A solar cell, a cell assembly, and a photovoltaic system

Abstract

This invention relates to the field of photovoltaic technology and provides a solar cell, a battery module, and a photovoltaic system. The solar cell includes a silicon substrate. The back surface of the silicon substrate includes a plurality of first regions and a plurality of second regions alternately arranged along a first direction. The distance between the center line of the first region and the center line of the adjacent second region is the center distance. The positions on both sides of the center line extending along the second direction of the silicon substrate are central regions, and the positions near the edge of the silicon substrate are edge regions. A transition region exists between the central regions and the edge regions. The center distance within the edge region is Lb, the center distance within the transition region is Lzc, and the center distance within the central region is Lz, where Lz < Lzc ≤ Lb or Lz ≤ Lzc < Lb. This optimizes the grid line arrangement, improves the collection efficiency of photogenerated electrons, and shortens the P / N transmission distance, thereby effectively improving the short-circuit current (Isc) and fill factor (FF) of the cell, and increasing the cell conversion efficiency.

Description

Technical Field

[0001] This utility model belongs to the field of photovoltaic technology, and in particular relates to a solar cell, a battery module and a photovoltaic system. Background Technology

[0002] With the development of the solar energy industry, improving the conversion efficiency of solar cells has become a key issue. Traditional solar cells suffer from deficiencies in the grid line arrangement on the silicon substrate back surface. The lack of rational planning in the grid line distribution across different regions leads to low photogenerated electron collection efficiency. During photogenerated electron transmission, due to the unreasonable grid line arrangement, the transmission distance is long, easily resulting in recombination losses. This leads to lower short-circuit current (Isc) and fill factor (FF), severely impacting the cell's conversion efficiency. Furthermore, an unreasonable grid line arrangement also increases the cell's resistance, further reducing cell performance. Therefore, an optimized grid line arrangement scheme is urgently needed to improve photogenerated electron collection efficiency, thereby effectively enhancing the cell's short-circuit current, fill factor, and conversion efficiency. Utility Model Content

[0003] This invention provides a solar cell, a battery module, and a photovoltaic system, aiming to solve the problem of low photoelectric conversion efficiency of existing solar cells.

[0004] This invention is achieved as follows: a solar cell, comprising: A silicon substrate, wherein the backlight surface of the silicon substrate includes a plurality of first regions and a plurality of second regions alternately arranged along a first direction, the first regions and the second regions extend along a second direction, the distance between the center line of the first region and the center line of the adjacent second region is the center distance, and the first direction and the second direction intersect. The positions on both sides of the center line extending along the second direction of the silicon substrate are the central region, and the positions near the edge of the silicon substrate are the edge region. There is a transition region between the central region and the edge region. The center distance within the edge region is Lb, the center distance within the transition region is Lzc, and the center distance within the central region is Lz, where Lz < Lzc ≤ Lb or Lz ≤ Lzc < Lb.

[0005] Optionally, Lzc ≤ 1 / 2 × (Lz + Lb).

[0006] Optionally, on one side of the centerline of the silicon substrate, the width of the central region, the width of the transition region, and the width of the edge region are the same.

[0007] Optionally, 0.1mm≤Lz and Lb≤0.8mm.

[0008] Optionally, the value of Lz can range from 0.1 mm to 0.4 mm.

[0009] Optionally, the value of Lzc ranges from 0.2mm to 0.6mm. Optionally, the value of Lb ranges from 0.3 mm to 0.8 mm.

[0010] Optionally, the first region has a first polar doped layer, and the second region has a second polar doped layer, wherein the polarity of the first polar doped layer is different from that of the second polar doped layer.

[0011] Optionally, an interval region is provided between the first region and the second region.

[0012] Optionally, the widths of the interval regions are the same.

[0013] This invention also provides a battery assembly, including the aforementioned solar cell.

[0014] This utility model also provides a photovoltaic system, including the above-mentioned battery components.

