Back contact solar cell, photovoltaic module and photovoltaic system

Abstract

The invention is suitable for the technical field of solar cells, and provides a back contact solar cell, a photovoltaic module and a photovoltaic system.The back contact solar cell comprises a silicon wafer, the back face of the silicon wafer comprises a plurality of first areas, the first areas are P-type areas or N-type areas, and at least one first area comprises a first morphology area and a second morphology area; the first morphology area and the second morphology area are both polished surfaces; the first morphology area comprises a plurality of first tower footings, the second morphology area comprises a plurality of second tower footings, and the length of the longest diagonal line of the largest first tower footing of the first morphology area is smaller than that of the longest diagonal line of the largest second tower footing of the second morphology area. According to the back contact solar cell, the double-sided rate of the cell can be improved, meanwhile, small recombination loss of the back face of the cell is kept, and balance of the two effects is achieved, so that the power of a photovoltaic module is effectively improved, and the photovoltaic generating capacity is increased.

Description

Technical Field

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

[0002] Back contact (Interdigitated back contact, IBC) solar cells, also known as interdigitated back contact cells, have positive and negative electrode grid lines designed on the back of the cell, so that the front surface is completely free from the shading of metal grid lines, eliminating the optical loss caused by the shading of electrode grid lines. At the same time, the electrode grid lines can be designed to be wider than the existing ones, reducing the series resistance loss, thereby greatly improving the cell conversion efficiency. In addition, due to the design of no electrode grid lines on the front of the cell, the product appearance is more beautiful and suitable for a variety of application scenarios.

[0003] In the prior art, the entire P-type region or N-type region of a back-contact solar cell is usually a polished surface with the same morphology, which results in a lower bifaciality of the back-contact solar cell. However, if the P-type region and the N-type region are directly made into a velvet surface, although the bifaciality of the cell can be improved, it will lead to greater back-side recombination losses and affect the back-side passivation effect, thereby reducing cell efficiency. Therefore, it is difficult to achieve an increase in the bifaciality while maintaining a smaller recombination loss on the back of the cell. Summary of the invention

[0004] The present invention provides a back-contact solar cell, aiming to solve the problem that it is difficult to improve the bifaciality and keep the recombination loss on the back side of the cell at the same time in the prior art back-contact solar cells.

[0005] The present invention provides a back-contact solar cell, comprising a silicon wafer, wherein the back side of the silicon wafer comprises a plurality of first regions, wherein the first regions are P-type regions or N-type regions, and at least one of the first regions comprises a first morphology region and a second morphology region, wherein both the first morphology region and the second morphology region are polished surfaces;

[0006] The first morphology area includes a plurality of first tower bases, the second morphology area includes a plurality of second tower bases, and the longest diagonal length of the largest first tower base in the first morphology area is smaller than the longest diagonal length of the largest second tower base in the second morphology area.

[0007] A back-contact solar cell provided by the present invention sets at least one first area on the back side of a silicon wafer to include a first morphology area and a second morphology area, both of which are polished surfaces, and the longest diagonal length of the largest first tower base in the first morphology area is smaller than the longest diagonal length of the largest second tower base in the second morphology area, and by reducing the tower base size of the first morphology area, increasing the roughness of the first morphology area, and reducing the light reflectivity of the back side of the silicon wafer, the cell bifaciality is improved; and, since only the first tower base size of the first morphology area which is a polished surface needs to be set smaller than the second tower base size of the second morphology area, the cell bifaciality can be improved, and at the same time, a smaller composite loss on the back side is maintained, reducing the influence on the back side passivation effect, achieving a balance between the two effects, and effectively improving the efficiency of the back side of the cell, improving the power of the photovoltaic module, and increasing the photovoltaic power generation.

[0008] Preferably, the back side of the silicon wafer further includes a plurality of second regions, the first regions and the second regions are alternately arranged in sequence, one of the first region and the second region is a P-type region, and the other is an N-type region;

[0009] At least one of the second regions includes a third morphology region and a fourth morphology region, and both the third morphology region and the fourth morphology region are polished surfaces;

[0010] The third morphology area includes a plurality of third tower bases, the fourth morphology area includes a plurality of fourth tower bases, and the longest diagonal length of the largest third tower base in the third morphology area is smaller than the longest diagonal length of the largest fourth tower base in the fourth morphology area.

[0011] Under the premise of setting the first morphological region in the first region, the present invention further sets at least one second region to include a third morphological region and a fourth morphological region, which can further improve the bifaciality of the battery and maintain a low back side recombination loss, thereby achieving a balance between the two effects, further improving the efficiency of the back side of the battery, improving the power of the photovoltaic module, and increasing the photovoltaic power generation.

[0012] Preferably, the first region is a P-type region, and the second region is an N-type region; the longest diagonal length of the first tower base in the first morphology region is greater than the longest diagonal length of the third tower base in the third morphology region.

[0013] The longest diagonal length of the largest first tower base in the first morphology region of the present invention is greater than the longest diagonal length of the largest third tower base in the third morphology region, making the P-type region flatter than the N-type region, which can reduce the passivation effect of the setting of the first morphology region on the P-type region and ensure good battery efficiency.

[0014] Preferably, the area of ​​the first morphological region is less than or equal to the area of ​​the second morphological region.

[0015] The present invention controls the area of ​​the first morphology region to be less than or equal to the area of ​​the second morphology region, thereby improving the back light reflectivity of the first region while maintaining a low surface recombination loss in the first region, reducing the impact on the back passivation effect of the first region, and further achieving a balance between the two effects.

[0016] Preferably, the first region is a P-type region, and the total area of ​​the first morphological region accounts for 5% to 50% of the total area of ​​the first region.

[0017] The present invention reduces the light reflectivity on the back of the P-type region by controlling the total area of ​​the first morphology region to account for 5% to 50% of the total area of ​​the first region, thereby improving the cell bifaciality and ensuring that the P-type region has a smaller surface recombination loss.

[0018] Preferably, the second region is an N-type region, and the total area of ​​the third morphological region accounts for 10% to 70% of the total area of ​​the second region.

[0019] The present invention controls the total area of ​​the third morphology region to account for 10% to 70% of the total area of ​​the second region, thereby reducing the light reflectivity of the back side of the second region, thereby improving the battery bifaciality, and can ensure that the second region has a smaller surface recombination loss and has a better passivation effect.

[0020] Preferably, the sum of the areas of the first morphology region and the third morphology region accounts for 10% to 48% of the back surface area of ​​the silicon wafer.

