Back contact solar cell, cell module and photovoltaic system

Abstract

The utility model is suitable for the technical field of solar cells, and provides a back contact solar cell, a cell assembly and a photovoltaic system, the back contact solar cell comprises a silicon substrate, the back surface of the silicon substrate comprises a first doped region; the first doped layer is arranged in the first doped region and comprises a first main gate region; the third doped layer is stacked on the first doped layer and is arranged in a partial region of the first main gate region; a back passivation film covering the third doping layer and the first doping layer; and a part of the first main gate penetrates through the back passivation film to be in contact with the third doped layer, and a part of the first main gate penetrates through the back passivation film to be in contact with the first doped layer. According to the back contact solar cell of the utility model, through arranging the third doping layer, the contact area of the first main grid and the first doping layer can be reduced, the metallization composite loss of the first main grid can be reduced, the cell conversion efficiency can be improved, the welding tension of the first main grid can be increased, and the stable performance of the cell structure can be improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to solar cell technical field especially relates to a back contact solar cell, battery assembly and photovoltaic system. BACKGROUND

[0002] The back contact (Interdigitated back contact, IBC) solar cell, namely the interdigital back contact solar cell, the positive / negative electrode grid line is designed in the back of the cell, makes the front surface avoid the shelter of metal grid line completely, eliminates the optical loss brought by electrode grid line shelter, and the electrode grid line can be designed wider than the existing, reduces the series resistance loss, thereby greatly improves the cell conversion efficiency. In addition, due to the design of the electrode grid line on the front surface of the cell, the product appearance is more beautiful, is suitable for a variety of application scenarios.

[0003] In the prior art, the back of the back contact solar cell usually includes alternately arranged P-type doped regions and N-type doped regions, and the back contact solar cell adopts a burn-through type paste to manufacture main grids of the P-type doped regions and the N-type doped regions. In the process of printing the paste to form the main grids, the main grid paste directly contacts the passivation film layer and the underlying doped layer after burning through the passivation film layer. At the position of the main grid, the burn-through type paste burns through the passivation film layer and contacts the underlying doped layer in the entire region of the main grid of the P-type doped region and the N-type doped region, that is, the main grid of the P-type doped region and the N-type doped region contacts the corresponding doped layer in the entire region, which causes the contact area between the main grid and the doped layer to be too large, and the recombination in the metallization region is more serious, thereby reducing the conversion efficiency of the cell. SUMMARY

[0004] The utility model provides a kind of back contact solar cell, to solve the problem that the main grid of the prior art back contact solar cell and doped layer contact area are too large, which causes the recombination in the metallization region to be more serious, thereby reducing the conversion efficiency of the cell.

[0005] The utility model is implemented as follows: a kind of back contact solar cell is provided, comprising:

[0006] A silicon substrate, the back of the silicon substrate includes a first doped region;

[0007] A first doped layer is provided in the first doped region, and the first doped layer includes a first main grid region corresponding to a first main grid position;

[0008] A third doped layer is stacked on the first doped layer, the third doped layer has a doping polarity opposite to that of the first doped layer, and the third doped layer is provided in part of the first main grid region;

[0009] A back passivation film covers the third doped layer and the first doped layer;

[0010] a first main grid located in the first main grid region, the first main grid being disposed on the first doped layer and the third doped layer, a part of the first main grid being in contact with the third doped layer through the back passivation film, and a part of the first main grid being in contact with the first doped layer through the back passivation film.

[0011] Preferably, the back contact solar cell further comprises:

[0012] a plurality of first soldering points disposed on the first main grid, the first soldering points having a width greater than that of the first main grid, the first doped layer comprising a first soldering point region corresponding to the positions of the first soldering points, and the third doped layer being further disposed on a part of the first soldering point region.

[0013] a part of the first soldering points being in contact with the third doped layer through the back passivation film, and a part of the first soldering points being in contact with the first doped layer through the back passivation film.

[0014] Preferably, the back contact solar cell further comprises:

[0015] a first insulating layer disposed between the first doped layer and the third doped layer.

[0016] Preferably, the first insulating layer is one of borosilicate glass layer, phosphosilicate glass layer, borophosphosilicate glass layer, or a laminated structure of at least two of them.

[0017] Preferably, the contact area between the first main grid and the third doped layer accounts for 30% to 70% of the total area of the first main grid.

[0018] Preferably, the contact area between the first soldering points and the third doped layer accounts for 20% to 60% of the total area of the first soldering points.

[0019] Preferably, the contact area between the first main grid and the third doped layer is smaller than the contact area between the first main grid and the first doped layer.

[0020] Preferably, the first main grid region has a plurality of third doped layers disposed at intervals, and the plurality of third doped layers are linearly arranged along the length direction of the first main grid.

[0021] Preferably, the edge position of the first soldering point region is provided with a plurality of third doped layers, and the plurality of third doped layers are annularly arranged at intervals.