[0015] The beneficial effects achieved by this invention are as follows: by dividing the back surface of the silicon substrate of the solar cell into a central transition region and an edge region, and with the relationship between the center distances of each region being Lz<Lzc≤Lb or Lz≤Lzc<Lb, the grid line arrangement is optimized, the collection efficiency of photogenerated electrons is improved, and the P / N transmission distance is shortened, thereby effectively improving the short-circuit current (Isc) and fill factor (FF) of the cell and improving the cell conversion efficiency. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the solar cell provided by this utility model.

[0017] Explanation of reference numerals in the attached figures: 100. Solar cell; 101. Silicon substrate; 110. First region; 120. Second region; 130. Spacing region. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model 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, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model. Furthermore, it should be understood that the specific embodiments described herein are merely for explaining this utility model and are not intended to limit this utility model.

[0019] In the description of this utility model, it should be understood that the terms "length", "width", "upper", "lower", "left", "right", "horizontal", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0020] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0021] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0022] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0023] The following disclosure provides numerous different embodiments or examples for implementing various structures of the present invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0024] This invention divides the back surface of a silicon substrate in a solar cell into a central transition region and an edge region. The relationship between the center distances in each region is Lz<Lzc≤Lb or Lz≤Lzc<Lb. This optimizes the grid line arrangement, improves the collection efficiency of photogenerated electrons, and shortens the P / N transmission distance, thereby effectively improving the short-circuit current (Isc) and fill factor (FF) of the cell and increasing the cell conversion efficiency.

[0025] Example 1 like Figure 1 As shown, this embodiment provides a solar cell 100, including: The silicon substrate 101 has a backlight surface that includes a plurality of first regions 110 and a plurality of second regions 120 that are alternately arranged, and the distance between the center line of the first region 110 and the center line of the adjacent second region 120 is the center distance. The positions on both sides of the center line of the silicon substrate 101 are the central region, and the positions near the edge of the silicon substrate 101 are the edge region. There is a transition region between the central region and the edge region. The center distance within the edge region is Lb, the center distance within the transition region is Lzc, and the center distance within the central region is Lz, where Lz < Lzc ≤ Lb or Lz ≤ Lzc < Lb.

[0026] The silicon substrate 101 has two main surfaces: a light-facing surface and a back-lighting surface. The light-facing surface directly faces the sunlight, while the back-lighting surface is on the other side. The two surfaces are positioned opposite each other.

[0027] Two distinct regions, a first region 110 and a second region 120, are arranged alternately on the backlight surface of the silicon substrate 101. Specifically, a plurality of first regions 110 and a plurality of second regions 120 are arranged alternately along a first direction, and both the first regions 110 and 120 extend along a second direction, which intersects the first direction. The first regions 110 and 120 can be arranged alternately along the lateral direction of the silicon substrate 101 and both extend along the longitudinal direction; that is, the first direction can be the lateral direction of the back contact battery, and the second direction can be the longitudinal direction of the back contact battery, and the two are perpendicular to each other. Of course, in other embodiments, the first direction and the second direction can also be other directions, for example, they can be the diagonal directions of the silicon substrate 101, and no specific limitation is made here. The first regions 110 and 120 do not overlap and are arranged adjacent to each other.

[0028] A first polar doped layer is disposed within a first region 110, and a second polar doped layer is disposed within a second region 120. The first and second polar doped layers have opposite polarities. Specifically, the first polar doped layer can be a P-type doped layer and the second polar doped layer can be an N-type doped layer, or vice versa. The first and second polar doped layers form regions with different electrical characteristics, supporting the formation of a PN junction and the separation of charge carriers.

[0029] Both the first region 110 and the second region 120 have a certain width. The widths of the first region 110 and the second region 120 can be the same, or the width of the first region 110 can be greater than or less than the width of the second region 120; this is not limited here. It should be noted that if the first region 110 and the second region 120 extend along a second direction, then the width direction of the first region 110 and the second region 120 is perpendicular to the second direction. The distance between the centerline of the first region 110 and the centerline of the adjacent second region 120 is the center distance. Therefore, the wider the first region 110 and / or the second region 120, the greater the center distance between them.

