Back contact solar cell, cell assembly and photovoltaic system

Abstract

The utility model is suitable for the technical field of solar cells, and provides a back contact solar cell piece, a cell assembly and a photovoltaic system.In the back contact solar cell piece, the front face of a silicon substrate is a first surface of a substrate, and the surface, away from the front face, of the substrate is a second surface of the substrate; the substrate further comprises a plurality of side faces connecting the first surface and the second surface, the second surface is provided with a first edge area and a first middle area, the first edge area is located at the junction of the second surface and the side faces, and the first middle area is located on the inner side of the first edge area. The passivation layer is stacked on the substrate, the passivation layer on the first edge area has a first thickness, the passivation layer on the first middle area has a second thickness, and the first thickness is larger than the second thickness. Thus, the passivation effect at the edge position of the second surface of the substrate can be improved, edge recombination of the back contact solar cell is reduced, and the conversion efficiency is improved.

Description

Technical Field

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

[0002] Solar cell power generation is a sustainable source of clean energy. It uses the photovoltaic effect of semiconductor pn junction to convert sunlight into electrical energy. In solar cells, back-contact solar cells are cells in which both the p-region and the n-region are set on the back side (non-light-receiving side) of the cell. The light-receiving side of the cell is not blocked by any metal electrode, which effectively increases the short-circuit current of the cell.

[0003] In the related art, in a back-contact cell, a P-type doping layer and an N-type doping layer are arranged on a silicon substrate, and a passivation layer is arranged on each of the doping layers to passivate the cell. In current back-contact solar cells, the edge recombination of the cell is large, resulting in low conversion efficiency. Utility Model Content

[0004] The present application provides a back-contact solar cell sheet, a solar cell assembly and a photovoltaic system.

[0005] The present application is implemented in this way. The back contact solar cell of the embodiment of the present application comprises:

[0006] A substrate, the substrate comprising a silicon substrate, a plurality of P-type doped layers and a plurality of N-type doped layers, the silicon substrate having a front side and a back side opposite to each other, the plurality of P-type doped layers and the N-type doped layers being arranged alternately on the back side of the silicon substrate in sequence, and a spacing region being provided between adjacent P-type doped layers and N-type doped layers; the front side of the silicon substrate being a first surface of the substrate, the surface of the substrate away from the front side being a second surface of the substrate, the substrate further comprising a plurality of side surfaces connecting the first surface and the second surface, the second surface having a first edge region and a first middle region, the first edge region being located at a junction of the second surface and the side surface, and the first middle region being located inside the first edge region; and

[0007] A passivation layer is stacked on the substrate, the passivation layer covers the second surface, the passivation layer on the first edge area has a first thickness, the passivation layer on the first middle area has a second thickness, and the first thickness is greater than the second thickness.

[0008] In some embodiments, a ratio of the first thickness to the second thickness is greater than 1 and less than or equal to 3.

[0009] In some embodiments, in the first middle region, a thickness of the passivation layer on the N-type doping layer is greater than a thickness of the passivation layer on the P-type doping layer.

[0010] In some embodiments, a ratio of a thickness of the passivation layer on the N-type doping layer to a thickness of the passivation layer on the P-type doping layer is greater than 1 and less than or equal to 2.

[0011] In some embodiments, the passivation layer further covers at least a portion of the side surface, and the passivation layer on the side surface has a third thickness, which is greater than the second thickness and less than or equal to the first thickness.

[0012] In some embodiments, the first surface has a second edge region and a second middle region, the second edge region is located at the junction of the first surface and the side surface, and the second middle region is located inside the second edge region;

[0013] The passivation layer also covers the first surface, the thickness of the passivation layer on the second edge region has a fourth thickness, the thickness of the passivation layer on the second middle region has a fifth thickness, and the fourth thickness is greater than the fifth thickness.

[0014] In some embodiments, a ratio of the fourth thickness to the fifth thickness is greater than 1 and less than or equal to 3.

[0015] In some embodiments, the fourth thickness is less than the first thickness, and the fifth thickness is less than or equal to the second thickness.

[0016] In some embodiments, the passivation layer further covers at least a portion of the side surface, and a thickness of the passivation layer on the side surface is greater than or equal to the fourth thickness.

[0017] In some embodiments, the passivation layer includes a first film layer and a second film layer stacked in sequence, the first film layer has the same thickness on the second surface, and the thickness of the second film layer covering the first edge area is greater than the thickness of the second film layer covering the first middle area.

[0018] The present application also provides a battery assembly, comprising a plurality of back-contact solar cells as described in any one of the above items.

[0019] The present application also provides a photovoltaic system, which includes the above-mentioned battery assembly.