[0022] Preferably, the back surface of the silicon substrate further comprises a second doped region, and the back contact solar cell further comprises:

[0023] A second doped layer is disposed on the second doped region, the second doped layer has a doping polarity opposite to that of the first doped layer, and the second doped layer includes a second main grid region corresponding to a second main grid position;

[0024] A fourth doped layer is disposed on the second doped layer, the fourth doped layer has a doping polarity opposite to that of the second doped layer, and the fourth doped layer is disposed on a partial region of the second main grid region, and the back passivation film covers the second doped layer and the fourth doped layer;

[0025] A second main grid is located in the second main grid region, the second main grid is disposed on the second doped layer and the fourth doped layer, a partial region of the second main grid is in contact with the fourth doped layer through the back passivation film, and a partial region of the second main grid is in contact with the second doped layer through the back passivation film.

[0026] Preferably, the battery assembly further comprises:

[0027] A second insulating layer is disposed between the second doped layer and the fourth doped layer.

[0028] Preferably, the second insulating layer is one of a borosilicate glass layer, a phosphosilicate glass layer, and a borophosphosilicate glass layer, or a laminated structure of at least two of them.

[0029] Preferably, the contact area of the second main grid with the fourth doped layer is smaller than the contact area of the second main grid with the second doped layer.

[0030] Preferably, the first doped layer is a P-type doped layer, and the second doped layer is an N-type doped layer; the contact area of the first main grid with the first doped layer is greater than the contact area of the second main grid with the second doped layer.

[0031] Preferably, the battery assembly further comprises:

[0032] A second soldering point is disposed on the second main grid, the second soldering point has a width greater than that of the second main grid, the second doped layer includes a second soldering point region corresponding to a position of the second soldering point, and the fourth doped layer is further disposed on a partial region of the second soldering point region.

[0033] The second soldering point is disposed on the second doped layer and the fourth doped layer, a partial region of the second soldering point is in contact with the fourth doped layer through the back passivation film, and a partial region of the second soldering point is in contact with the second doped layer through the back passivation film.

[0034] The utility model provides a kind of battery assembly, including above-mentioned back contact solar cell.

[0035] The utility model provides a kind of photovoltaic system, including above-mentioned battery component.

[0036] The utility model provides a kind of back contact solar cell, third doped layer is arranged in the partial area of first doped layer corresponding first main grid area, first main grid only burns through back passivation film and third doped layer contact but does not contact with first doped layer by using third doped layer to block first main grid burn through, and first main grid penetrates back passivation film and first doped layer contact at the place where first doped layer is shielded by third doped layer, so that first main grid has partial area and third doped layer contact, another partial area of first main grid and first doped layer contact, can reduce the contact area of first main grid and first doped layer, reduce metallization recombination loss caused by first main grid, to improve battery conversion efficiency;Moreover, first main grid partial area and third doped layer contact, partial area of first main grid and first doped layer contact, can increase the welding tension of first main grid, benefit to improve battery structure stability. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 It is the back surface schematic view of a kind of back contact solar cell provided by the utility model embodiment;

[0038] Figure 2 It is the schematic view along the section of A-A direction; Figure 1

[0039] Figure 3 It is the schematic view along the section of B-B direction; Figure 1

[0040] Figure 4 It is the schematic view along the section of C-C direction; Figure 1

[0041] Figure 5 It is the first kind of schematic view of first main grid, first solder point corresponding third doped layer of a kind of back contact solar cell provided by the utility model embodiment;

[0042] Figure 6 It is the second kind of schematic view of first main grid, first solder point corresponding third doped layer of a kind of back contact solar cell provided by the utility model embodiment;

[0043] Figure 7 It is the third kind of schematic view of first main grid, first solder point corresponding third doped layer of a kind of back contact solar cell provided by the utility model embodiment;

[0044] Figure 8 It is the fourth kind of schematic view of first main grid, first solder point corresponding third doped layer of a kind of back contact solar cell provided by the utility model embodiment. DETAILED DESCRIPTION​​​

[0045] In order to make the purpose, technical scheme and advantages of the utility model clearer, the utility model will be described in further detail below in combination with the drawings and examples. The examples of the examples are shown in the drawings, wherein the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The examples described below by referring to the drawings are exemplary and are only used to explain the utility model and cannot be understood as limiting the utility model. In addition, it should be understood that the specific examples described herein are only used to explain the utility model and are not used to limit the utility model.

[0046] In the description of the utility model, it should be understood that the orientation or position relationship indicated by the terms "upper", "lower", "back", "front" and the like is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore it cannot be understood as limiting the utility model.

[0047] In the utility model, unless otherwise explicitly specified and limited, the "upper" or "lower" of the first feature to the second feature can include that the first and second features are in direct contact, or the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the "upper", "upper" and "upper" of the first feature to the second feature include that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The "below", "below" and "below" of the first feature to the second feature include that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0048] The following disclosure provides many different embodiments or examples for implementing different structures of the utility model. In order to simplify the disclosure of the utility model, the components and settings of specific examples are described below. Of course, they are only examples and the purpose is not to limit the utility model. In addition, the utility model can repeatedly refer to numerals and / or reference letters in different examples, and such repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the utility model provides examples of various specific processes and materials, but those skilled in the art can realize the application of other processes and / or the use of other materials.

