Solar cell, cell module and photovoltaic system

Abstract

The invention provides a solar cell, a cell module and a photovoltaic system, and the solar cell comprises a substrate which is provided with a first doping type; the doped conductive layer is located on the substrate and has a second doping type; the first doping part is located in the substrate and has a first doping type, and the doping concentration of the first doping part is larger than that of the substrate; and the second doped part is located in the doped conductive layer and is in contact with the first doped part, the second doped part has a second doping type, and the doping concentration of the second doped part is greater than that of the doped conductive layer. The problem that a hot spot effect is likely to happen to a solar cell is solved.

Description

Technical Field

[0001] The present application relates to the field of photovoltaics, and more specifically, to a solar cell, a battery assembly, and a photovoltaic system. Background Art

[0002] Photovoltaic cells are currently the most widely used solar power generation technology. They generate electricity by utilizing the photovoltaic effect of a semiconductor PN junction. Conventional semiconductor solar cells (such as mainstream crystalline silicon solar cells) are subject to obstructions such as bird droppings, leaves, and dust during use. This can cause localized temperature rise in the cell, creating a hot spot effect. If the temperature of a hot spot exceeds a certain threshold, it can lead to delamination of the photovoltaic module, backsheet burns, and glass cracking, rendering the entire solar cell useless. In severe cases, it can also pose a fire risk. Summary of the Invention

[0003] The main purpose of the present application is to provide a solar cell, a battery assembly and a photovoltaic system to solve the problem of hot spot effect easily occurring in solar cells in the prior art.

[0004] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a solar cell is provided, comprising: a substrate having a first doping type; a doped conductive layer located on the substrate and having a second doping type; a first doping portion located in the substrate and having the first doping type, the doping concentration of the first doping portion being greater than the doping concentration of the substrate; a second doping portion located in the doped conductive layer and in contact with the first doping portion, the second doping portion having the second doping type, the doping concentration of the second doping portion being greater than the doping concentration of the doped conductive layer.

[0005] Optionally, the doping concentration of the first doping portion is 10 to 100 times the doping concentration of the substrate.

[0006] Optionally, the doping concentration of the second doping portion is 10 to 100 times the doping concentration of the doped conductive layer.

[0007] Optionally, the solar cell includes a plurality of first doping portions and a plurality of second doping portions, and the first doping portions are in contact with the second doping portions in a one-to-one correspondence.

[0008] Optionally, a plurality of the first doping portions are arranged at intervals in the substrate, and a plurality of the second doping portions are arranged at intervals in the doped conductive layer.

[0009] Optionally, a plurality of the first doped portions are arranged in a grid shape in the substrate, and a plurality of the second doped portions are arranged in a grid shape in the doped conductive layer.

[0010] Optionally, the first doping portion and the second doping portion are both strip-shaped.

[0011] Optionally, the first doping portion and the second doping portion are both in a spot shape.

[0012] Optionally, the substrate and the doped conductive layer both include a middle region and an edge region surrounding the middle region along a predetermined direction, wherein the predetermined direction is perpendicular to the stacking direction of the substrate and the doped conductive layer, and the first doped portion and the second doped portion are respectively located in at least one of the following: the middle region and the edge region.

[0013] According to another aspect of the present application, a battery assembly is provided, comprising: any one of the solar cells described above.

[0014] Optionally, there are multiple solar cells, and the multiple solar cells are connected in series.

[0015] According to another aspect of the present application, a photovoltaic system is provided, comprising: the battery assembly; a packaging film for covering the surface of the battery assembly; and a cover plate for covering the surface of the packaging film facing away from the battery assembly.

[0016] By applying the technical solution of the present application, a substrate and a doped conductive layer of different doping types contact to form a first PN junction. On this basis, a highly doped first doped portion is formed in the substrate, and a highly doped second doped portion is formed in the doped conductive layer. The first doped portion and the second doped portion contact to form a local PN junction. Since the first doped portion and the second doped portion have higher doping concentrations, the local PN junction has a lower reverse breakdown voltage than the first PN junction. When a part of the solar cell is blocked, causing the local area to be reverse biased, the local PN junction will turn on earlier than the first PN junction and a larger reverse current will flow through it, preventing the current and voltage at the first PN junction from being too high, reducing heat accumulation in the blocked area, and avoiding battery damage caused by overheating in the blocked area, thereby reducing the risk of hot spots in the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings that constitute part of this application are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation on this application. In the drawings:

