Solar cell, cell assembly and photovoltaic system

Abstract

The utility model is applicable to the technical field of solar cells, and provides a solar cell, a cell module and a photovoltaic system, in the solar cell, at least part of the side wall surface of a cell substrate is covered with two passivation film layers, the side wall surface can be efficiently passivated, so that edge recombination is reduced, and the service life of the solar cell is prolonged. And the conversion efficiency of the solar cell is improved. Meanwhile, a third part and a fourth part are sequentially arranged on a partial region, adjacent to the side wall surface, of the first surface, and a first part and a sixth part are sequentially arranged on a partial region, adjacent to the side wall surface, of the second surface, so that the passivation effect of the edge of the solar cell is further improved, and the conversion efficiency is further improved.

Description

Technical Field

[0001] This application relates to the technical field of solar cells, and particularly to a solar cell, a battery module, and a photovoltaic system. Background Art

[0002] Power generation by solar cells is a sustainable source of clean energy, which can convert sunlight into electrical energy by utilizing the photovoltaic effect of the semiconductor p-n junction. In a solar cell, a P-type doping layer and an N-type doping layer are provided on a silicon substrate, and a passivation film layer is provided on each doping layer to passivate the battery.

[0003] In current solar cells, the edge recombination of the solar cell is relatively large, resulting in a low conversion efficiency. Summary of the Utility Model

[0004] This application provides a solar cell, a battery module, and a photovoltaic system.

[0005] This application is implemented as follows. The solar cell of the embodiment of this application includes:

[0006] A battery substrate having opposite first and second surfaces and a plurality of side wall surfaces connecting the first and second surfaces;

[0007] A first passivation film layer, which is a continuous structure and includes a first portion covering the first surface, a second portion covering at least one of the side wall surfaces, and a third portion covering a partial area of the second surface adjacent to the side wall surface; and

[0008] A second passivation film layer, which is a continuous structure and includes a fourth portion covering the second surface to cover the third portion, a fifth portion covering the second portion, and a sixth portion covering a partial area of the first portion adjacent to the side wall surface.

[0009] In some embodiments, the second portion covers all the side wall surfaces.

[0010] In some embodiments, the thickness of the fourth portion is greater than the thickness of the first portion.

[0011] In some embodiments, the sum of the thicknesses of the second portion and the fifth portion is greater than the sum of the thicknesses of the third portion and the portion of the fourth portion covering the third portion.

[0012] In some embodiments, the sum of the thicknesses of the third portion and the fourth portion covering the third portion is greater than the thickness of the portion of the fourth portion covering the area of the second surface not covered by the third portion.

[0013] In some embodiments, the thickness of the first part is greater than the thickness of the third part; and / or

[0014] the thickness of the fourth part is greater than the thickness of the sixth part.

[0015] In some embodiments, the thickness of the third part gradually decreases in a direction away from the side wall surface of the third part; and / or

[0016] the thickness of the sixth part gradually decreases in a direction away from the side wall surface of the sixth part.

[0017] In some embodiments, the first passivation film layer is composed of at least one of a silicon oxide film layer, a silicon oxynitride film layer, and a silicon nitride film layer;

[0018] the second passivation film layer is also composed of at least one of a silicon oxide film layer, a silicon oxynitride film layer, and a silicon nitride film layer.

[0019] In some embodiments, the solar cell is a back-contact solar cell, and the cell substrate includes:

[0020] a silicon wafer having opposite front and back surfaces;

[0021] a plurality of P-type doping layers and N-type doping layers alternately arranged on the back surface of the silicon wafer, with a spacer region between adjacent P-type doping layers and N-type doping layers;

[0022] wherein, the front surface of the silicon wafer is the first surface, the surface of the cell substrate facing away from the front surface is the second surface, the second surface has an edge region and a middle region, the middle region is located inside the edge region, the edge region is closer to the edge of the second surface than the middle region, the first part covers the front surface of the silicon wafer, the third part covers the edge region, and the fourth part covers the middle region and the third part.

[0023] In some embodiments, on the middle region, the portion of the fourth part covering the N-type doping layer has a first thickness, and the portion of the fourth part covering the P-type doping layer has a second thickness, and the first thickness is greater than the second thickness.

[0024] In some embodiments, the ratio of the first thickness to the second thickness is greater than 1 and less than or equal to 2.

[0025] In some embodiments, on the middle region, the portion of the fourth part covering the spacer region has a third thickness, and the second thickness is greater than the third thickness.

[0026] In some embodiments, the ratio of the second thickness to the third thickness is greater than 1 and less than or equal to 2.

[0027] In some embodiments, the solar cell further includes a third passivation film layer, which covers the first surface, the second surface, and at least part of the side wall surfaces, and both the first passivation film layer and the second passivation film layer cover the third passivation film layer.

[0028] In some embodiments, the thickness of the part of the third passivation film layer covering the second surface is greater than the thickness of the part of the third passivation film layer covering the first surface.

[0029] In some embodiments, the third passivation film layer contains aluminum or phosphorus, and the material of the third passivation film layer is different from the materials of the first passivation film layer and the second passivation film layer.