[0049] The back contact solar cell provided by the utility model reduces the contact area of the first main grid and the first doped layer, reduces the metallization area recombination loss caused by the first main grid, and thus improves the battery conversion efficiency; moreover, the partial area of the first main grid is in contact with the third doped layer, and the partial area of the first main grid is in contact with the first doped layer, which can increase the welding tension of the first main grid and is beneficial to improving the stability of the battery structure.

[0050] Please refer to Figures 1-3 The utility model provides a kind of back contact solar cell, comprising:

[0051] Silicon substrate 10, silicon substrate 10 has oppositely arranged front 11 and back 12, and the back 12 of silicon substrate 10 includes first doped region 121;

[0052] First doped layer 13 is arranged in first doped region 121, and the first doped layer 13 includes the first main grid area corresponding to the position of first main grid 16;

[0053] Third doped layer 14 is stacked on the first doped layer 13, and the doping polarity of the third doped layer 14 is opposite to that of the first doped layer 13, and the third doped layer 14 is arranged in part of the first main grid area;

[0054] Back passivation film 15 covers the third doped layer 14 and the first doped layer 13;

[0055] First main grid 16 is located in the first main grid area, and the first main grid 16 is arranged on the first doped layer 13 and the third doped layer 14, part of the first main grid 16 is in contact with the third doped layer 14 through the back passivation film 15, and part of the first main grid 16 is in contact with the first doped layer 13 through the back passivation film 15.

[0056] In the embodiment of the utility model, the front 11 of silicon substrate 10 is the side facing the sunlight when the back contact solar cell is working, and the back 12 of silicon substrate 10 is the side away from the sunlight when the back contact solar cell is working.

[0057] In the embodiment of the utility model, the first doped region 121 can be a P-type doped region or an N-type doped region. When the first doped region 121 is a P-type doped region, the first doped layer 13 is a P-type doped layer, and the P-type doped layer is doped with a group IIIA element. When the first doped region 121 is an N-type doped region, the first doped layer 13 is an N-type doped layer, and the N-type doped layer is doped with a group VA element.

[0058] In the embodiment of the utility model, the back surface 12 is provided with first doped areas 121 and second doped areas 122 which are arranged alternately in sequence along the first direction X, the first doped areas 121 and the second doped areas 122 are provided with isolation areas 123, and the back surface passivation film 15 also covers the isolation areas 123. The first doped areas 121 can be P-type doped areas or N-type doped areas.

[0059] In the embodiment of the utility model, the first main grid area is specifically an area covered by the normal projection of the first main grid 16 to the silicon substrate direction. By arranging the third doped layer 14 on the part of the area of the first doped layer 13 of the back contact solar cell corresponding to the first main grid area, the part of the area of the first doped layer 13 corresponding to the first main grid area is shielded by the third doped layer 14, and the part of the first doped layer 13 shielded by the third doped layer 14 can block the burning-through depth of the first main grid 16 due to the blocking and isolating effect of the third doped layer 14, the first main grid 16 cannot completely burn through the third doped layer 14, and the first main grid 16 only burns through the back surface passivation film 15 to contact the third doped layer 14 but does not contact the first doped layer 13; while the part of the first doped layer 13 not shielded by the third doped layer 14, the first main grid 16 penetrates the back surface passivation film 15 to contact the first doped layer 13, so that a part of the area of the first main grid 16 contacts the third doped layer 14 and another part of the area of the first main grid 16 contacts the first doped layer 13, thus the first main grid 16 only contacts the first doped layer 13 in part, the contact area of the first main grid 16 and the first doped layer 13 can be reduced, the metallization area recombination loss caused by the first main grid 16 can be reduced, and thus the battery conversion efficiency is improved; moreover, the part of the area of the first main grid 16 contacting the third doped layer 14 and the part of the area of the first main grid 16 contacting the first doped layer 13 can increase the welding tension of the first main grid 16, and thus the battery structure stability performance is improved.

[0060] As an embodiment of the utility model, further comprising:

[0061] A plurality of first soldering points 17 are arranged on the first main grid 16, the width of the first soldering point 17 is greater than the width of the first main grid 16, the first doped layer 13 comprises a first soldering point area corresponding to the position of the first soldering point 17, and the third doped layer 14 is further arranged on part of the area of the first soldering point area;

[0062] Part of the area of the first soldering point 17 contacts the third doped layer 14 through the back surface passivation film 15, and part of the area of the first soldering point 17 contacts the first doped layer 13 through the back surface passivation film 15.