[0018] Figure 1 shows a schematic top view of a solar cell according to an embodiment of the present application;

[0019] Figure 2 FIG2 shows a schematic top view of a solar cell according to another embodiment of the present application;

[0020] Figure 3 Shown along Figure 1 or Figure 2 A schematic diagram of the cross-sectional structure obtained by the dotted line AA';

[0021] Figure 4 FIG2 shows a schematic top view of a solar cell according to another embodiment of the present application;

[0022] Figure 5 Shown along Figure 4 A schematic diagram of the cross-sectional structure obtained by the dotted line AA';

[0023] Figure 6 FIG2 shows a schematic top view of a solar cell according to another embodiment of the present application;

[0024] Figure 7 Shown along Figure 6 A schematic diagram of the cross-sectional structure obtained by the dotted line AA';

[0025] Figure 8 shows a schematic cross-sectional structure diagram of a solar cell according to another embodiment of the present application;

[0026] Figure 9 A flow chart of a method for preparing a solar cell according to an embodiment of the present application is shown.

[0027] The above drawings include the following reference numerals:

[0028] 10. Substrate; 11. Doped conductive layer; 12. First doped portion; 13. Second doped portion. DETAILED DESCRIPTION

[0029] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0030] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0031] It should be noted that the terms "first," "second," and the like in the specification and claims of the present invention and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a particular order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate for the embodiments of the present invention described herein. In addition, the terms "including," "having," and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to these processes, methods, products, or apparatuses.

[0032] It should be understood that when an element (such as a layer, film, region, or substrate) is described as being "on" another element, the element may be directly on the other element or intervening elements may be present. Moreover, in the specification and claims, when it is described that an element is "connected to" another element, the element may be "directly connected to" the other element or "connected to" the other element through a third element.

[0033] As mentioned in the background, solar cells face a common problem: the hot spot effect. This phenomenon arises from obstructions on the cell surface, such as bird droppings, leaves, and dust. This prevents the obscured portion of the cell from receiving sufficient sunlight, while the unobstructed portion continues to function normally. In a solar cell array, cells are typically connected in series to increase the output voltage. When a cell is obscured, its power generation capacity decreases significantly, but it still has to withstand reverse current from the array. This causes the temperature in the obscured area to rise sharply, forming the so-called "hot spot." High temperatures not only accelerate the degradation of cell materials but can also damage the encapsulation material, leading to module delamination, backsheet burns, and even glass cracking, ultimately affecting the performance and lifespan of the entire solar cell module. To prevent the damage caused by the hot spot effect, bypass diodes are currently connected in parallel across each cell string in a photovoltaic module. When a cell is detected to be obscured, the bypass diode automatically turns on, bypassing the affected cell and reducing the current flowing through it, thereby limiting the rise in the hot spot temperature. However, bypass diodes require additional physical space for installation, which may affect the design layout and overall size of the PV module, and sometimes even reduce the effective area of ​​the cell, thereby affecting the output power of the module.

[0034] In response to the above problems, the present application provides a solar cell, a battery module and a photovoltaic system for reducing the risk of hot spots in solar cells, effectively improving the safety performance of solar cells, and controlling leakage losses.

[0035] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0036] The present application provides a solar cell, Figures 1 to 8 The schematic structural diagram of the solar cell according to the embodiment of the present application is shown as an example, wherein: Figure 1 Schematic diagram of a top view of a solar cell in one embodiment of the present application is shown as an example. Figure 2 Schematic diagram of a top view of a solar cell in another embodiment of the present application is shown as an example. Figure 3 Can be along Figure 1 The cross-sectional structure diagram obtained by the AA' dashed line can also be Figure 2 Schematic diagram of the cross-sectional structure obtained by the AA' dotted line. Figure 4 Schematic diagram of a top view of a solar cell according to an embodiment of the present application is shown as an example. Figure 5 For the Figure 4 The cross-sectional structure diagram obtained by the dotted line AA' in the figure is as follows: Figure 6 exemplarily shows a schematic top view of a solar cell according to another embodiment of the present application, Figure 7 For the Figure 6 The cross-sectional structure diagram obtained by the dotted line AA' in the figure is as follows: Figure 8 For the Figure 6 Another cross-sectional structural schematic diagram obtained by the dotted line AA' in FIG.