[0021] The present invention controls the sum of the areas of the first morphology region and the third morphology region to account for 10% to 48% of the back area of ​​the silicon wafer, thereby reducing the light reflectivity of the back side of the silicon wafer, thereby improving the bifaciality of the battery, and can ensure that the back side of the silicon wafer has a smaller surface recombination loss and a better passivation effect, thereby achieving a balance between the two effects.

[0022] Preferably, the first region is a P-type region, and the second region is an N-type region; the area of ​​the first morphological region is smaller than the area of ​​the third morphological region, which can make the surface recombination loss of the P-type region smaller than the surface recombination loss of the N-type region, thereby balancing the passivation performance of the P-type region and further improving the battery efficiency.

[0023] Preferably, the first morphology region and the third morphology region are arranged close to the edge of the silicon wafer, which can reduce the composite loss caused by the first morphology region and the third morphology region, thereby maintaining good battery efficiency.

[0024] Preferably, at least one of the first regions includes multiple first morphology regions, and the multiple first morphology regions are evenly spaced within the first region, so that surfaces of two different roughnesses are alternately arranged, and the multiple first morphology regions are evenly distributed, which is beneficial to further reduce the surface composite loss of the first region.

[0025] Preferably, at least one of the second regions includes a plurality of the third morphology regions, and the plurality of the third morphology regions are evenly spaced within the second region, so that surfaces of two different roughnesses are alternately arranged, and the plurality of third morphology regions are evenly distributed, which is beneficial to further reduce the surface composite loss of the second region.

[0026] Preferably, the maximum diagonal length of the first tower base in the first morphology area is 5 to 20 microns, and the maximum diagonal length of the second tower base in the second morphology area is 10 to 40 microns. The coordinated design of the first tower base and the second tower base can not only increase the roughness of the first morphology area and reduce the light reflectivity of the back side of the silicon wafer, thereby improving the bifaciality of the battery, but also ensure that both the first morphology area and the second morphology area have smaller surface recombination losses and better passivation effect.

[0027] Preferably, the maximum diagonal length of the third tower base in the third morphology region is 3 to 15 microns, and the maximum diagonal length of the fourth tower base in the fourth morphology region is 5 to 50 microns. This can increase the roughness of the third morphology region and reduce the light reflectivity on the back of the silicon wafer, thereby improving the bifaciality of the battery, and ensure that both the third morphology region and the fourth morphology region have smaller surface recombination losses and better passivation effect.

[0028] Preferably, the ratio of the longest diagonal length of the second tower base in the second morphology area to the longest diagonal length of the first tower base in the first morphology area is 1.2 to 10. By reasonably controlling the ratio range of the two and coordinating the diagonal lengths of the first tower base and the second tower base, the roughness of the first morphology area can be increased and the light reflectivity of the back side of the silicon wafer can be reduced, thereby improving the bifaciality of the battery, and it can ensure that both the first morphology area and the second morphology area have smaller surface recombination losses and better passivation effect.

[0029] Preferably, the ratio of the longest diagonal length of the largest fourth tower base in the fourth morphology region to the longest diagonal length of the largest third tower base in the third morphology region is 1.2-18, so that the diagonal lengths of the third tower base and the fourth tower base are designed in coordination, which can not only increase the roughness of the third morphology region and reduce the light reflectivity of the back side of the silicon wafer, thereby improving the bifaciality of the battery, but also ensure that the third morphology region and the fourth morphology region have smaller surface recombination losses and better passivation effect.

[0030] Preferably, the silicon wafer comprises a first edge and a second edge arranged opposite to each other along a first direction, a third edge and a fourth edge arranged opposite to each other along a second direction, and the first region and the second region are alternately arranged on the back side of the silicon wafer along the first direction;

[0031] The first region near the first edge and the first region near the second edge are both provided with the first morphology region, the second region near the first edge and the second edge are both provided with the third morphology region, and the first morphology region and the third morphology region are staggered in the second direction, so that the back side recombination losses of the first morphology region and the third morphology region are evenly distributed, thereby reducing the impact of the surface recombination loss on the battery and improving the battery efficiency.

[0032] Preferably, at least one of the first regions located in the middle of the silicon wafer is provided with the first morphology region close to the third edge, and at least one of the second regions located in the middle of the silicon wafer is provided with the third morphology region close to the fourth edge, which can further improve the bifaciality of the battery.

[0033] Preferably, the area of ​​the first morphology region of the first region near the center position of the silicon wafer is smaller than the area of ​​the first morphology region of the first region near the edge position of the silicon wafer, which can reduce the surface recombination loss caused by the first morphology region design to the middle region of the silicon wafer, thereby better balancing the cell bifaciality and surface recombination loss.

[0034] Preferably, the area of ​​the third morphology region of the second region near the center position of the silicon wafer is smaller than the area of ​​the third morphology region of the second region near the edge position of the silicon wafer, which can reduce the surface recombination loss caused by the design of the third morphology region to the middle region of the silicon wafer, thereby better balancing the cell bifaciality and surface recombination loss.

[0035] The present invention also provides a photovoltaic module, comprising the above-mentioned back-contact solar cell.

[0036] The present invention also provides a photovoltaic system, comprising the photovoltaic assembly mentioned above. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic diagram of the back side of a back-contact solar cell provided by an embodiment of the present invention;

[0038] Figure 2 A schematic diagram of the back side of a second back-contact solar cell provided by an embodiment of the present invention;

[0039] Figure 3A SEM image of a first morphology region of a back contact solar cell provided by an embodiment of the present invention;

[0040] Figure 4 A SEM image of a second morphology region of a back contact solar cell provided by an embodiment of the present invention;

[0041] Figure 5 A schematic diagram of the back side of a third back-contact solar cell provided by an embodiment of the present invention;

[0042] Figure 6 A schematic diagram of the back side of a fourth back-contact solar cell provided in an embodiment of the present invention.

[0043] Figure 7 A SEM image of a third morphology region of a back contact solar cell provided by an embodiment of the present invention;

[0044] Figure 8 This is a SEM image of the fourth morphology region of a back-contact solar cell provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0046] A back-contact solar cell provided by an embodiment of the present invention sets at least one first area on the back side of a silicon wafer to include a first morphology area and a second morphology area, both of which are polished surfaces, and the longest diagonal length of the largest first tower base in the first morphology area is smaller than the longest diagonal length of the largest second tower base in the second morphology area. By reducing the tower base size of the first morphology area, the roughness of the first morphology area is increased, and the light reflectivity of the back side of the silicon wafer is reduced, thereby improving the cell bifaciality; and, since it is only necessary to set the first tower base size of the first morphology area which is a polished surface to be smaller than the second tower base size of the second morphology area, it is possible to improve the cell bifaciality and at the same time maintain a smaller recombination loss on the back side, reduce the influence on the passivation effect on the back side, achieve a balance between the two effects, effectively improve the efficiency of the back side of the cell, improve the power of the photovoltaic module, and increase the photovoltaic power generation.