[0020] In the back-contact solar cell, battery assembly and photovoltaic system of the present application embodiment, the front side of the silicon substrate is the first surface of the substrate, the surface of the substrate facing away from the front side is the second surface of the substrate, the substrate also includes a plurality of side surfaces connecting the first surface and the second surface, the second surface has a first edge region and a first middle region, the first edge region is located at the junction of the second surface and the side surface, and the first middle region is located inside the first edge region. The passivation layer is stacked on the substrate, the passivation layer covers the second surface, the passivation layer on the first edge region has a first thickness, the passivation layer on the first middle region has a second thickness, and the first thickness is greater than the second thickness. In this way, the thickness of the passivation layer at the first edge region position of the second surface of the substrate is greater than the thickness of the passivation layer at the first middle region position, which can enhance the passivation effect at the edge position of the second surface of the substrate, reduce the edge recombination of the back-contact solar cell, and thus enhance the conversion efficiency.

[0021] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a module schematic diagram of a photovoltaic system provided in an embodiment of the present application;

[0023] Figure 2 is a schematic diagram of the cross-sectional structure of a back-contact solar cell provided in an embodiment of the present application;

[0024] Figure 3 is another cross-sectional structural schematic diagram of a back-contact solar cell provided in an embodiment of the present application;

[0025] Figure 4 is another schematic cross-sectional structure diagram of a back-contact solar cell provided in an embodiment of the present application;

[0026] Figure 5 is a schematic diagram of the cross-sectional structure of the passivation layer provided in an embodiment of the present application;

[0027] Figure 6 It is another schematic diagram of the cross-sectional structure of the passivation layer provided in an embodiment of the present application. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. It should be noted that the embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain 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.

[0029] In the description of the present application, it should be understood that the terms "upper", "lower", "left", "right", "top", "bottom", "side", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0030] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "several" is two or more, unless otherwise clearly and specifically defined.

[0031] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0032] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, and does not indicate the relationship between the various embodiments and / or settings discussed in itself. In addition, the various specific processes and examples of materials provided by the present application, 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.

[0033] See also Figure 1 The photovoltaic system 1000 in the embodiment of the present application may include the battery assembly 200 in the embodiment of the present application. The battery assembly 200 in the embodiment of the present application may include a number of back-contact solar cells 100 in the embodiment of the present application. The several back-contact solar cells 100 may be connected in series through welding ribbons to form a number of battery strings. Each battery string may be connected in series, in parallel, or in series and parallel to form a battery assembly 200.

[0034] See also Figure 2 The back contact solar cell 100 in the embodiment of the present application may include a substrate 10 and a passivation layer 20 .

[0035] The substrate 10 has a first surface 101 and a second surface 102 opposite to each other. Figure 2 As shown, the substrate 10 may include a silicon substrate 11, a plurality of P-type doped layers 12 and a plurality of N-type doped layers 13, the silicon substrate 11 having a front side 111 and a back side 112 relative to each other, the plurality of P-type doped layers 12 and the plurality of N-type doped layers 13 are stacked on the back side 112 of the silicon substrate 11, and the plurality of P-type doped layers 12 and the plurality of N-type doped layers 13 are alternately arranged in sequence, and a spacing region 110 is provided between adjacent P-type doped layers 12 and N-type doped layers 13.

[0036] Among them, the front side 111 of the silicon substrate 11 is the first surface 101 of the substrate 10, and the surface of the substrate 10 away from the front side 101 is the second surface 102 of the substrate 10, that is, the second surface 102 includes the surface of the P-type doping layer 12 and the N-type doping layer 13 away from the back side 112 of the silicon substrate 11, the surface of the P-type doping layer 12 and the N-type doping layer 13 exposed at the spacer area 110, and the surface of the silicon substrate 11 exposed at the spacer area 110. It can be seen that the second surface 102 is not a flat surface.

[0037] The substrate 10 further includes a plurality of side surfaces 103 connecting the first surface 101 and the second surface 102. The second surface 102 has a first edge region 1021 and a first middle region 1022. The first edge region 1021 is located at the junction of the second surface 102 and the side surface 103, and the first middle region 1022 is located inside the first edge region 1021. That is, the first edge region 1021 is located at the edge of the second surface 102, and the first middle region 1022 is located at the middle of the second surface 102. The first edge region 1021 is located between the first middle region 1022 and the side surface 103. Figure 2 As shown, the “first edge region 1021 ” refers to the edge region of the second surface 102 located at the junction of the second surface 102 and the side surface 103 , and the “first middle region 1022 ” refers to the region of the second surface 102 excluding the first edge region 1021 .