[0037] like Figures 1 to 8 As shown, the solar cell of the present application includes:

[0038] The substrate 10 has a first doping type;

[0039] Specifically, the first doping type can be N-type or P-type. The substrate 10 serves as the basic structure of the cell, and its doping type determines the basic conductive properties of the solar cell.

[0040] a doped conductive layer 11 , located on the substrate 10 and having a second doping type;

[0041] Specifically, the second doping type is different from the first doping type. The doped conductive layer 11 forms a PN junction with the substrate 10, which is a key part for generating current in the solar cell.

[0042] a first doping portion 12 located in the substrate 10 and having the first doping type, wherein the doping concentration of the first doping portion 12 is greater than the doping concentration of the substrate 10;

[0043] The second doping portion 13 is located in the doped conductive layer 11 and contacts the first doping portion 12 . The second doping portion 13 has the second doping type, and the doping concentration of the second doping portion 13 is greater than the doping concentration of the doped conductive layer 11 .

[0044] Specifically, the surface of the first doping portion 12 contacting the second doping portion 13 overlaps with a portion of the surface of the substrate 10 ; the surface of the second doping portion 13 contacting the first doping portion 12 overlaps with a portion of the surface of the doped conductive layer 11 .

[0045] Through the described embodiment, the substrate and the doped conductive layer of different doping types contact to form a first PN junction. On this basis, a highly doped first doped portion is formed in the substrate, and a highly doped second doped portion is formed in the doped conductive layer 11. The first doped portion and the second doped portion contact to form a local PN junction. Since the first doped portion and the second doped portion have higher doping concentrations, the local PN junction has a lower reverse breakdown voltage than the first PN junction. When a part of the solar cell is blocked, causing the local area to be reverse biased, the local PN junction will be turned on earlier than the first PN junction and a larger reverse current will flow through it, preventing the current and voltage at the first PN junction from being too high, reducing heat accumulation in the blocked area, and avoiding battery damage caused by overheating in the blocked area, thereby reducing the risk of hot spots in the battery.

[0046] In one alternative, the first doped portion 12 and the second doped portion 13 form a Zener diode. This diode, with its low breakdown voltage and voltage-stabilizing properties, acts as a bypass, protecting the battery from high reverse bias voltages. This prevents overheating in unlit areas of the battery, which could compromise overall battery performance and reduce the risk of hot spots. This design not only enhances the battery's thermal stability but also reduces energy loss due to the hot spot effect, improving battery reliability and service life.

[0047] In actual applications, this application does not specifically limit the material and conductivity type of substrate 10. In some embodiments, substrate 10 can be made of any semiconductor material, such as silicon substrate 10, silicon germanium substrate 10, germanium substrate 10, or gallium arsenide substrate 10. In terms of the arrangement of the material, the crystalline phase of all substrates 10 can be amorphous, microcrystalline, nanocrystalline, single crystal, or polycrystalline.

[0048] In a specific application process, the material of the doped conductive layer 11 can be the same as or different from the material of the substrate 10. In some embodiments, the material of the doped conductive layer 11 is the same as the material of the substrate 10.

[0049] In some embodiments, the substrate 10 is a P-type substrate, that is, the substrate 10 is doped with P-type ions, and the P-type ions can be any one of boron, aluminum or gallium. The doped conductive layer 11 is an N-type doped conductive layer, that is, the doped conductive layer 11 is doped with N-type ions, and the N-type ions can be any one of phosphorus, arsenic or antimony.

[0050] In other embodiments, the substrate 10 is an N-type substrate, that is, the substrate 10 is doped with N-type ions, and the N-type ions can be any one of phosphorus, arsenic or antimony. The doped conductive layer 11 is a P-type doped conductive layer, that is, the doped conductive layer 11 is doped with P-type ions, and the P-type ions can be any one of boron, aluminum or gallium.

[0051] Optionally, the solar cell is a monofacial cell, ie, it receives solar light through only one surface of the substrate 10. In some embodiments, the solar cell is a bifacial cell, ie, two opposite surfaces of the substrate 10 are used to receive solar light.