[0030] Along the second direction, the area near the edge of the silicon substrate 101 is the edge region, the area closest to the center of the silicon substrate 101 is the center region, and the area between the edge region and the center region is the transition region. The center region, the transition region, and the edge region are symmetrically arranged on both sides of the center line.

[0031] The center distance within the edge region is Lb, the center distance within the transition region is Lzc, and the center distance within the central region is Lz, where Lz < Lzc ≤ Lb or Lz ≤ Lzc < Lb. Specifically, it can be Lz = Lzc < Lb, Lz < Lzc = Lb, or Lz < Lzc < Lb; no specific limitation is made here. During production, the center distance of different regions can be controlled by adjusting the pattern of the photomask.

[0032] During the manufacturing process of solar cells 100, various process factors can lead to performance differences at different locations within the cell. For example, in processes such as high-temperature diffusion and deposition, the edges of the cell are in greater contact with the external environment and are subject to more impurity contamination and stress. These factors can disrupt the crystal structure of the silicon material at the cell edges, increasing the surface state density. Higher surface state density leads to a higher surface recombination rate, thereby reducing minority carrier lifetime. Simultaneously, the passivation effect at the edges can be compromised due to process inhomogeneities; the passivation layer may contain defects or have uneven thickness, failing to effectively reduce the surface recombination rate. Conversely, the center of the cell is less affected by the external environment, has a more complete crystal structure, lower surface state density, and a longer minority carrier lifetime. Furthermore, the passivation effect at the center is better, effectively reducing the recombination loss of photogenerated carriers at the surface, thus becoming a high-power generation region. The edges, due to their shorter minority carrier lifetime and poorer passivation, are more prone to surface recombination of photogenerated carriers, resulting in lower power generation efficiency, becoming a low-power generation region.

[0033] Grid lines are respectively set in the first region 110 and the second region 120. The main function of the grid lines is to collect photogenerated electrons and transfer them to the electrodes of the battery. The center distance is closely related to the density of the grid line arrangement. The smaller the center distance, the smaller the distance between adjacent first regions 110 and second regions 120. In the same area, more grid lines can be set, and the grid line arrangement is more dense.

[0034] In the high-power generation region (central area), due to the high generation rate of photogenerated carriers, more efficient collection of these photoelectrons is required. By setting a smaller center distance Lz and making the grid lines more densely arranged, the contact area between the grid lines and photogenerated carriers can be increased, improving the collection efficiency of photogenerated electrons. More photogenerated electrons can be collected and transported to the electrodes in a timely manner, reducing recombination losses of photogenerated carriers inside the battery, thereby increasing the battery's short-circuit current (Isc). In the low-power generation region (edge ​​area), the generation rate of photogenerated carriers is relatively low. If the grid lines are set too densely, it will not only increase manufacturing costs but may also reduce the light-receiving area of ​​the battery due to grid lines blocking light, affecting power generation efficiency. Therefore, setting a larger center distance Lb and appropriately reducing the number of grid lines can meet the collection needs of photogenerated electrons in the edge area while avoiding unnecessary cost increases and light blocking problems.

[0035] The width of a single first region 110 and second region 120 is closely related to the center-to-center distance; the smaller the center-to-center distance, the smaller the width of a single first region 110 and second region 120. In the solar cell 100, photogenerated carriers (electrons and holes) need to be transported between P-type and N-type semiconductor regions to form a current. The P / N transport distance refers to the distance traveled by photogenerated carriers from their generation location to their collection location. When the width of a single first region 110 and second region 120 is small, the transport distance of photogenerated carriers between the P-type and N-type semiconductor regions is correspondingly shortened. A shorter transport distance means a lower probability that photogenerated carriers will encounter recombination centers during transport, reducing recombination losses during transport. More photogenerated carriers can reach the electrodes smoothly, thereby increasing the short-circuit current (Isc) of the cell. At the same time, a shorter P / N transport distance can also reduce the series resistance of the cell. A reduction in series resistance can reduce energy loss during cell operation and increase the fill factor (FF) of the cell. The fill factor is an important parameter that measures the ratio of the maximum output power of a solar cell to the product of its open-circuit voltage and short-circuit current. A higher fill factor means that the cell can convert light energy into electrical energy more efficiently, thereby increasing the cell's conversion efficiency.