[0063] In the embodiment, a plurality of first soldering points 17 are arranged in the second direction Y on the first main grid 16 in sequence and at intervals, the second direction Y is the length direction of the first main grid 16, and the width direction of the first soldering point 17 is the first direction X perpendicular to the second direction Y. The first soldering point area is specifically an area covered by the normal projection of the first soldering point 17 to the silicon substrate 10. By arranging the third doped layer 14 in the part area of the first doped layer 13 of the back contact solar cell corresponding to the first soldering point 17, the part area of the first doped layer 13 corresponding to the first soldering point area is shielded by the third doped layer 14. Since the third doped layer 14 can block the first soldering point 17 from burning through, at the position where the first doped layer 13 under the first soldering point area is shielded by the third doped layer 14, the first soldering point 17 burns through the back passivation film 15 and contacts the third doped layer 14 but does not contact the first doped layer 13, and at the position where the first doped layer 13 under the first soldering point area is not shielded by the third doped layer 14, the first soldering point 17 burns through the back passivation film 15 and contacts the first doped layer 13, so that the part area of the first soldering point 17 contacts the third doped layer 14 and the part area of the first soldering point 17 contacts the first doped layer 13, the contact area of the first soldering point 17 and the first doped layer 13 can be reduced, thereby reducing the metallization recombination loss caused by the first soldering point 17, further improving the conversion efficiency of the cell, especially in the case of increasing the area of the first soldering point 17, the first soldering point 17 can also cause lower metallization recombination loss; and since the part area of the first soldering point 17 on the first main grid 16 contacts the third doped layer 14 and the part area of the first soldering point 17 contacts the first doped layer 13, the bonding force between the first soldering point 17 and the back film layer of the cell can be increased, the welding tension of the first soldering point 17 during welding can be increased, and the stability of the cell structure is further improved.

[0064] Of course, in some other embodiments, the burn-through capability of the metal paste component of the first soldering point 17 is smaller than the burn-through capability of the metal paste component of the first main grid 16, and the contact area of the first soldering point 17 and the first doped layer 13 can also be reduced, thereby reducing the metallization recombination loss of the first soldering point 17; of course, the metal paste component of the first soldering point 17 can also be adjusted so that the first soldering point 17 does not burn through the back passivation film 15, and the metallization recombination loss caused by the first soldering point 17 can also be avoided.

[0065] Please refer to Figure 3 and Figure 4 as an embodiment of the utility model, the back surface 12 of the silicon substrate 10 further comprises a second doped area 122, and the back contact solar cell further comprises:

[0066] a second doped layer 18 arranged in the second doped area 122, the second doped layer 18 is opposite to the first doped layer 13 in doping polarity, and the second doped layer 18 comprises a second main grid area corresponding to the position of the second main grid 21;

[0067] A fourth doped layer 19 is arranged on the second doped layer 18, the fourth doped layer 19 is opposite to the second doped layer 18 in polarity, and the fourth doped layer 19 is arranged on a part of the second main grid region. The back passivation film 15 covers the fourth doped layer 19 and the second doped layer 18.

[0068] A second main grid 21 is arranged on the second doped layer 18 and the fourth doped layer 19. A part of the second main grid 21 is in contact with the fourth doped layer 19 through the back passivation film 15, and a part of the second main grid 21 is in contact with the second doped layer 18 through the back passivation film 15.

[0069] In the embodiment, the first doped region 121 and the second doped region 122 are arranged in the first direction X. The first doped region 121 can be a P-type doped region, and the first doped layer 13 is a P-type doped layer. The second doped region 122 is an N-type doped region, and the second doped layer 18 is an N-type doped layer. Alternatively, the first doped region 121 can be an N-type doped region, and the first doped layer 13 is an N-type doped layer. The second doped region 122 is a P-type doped region, and the second doped layer 18 is a P-type doped layer.

[0070] In the embodiment, the second main grid region is a region covered by the orthographic projection of the second main grid 21 to the silicon substrate 10. The fourth doped layer 19 is arranged on a part of the second doped layer 18 corresponding to the second main grid region of the back contact solar cell. The part of the second doped layer 18 corresponding to the second main grid region is shielded by the fourth doped layer 19. The fourth doped layer 19 blocks the burning-through depth of the second main grid 21. The second main grid 21 penetrates the back passivation film 15 and is in contact with the fourth doped layer 19 without being in contact with the second doped layer 18. In the part not shielded by the fourth doped layer 19, the second main grid 21 penetrates the second passivation film and is in contact with the second doped layer 18. The part of the second main grid 21 is in contact with the fourth doped layer 19, and the part of the second main grid 21 is in contact with the second doped layer 18. Therefore, only part of the second main grid 21 is in contact with the second doped layer 18, which can reduce the contact area of the second main grid 21 and the second doped layer 18. Thus, the metallization recombination loss of the first main grid 16 of the first doped region 121 and the second main grid 21 of the second doped region 122 can be reduced, and the conversion efficiency of the cell can be improved. Moreover, the part of the second main grid 21 is in contact with the fourth doped layer 19, and the part of the first main grid 16 is in contact with the second doped layer 18, which can increase the welding tension of the second main grid 21. Thus, the welding tension of the first main grid 16 and the second main grid 21 can be increased, which is beneficial to further improving the stability of the cell structure.

[0071] As an embodiment of the utility model, further include:

[0072] a plurality of second soldering points 24 arranged on the second main grid 21, the width of the second soldering points 24 is greater than the width of the second main grid 21, the second doped layer 18 comprises a second soldering point area corresponding to the position of the second soldering points 24, and the fourth doped layer 19 is further arranged on part of the second soldering point area;

[0073] Part of the second soldering points 24 is in contact with the fourth doped layer 19 through the back passivation film 15, and part of the second soldering points 24 is in contact with the second doped layer 18 through the back passivation film 15.