[0052] Figure 3 An embodiment is exemplified in which the surface of the first doped portion 12 away from the second doped portion 13 coincides with a portion of the surface of the substrate 10 away from the doped conductive layer 11, and the surface of the second doped portion 13 away from the first doped portion 12 coincides with a portion of the surface of the doped conductive layer 11 away from the substrate 10. The solar cell further includes an electrode (not shown) electrically connected to the first doped portion 12 and an electrode (not shown) electrically connected to the second doped portion 13. Based on the embodiment, the electrode can be in electrical contact with the second doped portion 13, and the electrode can be in electrical contact with the first doped portion 12.

[0053] In some other embodiments of the present application, such as Figure 8 As shown, along the stacking direction of the substrate 10 and the doped conductive layer 11, the thickness of the first doped portion 12 is less than the thickness of the substrate 10, and the thickness of the second doped portion 13 is less than the thickness of the doped conductive layer 11. That is, the surface of the first doped portion 12 away from the second doped portion 13 does not overlap with the surface of the substrate 10 away from the doped conductive layer 11, and the surface of the second doped portion 13 away from the first doped portion 12 does not overlap with the surface of the doped conductive layer 11 away from the substrate 10. Based on this embodiment, an electrode can be electrically contacted with the second doped portion 13 through the doped conductive layer 11, and an electrode can be electrically contacted with the first doped portion 12 through the substrate 10.

[0054] In other embodiments of the present application, along the stacking direction of the substrate 10 and the doped conductive layer 11, the thickness of the first doped portion 12 is less than the thickness of the substrate 10, and the thickness of the second doped portion 13 is equal to the thickness of the doped conductive layer 11. That is, the surface of the first doped portion 12 distal from the second doped portion 13 does not overlap with the surface of the substrate 10 distal from the doped conductive layer 11, and the surface of the second doped portion 13 distal from the first doped portion 12 overlaps with a portion of the surface of the doped conductive layer 11 distal from the substrate 10. Based on these embodiments, an electrode can be in electrical contact with the second doped portion 13, and an electrode can be in electrical contact with the first doped portion 12 through the substrate 10.

[0055] In still other embodiments of the present application, along the stacking direction of the substrate 10 and the doped conductive layer 11, the thickness of the first doped portion 12 is equal to the thickness of the substrate 10, and the thickness of the second doped portion 13 is less than the thickness of the doped conductive layer 11. That is, the surface of the first doped portion 12 away from the second doped portion 13 overlaps with a portion of the surface of the substrate 10 away from the doped conductive layer 11, and the surface of the second doped portion 13 away from the first doped portion 12 does not overlap with the surface of the doped conductive layer 11 away from the substrate 10. Based on these embodiments, an electrode can be in electrical contact with the second doped portion 13 through the doped conductive layer 11, and an electrode can be in electrical contact with the first doped portion 12.

[0056] In the present application, the doping concentrations of the first doping portion 12 and the second doping portion 13 directly affect the reverse blocking capability and forward conduction characteristics of the Zener diode.

[0057] According to an exemplary embodiment of the present application, the doping concentration of the first doping portion 12 is 10 to 100 times the doping concentration of the substrate 10. For example, the ratio of the doping concentration of the first doping portion 12 to the doping concentration of the substrate 10 can be 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100. In this embodiment, by precisely controlling the doping concentration difference range between the first doping portion 12 and the substrate 10, the electrical performance of the local PN junction can be optimized, ensuring that when needed (for example, when a hot spot effect occurs), the local PN junction can promptly play its role of voltage stabilization and conduction, effectively dispersing current and preventing local overheating, further solving the problem that solar cells are easily damaged under uneven lighting conditions. At the same time, under normal working conditions, the normal current path of the battery will not be interfered with, thereby preventing the local PN junction from affecting the photoelectric conversion efficiency of the solar cell under normal conditions.

[0058] In some embodiments, the doping concentration of the first doping portion 12 is 10 to 50 times the doping concentration of the substrate 10 .

[0059] In some embodiments, the doping concentration of the first doping portion 12 is 50 to 100 times the doping concentration of the substrate 10 .

[0060] In some embodiments, the doping concentration of the first doping portion 12 is 30 to 60 times the doping concentration of the substrate 10 .