[0036] This embodiment divides the backlight surface of the silicon substrate 101 of the solar cell 100 into a central transition region and an edge region. The relationship between the center distances of each region is Lz<Lzc≤Lb or Lz≤Lzc<Lb. This optimizes the grid line arrangement, improves the collection efficiency of photogenerated electrons, and shortens the P / N transmission distance, thereby effectively improving the short-circuit current (Isc) and fill factor (FF) of the cell and increasing the cell conversion efficiency.

[0037] In some embodiments, Lzc ≤ 1 / 2 × (Lz + Lb). For example, if Lz = 0.2 mm and Lb = 0.6 mm, then the value of Lzc must not exceed 1 / 2 × (0.2 + 0.6) = 0.4 mm, which can be set to 0.3 mm. This allows the center distance of the transition region to transition more reasonably between the central and edge regions. When transitioning from the high-power-generating central region to the low-power-generating edge region, the grid line density can be adjusted more smoothly. Compared to cells that do not meet this condition, the photogenerated carrier collection efficiency is optimized in the transition region, reducing the problem of abrupt changes in carrier collection efficiency caused by regional changes, thereby further improving the overall short-circuit current (Isc) and fill factor (FF) of the cell.

[0038] In some embodiments, on one side of the centerline of the silicon substrate 101, the width of the central region, the width of the transition region, and the width of the edge region are consistent. That is, the total width on one side of the centerline of the silicon substrate 101 is divided into three equal parts along the first direction. Consistent widths in each region facilitate standardized operations in photolithography, printing, and other processes, reducing the difficulty of process adjustments caused by differences in region widths, and improving production efficiency and yield. Simultaneously, from the perspective of battery performance, this regular structure helps to uniformly distribute and transport photogenerated carriers between different regions, avoiding the problem of uneven carrier distribution caused by excessive differences in region widths, further improving the overall performance of the battery.

[0039] In some embodiments, 0.1mm ≤ Lz and Lb ≤ 0.8mm. From a manufacturing perspective, Lz ≥ 0.1mm ensures the manufacturability of the grid lines in the central region. If Lz is too small, the grid line spacing is too narrow, which can easily lead to problems such as grid line adhesion and unclear printing during grid line fabrication processes such as screen printing or electroplating, affecting battery performance and yield. Lb ≤ 0.8mm, on the other hand, ensures the photogenerated carrier collection efficiency in the edge region while avoiding insufficient collection caused by excessively sparse grid lines.

[0040] Specifically, the value of Lz ranges from 0.1mm to 0.4mm, and can be 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, or 0.4mm, or other values ​​within the range of 0.1mm to 0.4mm; no limitation is made here. When Lz is less than 0.1mm, the difficulty of the grid line fabrication process increases significantly, and the yield rate decreases; while when Lz is greater than 0.4mm, the collection efficiency of the grid lines in the central region decreases significantly, affecting the performance of the battery. A value of Lz within the range of 0.1mm to 0.4mm ensures the density of the grid lines in the central region, effectively collecting photogenerated carriers in the high-power generation area, without causing excessive manufacturing difficulty due to excessively small grid line spacing.