[0038] The passivation layer 20 is stacked on the substrate 10 and covers the second surface 102 . The passivation layer 20 on the first edge region 1021 has a first thickness D1 , and the passivation layer 20 on the first middle region 1022 has a second thickness D2 . The first thickness D1 is greater than the second thickness D2 .

[0039] In the back-contact solar cell 100, the battery assembly 200 and the photovoltaic system 1000 in the embodiment of the present application, the front side 111 of the silicon substrate 11 is the first surface 101 of the substrate 10, and the surface of the substrate 10 away from the front side 111 is the second surface 102 of the substrate 10. The substrate 10 also includes a plurality of side surfaces 103 connecting the first surface 101 and the second surface 102. The second surface 102 has a first edge region 1021 and a first middle region 1022. The first edge region 1021 is located at the junction of the second surface 102 and the side surface 103, and the first middle region 1022 is located inside the first edge region 1021. The passivation layer 20 is stacked on the substrate 10, and the passivation layer 20 covers the second surface 102. The passivation layer 20 on the first edge region 1021 has a first thickness D1, and the passivation layer 20 on the first middle region 1022 has a second thickness D2, and the first thickness D1 is greater than the second thickness D2. In this way, the thickness of the passivation layer 20 at the first edge area 1021 of the second surface 102 of the substrate 10 is greater than the thickness of the passivation layer 20 at the first middle area 1022, which can improve the passivation effect at the edge of the second surface 102 of the substrate 10, reduce the edge recombination of the back contact solar cell 100, and thus improve the conversion efficiency.

[0040] Specifically, it is not difficult to understand that in the back-contact solar cell 100, in the substrate 10, a tunneling layer (tunneling layer) may be generally provided between the P-type doped layer 12 and the N-type doped layer 13 and the silicon substrate 11. In addition, it is also understandable that in the back-contact solar cell 100, a P-type electrode and an N-type electrode (not shown) are also provided, the P-type electrode penetrates the passivation layer 20 and contacts the P-type doped layer 12, and the N-type electrode penetrates the passivation layer 20 and contacts the N-type doped layer 13.

[0041] In addition, in this article, a certain film layer covering a certain surface or a certain film layer may be that the film layer is directly stacked on the surface or a certain film layer, or other film layers may be arranged between the film layer and the surface or film layer. Covering is only used to limit the specific setting range of the film layer.

[0042] In some embodiments, the ratio of the first thickness D1 to the second thickness D2 is greater than 1 and less than or equal to 3, that is, 1<D1 / D2≤3.

[0043] Thus, by setting the ratio of the first thickness D1 to the second thickness D2 within the reasonable range, the passivation effect at the edge region of the second surface 102 can be improved while keeping the cost relatively low.

[0044] Specifically, in such an embodiment, the ratio of the first thickness D1 to the second thickness D2 may 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, 2.2, 2.4, 2.6, 2.8, 3 or any value greater than 1 and less than or equal to 3, and is not limited here.

[0045] In some embodiments, in the first intermediate region 1022 , the thickness of the passivation layer 20 on the N-type doping layer 13 is greater than the thickness of the passivation layer 20 on the P-type doping layer 12 .

[0046] In this way, in the first middle region 1022, the thickness of the passivation layer 20 on the N-type doped layer 13 is relatively large, which can improve the passivation effect of the corresponding area of ​​the N-type doped layer 13, so that the passivation effects of the corresponding areas of the P-type doped layer 12 and the N-type doped layer 13 can achieve a better matching effect, thereby improving the performance of the back-contact solar cell 100.

[0047] Further, in such an embodiment, the ratio of the thickness of the passivation layer 20 on the N-type doping layer 13 to the thickness of the passivation layer 20 on the P-type doping layer 12 is greater than 1 and less than or equal to 2.

[0048] In this way, the ratio between the thickness of the passivation layer 20 on the N-type doped layer 13 and the thickness of the passivation layer 20 on the P-type doped layer 12 is set within this reasonable range, which can achieve the best matching effect of the passivation effect of the corresponding areas of the P-type doped layer 12 and the N-type doped layer 13 while keeping the cost relatively low.

[0049] Specifically, in such an embodiment, the thickness ratio of the two may 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, and is not limited here.

[0050] See also Figure 3 In some embodiments, the passivation layer 20 also covers at least a portion of the side surface 103, preferably completely covers at least a portion of the side surface 103, and the passivation layer 20 on the side surface 103 has a third thickness D3, which is greater than the second thickness D2 and less than or equal to the first thickness D1.