[0047] Please refer to Figure 1-Figure 4 The present invention provides a back-contact solar cell, comprising a silicon wafer 10, wherein the back side of the silicon wafer 10 comprises a plurality of first regions 1, wherein the first regions 1 are P-type regions or N-type regions, wherein at least one first region 1 comprises a first morphology region 11 and a second morphology region 12, wherein both the first morphology region 11 and the second morphology region 12 are polished surfaces;

[0048] The first morphology area 11 includes a plurality of first tower bases 111 , and the second morphology area 12 includes a plurality of second tower bases 121 . The longest diagonal length L1 of the largest first tower base 111 in the first morphology area 11 is smaller than the longest diagonal length L2 of the largest second tower base 121 in the second morphology area 12 .

[0049] In the embodiment of the present invention, the silicon wafer 10 includes a front side and a back side that are arranged opposite to each other, the front side is the side facing the sunlight when the back contact solar cell is working, and the back side is the side facing away from the sunlight when the back contact solar cell is working. The specific number of first regions 1 included in the back side of the silicon wafer 10 is not limited, and the first region 1 can be a P-type region or an N-type region. The back side of the silicon wafer 10 also includes a plurality of second regions 2, and the specific number of second regions 2 included in the back side of the silicon wafer 10 is not limited. The first region 1 and the second region 2 are alternately arranged in sequence, and one of the first region 1 and the second region 2 is a P-type region and the other is an N-type region.

[0050] Among them, the P-type region is a region where a P-type doped layer is set, and the P-type doped layer can be one or a combination of P-type doped polycrystalline silicon, P-type doped amorphous silicon or P-type doped microcrystalline silicon; the N-type region is a region where an N-type doped layer is set, and the N-type doped layer can be one or a combination of N-type doped polycrystalline silicon, N-type doped amorphous silicon or N-type doped microcrystalline silicon.

[0051] In the embodiment of the present invention, a passivation film layer is further provided on the back side of the P-type doping layer and the N-type doping layer to further improve the back side passivation performance of the battery.

[0052] As an optional embodiment of the present invention, the back side of the silicon wafer 10 includes a plurality of first regions 1, the plurality of first regions 1 are sequentially arranged on the back side at intervals along the first direction X, the first morphology region 11 is arranged in the first region 1 along the second direction Y, and the first direction X is arranged perpendicular to the second direction Y. Among them, only one of the first regions 1 may be arranged to include the first morphology region 11 and the second morphology region 12, and the other first regions 1 may be arranged to include only the second morphology region 12; of course, two or more of the first regions 1 may be arranged to include the first morphology region 11 and the second morphology region 12, and the other first regions 1 without the first morphology region 11 may be arranged to include only the second morphology region 12. Figure 1 Only three first regions 1 are schematically shown to be arranged to include the first morphology region 11 and the second morphology region 12 , while the other first regions 1 only include the second morphology region 12 . Figure 2 Only four first regions 1 are shown to include the first morphological region 11 and the second morphological region 12, while the other first regions 1 only include the second morphological region 12. In practical applications, the specific position of the first morphological region 11 in the first region 1, the number of the first morphological regions 11 and the area can be flexibly set according to actual needs.

[0053] As an optional embodiment of the present invention, the first morphological regions 11 and the second morphological regions 12 are alternately arranged in the first region 1 along the second direction Y, which is more conducive to reducing the recombination loss on the back side of the battery. In addition, the first morphological regions 11 and the second morphological regions 12 can also be arranged in an array in the first region 1, which is also conducive to reducing the recombination loss on the back side of the battery.

[0054] In the embodiment of the present invention, the first morphology region 11 and the second morphology region 12 are both polished surfaces, which can be understood as the surface reflectivity of the first morphology region 11 and the second morphology region 12 to sunlight reaches more than 20%, and the surfaces of the first morphology region 11 and the second morphology region 12 both have a tower base structure rather than a velvet structure. The specific shapes of the first morphology region 11 and the second morphology region 12 are not limited, for example, the first morphology region 11 and the second morphology region 12 can be square, circular, triangular, trapezoidal, polygonal or irregular.

[0055] A back-contact solar cell provided by an embodiment of the present invention is configured to have at least one first region 1 including a first morphology region 11 and a second morphology region 12, wherein the first morphology region 11 and the second morphology region 12 are both polished surfaces, and the longest diagonal length L1 of the largest first tower base 111 of the first morphology region 11 is smaller than the longest diagonal length L2 of the largest second tower base 121 of the second morphology region 12, that is, by reducing the tower base size of the first morphology region 11, the longest diagonal length L1 of the largest first tower base 111 of the first morphology region 11 is smaller than the longest diagonal length L2 of the largest second tower base 121 of the second morphology region 12, thereby increasing the roughness of the first morphology region 11 and reducing The light reflectivity of the back side of the silicon wafer 10 is improved, thereby improving the cell bifaciality; moreover, since it is only necessary to set the first tower base 111 of the first morphological area 11 with a polished surface to be smaller, there is no need to make the first morphological area 11 into a velvet surface. Compared with the velvet structure, the first morphological area 11 set with a polished surface can keep the first area 1 at a lower composite loss, while improving the back light reflectivity of the first area 1, the back side of the cell is kept at a lower composite loss, reducing the impact on the back passivation effect. Therefore, the present invention can improve the cell bifaciality and maintain a smaller surface composite loss on the back side of the back-contact solar cell, achieving a balance between the two effects, improving the efficiency of the back side of the cell, improving the power of the photovoltaic module, and increasing the power generation.

[0056] In the embodiment of the present invention, a first morphology region 11 and a second morphology region 12 with two different polishing morphologies can be formed in the first region 1 by a wet etching process using an alkaline solution or an acid solution. When an acid solution is used for wet etching, a corrosive acidic solution such as hydrofluoric acid or nitric acid can be used. A corrosive alkaline solution such as potassium hydroxide or sodium hydroxide can be used for the acid solution wet etching process.

[0057] For example, an alkaline solution or an acid solution is used to simultaneously polish to form a first morphology region 11 and a second morphology region 12, and a mask is used to block the first morphology region 11, so that the corrosion rate of the first morphology region 11 is less than the corrosion rate of the second morphology region 12, thereby making the polishing degree of the first morphology region 11 less than the polishing degree of the second morphology region 12, thereby making the longest diagonal length L1 of the largest first tower base 111 of the first morphology region 11 less than the longest diagonal length L2 of the largest second tower base 121 of the second morphology region 12, and the roughness of the first morphology region 11 is greater than that of the second morphology region 12, which is more conducive to reducing the back side sunlight reflectivity.

