second preset area and one 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 middle 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 further arranged around the main base surface.

[0139] The first preset area and the second preset area are provided with a plurality of first doped layers and second doped layers, and the first doped layers and the second doped layers are alternately arranged along the first direction. A first auxiliary grid is arranged above the first doped layer and contacts the first doped layer through an opening arranged on a passivation film layer, and a second auxiliary grid is arranged above the second doped layer and contacts the second doped layer through an opening arranged on the passivation film layer. The second preset area is further provided with a plurality of first main grids and second main grids, wherein the first main grids and the second main grids are alternately arranged along a second direction and extend along the first direction; the first auxiliary grid is connected with the first main grid and is insulated from the second main grid; and the second auxiliary grid is connected with the second main grid and is insulated from the first main grid.

[0140] The third preset area is provided with a third doped layer covering the whole surface of the third preset area, and the third doped layer has the same doping polarity as the first doped layer. A passivation film layer and a third auxiliary grid are sequentially arranged on the third doped layer, and the third auxiliary grid contacts the third doped layer through an opening on the passivation film layer. The first main grid extends to the third preset area and is connected with the third auxiliary grid. The fourth preset area is only fully covered with the passivation film layer.

[0141] One side of the solar cell piece obtained by cutting in the embodiment is not provided with a GAP area, and the other three sides are provided with GAP areas. It should be noted that in the embodiment, the GAP area refers to an area covered only with a passivation film layer and not with a doped layer.

[0142] Example 2

[0143] The embodiment provides a solar cell piece, which is different from the solar cell piece of example 1 in that:

[0144] In the four fourth preset regions, the fourth preset regions close to either of the two edges of the first direction of the silicon substrate are entirely covered with a fourth doped layer, and a passivation film layer and a fifth auxiliary gate are sequentially arranged on the fourth doped layer, and the fifth auxiliary gate is in contact with the fourth doped layer through an opening arranged on the passivation film layer.

[0145] The solar cell pieces obtained by cutting in the embodiment do not have a GAP region on two side edges. It should be noted that in the embodiment, the GAP region refers to a region covering only the passivation film layer but not the doped layer.

[0146] Embodiment 3

[0147] The solar cell piece provided in the embodiment is different from that in Embodiment 1 in that:

[0148] In the four fourth preset regions, the fourth preset regions close to either of the two edges of the first direction of the silicon substrate are entirely covered with a fourth doped layer, and a passivation film layer and a fifth auxiliary gate are sequentially arranged on the fourth doped layer, and the fifth auxiliary gate is in contact with the fourth doped layer through an opening arranged on the passivation film layer.

[0149] The solar cell pieces obtained by cutting in the embodiment do not have a GAP region on three side edges. It should be noted that in the embodiment, the GAP region refers to a region covering only the passivation film layer but not the doped layer.

[0150] Embodiment 4

[0151] The solar cell piece provided in the embodiment is different from that in Embodiment 1 in that:

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

[0153] The solar cell pieces obtained by cutting in the embodiment do not have a GAP region on four side edges. It should be noted that in the embodiment, the GAP region refers to a region covering only the passivation film layer but not the doped layer.

[0154] Comparative Example 1

[0155] The solar cell piece provided in the comparative example is different from that in Embodiment 1 in that:

[0156] The third preset region is only covered with a passivation film layer. That is, the solar cell piece obtained by cutting in the comparative example has a GAP region around the periphery.

[0157] The solar cells obtained in Examples 1 to 4 and Comparative Example 1 were tested, and the 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] As can be seen from the table, when the back contact solar cell structure of the present embodiment is used, the open circuit voltage and the fill factor can be effectively improved, and thus the conversion efficiency of the solar cell is improved.

[0160] The above is the preferred embodiment of the utility model, it should be pointed out that, for ordinary skilled in the art, without departing from the principle of the utility model, can also make a number of improvements and refinements, these improvements and refinements also as the protection scope of the utility model.