[0030] In some embodiments, the cell substrate includes a silicon wafer, a first doping layer and a second doping layer that are respectively stacked and covered on opposite sides of the silicon wafer, the first surface is the surface of the first doping layer facing away from the silicon wafer, and the second surface is the surface of the second doping layer facing away from the silicon wafer.

[0031] In some embodiments, the cell substrate further includes a first tunneling oxide layer stacked between the silicon wafer and the second doping layer.

[0032] In some embodiments, the solar cell further includes a fourth passivation film layer, which covers the first surface, the second surface, and at least part of the side wall surfaces, and both the first passivation film layer and the second passivation film layer cover the fourth passivation film layer.

[0033] In some embodiments, the thickness of the part of the fourth passivation film layer covering the first surface is greater than the thickness of the part of the fourth passivation film layer covering the second surface.

[0034] In some embodiments, the cell substrate further includes a second tunneling oxide layer located between the first doping layer and the silicon wafer.

[0035] The present application also provides a battery assembly, including a plurality of the solar cells described in any one of the above.

[0036] The present application also provides a photovoltaic system, and the photovoltaic system includes the above-mentioned battery assembly.

[0037] In the embodiments of the present application, in a solar cell, a battery module, and a photovoltaic system, the first passivation film layer has a continuous structure and includes a first portion covering the first surface, a second portion covering at least one side wall surface, and a third portion covering a partial area adjacent to the side wall surface on the second surface. The second passivation film layer has a continuous structure and includes a fourth portion covering the second surface to cover the third portion, a fifth portion covering the second portion, and a sixth portion covering a partial area adjacent to the side wall surface in the first portion. In this way, on the one hand, at least a part of the side wall surface of the battery substrate is covered with two passivation film layers, which can efficiently passivate the side wall surface, thereby reducing edge recombination and improving the conversion efficiency of the solar cell. On the other hand, the third portion and the fourth portion are sequentially disposed on the partial area adjacent to the side wall surface on the first surface, and the first portion and the sixth portion are sequentially disposed on the partial area adjacent to the side wall surface on the second surface, which can further enhance the passivation effect on the edge of the solar cell, and further improve the conversion efficiency.

[0038] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present application. Description of the Drawings

[0039] Figure 1 is a schematic diagram of a module of a photovoltaic system provided by an embodiment of the present application;

[0040] Figure 2 is a schematic cross-sectional structure diagram of a solar cell provided by an embodiment of the present application;

[0041] Figure 3 is another schematic cross-sectional structure diagram of a solar cell provided by an embodiment of the present application;

[0042] Figure 4 is yet another schematic cross-sectional structure diagram of a solar cell provided by an embodiment of the present application;

[0043] Figure 5 is still another schematic cross-sectional structure diagram of a solar cell provided by an embodiment of the present application;

[0044] Figure 6 is still another schematic cross-sectional structure diagram of a solar cell provided by an embodiment of the present application;

[0045] Figure 7 is still another schematic cross-sectional structure diagram of a solar cell provided by an embodiment of the present application;

[0046] Figure 8 is still another schematic cross-sectional structure diagram of a solar cell provided by an embodiment of the present application. Detailed Embodiments

[0047] To make the objectives, technical solutions and advantages of the present application more clear and understandable, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements with the same or similar functions throughout. It should be noted that the embodiments described below with reference to the accompanying drawings are exemplary only for explaining the present application and should not be construed as limiting the present application. In addition, it should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0048] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "top", "bottom", "side", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be construed as limiting the present application.

[0049] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the number of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present application, "a number of" means two or more unless otherwise specifically defined.

[0050] In the present application, unless otherwise clearly specified and limited, the first feature being "on" or "under" the second feature may include the first and second features being in direct contact, or may also include the first and second features not being in direct contact but being in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature has a lower horizontal height than the second feature.

[0051] The following disclosure provides many different embodiments or examples for implementing different structures of the present application. To simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present application. In addition, the present application may repeat reference numerals and / or reference letters in different examples. Such repetition is for the purpose of simplification and clarity and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use scenarios of other materials.

[0052] Please refer to Figure 1 , the photovoltaic system 1000 in the embodiment of the present application may include the battery module 200 in the embodiment of the present application. The battery module 200 in the embodiment of the present application may include a plurality of solar cells 100 in the embodiment of the present application. A plurality of solar cells 100 may be connected in series by welding tapes to form a plurality of cell strings, and each cell string may form the battery module 200 in a series, parallel, or series-parallel manner.

[0053] Please refer to Figure 2 , the solar cell 100 in the embodiment of the present application may include a cell substrate 10, a first passivation film layer 20, and a second passivation film layer 30.

[0054] The cell substrate 10 has opposite first and second surfaces 101 and 102 and a plurality of side wall surfaces 103 connecting the first surface 101 and the second surface 102.

[0055] The first passivation film layer 20 is a continuous structure and includes a first part 21, a second part 22, and a third part 23. The first part 21 covers the first surface 101, the second part 22 covers at least one side wall surface 103, and the third part 23 covers a partial area of the second surface 102 adjacent to the side wall surface 103. That is, as Figure 2 shown, the first passivation film layer 20 covers the first surface 101 and continuously extends along at least one side wall surface 103 to the edge position of the second surface 102.