[0061] According to another exemplary embodiment of the present application, the doping concentration of the second doping portion 13 is 10 to 100 times the doping concentration of the doped conductive layer 11. For example, the ratio of the doping concentration of the second doping portion 13 to the doping concentration of the doped conductive layer 11 can be 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100. In this embodiment, by precisely controlling the doping concentration difference range between the second doping portion 13 and the doped conductive layer 11, the electrical performance of the local PN junction can be optimized, ensuring that when needed (for example, when a hot spot effect occurs), the local PN junction can promptly play its role of voltage stabilization and conduction, effectively dispersing current and preventing local overheating, further solving the problem that solar cells are easily damaged under uneven lighting conditions. At the same time, under normal working conditions, the normal current path of the battery will not be interfered with, thereby preventing the local PN junction from affecting the photoelectric conversion efficiency of the solar cell under normal conditions.

[0062] In some embodiments, the doping concentration of the second doping portion 13 is 10 to 50 times the doping concentration of the doped conductive layer 11 .

[0063] In some embodiments, the doping concentration of the second doping portion 13 is 50 to 100 times the doping concentration of the doped conductive layer 11 .

[0064] In some embodiments, the doping concentration of the second doping portion 13 is 30 to 60 times the doping concentration of the doped conductive layer 11 .

[0065] In some options, such as Figure 2 and Figure 3 As shown, the solar cell may have only one first doping portion 12 and one second doping portion 13 .

[0066] Other options, such as Figure 1 and Figure 3As shown, the solar cell includes multiple first doping portions 12 and multiple second doping portions 13, with the first doping portions 12 and the second doping portions 13 in one-to-one contact. In this embodiment, the multiple first doping portions 12 and the multiple second doping portions 13 are in one-to-one contact, forming multiple Zener diode structures. The integrated design of multiple Zener diodes enables the cell to maintain stable operation even when shielded by a larger area, thereby further reducing the risk of hot spots in the solar cell.

[0067] In the embodiment, each Zener diode can independently respond to a local shading event, thereby achieving hot spot protection for the entire battery, greatly improving the adaptability and safety of the battery in complex lighting environments.

[0068] Optionally, a plurality of the first doped portions 12 are arranged at intervals in the substrate 10, and a plurality of the second doped portions 13 are arranged at intervals in the doped conductive layer 11. The dispersed Zener diode layout ensures that when any point on the cell is blocked, an adjacent Zener diode is available to function, thereby reducing the impact of the hot spot effect on the overall performance of the cell. This dispersed layout effectively controls the local impact of the hot spot effect.

[0069] The layout strategy is particularly suitable for irregular shading environments, improves the thermal stability of the battery, and extends its service life.

[0070] Optionally, multiple first doped portions 12 are arranged in a grid pattern in the substrate 10 (not shown), and multiple second doped portions 13 are arranged in a grid pattern in the doped conductive layer 11. In this embodiment, the grid-shaped Zener diode structure ensures that every small area on the cell surface is uniformly protected from hot spots, enabling rapid response even in the presence of minor obstructions to avoid local overheating.

[0071] The layout strategy is particularly suitable for high-density photovoltaic arrays and can improve the overall efficiency and reliability of the photovoltaic system.

[0072] Alternatively, as Figure 2 and Figure 3 As shown, the first doped portion 12 and the second doped portion 13 are each strip-shaped. This strip-shaped design not only simplifies manufacturing processes, such as photolithography and ion implantation, but also effectively covers the primary light-receiving area of ​​the cell, providing continuous hot spot protection. This design allows the cell to maintain good performance even in the presence of linear or large-area shading, preventing damage to the cell due to localized overheating.

[0073] Optionally, the first doped portion 12 and the second doped portion 13 are both in the shape of spots (not shown in the figure). The spot-shaped design can flexibly adjust the hot spot protection area to adapt to different shielding conditions.

[0074] In some further exemplary embodiments, the substrate 10 and the doped conductive layer 11 each include a middle region and an edge region surrounding the middle region along a predetermined direction, the predetermined direction being perpendicular to the stacking direction of the substrate 10 and the doped conductive layer 11, and the first doped portion 12 and the second doped portion 13 are respectively located in at least one of the following: the middle region and the edge region. That is, the distribution of the first doped portion 12 and the second doped portion 13 includes the following three situations: the first situation, such as Figure 6 and Figure 7 As shown, the first doping portion 12 and the second doping portion 13 are located in the middle area and not in the edge area; the second type, as shown in FIG. Figure 2 and Figure 3 ,as well as Figure 4 and Figure 5 In the embodiment shown in FIG. 1 , the first doped portion 12 and the second doped portion 13 are located in the edge region and not in the middle region. In the third embodiment (not shown), part of the first doped portion 12 and the second doped portion 13 are located in the middle region, and part of the first doped portion 12 and the second doped portion 13 are located in the edge region. By arranging the local PN junction in the middle region and / or the edge region of the solar cell, the solar cell can be further effectively protected from hot spots.