[0058] For another example, the concentration, reaction time and reaction temperature of the alkaline solution or acid solution used to polish the first morphological region 11 and the second morphological region 12 can be controlled by controlling the alkaline solution or acid solution, and the first morphological region 11 and the second morphological region 12 with different tower base morphologies can also be formed. For example, the first morphological region 11 is wet-etched with a potassium hydroxide concentration of 1-3%, an additive concentration of 0.5-1.5%, a reaction temperature of 60-80°C and a reaction time of 100-400 seconds; the second morphological region 12 is wet-etched with a potassium hydroxide concentration of 3-10%, an additive concentration of 0.5-1.5%, a reaction temperature of 70-90°C and a reaction time of 100-300 seconds.

[0059] Please refer to Figure 3-Figure 4 In the embodiment of the present invention, the first tower base 111 of the first morphological region 11 can be a linear array, which can increase the structural stability of the first morphological region 11; of course, the first tower base 111 of the first morphological region 11 can also be arranged irregularly. The second tower base 121 of the second morphological region 12 can be a linear array, of course, the second tower base 121 of the second morphological region 12 can also be arranged irregularly.

[0060] In the embodiment of the present invention, the top view of each first tower base 111 of the first morphological area 11 is a quadrilateral, an approximate quadrilateral, or a polygon, each first tower base 111 may have a plurality of diagonals, and the lengths of the diagonals of each first tower base 111 may be equal or different. The top view of each second tower base 121 of the second morphological area 12 is a quadrilateral, an approximate quadrilateral, or a polygon; each second tower base 121 may have a plurality of diagonals, and the lengths of the diagonals of each second tower base 121 may be the same or different. Generally speaking, the longer the maximum diagonal length of the tower base, the larger the tower base area, and the flatter the surface where the tower base is located; conversely, the shorter the diagonal length of each tower base, the smaller the tower base area, and the rougher the surface where the tower base is located.

[0061] In the embodiment of the present invention, the largest first tower base 111 of the first morphological region 11 refers to the first tower base 111 with the largest area in the first morphological region 11; the longest diagonal length L1 of the largest first tower base 111 of the first morphological region 11 refers to the longest diagonal length of the first tower base 111 with the largest area. The largest second tower base 121 of the second morphological region 12 refers to the second tower base 121 with the largest area in the second morphological region 12, and the longest diagonal length L2 of the largest second tower base 121 of the second morphological region 12 refers to the longest diagonal length of the second tower base 121 with the largest area in the second morphological region 12.

[0062] In the embodiment of the present invention, the longest diagonal length L1 of the largest first tower base 111 of the first morphology region 11 is smaller than the longest diagonal length L2 of the largest second tower base 121 of the second morphology region 12. It can be understood that the diagonal length of the largest first tower base 111 in the first morphology region 11 within the same unit area is smaller than the diagonal length of the largest second tower base 121 of the second morphology region 12. Of course, it can also be that the longest diagonal length L1 of the largest first tower base 111 in the entire area of ​​the first morphology region 11 is smaller than the longest diagonal length L2 of the largest second tower base 121 in the entire area of ​​the second morphology region 12, so that the first morphology region 11 is rougher than the second morphology region 12.

[0063] Of course, the longest side length of the first base 111 can also be compared with the longest side length of the second base 121, that is, the maximum side length of the first base 111 in the first morphology region 11 within the same unit area is greater than the maximum side length of the first base 111 in the second morphology region 12, which also makes the first morphology region 11 rougher than the second morphology region 12.

[0064] As an embodiment of the present invention, the area of ​​the first morphology region 11 is less than or equal to the area of ​​the second morphology region 12 .

[0065] In this embodiment, by controlling the area of ​​the first morphology region 11 to be less than or equal to the area of ​​the second morphology region 12, while improving the back light reflectivity of the first region 1, the first region 1 maintains a low surface recombination loss, reducing the impact on the back passivation effect of the first region 1, and further achieving a balance between the two effects.

[0066] As an embodiment of the present invention, the first region 1 is a P-type region, and the total area of ​​the first morphology region 11 accounts for 5% to 50% of the total area of ​​the first region 1 .

[0067] In this embodiment, the total area of ​​the first morphology region 11 is the sum of the areas of all the first morphology regions 11, and the total area of ​​the first region 1 is the sum of the areas of all the first regions 1. In this embodiment, the first region 1 is a P-type region, and the total area of ​​the first morphology region 11 is set to only account for 5% to 50% of the total area of ​​the first region 1, which can control 15% to 50% of the area of ​​the P-type region to increase the roughness and reduce the light reflectivity of the back of the P-type region, thereby improving the bifaciality of the battery, and can ensure that the P-type region has a smaller surface recombination loss and has a better passivation effect, achieving a balance between the two effects.

[0068] Among them, the total area of ​​the first morphological region 11 can account for any value of 5%, 6%, 7%, 8%, 9%, 10%, 12%, 15%, 19%, 20%, 22%, 25%, 28%, 30%, 32%, 34%, 35%, 39%, 40%, 42%, 45%, 48%, and 50% of the total area of ​​the first region 1.

[0069] Please refer to Figure 5-Figure 8 As an embodiment of the present invention, the back side of the silicon wafer 10 further includes a plurality of second regions 2, wherein the first regions 1 and the second regions 2 are alternately arranged in sequence, and one of the first regions 1 and the second region 2 is a P-type region and the other is an N-type region;

[0070] At least one second region 2 includes a third morphological region 21 and a fourth morphological region 22, and both the third morphological region 21 and the fourth morphological region 22 are polished surfaces;

[0071] The third morphology area 21 includes a plurality of third tower bases 211 , and the fourth morphology area 22 includes a plurality of fourth tower bases 221 . The longest diagonal length L3 of the largest third tower base 211 in the third morphology area 21 is smaller than the longest diagonal length L4 of the largest fourth tower base 221 in the fourth morphology area 22 .

[0072] In this embodiment, one of the first region 1 and the second region 2 is a P-type region, and the other is an N-type region. The first region 1 and the second region 2 are alternately disposed on the back side of the silicon wafer 10 along a first direction.