[0056] The second passivation film layer 30 is a continuous structure and includes a fourth part 31, a fifth part 32, and a sixth part 33. The fourth part 31 covers the second surface 102 to cover the third part 23, the fifth part 32 covers the second part 22, and the sixth part 33 covers a partial area of the first part 21 adjacent to the side wall surface 103. That is, the second passivation film layer 30 covers the second surface 102 and extends along at least one side wall surface 103 to the edge position of the first passivation film layer 20 on the first surface 101. The fourth part 31 covers the area of the second surface 102 not covered by the third part 23 and the third part 23.

[0057] In the solar cell 100, the battery module 200, and the photovoltaic system 1000 according to the embodiments of the present application, the first passivation film layer 20 has a continuous structure and includes a first portion 21 covering the first surface 101, a second portion 22 covering at least one side wall surface 103, and a third portion 23 covering a partial area of the second surface 102 adjacent to the side wall surface 103. The second passivation film layer 30 has a continuous structure and includes a fourth portion 31 covering the second surface 102 to cover the third portion 23, a fifth portion 32 covering the second portion 22, and a sixth portion 33 covering a partial area of the first portion 21 adjacent to the side wall surface 103. In this way, on the one hand, at least a partial side wall surface 103 of the battery substrate 10 is covered with two passivation film layers, which can efficiently passivate the side wall surface 103, thereby reducing edge recombination and improving the conversion efficiency of the solar cell 100. On the other hand, the third portion 23 and the fourth portion 31 are sequentially provided in a partial area of the first surface 101 adjacent to the side wall surface 103, and the first portion 21 and the sixth portion 33 are sequentially provided in a partial area of the second surface 102 adjacent to the side wall surface 103, which can further improve the passivation effect of the edge of the solar cell, and further improve the conversion efficiency.

[0058] It should be noted that in the embodiments of the present application, the "continuous structure" refers to that both the first passivation film layer 20 and the second passivation film layer 30 are continuous film layers formed during the preparation process. After the preparation is completed, neither of them has a disconnected structure. That is, the first portion 21, the second portion 22, and the third portion 23 have a continuous and uninterrupted structure, and the fourth portion 31, the fifth portion 32, and the sixth portion 33 also have a continuous and uninterrupted structure.

[0059] It can be understood that in the solar cell 100, it also includes metal electrodes (not shown in the figure). The metal electrodes will burn through the first passivation film layer 20 and / or the second passivation film layer 30, causing partial ablation of the passivation film layer. The passivation film layer having a continuous structure can be understood as that in areas other than those burned through by the metal electrodes, the other areas have a continuous and uninterrupted structure.

[0060] In addition, in this article, a certain film layer covering a certain surface or a certain film layer can be that the film layer is directly stacked on the surface or a certain film layer, or there are other film layers provided between the film layer and the surface or the film layer. The covering only serves to define the specific setting range of the film layer.

[0061] In addition, as Figure 2As shown, it is not difficult to understand that the "partial area adjacent to the side wall surface 103 in the second surface 102" refers to the edge area at the junction of the second surface 102 and the side wall surface 103 in the second surface 102, that is, the partial area at the edge of the second surface 102. The "partial area adjacent to the side wall surface 103 in the first part 21" refers to the edge area at the junction of the first surface 101 and the side wall surface 103 in the first part 21, that is, the partial area at the edge of the first part 21.

[0062] Specifically, in the embodiments of the present application, the battery substrate 10 may be substantially in the shape of a cuboid or a cube, and may be a right-angled rectangle or a chamfered rectangle, and specific limitations are not made here. The first passivation film layer 20 and the second passivation film layer 30 may each be one or a combination of silicon oxide, silicon nitride film layer, and silicon oxynitride film layer, and specific limitations are not made here. The first passivation film layer 20 and the second passivation film layer 30 can both be prepared by PECVD deposition.

[0063] In some embodiments, the second part 22 of the first passivation film layer 20 may cover all the side wall surfaces 103. That is, the first passivation film layer 20 covers the first surface 101 and surrounds all the side wall surfaces 103, and extends along the side wall surfaces 103 to the partial area at the junction of the second surface 102 and the side wall surfaces 103. The second passivation film layer 30 then covers the second surface 102 and surrounds all the second parts 22, and extends along the second parts 22 to the partial area at the junction of the first part 21 and the side wall surfaces 103.

[0064] In this way, all the side wall surfaces 103 can be efficiently passivated, reducing edge recombination to the greatest extent and improving the conversion efficiency.

[0065] Of course, it can be understood that in some embodiments, the second part 22 of the first passivation film layer 20 may also only cover some of the side wall surfaces 103. For example, in a possible embodiment, in a half-cell, after cutting, the side wall surfaces 103 (i.e., the cut surfaces) formed by cutting the half-cell do not have the second part 22 and do not have any passivation layer, while the other side wall surfaces 103 have the second part 22.

[0066] Please refer to Figure 2 , in some embodiments, the thickness D4 of the fourth part 31 is greater than the thickness D1 of the first part 21.

[0067] In this way, while the first part 21 can achieve good passivation of the first surface 101, the passivation effect of the fourth part 31 on the second surface 102 can be improved. Moreover, through such a differential matching design, the passivation effects of the first surface 101 and the second surface 102 can reach a better matching effect, improving the performance of the solar cell 100.