[0051] Thus, the side surface 103 of the substrate 10 is also covered with the passivation layer 20 and the passivation layer 20 on the side surface 103 is greater than the second thickness D2 and less than the first thickness D1. This allows the side surface 103 of the substrate 10 to be efficiently passivated, further reducing edge recombination and further improving conversion efficiency.

[0052] Specifically, in such an embodiment, the passivation layer 20 may preferably completely cover all the side surfaces 103 of the substrate 10, so as to achieve the best passivation effect. Of course, it is understandable that in some embodiments, the passivation layer 20 may only cover part of the side surfaces 103. For example, in a possible embodiment, in a half-cell battery, after cutting, the side surfaces 103 formed by cutting the half-cell battery do not have the passivation layer 20, and the other side surfaces 103 have the passivation layer 20.

[0053] See also Figure 4 In some embodiments, the first surface 101 has a second edge region 1011 and a second middle region 1012, the second edge region 1011 is located at the junction of the first surface 101 and the side surface 103, and the second middle region 1012 is located inside the second edge region 1011. That is, the second edge region 1011 is located at the edge of the first surface 101, the second middle region 1012 is located in the middle of the first surface 101, and the second edge region 1011 is located between the second middle region 1012 and the side surface 103. That is, as Figure 4As shown, the “second edge region 1011 ” refers to the edge region of the first surface 101 located at the junction of the first surface 101 and the side surface 103 , and the “second middle region 1012 ” refers to the region of the first surface 101 excluding the second edge region 1011 .

[0054] In such an embodiment, the passivation layer 20 also covers the first surface 101, that is, the passivation layer 20 covers the first surface 101, the second surface 102, and at least a portion of the side surface 103. The thickness of the passivation layer 20 on the second edge region 1011 has a fourth thickness D4, and the thickness of the passivation layer 20 on the second middle region 1012 has a fifth thickness D5, and the fourth thickness D4 is greater than the fifth thickness D5.

[0055] In this way, the thickness of the passivation layer 20 at the second edge area 1011 of the first surface 101 of the substrate 10 is greater than the thickness of the passivation layer 20 at the second middle area 1012, which can enhance the passivation effect at the edge of the first surface 101 of the substrate 10, further reduce the edge recombination of the back contact solar cell 100, and further enhance the conversion efficiency.

[0056] In some embodiments, the ratio of the fourth thickness D4 to the fifth thickness D5 is greater than 1 and less than or equal to 3, that is, 1<D4 / D5≤3.

[0057] Thus, by setting the ratio of the fourth thickness D4 to the fifth thickness D5 within the reasonable range, the passivation effect at the edge region of the first surface 101 can be improved while keeping the cost relatively low.

[0058] Specifically, in such an embodiment, the ratio of the fourth thickness D4 to the fifth thickness D5 may 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, 2.2, 2.4, 2.6, 2.8, 3 or any value greater than 1 and less than or equal to 3, and is not limited here.

[0059] In some embodiments, the fourth thickness D4 is less than the first thickness D1 , and the fifth thickness D5 is less than or equal to the second thickness D2 .

[0060] In this way, by reasonably configuring the thickness of the passivation layer 20 in each region of the first surface 101 and the second surface 102 , it is possible to achieve a better matching effect of the passivation effect in each region, while also making the cost relatively low.

[0061] Furthermore, in such an embodiment, the passivation layer 20 also covers at least a portion of the side surface 103, and the thickness of the passivation layer 20 on the side surface 103 is greater than or equal to the fourth thickness D4, that is, the third thickness D3 mentioned above is greater than or equal to the fourth thickness D4. In this way, the passivation effect at each region can be matched to a better state while improving the passivation effect of the side surface 103 to reduce edge recombination.

[0062] In this article, a certain thickness is greater than or equal to another thickness can mean that the thickness of the passivation layer 20 in a certain area at any position is greater than the thickness of the passivation layer 20 in another area, or it can mean that the thickness of part of the passivation layer 20 in the area is greater than the thickness of the passivation layer 20 in another area, while the thickness of the passivation layer 20 in other parts of the area is the same as the thickness of the passivation layer 20 in another area. In the following text, if the same description appears, please refer to this for understanding.

[0063] See also Figure 5 In some embodiments, the passivation layer 20 may include a first film layer 21 and a second film layer 22 stacked in sequence, the first film layer 21 has the same thickness on the second surface 102, and the thickness of the second film layer 22 covering the first edge area 1021 is greater than the thickness of the second film layer 22 covering the first middle area 1022.

[0064] In this way, the thickness of the second film layer 22 can be adjusted to achieve different thicknesses in different areas of the passivation layer 20 .