[0073] In this embodiment, under the premise of setting the first morphological region in the first region 1, at least one second region 2 is further set to include a third morphological region 21 and a fourth morphological region 22, the third morphological region 21 and the fourth morphological region 22 are both polished surfaces, and the longest diagonal length L3 of the largest third tower base 211 of the third morphological region 21 is smaller than the longest diagonal length L4 of the largest fourth tower base 221 of the fourth morphological region 22, that is, by reducing the tower base size of the third morphological region 21, the longest diagonal length L3 of the largest third tower base 211 of the third morphological region 21 is smaller than The longest diagonal length L4 of the maximum fourth tower base 221 of the fourth morphology region 22 increases the roughness of the third morphology region 21, further reduces the light reflectivity of the back side of the silicon wafer 10, and further improves the cell bifaciality; moreover, while improving the back light reflectivity of the second region 2, the back side of the cell maintains a low recombination loss, reducing the impact on the back passivation effect, which can further improve the cell bifaciality and maintain a low back side recombination loss, achieving a balance between the two effects, further improving the efficiency of the back side of the cell, increasing the power of the photovoltaic module, and increasing photovoltaic power generation.

[0074] In this embodiment, the back side of the silicon wafer 10 includes the second regions 2, and the specific number is not limited. Preferably, the back side includes a plurality of second regions 2, and the second regions 2 and the first regions 1 are alternately arranged on the back side, and an isolation region may be arranged between the second regions 2 and the first regions 1. Among them, only one second region 2 may be arranged to include the third morphology region 21 and the fourth morphology region 22, and the other second regions 2 may be arranged to include only the fourth morphology region 22. It is also possible that two or more second regions 2 are arranged to include the third morphology region 21 and the fourth morphology region 22, and the second region 2 without the third morphology region 21 is arranged to include only the fourth morphology region 22.

[0075] As an optional embodiment of the present invention, the third morphological region 21 and the fourth morphological region 22 are alternately arranged in the second region 2 along the second direction Y, which is more conducive to reducing the recombination loss on the back side of the battery. In addition, the third morphological region 21 and the fourth morphological region 22 can also be arranged in an array in the second region 2, which is also conducive to reducing the recombination loss on the back side of the battery.

[0076] In the embodiment of the present invention, a third morphology region 21 and a fourth morphology region 22 with two different polishing morphologies can be formed in the second region 2 by a wet etching process using an alkaline solution or an acid solution. When an acid solution is used for wet etching, a corrosive acidic solution such as hydrofluoric acid or nitric acid can be used, and a corrosive alkaline solution such as potassium hydroxide or sodium hydroxide can be used for the acid solution wet etching process.

[0077] For example, an alkaline solution or an acid solution is used to simultaneously polish to form the third morphology region 21 and the fourth morphology region 22, and a mask is used to block the third morphology region 21, so that the corrosion rate of the third morphology region 21 is less than the corrosion rate of the fourth morphology region 22, thereby making the polishing degree of the third morphology region 21 less than the polishing degree of the fourth morphology region 22, thereby making the longest diagonal length L3 of the maximum third tower base 211 of the third morphology region 21 less than the longest diagonal length L4 of the maximum fourth tower base 221 of the fourth morphology region 22, and the roughness of the third morphology region 21 is greater than that of the fourth morphology region 22, which is more conducive to reducing the back side sunlight reflectivity.

[0078] For another example, the third morphology region 21 and the fourth morphology region 22 can be polished by controlling the concentration of the alkaline solution or acid solution, the reaction time, and the reaction temperature to form the third morphology region 21 and the fourth morphology region 22 with different tower base morphologies.

[0079] As an embodiment of the present invention, the second region 2 is an N-type region, and the total area of ​​the third morphology region 21 accounts for 10%-70% of the total area of ​​the second region 2 .

[0080] In this embodiment, the total area of ​​the third morphology region 21 is the sum of the areas of all the third morphology regions 21, and the total area of ​​the second region 2 is the sum of the areas of all the second regions 2. In this embodiment, the second region 2 is an N-type region, and the total area of ​​the third morphology region 21 is set to account for 10%-70% of the total area of ​​the second region 2, which can control the area of ​​10%-70% of the second region to increase the roughness and reduce the light reflectivity of the back of the second region 2, thereby improving the battery bifaciality, and can ensure that the second region 2 has a smaller surface recombination loss and has a better passivation effect, achieving a balance between the two effects.

[0081] As an embodiment of the present invention, the sum of the areas of the first morphology region 11 and the third morphology region 21 accounts for 10% to 48% of the back surface area of ​​the silicon wafer 10 .

[0082] In this embodiment, the sum of the areas of the first morphology region 11 and the third morphology region 21 accounts for 10% to 48% of the area of ​​the back side of the silicon wafer 10. The roughness of parts of the first region 1 and the second region 2 can be controlled to increase, and the light reflectivity of the back side of the silicon wafer 10 can be reduced, thereby improving the bifaciality of the battery. It can also ensure that the back side of the silicon wafer 10 has a smaller surface recombination loss and a better passivation effect, thereby achieving a balance between the two effects.

[0083] As an embodiment of the present invention, the first region 1 is a P-type region, and the second region 2 is an N-type region; the area of ​​the first morphology region 11 is smaller than the area of ​​the third morphology region 21 .

[0084] In this embodiment, since the passivation performance of the P-type doped layer is worse than that of the N-type region doped layer, the area of ​​the first morphology region 11 of the P-type region is smaller than the area of ​​the third morphology region 21 of the N-type region. In this way, the surface recombination loss of the first morphology region 11 can be smaller than the surface recombination loss of the third morphology region 21, thereby balancing the passivation performance of the P-type region and the N-type region, and further improving the battery efficiency.

[0085] Among them, the area ratio of the third morphology region 21 to the area ratio of the first morphology region 11 can be flexibly set. For example, the area ratio of the third morphology region 21 to the first morphology region 11 can be 1.2 to 1.5, so that the area of ​​the first morphology region 11 in the P-type region and the area of ​​the third morphology region 21 in the N-type region are reasonably designed, so that the good passivation performance of the P-type region and the N-type region can be maintained, and the local roughness of the P-type region and the N-type region can be improved, and the local light reflectivity of the P-type region and the N-type region can be reduced, thereby improving the battery efficiency.

[0086] As an embodiment of the present invention, the first morphology region 11 and the third morphology region 21 are disposed close to the edge of the silicon wafer 10 .

[0087] In this embodiment, since the edge recombination loss of the silicon wafer 10 is large and the middle area of ​​the silicon wafer 10 is small, the first morphology area 11 and the third morphology area 21 are set at the edge of the silicon wafer 10, which can further reduce the recombination loss caused by the first morphology area 11 and the third morphology area 21, thereby maintaining good battery efficiency.