[0074] In the embodiment, the plurality of second soldering points 24 are arranged on the second main grid 21 along the second direction Y in sequence and at intervals, and the second direction Y is the length direction of the second main grid 21. The second soldering point area is specifically an area covered by the normal projection of the second soldering point area in the direction of the silicon substrate. By arranging the fourth doped layer 19 on part of the second soldering point area of the second doped layer 18 of the back contact solar cell corresponding to the second soldering points 24, part of the second soldering point area of the second doped layer 18 is shielded by the fourth doped layer 19. Since the fourth doped layer 19 can block the burn-through depth of the second soldering points 24, at the position where the first doped layer 13 below the first soldering point area is shielded by the fourth doped layer 19, the second soldering points 24 are in contact with the fourth doped layer 19 through the burn-through of the back passivation film 15 and are not in contact with the second doped layer 18, at the position where the second doped layer 18 below the second soldering point area is not shielded by the fourth doped layer 19, the second soldering points 24 are in contact with the second doped layer 18 through the burn-through of the back passivation film 15, the part of the second soldering point area is in contact with the fourth doped layer 19, and the part of the second soldering point area is in contact with the second doped layer 18, which can reduce the contact area of the second soldering points 24 and the second doped layer 18, thereby reducing the metallization recombination loss caused by the second soldering points 24, thereby further improving the conversion efficiency of the cell, especially in the case of increasing the area of the second soldering points 24, the second soldering points 24 can also cause lower metallization recombination loss; and since the part of the second soldering points 24 on the second main grid 21 is in contact with the fourth doped layer 19 and the part of the second soldering points 24 is in contact with the second doped layer 18, the bonding force between the second soldering points 24 and the back film layer of the cell can be increased, the welding tension of the second soldering points 24 during welding can be increased, and the stability of the cell structure is further improved.

[0075] As an embodiment of the utility model, the third doped layer 14 can be a doped polysilicon layer, a doped amorphous silicon layer or a doped microcrystalline silicon layer.

[0076] In the case that the first doped layer 13 is a P-type doped layer, the second doped layer 18 is an N-type doped layer, the third doped layer 14 is an N-type doped layer, and the fourth doped layer 19 is a P-type doped layer, or in the case that the first doped layer 13 is an N-type doped layer, the second doped layer 18 is a P-type doped layer, the third doped layer 14 is a P-type doped layer, and the fourth doped layer 19 is an N-type doped layer. In this case, the second doped layer 18 is formed by deposition, and after the first doped layer 13 is formed on the back surface, during the process of depositing the second doped layer 18, a wrap plating layer of the same doping type as the second doped layer 18 will be formed on the first doped layer 13. In the conventional technical solution, the wrap plating layer needs to be completely removed in the subsequent process, but in the present application, only the local wrap plating layer needs to be removed, that is, the wrap plating layer in the local area is retained, thereby forming the third doped layer 14, which is simple to implement and low in implementation cost.

[0077] As an embodiment of the present application, the thickness of the third doped layer 14 can be greater than the thickness of the first doped layer 13, which can further improve the burn-through blocking effect of the third doped layer 14 on the first main grid 16. Of course, the thickness of the third doped layer 14 can also be less than or equal to the thickness of the first doped layer 13.

[0078] As an embodiment of the present application, the fourth doped layer 19 can be a doped polysilicon layer, a doped amorphous silicon layer, or a doped microcrystalline silicon layer.

[0079] Similarly, the fourth doped layer 19 can also be prepared by the same method as the third doped layer 14, which is simple to implement and low in implementation cost. Alternatively, the third doped layer 14 and the fourth doped layer 19 can be formed by deposition respectively.

[0080] As an embodiment of the present application, it further comprises:

[0081] The first insulating layer 22 is arranged between the first doped layer 13 and the third doped layer 14.

[0082] In the present embodiment, the first insulating layer 22 is arranged between the first doped layer 13 and the third doped layer 14, and the first doped layer 13 and the third doped layer 14 are insulated and isolated by the first insulating layer 22. In this way, the first insulating layer 22 can insulate and isolate the first doped layer 13 and the third doped layer 14, and can avoid electric leakage when the third doped layer 14 is a doped layer with a polarity opposite to that of the first doped layer 13 (i.e., the third doped layer 14).

[0083] As an embodiment of the present application, the first insulating layer 22 is one of a borosilicate glass layer, a phosphosilicate glass layer, and a borophosphosilicate glass layer, or a laminated structure of at least two of them.

[0084] For example, when the first doped layer 13 is a P-type doped layer and the second doped layer 18 is an N-type doped layer, a boron silicon glass layer is formed above the first doped layer 13 when the first doped layer 13 is formed. When the boron silicon glass layer is not removed and the second doped layer 18 is formed by deposition, the boron silicon glass layer, a boron phosphorus silicon glass layer (both of which are the first insulating layer 22), and the third doped layer 14 (i.e., an N-type doped layer) are sequentially formed above the first doped layer 13. When the boron silicon glass layer on the first doped layer 13 is removed, a phosphorus silicon glass layer (i.e., the first insulating layer 22) and the third doped layer 14 (i.e., an N-type doped layer) are formed above the first doped layer 13. In addition, when the second doped layer 18 is formed by diffusion, the boron silicon glass layer and the boron phosphorus silicon glass layer (i.e., the first insulating layer 22) are sequentially formed above the first doped layer 13.