[0068] It should be noted that in this text, when it is stated that the thickness of a certain layer structure is greater than that of another layer structure, it means that the thickness of the layer structure at any position is greater than the thickness of the other layer structure at any position. In the following text, if a similar description appears, this understanding can be referred to.

[0069] Please continue to refer to Figure 2 , in some embodiments, the sum D2 of the thicknesses of the second part 22 and the fifth part 32 (i.e., the sum of the thicknesses of the passivation film layers on the side wall surface 103) is greater than the sum D3 of the thicknesses of the third part 23 and the part of the fourth part 31 covering the third part 23 (i.e., the sum of the thicknesses of the passivation film layers at the edge position of the second surface 102).

[0070] In this way, by setting the overall thickness of the passivation film layer on the side wall surface 103 of the battery substrate 10 to be thicker, the passivation effect of the side wall surface 103 can be greatly improved, thereby further reducing the edge recombination on the side wall surface 103 and further enhancing the conversion efficiency of the solar cell 100.

[0071] Specifically, it can be understood that the edge recombination of the side wall surface 103 of the battery substrate 10 is relatively large. By setting the overall thickness of the passivation film layer on the side wall surface 103 to be thicker, the passivation effect can be improved, thereby greatly reducing the edge recombination.

[0072] In some embodiments, the sum D3 of the thicknesses of the third part 23 and the fourth part 31 covering the third part 23 (i.e., the sum of the thicknesses of the passivation film layers at the edge position of the second surface 102) is greater than the thickness of the part of the fourth part 31 covering the area on the second surface 102 that is not covered by the third part 23 (i.e., the thickness of the passivation layer on the area of the second surface 102 except the area covered by the third part 23).

[0073] In this way, by setting the overall thickness of the passivation film layer at the edge position of the second surface 102 to be thicker than that at the middle position of the second surface 102, the edge recombination can be further reduced, and thus the efficiency of the solar cell 100 can be further enhanced.

[0074] Specifically, in the solar cell 100, the edge recombination at the edge position of the second surface 102 is relatively large, and the recombination in the middle region is relatively small. In this embodiment, by setting the overall thickness of the passivation film layer at the edge position of the second surface 102 to be thicker, the edge recombination at the edge position of the second surface 102 can be reduced, and thus the conversion efficiency can be enhanced.

[0075] In some embodiments, the thickness D1 of the first part 21 is greater than the thickness of the third part 23.

[0076] In this way, while passivating the first surface 101 and enhancing the passivation effect at the edge position of the second surface 102, the cost can be relatively low.

[0077] In some embodiments, the thickness D4 of the fourth part 31 is greater than the thickness of the sixth part 33.

[0078] In this way, while passivating the second surface 102 and enhancing the passivation effect at the edge position of the first surface 101, the cost can be relatively low.

[0079] Please refer to Figure 2 , in some embodiments, the thickness of the third part 23 gradually decreases in a direction away from the side wall surface along the third part 23.

[0080] In this way, the third part 23 can enhance the passivation effect at the edge position of the second surface 102 while keeping the cost relatively low.

[0081] Specifically, on the second surface 102, the closer to the side wall surface 103, the more the edge recombination gradually decreases. In such a case, the thickness of the third part 23 can gradually decrease in a direction away from the side wall surface 103. In this way, the cost can be relatively low while reducing the edge recombination of the second surface 102.

[0082] Please continue to refer to Figure 2 , in some embodiments, the thickness of the sixth part 33 gradually decreases in a direction away from the side wall surface along the sixth part 33.

[0083] In this way, the sixth part 33 can enhance the passivation effect at the edge position of the first surface 101 while keeping the cost relatively low.

[0084] Specifically, similarly, on the first surface 101, the closer to the side wall surface 103, the more the edge recombination gradually decreases. In such a case, the thickness of the sixth part 33 can gradually decrease in a direction away from the side wall surface 103. In this way, the cost can be relatively low while reducing the edge recombination of the first surface 101.

[0085] In some embodiments, the first passivation film layer 20 is composed of at least one of a silicon oxide film layer, a silicon oxynitride film layer, and a silicon nitride film layer. The second passivation film layer 30 is also composed of at least one of a silicon oxide film layer, a silicon oxynitride film layer, and a silicon nitride film layer.

[0086] Please refer to Figure 3 , in some embodiments, the solar cell 100 can be a back contact solar cell. In such a case, the cell substrate 10 can include a silicon wafer 11, a plurality of P-type doping layers 18, and a plurality of N-type doping layers 19.

[0087] The silicon wafer 11 has opposite front side 111 and back side 112. A plurality of P-type doping layers 18 and a plurality of N-type doping layers 19 are stacked on the back side 112 of the silicon wafer 11, and the plurality of P-type doping layers 18 and the plurality of N-type doping layers 19 are alternately arranged in sequence. There is a spacer region 110 between adjacent P-type doping layer 18 and N-type doping layer 19.

[0088] Among them, the front side 111 of the silicon wafer 11 is the first side 101, and the surface of the battery substrate 10 facing away from the front side 101 is the second side 102. That is to say, the second side 102 includes the surfaces of the P-type doping layer 18 and the N-type doping layer 19 facing away from the back side 112 of the silicon wafer 11, the surfaces of the P-type doping layer 18 and the N-type doping layer 19 exposed at the spacer region 110, and the surface of the silicon wafer 11 exposed at the spacer region. It can be seen therefrom that the second side 102 is not a flat surface. The first part 21 covers the front side 111 of the silicon wafer 11, and the third part 31 covers the second side 102.