[0088] As an embodiment of the present invention, at least one first region 1 includes a plurality of first morphology regions 11 , and the plurality of first morphology regions 11 are evenly spaced apart in the first region 1 .

[0089] In this embodiment, multiple first morphology regions 11 are evenly spaced in the first region 1, and the multiple first morphology regions 11 are utilized to reduce the reflection of sunlight in the first region 1 and increase the absorption of sunlight. The multiple first morphology regions 11 are evenly distributed in the first region 1 to form a structure in which the first morphology regions 11 and the second morphology regions 12 are alternately arranged, so that two surfaces with different roughness are alternately arranged and the multiple first morphology regions 11 are evenly distributed, which is beneficial to further reduce the surface composite loss of the first region 1.

[0090] As an embodiment of the present invention, at least one second region 2 includes a plurality of third morphology regions 21 , and the plurality of third morphology regions 21 are evenly spaced apart and arranged in the second region 2 .

[0091] In this embodiment, multiple third morphology regions 21 are evenly spaced in the second region 2, and the multiple third morphology regions 21 are used to reduce the reflection of sunlight in the second region 2 and increase the absorption of sunlight. The multiple third morphology regions 21 are evenly distributed in the second region 2 to form a structure in which the third morphology regions 21 and the fourth morphology regions 22 are alternately arranged, so that two surfaces with different roughness are alternately arranged, which is beneficial to further reduce the surface composite loss of the second region 2.

[0092] Please refer to Figure 6 As an embodiment of the present invention, the area of ​​the first morphology region 11 of the first region 1 close to the center position of the silicon wafer 10 is smaller than the area of ​​the first morphology region 11 of the first region 1 close to the edge position of the silicon wafer 10 .

[0093] In this embodiment, since the edge recombination loss of the silicon wafer 10 is large and the middle area of ​​the silicon wafer 10 is small, the area of ​​the first morphology region 11 of the first region 1 close to the center position of the silicon wafer 10 is smaller than the area of ​​the first morphology region 11 of the first region 1 close to the edge position of the silicon wafer 10. The recombination loss caused by the design of the first morphology region 11 to the middle area of ​​the silicon wafer 10 can be reduced, thereby better balancing the cell bifaciality and surface recombination loss.

[0094] In actual comparison, any two adjacent first regions 1 can be taken, wherein the area of ​​the first morphology region 11 of one first region 1 close to the center of the silicon wafer 10 is smaller than the area of ​​the first morphology region 11 of another first region 1 close to the edge of the silicon wafer 10 .

[0095] As an embodiment of the present invention, the area of ​​the third morphology region 21 of the second region 2 close to the center of the silicon wafer 10 is smaller than the area of ​​the third morphology region 21 of the second region 1 close to the edge of the silicon wafer 10 .

[0096] In this embodiment, since the edge recombination loss of the silicon wafer 10 is large and the middle area of ​​the silicon wafer 10 is small, the area of ​​the third morphology region 21 of the second area 2 close to the center of the silicon wafer 10 is smaller than the area of ​​the third morphology region 21 of the second area 1 close to the edge of the silicon wafer 10. The recombination loss caused by the design of the third morphology region 21 to the middle area of ​​the silicon wafer 10 can be reduced, thereby better balancing the cell bifaciality and surface recombination loss.

[0097] In actual comparison, any two adjacent second regions 2 can be taken, wherein the area of ​​the third morphology region 21 of a second region 2 close to the center of the silicon wafer 10 is smaller than the area of ​​the third morphology region 21 of another second region 2 close to the edge of the silicon wafer 10 .

[0098] As an embodiment of the present invention, the silicon wafer 10 includes a first edge 101 and a second edge 102 arranged oppositely along a first direction X, a third edge 103 and a fourth edge 104 arranged oppositely along a second direction Y, and the first region 1 and the second region 2 are alternately arranged on the back side of the silicon wafer 10 along the first direction X;

[0099] The first region 1 near the first edge 101 and the second edge 102 are both provided with a first morphology region 11; the second region 2 near the first edge 101 and the second edge 102 are both provided with a third morphology region 21, and the first morphology region 11 and the third morphology region 21 are staggered in the second direction Y.

[0100] In the present embodiment, the first region 1 near the first edge and the first region 1 near the second edge are both provided with a first morphology region 11; the second region 2 near the first edge and the second edge are both provided with a third morphology region 21, and the first morphology region 11 and the third morphology region 21 are staggered in the second direction Y. Since the first morphology region 11 and the third morphology region 21 are staggered in the second direction, the back-side recombination losses of the first morphology region 11 and the third morphology region 21 can be evenly distributed, thereby reducing the impact of the recombination losses and improving the battery efficiency.

[0101] As an embodiment of the present invention, at least one first region 1 located in the middle of the silicon wafer 10 is provided with a first morphology region 11 close to the third edge 103 , and at least one second region 2 located in the middle of the silicon wafer 10 is provided with a third morphology region 21 close to the fourth edge 104 .

[0102] In this embodiment, a first morphology region 11 and a third morphology region 21 are arranged in the middle position of the silicon wafer 10, which can further improve the cell bifaciality; at the same time, the first morphology region 11 is close to the third edge, and the third morphology region 21 is close to the fourth edge, so that the first morphology region 11 of at least one first region 1 in the middle position of the silicon wafer 10 and the third morphology region 21 of at least one second region 2 in the middle position of the silicon wafer 10 are arranged near different edges, which can further improve the cell bifaciality.

[0103] Please refer to Figure 5-Figure 6 As an embodiment of the present invention, the first region 1 is a P-type region, and the second region 2 is an N-type region; the longest diagonal length L1 of the maximum first tower base 111 of the first morphology region 11 is greater than the longest diagonal length L3 of the maximum third tower base 211 of the third morphology region 21.

[0104] In the present embodiment, the longest diagonal length L1 of the largest first base 111 of the first morphology region 11 is greater than the longest diagonal length L3 of the largest third base 211 of the third morphology region 21, which can make the size of the first base 111 in the P-type region larger than the size of the third base 211 in the N-type region, making the P-type region flatter than the N-type region, and reducing the passivation effect of the setting of the first morphology region 11 on the P-type region, thereby ensuring good battery efficiency.

[0105] As an embodiment of the present invention, the longest diagonal length L1 of the largest first tower base 111 of the first morphology region 11 is 5 to 20 microns, and the longest diagonal length L2 of the largest second tower base 121 of the second morphology region 12 is 10 to 40 microns.