[0085] When the first doped layer 13 is an N-type doped layer and the second doped layer 18 is a P-type doped layer, a phosphorus silicon glass layer is formed above the first doped layer 13 when the first doped layer 13 is formed. When the phosphorus silicon glass layer is not removed and the second doped layer 18 is formed by deposition, the phosphorus silicon glass layer, a boron phosphorus silicon glass layer (both of which are the first insulating layer 22), and the third doped layer 14 (i.e., a P-type doped layer) are sequentially formed above the first doped layer 13. In addition, when the second doped layer 18 is formed by diffusion, the phosphorus silicon glass layer and the boron phosphorus silicon glass layer (i.e., the first insulating layer 22) are sequentially formed above the first doped layer 13.

[0086] As an embodiment of the present application, the contact area of the first main grid 16 and the third doped layer 14 accounts for 30% to 70% of the total area of the first main grid 16.

[0087] In this way, the contact area of the first main grid 16 and the third doped layer 14 is set within the above range, which can effectively reduce the metallization contact area of the first main grid 16 to reduce recombination, and can ensure good soldering tension of the first main grid 16, balance the relationship between the metal recombination and the soldering tension of the first main grid 16, and improve the efficiency of the back contact solar cell.

[0088] As an embodiment of the present application, the contact area of the first soldering point 17 and the third doped layer 14 accounts for 20% to 60% of the total area of the first soldering point 17.

[0089] In this way, the contact area of the first soldering point 17 and the third doped layer 14 is set within the above range, which can effectively reduce the metallization contact area of the first soldering point 17 to reduce recombination, and can ensure good soldering tension of the first soldering point 17, balance the relationship between the metal recombination and the soldering tension of the first soldering point 17, and improve the efficiency of the back contact solar cell.

[0090] As an embodiment of the present application, the contact area of the first main grid 16 and the third doped layer 14 is less than the contact area of the first main grid 16 and the first doped layer 13.

[0091] In this way, the contact area of the first main grid 16 and the third doped layer 14 is less than the contact area of the first main grid 16 and the first doped layer 13, which can effectively reduce the metallization contact area to reduce the recombination while avoiding the contact area being too small, and can also avoid the resistance being too large, thereby further improving the efficiency of the back contact solar cell.

[0092] Please refer to Figure 5 As an embodiment of the present application, the first main grid region has a plurality of third doped layers 14 arranged at intervals, and the plurality of third doped layers 14 are linearly arranged along the length direction of the first main grid 16.

[0093] The specific number and shape of the plurality of third doped layers 14 in the first main grid region are not limited, and the arrangement of the plurality of third doped layers 14 in the first main grid region is not limited. For example, the plurality of third doped layers 14 in the first main grid region can be linearly arranged along the length direction of the first main grid 16, which can make the first main grid metallization recombination uniformly distributed, and is beneficial to improving the conductivity of the first main grid, thereby further improving the efficiency of the back contact solar cell. Of course, the plurality of third doped layers 14 in the first main grid region can also be arranged in multiple rows and multiple columns.

[0094] In the present embodiment, the specific number and shape of the third doped layer 14 in the first solder point region are not limited, and the arrangement of the plurality of third doped layers 14 in the first solder point region is not limited, and the size of each third doped layer 14 can be the same or different.

[0095] As an embodiment of the present application, a plurality of third doped layers 14 are arranged at the edge position of the first solder point region, and the plurality of third doped layers 14 are arranged at intervals in a ring shape. The edge region of the first solder point 17 is blocked by the plurality of third doped layers 14 arranged at the edge position of the first solder point region, thereby reducing the recombination loss of the edge region of the first solder point 17. Among them, Figure 5 The edge position of the first solder point region is schematically provided with four third doped layers 14.

[0096] Please refer to Figure 6 As an embodiment of the present application, a third doped layer 14 is arranged at the middle position of the first solder point region.

[0097] In the present embodiment, a plurality of third doped layers 14 are arranged at the edge position of the first solder point region, and a third doped layer 14 is arranged at the middle position of the first solder point region, which can further increase the soldering tension of the first solder point 17.

[0098] The width of the third doped layer 14 at the middle position of the first solder point area is less than or equal to the width of the third doped layer 14 at the edge position of the first solder point area, so that the metal composite loss of the first solder point area is more uniform. In addition, please refer to Figure 7 The width of the third doped layer 14 at the middle position of the first solder point area can also be greater than the width of the third doped layer 14 at the edge position of the first solder point area, which is beneficial to increase the soldering tension of the first solder point 17. The width direction of the third doped layer 14 and the width direction of the first main grid 21 are both the first direction X, and the length direction of the third doped layer 14 and the length direction of the first main grid 21 are both the second direction Y.

[0099] Please refer to Figure 8 As another embodiment of the present application, the width of the third doped layer 14 of the first solder point area is greater than the width of the first main grid, and the third doped layer 14 is perpendicular to the length direction of the first main grid 21, which is beneficial to increase the soldering tension of the first solder point 17 and the first main grid 21. Wherein, Figure 8 As shown in the figure, the number of third doped layers 14 of each first solder point area is two parallel to each other.