[0075] For example, Figures 1 to 3 The first doping portion 12 and the second doping portion 13 are located in the edge region, and are only located at one edge of the edge region.

[0076] In addition to the above embodiment, in some other embodiments, the first doping portion 12 and the second doping portion 13 are located in the edge region and at least at two edges of the edge region. Figure 4 and Figure 5 As shown, the first doping portion 12 and the second doping portion 13 are located at all edges of the edge region, forming a U-shaped shape.

[0077] In actual application, the solar cell of the present application can be a variety of types of solar cells, for example, the solar cell of the present application can be a TOPCon (Tunnel Oxide Passivated Contact) cell, a BC (Back Contact) cell, an HJT (Heterojunction with Intrinsic Thin Layer) cell, or a Perc (Passivated Emitter and RearCell) cell.

[0078] For example, in the case where the solar cell is a TOPCon cell, the solar cell may further include: a first passivation layer, located on a side of the doped conductive layer 11 away from the substrate 10; a first electrode, located on a side of the first passivation layer away from the doped conductive layer 11; a tunneling oxide layer, located on a side of the substrate 10 away from the doped conductive layer 11; a semiconductor conductive layer having the first doping type, located on a side of the tunneling oxide layer away from the substrate 10; a second passivation layer, located on a side of the semiconductor conductive layer away from the tunneling oxide layer; and a second electrode, located on a side of the second passivation layer away from the semiconductor conductive layer.

[0079] For another example, when the solar cell is a BC cell, the solar cell may further include: a first passivation layer, located on a side of the substrate 10 away from the doped conductive layer 11; a first oxide layer, located between the doped conductive layer 11 and the substrate 10; a semiconductor conductive layer, having the first doping type, located on the same side of the substrate 10 as the doped conductive layer 11; a second oxide layer, located between the semiconductor conductive layer and the substrate 10; a second passivation layer, located on a side of the doped conductive layer 11 and the semiconductor conductive layer away from the substrate 10; a first electrode, located on a side of the second passivation layer away from the doped conductive layer 11; and a second electrode, located on a side of the second passivation layer away from the semiconductor conductive layer.

[0080] The present application also provides a method for preparing the solar cell. Figure 9 FIG. 1 is a flow chart of a method for preparing a solar cell according to an embodiment of the present application. Figure 9 As shown, the method includes the following steps:

[0081] Step S201, providing a substrate, wherein the substrate has a first doping type;

[0082] Step S202 , forming a first doping portion in the substrate, wherein the first doping portion has the first doping type and a doping concentration greater than a doping concentration of the substrate;

[0083] Step S203, forming a doped conductive layer on the substrate, wherein the doped conductive layer has a second doping type;

[0084] Specifically, the doped conductive layer may be a film layer obtained by epitaxy, or a film layer obtained by diffusion or ion implantation.

[0085] Step S204 : forming a second doped portion in the doped conductive layer so that the second doped portion contacts the first doped portion, the second doped portion having the second doping type and a doping concentration greater than the doping concentration of the doped conductive layer.

[0086] In a specific implementation, step S202 can be achieved by placing the substrate 10 with the mask in a high-temperature diffusion furnace, and introducing an impurity gas source or a solid impurity source of the first doping type into the high-temperature diffusion furnace to form the first doped portion 12 in the substrate 10. In addition to the above method, step S202 can also be achieved by using an ion implanter to implant impurity ions into the mask window to form the first doped portion 12 in the substrate 10.

[0087] In a specific implementation, step S204 can be achieved by placing the masked doped conductive layer 11 in a high-temperature diffusion furnace, and introducing a second doping type impurity gas source or a second doping type solid impurity source into the high-temperature diffusion furnace to form the second doped portion 13 in the doped conductive layer 11 in contact with the first doped portion 12. In addition to the above method, step S204 can also be achieved by using an ion implanter to implant impurity ions into the mask window to form the second doped portion 13 in the doped conductive layer 11 in contact with the first doped portion 12.

[0088] According to another aspect of the present application, a battery assembly is provided, comprising: any one of the solar cells described above.