Claims

1. A back contact solar cell, characterized by, The application relates to a silicon substrate, which comprises a light-receiving surface and a back surface arranged oppositely; the back 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, the third preset area is an area for cutting the back-contact solar cell; a first doped layer, a second doped layer and a third doped layer are arranged alternately in the first preset area and the second preset area along the first direction; the third doped layer is arranged in the third preset area and at least partially covers the third preset area. The back surface further comprises 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 form a main base surface, and the fourth preset area is arranged 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 and the second direction intersect; the fourth preset area is at least partially covered with a passivation film layer, and no doped layer is arranged. The back surface further comprises 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 form a main base surface, and the fourth preset area is arranged 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 and the second direction intersect; the fourth preset area is at least partially covered with a passivation film layer, and no doped layer is arranged. The back surface further comprises 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 form a main base surface, and the fourth preset area is arranged 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 and the second direction intersect; the fourth preset area is at least partially covered with a passivation film layer, and no doped layer is arranged. The back surface further comprises 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 form a main base surface, and the fourth preset area is arranged 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 and the second direction intersect; the fourth preset area is at least partially covered with a passivation film layer, and no doped layer is arranged.

2. The back contact solar cell of claim 1, wherein, The silicon substrate falls in the third preset area along the middle line of the first direction. The application further relates to a silicon substrate, which comprises a light-receiving surface and a back surface arranged oppositely; the back 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, the third preset area is an area for cutting the back-contact solar cell; a first doped layer, a second doped layer and a third doped layer are arranged alternately in the first preset area and the second preset area along the first direction; the third doped layer is arranged in the third preset area and at least partially covers the third preset area. The application further relates to a silicon substrate, which comprises a light-receiving surface and a back surface arranged oppositely; the back 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, the third preset area is an area for cutting the back-contact solar cell; a first doped layer, a second doped layer and a third doped layer are arranged alternately in the first preset area and the second preset area along the first direction; the third doped layer is arranged in the third preset area and at least partially covers the third preset area.

3. The back contact solar cell of claim 1, wherein, The application further relates to a silicon substrate, which comprises a light-receiving surface and a back surface arranged oppositely; the back 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, the third preset area is an area for cutting the back-contact solar cell; a first doped layer, a second doped layer and a third doped layer are arranged alternately in the first preset area and the second preset area along the first direction; the third doped layer is arranged in the third preset area and at least partially covers the third preset area. The application further relates to a silicon substrate, which comprises a light-receiving surface and a back surface arranged oppositely; the back 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, the third preset area is an area for cutting the back-contact solar cell; a first doped layer, a second doped layer and a third doped layer are arranged alternately in the first preset area and the second preset area along the first direction; the third doped layer is arranged in the third preset area and at least partially covers the third preset area. The application further relates to a silicon substrate, which comprises a light-receiving surface and a back surface arranged oppositely; the back 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, the third preset area is an area for cutting the back-contact solar cell; a first doped layer, a second doped layer and a third doped layer are arranged alternately in the first preset area and the second preset area along the first direction; the third doped layer is arranged in the third preset area and at least partially covers the third preset area. ​ 4. The back contact solar cell of claim 1, wherein, ​ 5. The back contact solar cell according to any one of claims 1 to 4, wherein ​ ​ ​ ​ 6. The back contact solar cell of claim 1 wherein, ​ ​ ​ 7. The back contact solar cell of claim 6, wherein the back surface field is formed by a p-type layer of silicon doped with boron. ​ ​ 8. The back contact solar cell of claim 6, wherein, ​ ​ ​ 9. The back contact solar cell of claim 3, wherein, ​ ​ 10. The back contact solar cell of claim 6, wherein, ​ ​ The first auxiliary gate is connected with the first main gate and insulated from the second main gate; and the second auxiliary gate is connected with the second main gate and insulated from the first main gate.