[0089] As Figure 3 shown, the second side 102 has an edge region 1021 and a middle region 1022. The middle region 1022 is located inside the edge region 1021. The edge region 1021 is closer to the edge of the second side 102 than the middle region 1022. The first part 21 covers the front side 111 of the silicon wafer 11, the third part 23 covers the edge region 1021, and the fourth part 31 covers the middle region 1022 and the third part 23.

[0090] In this way, by specially designing the structures of the first passivation film layer 20 and the second passivation film layer 30, the passivation effect of the side wall surface 103 of the back-contact solar cell can be improved, the edge recombination can be reduced, and the conversion efficiency can be improved.

[0091] Specifically, it is not difficult to understand that in a back-contact solar cell, a tunneling layer (tunneling layer) is usually further provided between the P-type doping layer 18, the N-type doping layer 19 and the silicon wafer 11. In addition, it can also be understood that in a back-contact solar cell, a P-type electrode and an N-type electrode (not shown in the figure) are further provided. The P-type electrode penetrates through each passivation film layer and contacts the P-type doping layer 18, and the N-type electrode penetrates through each passivation film layer and contacts the N-type doping layer 19.

[0092] In addition, it can also be understood that the first side 101 also has an edge region and a middle region. The first part 21 covers the entire first side 101, and the sixth part 33 covers the region above the first part 21 located in the edge region.

[0093] Please continue to refer to Figure 3, in some embodiments, on the intermediate region 1022, the portion of the fourth part 41 covering the N-type doped layer 19 has a first thickness H1, and the portion of the fourth part 41 covering the P-type doped layer 18 has a second thickness H2, and the first thickness H1 is greater than the second thickness H2.

[0094] Thus, through the optimized design of the different thicknesses of the fourth part 41 on the N-type doped layer 19 and the P-type doped layer 18, and the larger thickness of the fourth part 41 on the N-type doped layer 19, the passivation effect of the corresponding regions of the P-type doped layer 18 and the N-type doped layer 19 can reach a better effect, thereby improving the performance of the back-contact solar cell, and at the same time, the material usage can be saved and the cost can be reduced.

[0095] In some embodiments, the ratio of the first thickness H1 to the second thickness H2 is greater than 1 and less than or equal to 2, that is, 1 < H1 / H2 ≤ 2.

[0096] Thus, the thickness of the passivation film layer on the N-type doped layer 19 is larger, which can improve the passivation effect of the corresponding region of the N-type doped layer 19, so that the passivation effect of the corresponding regions of the P-type doped layer 18 and the N-type doped layer 19 reaches a better matching effect, and further improves the performance of the back-contact solar cell.

[0097] Specifically, in such an embodiment, the ratio of the first thickness H1 to the second thickness H2 can be, for example, 1.01, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95, 2 or any value greater than 1 and less than or equal to 2. Specifically, it is not limited here.

[0098] In some embodiments, the ratio of the first thickness H1 to the second thickness H2 is preferably 1.025 - 1.6. Through repeated research and verification by the inventors of the present application, it is found that by setting the ratio of the first thickness H1 and the second thickness H2 within this preferred range, the passivation effect of the corresponding regions of the P-type doped layer 18 and the N-type doped layer 19 can reach the optimal matching effect while the cost is relatively low.

[0099] Specifically, in such an embodiment, the preferred ratio of the first thickness H1 to the second thickness H2 can be, for example, 1.025, 1.03, 1.04, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6 or any value between 1.025 - 1.6.

[0100] In some embodiments, the difference between the first thickness H1 and the second thickness H2 may be 2 nm to 50 nm. Thus, by reasonably designing the thickness difference between the two, the passivation effect of the regions corresponding to the P-type doping layer 18 and the N-type doping layer 19 can achieve a better matching effect, thereby improving the performance of the back-contact solar cell.

[0101] In such an embodiment, the difference between the first thickness H1 and the second thickness H2 is preferably 5 nm to 30 nm. Through repeated research and verification by the inventors of the present application, it is found that by setting the difference between the first thickness H1 and the second thickness H2 within this preferred range, the passivation effect of the regions corresponding to the P-type doping layer 18 and the N-type doping layer 19 can achieve the optimal matching effect while keeping the cost relatively low.

[0102] Specifically, in such an embodiment, the difference between the first thickness H1 and the second thickness H2 is preferably 5 nm, 7 nm, 9 nm, 10 nm, 12 nm, 14 nm, 16 nm, 18 nm, 20 nm, 22 nm, 24 nm, 26 nm, 28 nm, 30 nm or any value between 5 nm and 30 nm.

[0103] Please continue to refer to Figure 3 , in some embodiments, in the middle region, the third part 31 covering the spacer 110 has a third thickness H3, and the second thickness H2 is greater than the third thickness H3.

[0104] Thus, by reasonably optimizing the thicknesses of the N-type doping layer 19, the P-type doping layer 18, and the third part 31 on the spacer 110 therebetween, the passivation effects of the corresponding regions of the three can achieve a good matching effect, and the electrical performance of the back-contact solar cell can be improved while the cost is relatively low.