[0106] In this embodiment, the longest diagonal length L1 of the first base 111 is 5 to 20 microns, and the longest diagonal length L2 of the second base 121 is 10 to 40 microns. The coordinated design of the first base 111 and the second base 121 can increase the roughness of the first morphology area 11 and reduce the light reflectivity of the back side of the silicon wafer 10, thereby improving the bifaciality of the battery, and can ensure that the first morphology area 11 and the second morphology area 12 have smaller surface recombination losses and better passivation effect.

[0107] For example, the longest diagonal length L1 of the largest first tower base 111 of the first morphological area 11 can be any value among 5 micrometers, 5.5 micrometers, 6 micrometers, 6.2 micrometers, 7 micrometers, 7.5 micrometers, 9 micrometers, 9.6 micrometers, 10 micrometers, 11 micrometers, 13 micrometers, 14 micrometers, 15 micrometers, 16 micrometers, 17 micrometers, 18 micrometers, 19 micrometers, and 20 micrometers; the longest diagonal length L2 of the largest second tower base 121 of the second morphological area 12 can be any value among 10 micrometers, 10. Any value among 2 microns, 11 microns, 12 microns, 12.3 microns, 14 microns, 14.8 microns, 15 microns, 16 microns, 18 microns, 20 microns, 22 microns, 25 microns, 26 microns, 27 microns, 28 microns, 30 microns, 32 microns, 34 microns, 35 microns, 37 microns, 38 microns, 39 microns, and 40 microns, as long as the longest diagonal length L1 of the largest first tower base 111 is less than the longest diagonal length L3 of the third tower base 211.

[0108] As an embodiment of the present invention, the ratio of the longest diagonal length L2 of the largest second tower base 121 of the second morphology region 12 to the longest diagonal length L2 of the largest first tower base 111 of the first morphology region 11 is 1.2-10.

[0109] In this embodiment, the ratio of the longest diagonal length L2 of the largest second tower base 121 of the second morphology area 12 to the longest diagonal of the largest first tower base 111 of the first morphology area 11 is 1.2-10. By reasonably controlling the ratio range of the two, the diagonal lengths of the first tower base 111 and the second tower base 121 are designed to be coordinated, which can increase the roughness of the first morphology area 11 and reduce the light reflectivity of the back side of the silicon wafer 10, thereby improving the bifaciality of the battery, and ensure that the first morphology area 11 and the second morphology area 12 have smaller surface recombination losses and better passivation effects.

[0110] As an embodiment of the present invention, the longest diagonal length L3 of the largest third tower base 211 of the third morphology region 21 is 3 to 15 microns, and the longest diagonal length L4 of the largest fourth tower base 221 of the fourth morphology region 22 is 5 to 50 microns.

[0111] In this embodiment, the longest diagonal length L3 of the third base 211 is 3 to 15 microns, and the longest diagonal length L4 of the fourth base 221 is 5 to 50 microns. The coordinated design of the third base 211 and the fourth base 221 can increase the roughness of the third morphology area 21 and reduce the light reflectivity on the back of the silicon wafer 10, thereby improving the bifaciality of the battery, and can ensure that the third morphology area 21 and the fourth morphology area 22 have smaller surface recombination losses and better passivation effects.

[0112] For example, the longest diagonal length L3 of the largest third tower base 211 in the third morphology area 21 can be any value among 3 microns, 3.5 microns, 4 microns, 5 microns, 7 microns, 7.5 microns, 9 microns, 9.2 microns, 10 microns, 11 microns, 13 microns, 14 microns, and 15 microns; the longest diagonal length L4 of the largest fourth tower base 221 in the fourth morphology area 22 can be any value among 5 microns, 6 microns, 8 microns, 10 microns, 12 microns, 14 microns, 15 microns, 16 microns, 18 microns, 20 microns, 22 microns, 25 microns, 26 microns, 27 microns, 28 microns, 30 microns, 32 microns, 34 microns, 35 microns, 37 microns, 38 microns, 39 microns, 40 microns, 45 microns, 47 microns, 48 ​​microns, and 50 microns, as long as the longest diagonal length L3 of the largest third tower base 211 is less than the longest diagonal length L4 of the largest fourth tower base 221.

[0113] As an embodiment of the present invention, the ratio of the longest diagonal length L3 of the largest fourth tower base 221 of the fourth morphology region 22 to the longest diagonal length L3 of the largest third tower base 211 of the third morphology region 21 is 1.2-18.

[0114] In this embodiment, the ratio of the longest diagonal length L4 of the largest fourth base 221 of the fourth morphology region 22 to the longest diagonal of the largest third base 211 of the third morphology region 21 is 1.2 to 10. By reasonably controlling the ratio range of the two, the diagonal lengths of the third base 211 and the fourth base 221 are designed to be coordinated, which can increase the roughness of the third morphology region 21 and reduce the light reflectivity of the back side of the silicon wafer 10, thereby improving the bifaciality of the battery, and ensure that both the third morphology region 21 and the fourth morphology region 22 have smaller surface recombination losses and better passivation effects.

[0115] The embodiment of the present invention further provides a photovoltaic module, which includes the back-contact solar cell of the above embodiment. It should be noted that the photovoltaic module has the same or similar beneficial effects as the back-contact solar cell, and the relevant parts between the two can be referenced to each other. In order to avoid repetition, they will not be described here.

[0116] In this embodiment, multiple back-contact solar cells in a photovoltaic module can be connected in series in sequence to form a cell string, thereby realizing the series bus output of current. For example, the series connection of the cell sheets can be achieved by setting welding strips (bus bars, interconnecting strips), conductive back panels, etc.

[0117] It is understandable that in such an embodiment, the photovoltaic module may also include a metal frame, a back plate, photovoltaic glass and an adhesive film. The adhesive film may be filled between the front and back sides of the back contact solar cell and the photovoltaic glass, adjacent cells, etc. As a filler, it may be a transparent colloid with good light transmission and aging resistance. For example, the adhesive film may be an EVA adhesive film or a POE adhesive film. The specific selection may be based on actual conditions and is not limited here.

[0118] Photovoltaic glass can cover the adhesive film on the front of the back contact solar cell. The photovoltaic glass can be ultra-white glass, which has high light transmittance, high transparency, and excellent physical, mechanical and optical properties. For example, the light transmittance of ultra-white glass can reach more than 92%, which can protect the back contact solar cell without affecting the efficiency of the back contact solar cell as much as possible. At the same time, the adhesive film can bond the photovoltaic glass and the back contact solar cell together. The presence of the adhesive film can seal and insulate the back contact solar cell and make it waterproof and moisture-proof.