[0089] The battery assembly includes any one of the solar cells described above, in which a local PN junction is formed. The local PN junction has a low reverse breakdown voltage and voltage stabilization characteristics, which can protect the battery assembly from the influence of high reverse bias voltage and reduce the risk of hot spots in the battery assembly.

[0090] Optionally, there are multiple solar cells, which are connected in series. By connecting in series, the module can achieve a higher voltage output, and the hot spot protection of each cell is independent of each other, thereby improving the overall safety and reliability of the module.

[0091] An embodiment of the present application further provides a photovoltaic system, comprising:

[0092] The battery assembly;

[0093] A packaging film, used to cover the surface of the battery assembly;

[0094] The cover plate is used to cover the surface of the packaging film facing away from the battery assembly.

[0095] The photovoltaic system includes the battery assembly, packaging film and cover plate. The solar cell in the battery assembly has a local PN junction. The local PN junction has a low reverse breakdown voltage and voltage stabilization characteristics, which can protect the battery assembly from the influence of high reverse bias voltage, reduce the hot spot risk of the battery assembly, and avoid problems such as component delamination, backplane burning and even glass breakage caused by the hot spot effect, thereby ensuring a long life and high performance of the photovoltaic system.

[0096] From the above description, it can be seen that the embodiments described in this application achieve the following technical effects:

[0097] In the solar cell of the present application, a substrate and a doped conductive layer of different doping types contact to form a first PN junction. On this basis, a highly doped first doped portion is formed in the substrate, and a highly doped second doped portion is formed in the doped conductive layer. The first doped portion and the second doped portion contact to form a local PN junction. Since the first doped portion and the second doped portion have higher doping concentrations, the local PN junction has a lower reverse breakdown voltage than the first PN junction. When a part of the solar cell is blocked, causing the local area to be reverse biased, the local PN junction will turn on earlier than the first PN junction and a larger reverse current will flow through it, preventing the current and voltage at the first PN junction from being too high, reducing heat accumulation in the blocked area, and avoiding battery damage caused by overheating in the blocked area, thereby reducing the risk of hot spots in the battery.

[0098] The technical features of the above-described embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0099] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A solar cell, characterized in that: include: a substrate having a first doping type; a doped conductive layer, located on the substrate and having a second doping type; a first doping portion, located in the substrate and having the first doping type, wherein a doping concentration of the first doping portion is greater than a doping concentration of the substrate; The second doping portion is located in the doped conductive layer and contacts the first doping portion. The second doping portion has the second doping type, and the doping concentration of the second doping portion is greater than the doping concentration of the doped conductive layer.

2. The solar cell according to claim 1, wherein The doping concentration of the first doping portion is 10 to 100 times the doping concentration of the substrate.

3. The solar cell according to claim 1, wherein The doping concentration of the second doping portion is 10 to 100 times the doping concentration of the doped conductive layer.

4. The solar cell according to claim 1, wherein The solar cell includes a plurality of first doping portions and a plurality of second doping portions, and the first doping portions are in contact with the second doping portions in a one-to-one correspondence.

5. The solar cell according to claim 4, wherein A plurality of the first doping portions are arranged at intervals in the substrate, and a plurality of the second doping portions are arranged at intervals in the doped conductive layer.

6. The solar cell according to claim 4, characterized in that A plurality of the first doped portions are arranged in a grid shape in the substrate, and a plurality of the second doped portions are arranged in a grid shape in the doped conductive layer.

7. The solar cell according to claim 1, wherein The first doping portion and the second doping portion are both strip-shaped.

8. The solar cell according to claim 1, wherein The first doping portion and the second doping portion are both in a spot shape.

9. The solar cell according to any one of claims 1 to 8, characterized in that The substrate and the doped conductive layer both include a middle region and an edge region surrounding the middle region along a predetermined direction, wherein the predetermined direction is perpendicular to the stacking direction of the substrate and the doped conductive layer, and the first doped portion and the second doped portion are respectively located in at least one of the following: the middle region and the edge region.

10. A battery assembly, characterized in that: include: The solar cell according to any one of claims 1 to 9.

11. The battery assembly according to claim 10, characterized in that There are a plurality of solar cells, and the plurality of solar cells are connected in series.

12. A photovoltaic system, characterized in that: include: The battery assembly according to claim 10 or 11; A packaging film, used to cover the surface of the battery assembly; The cover plate is used to cover the surface of the packaging film facing away from the battery assembly.

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