[0105] Furthermore, in some embodiments, the ratio of the second thickness H2 to the third thickness H3 may be greater than 1 and less than 2, that is, 1 < H2 / H3 ≤ 2.

[0106] Thus, by designing the thicknesses of the third thickness H3, the second thickness H2, and the first thickness H1 to gradually increase and in accordance with the above ratio, the passivation effect of the entire back-contact solar cell can achieve a better matching effect, thereby improving the performance of the back-contact solar cell and keeping the cost relatively low at the same time.

[0107] Specifically, in such an embodiment, the ratio of the second thickness H2 to the third thickness H3 can be, for example, 1.01, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95, 2, or any value greater than 1 and less than or equal to 2. Specifically, there is no limitation here.

[0108] In some embodiments, in a back-contact solar cell, the ratio of the second thickness H2 to the third thickness H3 is preferably 1.1 - 1.8. Through repeated research and verification by the inventors of the present application, it is found that by setting the ratio of the second thickness H2 and the third thickness H3 within this preferred range, the passivation effects of the regions corresponding to the P-type doping layer 18, the N-type doping layer 19, and the spacer 110 can achieve an optimal matching effect, and at the same time, the cost is relatively low.

[0109] Specifically, in such an embodiment, the preferred ratio of the second thickness H2 to the third thickness H3 can be, for example, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, or any value between 1.1 - 1.8.

[0110] In some embodiments, the difference between the second thickness H2 and the third thickness H3 can be 2 nm - 50 nm. Thus, by reasonably designing the thickness difference between the two, the passivation effect of the region of the back-contact solar cell can achieve a relatively optimal matching effect, thereby improving the performance of the back-contact solar cell.

[0111] In such an embodiment, the difference between the second thickness H2 and the third thickness H3 is preferably 20 nm - 40 nm. Through repeated research and verification by the inventors of the present application, it is found that in a back-contact solar cell, by setting the difference between the second thickness H2 and the third thickness H3 within this preferred range, the passivation effects of the regions corresponding to the P-type doping layer 18, the N-type doping layer 19, and the spacer 110 can achieve an optimal matching effect, thereby improving the performance of the solar cell 100, and at the same time, the cost is relatively low.

[0112] Specifically, in such an embodiment, the difference between the second thickness H2 and the third thickness H3 is preferably 20 nm, 22 nm, 24 nm, 26 nm, 28 nm, 30 nm, 32 nm, 34 nm, 36 nm, 38 nm, 40 nm, or any value between 20 nm - 40 nm.

[0113] Please refer to Figure 4, in some embodiments, in a back-contact solar cell, a third passivation film layer 50 may further be included. The third passivation film layer 50 may cover the first surface 101, the second surface 102, and at least a part of the side wall surface 103. Both the first passivation film layer 20 and the second passivation film layer 30 are covered on the third passivation film layer 50.

[0114] Thus, by first passivating the first surface 101, the second surface 102, and at least a part of the side wall surface 103 with the third passivation film layer 50, and then using the first passivation film layer 20 and the second passivation film layer 30 for enhanced passivation, the passivation effect can be further improved, the edge recombination of the side wall surface 103 can be reduced, and the efficiency can be increased.

[0115] Specifically, in a back-contact solar cell, the third passivation film layer 50 may preferably be an aluminum oxide film layer, and the first passivation film layer 20 may preferably be a combination of one or more of a silicon oxide film layer, a silicon oxynitride film layer, and a silicon nitride film layer. The second passivation film layer 30 may preferably be a silicon nitride film layer.

[0116] It should be noted that in the first passivation film layer 20, the number of each type of film layer may be a single layer or multiple layers. For example, in one example, the first passivation film layer 20 may include a silicon oxide film layer, two silicon oxynitride film layers stacked on the oxide film layer, and three silicon nitride film layers stacked on the silicon oxynitride film layer. Also, for example, in one example, the second passivation film layer 30 may be a composite film layer composed of three silicon nitride film layers. In the present application, the number of various film layers included in the first passivation film layer 20 and the second passivation film layer 30 is not limited.

[0117] In some embodiments, the thickness of the part of the third passivation film layer 50 covering the second surface 102 is greater than the thickness of the part of the third passivation film layer 50 covering the first surface 101.

[0118] Thus, by setting the thickness of the part of the third passivation film layer 50 covering the second surface 102 to be thicker, the passivation effect of the second surface 102 can be further improved while ensuring the passivation effect of the first surface 101.

[0119] Specifically, it can be understood that in a back-contact solar cell, both the P-type doping layer 18 and the N-type doping layer 19 are disposed on the back surface 112 of the silicon wafer 11. Therefore, stronger passivation is required for the second surface 102 of the cell substrate 10. Based on this, setting the third passivation film layer 50 on the second surface 102 to be thicker can improve the passivation effect of the second surface 102, and thus improve the performance of the back-contact solar cell.

[0120] In some embodiments, the third passivation film layer 50 may contain aluminum or phosphorus, and the material of the third passivation film layer 50 is different from the materials of the first passivation film layer 20 and the second passivation film layer 30.