[0119] The backplane can be attached to the adhesive film on the back of the back-contact solar cell. The backplane can protect and support the back-contact solar cell and has reliable insulation, water resistance and aging resistance. There are multiple options for the backplane, which can usually be tempered glass, organic glass, aluminum alloy TPT composite adhesive film, etc. The specific configuration can be made according to the specific situation and is not limited here. The whole composed of the backplane, back-contact solar cell, adhesive film and photovoltaic glass can be set on a metal frame. The metal frame serves as the main external support structure of the entire back-contact solar photovoltaic module and can stably support and install the back-contact solar photovoltaic module. For example, the back-contact solar photovoltaic module can be installed at the required location through the metal frame.

[0120] The embodiment of the present invention further provides a photovoltaic system, which includes the photovoltaic module of the above embodiment. It should be noted that the photovoltaic system has the same or similar beneficial effects as the above back contact solar cell, and the relevant parts between the two can be referenced to each other. In order to avoid repetition, it will not be repeated here.

[0121] In this embodiment, the photovoltaic system can be applied to photovoltaic power stations, such as ground power stations, rooftop power stations, water power stations, etc., and can also be applied to equipment or devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars, solar buildings, etc. Of course, it can be understood that the application scenarios of the photovoltaic system are not limited to this, that is, the photovoltaic system can be applied in all fields that require solar energy to generate electricity. Taking the photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a junction box and an inverter. The photovoltaic array may be an array combination of multiple back-contact solar photovoltaic modules. For example, multiple back-contact solar photovoltaic modules can form multiple photovoltaic arrays. The photovoltaic array is connected to the junction box. The junction box can converge the current generated by the photovoltaic array. The converged current flows through the inverter and is converted into the alternating current required by the mains power grid, and then connected to the mains network to realize solar power supply.

[0122] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A back contact solar cell, characterized in that: A silicon wafer is included, wherein the back side of the silicon wafer includes a plurality of first regions, wherein the first regions are P-type regions or N-type regions, and at least one of the first regions includes a first morphology region and a second morphology region, and both the first morphology region and the second morphology region are polished surfaces; The first morphology area includes a plurality of first tower bases, and the second morphology area includes a plurality of second tower bases. The longest diagonal length of the largest first tower base in the first morphology area is smaller than the longest diagonal length of the largest second tower base in the second morphology area.

2. The back contact solar cell according to claim 1, characterized in that: The back side of the silicon wafer further includes a plurality of second regions, wherein the first regions and the second regions are alternately arranged in sequence, and one of the first regions and the second region is a P-type region, and the other is an N-type region; At least one of the second regions includes a third morphology region and a fourth morphology region, and both the third morphology region and the fourth morphology region are polished surfaces; The third morphology area includes a plurality of third tower bases, the fourth morphology area includes a plurality of fourth tower bases, and the longest diagonal length of the largest third tower base in the third morphology area is smaller than the longest diagonal length of the largest fourth tower base in the fourth morphology area.

3. The back contact solar cell according to claim 2, characterized in that: The first region is a P-type region, and the second region is an N-type region; the longest diagonal length of the first tower base in the first morphology region is greater than the longest diagonal length of the third tower base in the third morphology region.

4. The back contact solar cell according to claim 1, characterized in that: The area of ​​the first morphological region is less than or equal to the area of ​​the second morphological region.

5. The back contact solar cell according to claim 1, characterized in that: The first region is a P-type region, and the total area of ​​the first morphology region accounts for 5% to 50% of the total area of ​​the first region.

6. The back contact solar cell according to claim 2, characterized in that: The second region is an N-type region, and the total area of ​​the third morphology region accounts for 10% to 70% of the total area of ​​the second region.

7. The back contact solar cell according to claim 2, characterized in that: The sum of the areas of the first morphology region and the third morphology region accounts for 10% to 48% of the back surface area of ​​the silicon wafer.

8. The back contact solar cell according to claim 2, characterized in that: The first region is a P-type region, and the second region is an N-type region; the area of ​​the first morphology region is smaller than the area of ​​the third morphology region.

9. The back contact solar cell according to claim 2, characterized in that: The first morphology region and the third morphology region are arranged close to the edge of the silicon wafer.

10. The back contact solar cell according to claim 1, characterized in that: At least one of the first regions includes a plurality of the first morphology regions, and the plurality of the first morphology regions are evenly spaced within the first region.

11. The back contact solar cell according to claim 2, characterized in that: At least one of the second regions includes a plurality of the third morphology regions, and the plurality of the third morphology regions are evenly spaced within the second region.

12. The back contact solar cell according to claim 1, characterized in that: The longest diagonal length of the largest first tower base in the first morphology area is 5 to 20 micrometers, and the longest diagonal length of the largest second tower base in the second morphology area is 10 to 40 micrometers.

13. The back contact solar cell according to claim 2, characterized in that: The longest diagonal length of the largest third tower base in the third morphology area is 3 to 15 micrometers, and the longest diagonal length of the largest fourth tower base in the fourth morphology area is 5 to 50 micrometers.

14. The back contact solar cell according to claim 1, characterized in that: The ratio of the longest diagonal length of the second tower base in the second morphological area to the longest diagonal length of the first tower base in the first morphological area is 1.2-10.

15. The back contact solar cell according to claim 2, characterized in that: The ratio of the longest diagonal length of the largest fourth tower base in the fourth morphological area to the longest diagonal length of the largest third tower base in the third morphological area is 1.2-18.

16. The back contact solar cell according to claim 2, characterized in that: The silicon wafer comprises a first edge and a second edge arranged opposite to each other along a first direction, a third edge and a fourth edge arranged opposite to each other along a second direction, and the first region and the second region are alternately arranged on the back side of the silicon wafer along the first direction; The first regions near the first edge and the second edge are both provided with the first morphology regions, the second regions near the first edge and the second edge are both provided with the third morphology regions, and the first morphology regions and the third morphology regions are staggered in the second direction.

17. The back contact solar cell according to claim 16, characterized in that: At least one of the first regions located in the middle of the silicon wafer is provided with the first morphology region close to the third edge, and at least one of the second regions located in the middle of the silicon wafer is provided with the third morphology region close to the fourth edge.

18. The back contact solar cell according to claim 1, characterized in that: The area of ​​the first morphology region of the first region close to the center position of the silicon wafer is smaller than the area of ​​the first morphology region of the first region close to the edge position of the silicon wafer.

19. The back contact solar cell according to claim 2, characterized in that: The area of ​​the third morphology region of the second region close to the center position of the silicon wafer is smaller than the area of ​​the third morphology region of the second region close to the edge position of the silicon wafer.

20. A photovoltaic module, characterized in that: A back-contact solar cell comprising the step of:

21. A photovoltaic system, characterized in that: Comprising the photovoltaic module as claimed in claim 20.

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