[0100] The specific number, shape and arrangement of the fourth doped layer 19 corresponding to the second main grid area and the second solder point area can be the same as or different from the specific number, shape and arrangement of the fourth doped layer 19 corresponding to the first main grid area and the first solder point area.

[0101] As an embodiment of the present application, it further comprises:

[0102] The second insulating layer 23 is arranged between the second doped layer 18 and the fourth doped layer 19.

[0103] The second insulating layer 23 can also include at least one of borosilicate glass layer, phosphosilicate glass layer and boron phosphorus silicon glass layer or a combination of multiple thereof. In this way, the arrangement of the second insulating layer 23 can insulate and isolate the second doped layer 18 and the fourth doped layer 19, which can avoid the leakage caused by the polarity opposite doped layer (i.e. the fourth doped layer 19) of the second doped layer 18 and the fourth doped layer 19, and at the same time can improve the blocking effect of the fourth doped layer 19.

[0104] As an embodiment of the present application, the contact area of the second main grid 21 and the fourth doped layer 19 is less than the contact area of the second main grid 21 and the second doped layer 18.

[0105] Therefore, the contact area of the second main grid 21 and the fourth doped layer 19 is smaller than the contact area of the second main grid 21 and the second doped layer 18, so that the metallization contact area of the second main grid 21 can be effectively reduced to reduce the recombination, while avoiding too small contact area, and avoiding too large resistance, thereby further improving the efficiency of the back contact solar cell.

[0106] As an embodiment of the present application, the first doped layer 13 is a P-type doped layer, and the second doped layer 18 is an N-type doped layer; the contact area of the first main grid 16 and the first doped layer 13 is greater than the contact area of the second main grid 21 and the second doped layer 18.

[0107] Therefore, the contact area of the first main grid 16 and the first doped layer 13 is greater than the contact area of the second main grid 21 and the second doped layer 18, so that the contact area of the first main grid 16 and the first doped layer 13 can be increased, the contact effect of the first main grid 16 and the first doped layer 13 is improved, the conductivity of the P region is improved, and the efficiency of the back contact solar cell is further improved.

[0108] In some embodiments, a first tunneling layer (not shown in the figure) is arranged between the first doped region 121 and the first doped layer 13, and a second tunneling layer (not shown in the figure) is arranged between the second doped region 122 and the second doped layer 18. The first tunneling layer and the second tunneling layer can be one or a combination of silicon oxide and silicon nitride oxide.

[0109] The embodiment of the present application further provides a battery assembly, which comprises the back contact solar cell of the above-mentioned embodiment. It should be noted that the battery assembly has the same or similar beneficial effects as the above-mentioned back contact solar cell, and the related parts between the two can be mutually referred to. In order to avoid repetition, this will not be repeated here.

[0110] In the present embodiment, a plurality of back contact solar cells in the battery assembly can be sequentially connected in series to form a battery string, thereby realizing the series connection of the current, for example, the connection of the battery pieces can be realized by setting a welding strip (bus bar, interconnection strip), a conductive back plate and the like.

[0111] It can be understood that in such an embodiment, the battery assembly can further comprise a metal frame, a back plate, photovoltaic glass and a film. The film can be filled between the front and back surfaces 12 of the back contact solar cell, photovoltaic glass, adjacent battery pieces and the like, and can be a transparent gel with good light transmission performance and aging resistance, for example, the film can use EVA film or POE film, which can be selected according to actual conditions, and is not limited here.

[0112] The photovoltaic glass can be covered on the adhesive film on the front surface of the back contact solar cell, the photovoltaic glass can be super white glass, which has high light transmittance, high transparency, and has superior physical, mechanical and optical properties, for example, the light transmittance of the super 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, and the presence of the adhesive film can seal and insulate the back contact solar cell and prevent water and moisture.

[0113] The back plate can be attached to the adhesive film on the back surface 12 of the back contact solar cell, the back plate can protect and support the back contact solar cell, has reliable insulation, water resistance and aging resistance, the back plate can have multiple choices, which can be tempered glass, organic glass, aluminum alloy TPT composite adhesive film and the like, which can be set according to specific conditions, which is not limited here. The whole composed of the back plate, the back contact solar cell, the adhesive film and the photovoltaic glass can be arranged on the metal frame, the metal frame serves as the main external support structure of the entire back contact solar cell module, and can stably support and install the back contact solar cell module, for example, the back contact solar cell module can be installed at the position required to be installed through the metal frame.

[0114] The utility model embodiment further provides a photovoltaic system, the photovoltaic system includes the battery module of above -mentioned embodiment. It needs to be explained that, the photovoltaic system has same or similar beneficial effect with above -mentioned back contact solar cell, and the related place between both can be mutually referred to, in order to avoid repetition, here will not be repeated.

[0115] In the embodiment, the photovoltaic system can be applied in a photovoltaic power station, such as a ground power station, a roof power station, a water surface power station, etc., and can also be applied in a device or apparatus that generates electricity using solar energy, such as a user solar power source, a solar street lamp, a solar car, a solar building, 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 need to generate electricity using solar energy. Taking a photovoltaic power generation system network as an example, the photovoltaic system can include a photovoltaic array, a current combiner, and an inverter. The photovoltaic array can be an array combination of a plurality of back contact solar cell modules. For example, a plurality of back contact solar cell modules can form a plurality of photovoltaic arrays. The photovoltaic arrays are connected to the current combiner. The current combiner can combine the currents generated by the photovoltaic arrays. The combined current flows through the inverter to convert into alternating current required by a power grid, and then is connected to the power grid to realize solar power supply.