[0121] Specifically, in some embodiments, the materials of the first passivation film layer 20 and the second passivation film layer 30 are as shown above, and the third passivation film layer 50 may be an alumina film layer.

[0122] In such an embodiment, the third passivation film layer 50 preferably covers all the side wall surfaces 103. Of course, in a possible embodiment, in a half-cell, after cutting is completed, the side wall surfaces 103 formed by cutting the half-cell do not have the third passivation film layer 50, while the other side wall surfaces 103 have the third passivation film layer 50.

[0123] It can be understood that when the third passivation film layer 50 is present, the P-type electrode in the back-contact solar cell penetrates through the third passivation film layer 50 to contact the P-type doping layer 18, and the N-type electrode also penetrates through the third passivation film layer 50 to contact the N-type doping layer 19.

[0124] Please refer to Figure 5 , in some embodiments, the solar cell 100 may also be a bifacial solar cell, such as a PERC solar cell and a Topcon solar cell, etc. In such a case, the cell substrate 10 may include a silicon wafer 11 and a first doping layer 12 and a second doping layer 13 that are respectively stacked and covered on the opposite sides of the silicon wafer 11. The doping types of the first doping layer 12 and the second doping layer 13 are opposite, one of which is of the P-type doping type and the other is of the N-type doping type. The first surface 101 is the surface of the first doping layer 12 facing away from the silicon wafer 11, and the second surface 102 is the surface of the second doping layer 13 facing away from the silicon wafer 11.

[0125] Thus, by specifically designing the structures of the first passivation film layer 20 and the second passivation film layer 30, the passivation effects on the edges and side wall surfaces 103 of the first surface 101 and the second surface 102 of the bifacial solar cell can be improved, the edge recombination can be reduced, and the conversion efficiency can be enhanced.

[0126] It can be understood that in a bifacial solar cell, it also has a first metal electrode and a second metal electrode (not shown in the figure). The first metal electrode penetrates through each passivation film layer to contact the first doping layer 12, and the second metal electrode penetrates through each passivation film layer to contact the second doping layer 13.

[0127] Please refer to Figure 6 , in some embodiments, the solar cell 100 may be a Topcon solar cell. In such a case, the solar cell 100 may further include a first tunneling oxide layer 15 stacked between the silicon wafer 11 and the second doping layer 13.

[0128] Thus, by specially designing the structures of the first passivation film layer 20 and the second passivation film layer 30, the passivation effect of the Topcon solar cell can be improved, the edge recombination can be reduced, and the conversion efficiency can be increased.

[0129] Further, please refer to Figure 7 , in such an embodiment, in a Topcon solar cell, the solar cell 100 may further include a fourth passivation film layer 40, the fourth passivation film layer 40 covers the first surface 101, the second surface 102 and at least part of the side wall surface 103, and both the first passivation film layer 20 and the second passivation film layer 30 are covered on the fourth passivation film layer 40.

[0130] Thus, by first passivating the first surface 101, the second surface 102 and at least part of the side wall surface 103 with the fourth passivation film layer 40, and then using the first passivation film layer 20 and the second passivation film layer 30 for enhanced passivation, it can further improve the passivation effect, reduce the edge recombination of the side wall surface 103, and improve the efficiency.

[0131] Specifically, in such an embodiment, the material and type of the fourth passivation film layer 40 are basically the same as those of the above-mentioned third passivation film layer, which will not be elaborated here.

[0132] In such an embodiment, the fourth passivation film layer 40 preferably covers all the side wall surfaces 103. Of course, in a possible embodiment, in a half-cell, after cutting, the side wall surface 103 formed by cutting the half-cell does not have the fourth passivation film layer 40, while the other side wall surfaces 103 have the fourth passivation film layer 40.

[0133] In some embodiments, the thickness of the part of the fourth passivation film layer 40 covering the first surface 101 is greater than the thickness of the part of the fourth passivation film layer 40 covering the second surface 102. Specifically, in a Topcon solar cell, the first surface 101 may be the front side of the cell, the second surface 102 may be the back side of the cell, the first doping layer 12 is usually of P-type doping type, the second doping layer 13 is usually of N-type doping type, and the passivation effect of the P-type doped first doping layer 12 is relatively poor. Therefore, in a Topcon solar cell, setting the thickness of the fourth passivation film layer 40 covering the first doping layer 12 to be thicker can ensure the passivation effects of both the first surface 101 and the second surface 102, enabling the passivation effects of the two surfaces to achieve a better matching effect, thereby improving the performance of the Topcon solar cell.

[0134] It can be understood that in the case where the fourth passivation film layer 40 is provided, the first metal electrode of the Topcon solar cell also penetrates through the fourth passivation film layer 40 to contact the third doping layer 14, and the second metal electrode penetrates through the fourth passivation film layer 40 to contact the fourth doping layer 15.

[0135] It is not difficult to understand that in such an embodiment, the solar cell 100 is a Topcon solar cell with a tunneling layer on one side. In some embodiments, the solar cell 100 may also be a Topcon solar cell with tunneling layers on both sides. In such a case, please refer to Figure 8 , and the cell substrate 10 may further include a second tunneling oxide layer 17 located between the first doping layer 12 and the silicon wafer 11.