[0065] Specifically, in the embodiment of the present application, the first film layer 21 may be an aluminum oxide film layer, the second film layer 22 may be a silicon nitride film layer, the first film layer 21 may be prepared by an atomic deposition process, and the second film layer 22 may be prepared by a PECVD deposition process. In addition, it can also be understood that, in this article, all regions of the passivation layer 20 with different thicknesses can achieve different thicknesses by controlling the thickness of the second film layer 22.

[0066] Of course, see Figure 6 It can be understood that, in some embodiments, the passivation layer 20 may also include a third film layer 23, the third film layer 23 may be stacked between the first film layer 21 and the substrate 10, and the second film layer 22 may be stacked on the first film layer 21. For example, in some embodiments, the third film layer 23 may be a silicon oxide film layer, and the third film layer 23 may also be prepared by a PECVD deposition process. In this case, the thickness difference of the passivation layer 20 in different areas can be achieved by controlling the thickness difference of the second film layer 22 and / or the third film layer 23.

[0067] like Figure 4 As shown, in this application, it is preferred to use Figure 4In the structure shown, the passivation layer 20 covers the first surface 101, the side surface 103 and the second surface 102, wherein the first thickness D1 is greater than the second thickness D2, the third thickness D3 is greater than the second thickness D2 and less than or equal to the first thickness D1, and the fourth thickness D4 is greater than the fifth thickness D5 and less than the third thickness D3.

[0068] In the description of this specification, the description with reference to the terms "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction 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 embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0069] In addition, the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A back contact solar cell, characterized in that: include: A substrate, the substrate comprising a silicon substrate, a plurality of P-type doped layers and a plurality of N-type doped layers, the silicon substrate having a front side and a back side opposite to each other, the plurality of P-type doped layers and the N-type doped layers being arranged alternately on the back side of the silicon substrate in sequence, and a spacing region being provided between adjacent P-type doped layers and N-type doped layers; the front side of the silicon substrate is a first surface of the substrate, the surface of the substrate away from the front side is a second surface of the substrate, the substrate further comprises a plurality of side surfaces connecting the first surface and the second surface, the second surface having a first edge region and a first middle region, the first edge region being located at the junction of the second surface and the side surface, and the first middle region being located inside the first edge region; and A passivation layer is stacked on the substrate, the passivation layer covers the second surface, the passivation layer on the first edge area has a first thickness, the passivation layer on the first middle area has a second thickness, and the first thickness is greater than the second thickness.

2. The back contact solar cell according to claim 1, characterized in that: A ratio of the first thickness to the second thickness is greater than 1 and less than or equal to 3.

3. The back contact solar cell according to claim 1, characterized in that: In the first middle region, a thickness of the passivation layer on the N-type doping layer is greater than a thickness of the passivation layer on the P-type doping layer.

4. The back contact solar cell according to claim 3, characterized in that: A ratio of a thickness of the passivation layer on the N-type doping layer to a thickness of the passivation layer on the P-type doping layer is greater than 1 and less than or equal to 2.

5. The back contact solar cell according to claim 1, characterized in that: The passivation layer also covers at least a portion of the side surface, and the passivation layer on the side surface has a third thickness, which is greater than the second thickness and less than or equal to the first thickness.

6. The back contact solar cell according to claim 1, characterized in that: The first surface has a second edge region and a second middle region, the second edge region is located at the junction of the first surface and the side surface, and the second middle region is located inside the second edge region; The passivation layer also covers the first surface, the thickness of the passivation layer on the second edge region has a fourth thickness, the thickness of the passivation layer on the second middle region has a fifth thickness, and the fourth thickness is greater than the fifth thickness.

7. The back contact solar cell according to claim 6, characterized in that: A ratio of the fourth thickness to the fifth thickness is greater than 1 and less than or equal to 3.

8. The back contact solar cell according to claim 6, characterized in that: The fourth thickness is smaller than the first thickness, and the fifth thickness is smaller than or equal to the second thickness.

9. The back contact solar cell according to claim 6, characterized in that: The passivation layer also covers at least a portion of the side surface, and a thickness of the passivation layer on the side surface is greater than or equal to the fourth thickness.

10. The back contact solar cell according to any one of claims 1 to 9, characterized in that: The passivation layer includes a first film layer and a second film layer stacked in sequence, the first film layer has the same thickness on the second surface, and the thickness of the second film layer covering the first edge area is greater than the thickness of the second film layer covering the first middle area.

11. A battery assembly, characterized in that: A back-contact solar cell comprising any one of claims 1 to 10.

12. A photovoltaic system, characterized in that: A battery assembly comprising the battery assembly of claim 11.

Images