[0116] In the description of the specification, the description of the terms "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the utility model. In the specification, the illustrative description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0117] The above is only the preferred embodiment of the utility model, and does not limit the utility model, and any modification, equivalent replacement and improvement made within the spirit and principle of the utility model should be included in the protection scope of the utility model.

Claims

1. A back contact solar cell, characterized by, The back surface of the silicon substrate comprises a first doped region; A first doped layer is arranged on the first doped region, and the first doped layer comprises a first main grid area corresponding to a first main grid position; A third doped layer is arranged on the first doped layer, the third doped layer is opposite to the first doped layer in doping polarity, and the third doped layer is arranged in a partial area of the first main grid area; A back surface passivation film covers the third doped layer and the first doped layer; A first main grid is arranged on the first main grid area, the first main grid is arranged on the first doped layer and the third doped layer, a partial area of the first main grid is in contact with the third doped layer through the back surface passivation film, and a partial area of the first main grid is in contact with the first doped layer through the back surface passivation film. Further comprising:

2. The back contact solar cell of claim 1, wherein, A plurality of first solder points are arranged on the first main grid, the width of the first solder point is greater than the width of the first main grid, the first doped layer comprises a first solder point area corresponding to the position of the first solder point, and the third doped layer is further arranged in a partial area of the first solder point area; A partial area of the first solder point is in contact with the third doped layer through the back surface passivation film, and a partial area of the first solder point is in contact with the first doped layer through the back surface passivation film. Further comprising:

3. The back contact solar cell of claim 1, wherein, A first insulating layer is arranged between the first doped layer and the third doped layer. The first insulating layer is one of a borosilicate glass layer, a phosphosilicate glass layer, and a borophosphosilicate glass layer, or a laminated structure of at least two of them.

4. The back contact solar cell of claim 3, wherein, The contact area of the first main grid and the third doped layer accounts for 30% to 70% of the total area of the first main grid.

5. The back contact solar cell of claim 1, wherein, The contact area of the first solder point and the third doped layer accounts for 20% to 60% of the total area of the first solder point.

6. The back contact solar cell of claim 2, wherein, The contact area of the first main grid and the third doped layer is less than the contact area of the first main grid and the first doped layer.

7. The back contact solar cell of claim 1 wherein, The first main grid area has a plurality of third doped layers arranged at intervals, and the plurality of third doped layers are linearly arranged along the length direction of the first main grid.

8. The back contact solar cell of claim 2, wherein, The edge position of the first solder point area is provided with a plurality of third doped layers, and the plurality of third doped layers are arranged in a ring shape at intervals.

9. The back contact solar cell of claim 8, wherein, The back surface of the silicon substrate further comprises a second doped region, and the back contact solar cell further comprises:

10. The back contact solar cell of claim 1 wherein, A second doped layer is arranged on the second doped region, and the second doped layer is opposite to the first doped layer in doping polarity, and the second doped layer comprises a second main grid area corresponding to a second main grid position; A fourth doped layer is arranged on the second doped layer, the fourth doped layer is opposite to the second doped layer in doping polarity, and the fourth doped layer is arranged in a partial area of the second main grid area, and the back surface passivation film covers the second doped layer and the fourth doped layer; ​ A second main grid located in the second main grid region, the second main grid being disposed on the second doped layer and the fourth doped layer, a portion of the second main grid being in contact with the fourth doped layer through the back passivation film, and a portion of the second main grid being in contact with the second doped layer through the back passivation film.

11. The back contact solar cell of claim 10, wherein, Further comprising: A second insulating layer disposed between the second doped layer and the fourth doped layer.

12. The back contact solar cell of claim 11, wherein, The second insulating layer is one of borosilicate glass layer, phosphosilicate glass layer, borophosphosilicate glass layer, or a laminated structure of at least two of them.

13. The back contact solar cell of claim 10, wherein, The contact area of the second main grid with the fourth doped layer is smaller than the contact area of the second main grid with the second doped layer.

14. The back contact solar cell of claim 10, wherein, The first doped layer is a P-type doped layer, and the second doped layer is an N-type doped layer; the contact area of the first main grid with the first doped layer is larger than the contact area of the second main grid with the second doped layer.

15. The back contact solar cell of claim 10, wherein, Further comprising: A second soldering point disposed on the second main grid, the width of the second soldering point being larger than the width of the second main grid, the second doped layer including a second soldering point region corresponding to the position of the second soldering point, and the fourth doped layer being further disposed in a portion of the second soldering point region; The second soldering point is disposed on the second doped layer and the fourth doped layer, a portion of the second soldering point being in contact with the fourth doped layer through the back passivation film, and a portion of the second soldering point being in contact with the second doped layer through the back passivation film.

16. A battery assembly characterized by, The back contact solar cell as claimed in any one of claims 1-15.

17. A photovoltaic system characterized by, The battery assembly as claimed in claim 16.

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