[0136] In the description of this specification, the description with reference to terms such as "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" 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 present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0137] In addition, the above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A solar cell, characterized in that: include: A battery substrate, the battery substrate having a first surface and a second surface opposite to each other and a plurality of sidewall surfaces connecting the first surface and the second surface; A first passivation film layer, the first passivation film layer is a continuous structure and includes a first portion covering the first surface, a second portion covering at least one of the sidewall surfaces, and a third portion covering a partial area of ​​the second surface adjacent to the sidewall surface; and The second passivation film layer is a continuous structure and includes a fourth portion covering the second surface to cover the third portion, a fifth portion covering the second portion, and a sixth portion covering a partial area of ​​the first portion adjacent to the sidewall surface.

2. The solar cell according to claim 1, characterized in that: The second portion covers all of the side wall surfaces.

3. The solar cell according to claim 1, characterized in that: The thickness of the fourth portion is greater than the thickness of the first portion.

4. The solar cell according to claim 1, characterized in that: The sum of the thicknesses of the second portion and the fifth portion is greater than the sum of the thicknesses of the third portion and a portion of the fourth portion covering the third portion.

5. The solar cell according to claim 4, characterized in that: The sum of the thicknesses of the third portion and the fourth portion covering the third portion is greater than the thickness of a portion of the fourth portion covering an area of ​​the second surface not covered by the third portion.

6. The solar cell according to claim 1, characterized in that: The thickness of the first portion is greater than the thickness of the third portion; and / or The thickness of the fourth portion is greater than the thickness of the sixth portion.

7. The solar cell according to claim 1, characterized in that: The thickness of the third portion gradually decreases along a direction in which the third portion is away from the side wall surface; and / or The thickness of the sixth portion gradually decreases along a direction in which the sixth portion is away from the side wall surface.

8. The solar cell according to claim 1, characterized in that: The first passivation film layer is composed of at least one of a silicon oxide film layer, a silicon oxynitride film layer, and a silicon nitride film layer; The second passivation film layer also consists of at least one of a silicon oxide film layer, a silicon oxynitride film layer, and a silicon nitride film layer.

9. The solar cell according to claim 1, characterized in that: The solar cell is a back contact solar cell, and the cell substrate comprises: A silicon wafer having a front side and a back side facing each other; A plurality of P-type doping layers and N-type doping layers are alternately arranged on the back side of the silicon wafer, and a spacing region is provided between adjacent P-type doping layers and N-type doping layers; Among them, the front side of the silicon wafer is the first side, the surface of the battery substrate facing away from the front side is the second side, the second side has an edge area and a middle area, the middle area is located inside the edge area, and the edge area is closer to the edge of the second side than the middle area, the first part covers the front side of the silicon wafer, the third part covers the edge area, and the fourth part covers the middle area and the third part.

10. The solar cell according to claim 9, characterized in that: In the middle region, a portion of the fourth portion covering the N-type doping layer has a first thickness, and a portion of the fourth portion covering the P-type doping layer has a second thickness, and the first thickness is greater than the second thickness.

11. The solar cell according to claim 10, characterized in that: A ratio of the first thickness to the second thickness is greater than 1 and less than or equal to 2.

12. The solar cell according to claim 10, characterized in that: In the middle region, a portion of the fourth portion covering the spacer has a third thickness, and the second thickness is greater than the third thickness.

13. The solar cell according to claim 12, characterized in that: A ratio of the second thickness to the third thickness is greater than 1 and less than or equal to 2.

14. The solar cell according to claim 9, characterized in that: The solar cell further includes a third passivation film layer, which covers the first surface, the second surface and at least a portion of the side wall surface, and the first passivation film layer and the second passivation film layer both cover the third passivation film layer.

15. The solar cell according to claim 14, characterized in that: The thickness of a portion of the third passivation film layer covering the second surface is greater than the thickness of a portion of the third passivation film layer covering the first surface.

16. The solar cell according to claim 14, characterized in that: The third passivation film layer contains aluminum or phosphorus, and the material of the third passivation film layer is different from the materials of the first passivation film layer and the second passivation film layer.

17. The solar cell according to claim 1, characterized in that: The battery substrate includes a silicon wafer and a first doped layer and a second doped layer stacked and covering opposite sides of the silicon wafer, respectively. The first surface is a surface of the first doped layer facing away from the silicon wafer, and the second surface is a surface of the second doped layer facing away from the silicon wafer.

18. The solar cell according to claim 17, characterized in that: The battery substrate further includes a first tunneling oxide layer stacked between the silicon wafer and the second doping layer.

19. The solar cell according to claim 17 or 18, characterized in that: The solar cell further includes a fourth passivation film layer, which covers the first surface, the second surface and at least a portion of the side wall surface, and the first passivation film layer and the second passivation film layer both cover the fourth passivation film layer.

20. The solar cell according to claim 19, characterized in that: The thickness of a portion of the fourth passivation film layer covering the first surface is greater than the thickness of a portion of the fourth passivation film layer covering the second surface.

21. The solar cell according to claim 18, characterized in that: The battery substrate also includes a second tunneling oxide layer located between the first doping layer and the silicon wafer.

22. A battery assembly, characterized in that: The invention comprises the solar cell sheets according to any one of claims 1 to 21.

23. A photovoltaic system, characterized in that: A battery assembly comprising the battery assembly of claim 22.

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