11. The back contact solar cell of claim 7, wherein the back surface field is formed by a p-type layer of silicon doped with boron. Further comprising: The first main gate and the second main gate are arranged alternately along a second direction and extend along a first direction; The first auxiliary gate is connected with the first main gate and insulated from the second main gate; and the second auxiliary gate is connected with the second main gate and insulated from the first main gate. The first main gate and the second main gate are arranged only in the first preset area and the second preset area; 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 and the second main gate are insulated from the third auxiliary gate; 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 with the third auxiliary gate, and the second main gate is insulated from the third auxiliary gate.

12. The back contact solar cell of claim 8, wherein, Further comprising: The first main gate and the second main gate are arranged alternately along a second direction and extend along a first direction; The first auxiliary gate is connected with the first main gate and insulated from the second main gate; and the second auxiliary gate is connected with the second main gate and insulated from the first main gate. The first main gate and the second main gate are arranged only in the first preset area and the second preset area; 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 and the second main gate are insulated from the third auxiliary gate and the fourth auxiliary gate; 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 with the third auxiliary gate, and the first main gate is insulated from the fourth auxiliary gate; the second main gate is connected with the fourth auxiliary gate, and the second main gate is insulated from the third auxiliary gate.

13. The back contact solar cell of any of claims 1-3, wherein the back surface field is formed by a p-type layer of silicon doped with boron. Further comprising: The sixth doped layer and the seventh doped layer are arranged alternately along a second direction in the first preset area and the second preset area and extend along a first direction; The first direction intersects with the second direction; The sixth doped layer is in contact with the first doped layer, and the second doped layer is disconnected at the sixth doped layer; The seventh doped layer is in contact with the second doped layer, and the first doped layer is disconnected at the seventh doped layer.

14. The back contact solar cell of claim 13, wherein, Further comprising: The fifth doped layer; The third doped layer and the fifth doped layer are arranged alternately along a second direction in the third preset area; The third doped layer is in contact with the sixth doped layer, and the fifth doped layer is in contact with the seventh doped layer.

15. The back contact solar cell of claim 13, wherein the back surface field is formed by a p-type layer of silicon doped with boron. 15 Further comprising: The first auxiliary gate and the second auxiliary gate; The first auxiliary gate and the second auxiliary gate are arranged alternately along a first direction in the first preset area and the second preset area and extend along a second direction; the first auxiliary gate is arranged above the first doped layer and in contact with the first doped layer, and the second auxiliary gate is arranged above the second doped layer and in contact with the second doped layer; And a first main grid and a second main grid; the first main grid and the second main grid are arranged alternately along a second direction and extend along a first direction; the first main grid is arranged above the sixth doped layer; the second main grid is arranged above the seventh doped layer; the first main grid is connected with the first auxiliary grid and is insulated from the second auxiliary grid; the second main grid is connected with the second auxiliary grid and is insulated from the first auxiliary grid.

16. The back contact solar cell of claim 14, wherein, Further comprising: a first main grid and a second main grid; the first main grid and the second main grid are arranged alternately along a second direction and extend along a first direction; the first main grid arranged in the first preset area and the second preset area is arranged above the sixth doped layer; the first main grid arranged in the third preset area is arranged above the third doped layer; the second main grid arranged in the first preset area and the second preset area is arranged above the seventh doped layer; the second main grid arranged in the third preset area is arranged above the fifth doped layer.

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

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

19. The back contact solar cell of any of claims 1-3, wherein, Further comprising a contact layer arranged between adjacent first doped layer and second doped layer and making the first doped layer and the second doped layer form a contact; the contact layer is arranged close to the edge of the silicon substrate.

20. A solar cell chip, characterized by It is cut from the back contact solar cell as claimed in any one of claims 1-19 along a cutting line arranged in the third preset area and extending along the second direction.

21. A battery assembly characterized by, It comprises the back contact solar cell as claimed in any one of claims 1-19 or the solar cell fragment as claimed in claim 20.

22. A photovoltaic system characterized by, It comprises the battery assembly as claimed in claim 21.

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