[0041] The value of Lzc ranges from 0.2mm to 0.6mm. It can be 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, or 0.6mm, or other values ​​within this range; no specific limitation is imposed here. If Lzc is less than 0.2mm, the grid lines in the transition region are too dense, increasing manufacturing costs and potentially reducing the light-receiving area of ​​the battery due to grid lines blocking light. If Lzc is greater than 0.6mm, the grid lines in the transition region are too sparse, failing to effectively collect photogenerated carriers and affecting the smoothness of the battery's performance transition. By controlling Lzc between 0.2mm and 0.6mm, the collection efficiency of photogenerated carriers in the transition region can be optimized, resulting in more stable overall battery performance. The value of Lb ranges from 0.3mm to 0.8mm. It can be 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, or 0.8mm, or other values ​​within this range; no specific limitation is imposed here. When Lb is less than 0.3mm, the grid lines in the edge region are too dense, increasing manufacturing costs and easily leading to unclear grid line printing and adhesion problems in processes such as screen printing, thus reducing yield. When Lb is greater than 0.8mm, the grid lines in the edge region are too sparse, failing to effectively collect photogenerated carriers, resulting in low power generation efficiency in the edge region and affecting the overall performance of the battery. Controlling it between 0.3mm and 0.8mm ensures both the collection efficiency of photogenerated carriers in the edge region and controls manufacturing costs while maintaining a high yield rate.

[0042] In some embodiments, a gap region 130 is provided between the first region 110 and the second region 120. The gap region 130 can serve as an electrical isolation layer to prevent current leakage and short circuits between different regions. Typically, the gap region 130 is a trench that spatially separates the first region 110 and the second region 120. When the gap region 130 is provided between the first region 110 and the second region 120, the calculation method for the center distance needs to take into account the width of the gap region 130.

[0043] Furthermore, the spacing regions 130 are all the same width. In the manufacturing process of the solar cell 100, the spacing regions 130 are typically produced using photolithography. When the spacing regions 130 have the same width, the design of the photomask becomes much simpler. This is because it only requires repeating the pattern of the spacing regions 130 with the same width, eliminating the need to design complex photolithographic patterns for spacing regions 130 with different widths. This reduces the design and manufacturing difficulty of the photomask and lowers costs. Simultaneously, during the photolithography process, due to the repeatability of the pattern, the operation and parameter settings of the photolithography equipment are more uniform and stable, reducing photolithography errors caused by pattern variations and improving the accuracy and efficiency of photolithography.

[0044] Example 2 This embodiment provides a battery assembly, including the solar cell 100 described above.

[0045] The battery module may include multiple back-contact solar cells 100 each. The multiple back-contact solar cells 100 each in the battery module can be connected in series to form a battery string. The battery strings can be connected in series, in parallel, or in a series-parallel combination to achieve current collection and output. For example, the connection between the individual cells can be achieved by welding solder strips, or the connection between the battery strings can be achieved by busbars.

[0046] The battery module may also include a metal frame, a backsheet, photovoltaic glass, and an encapsulant film (not shown in the figures). The encapsulant film can be filled between the light-facing side of the solar cell 100 and the photovoltaic glass, the back-facing side and the backsheet, and adjacent cells. As a filler, it can be a transparent colloid with good light transmittance and aging resistance. For example, the encapsulant film can be EVA film or POE film, and the specific choice can be made according to the actual situation. There are no restrictions here.

[0047] Photovoltaic glass can be applied to the encapsulating film on the light-facing side of the solar cell 100. The photovoltaic glass can be ultra-clear glass, which has high light transmittance, high transparency, and superior physical, mechanical, and optical properties. For example, ultra-clear glass can achieve a light transmittance of over 92%. It can protect the solar cell 100 while minimizing impact on its efficiency. Simultaneously, the encapsulating film bonds the photovoltaic glass and the solar cell 100 together, providing sealing, insulation, waterproofing, and moisture protection for the solar cell 100.

[0048] The backsheet can be attached to the adhesive film on the back side of the solar cell 100. The backsheet provides protection and support for the solar cell 100, offering reliable insulation, water resistance, and aging resistance. Multiple backsheet options are available, typically including tempered glass, acrylic glass, and aluminum alloy TPT composite adhesive film, etc. The specific choice depends on the specific circumstances and is not limited here. The backsheet, solar cell 100, adhesive film, and photovoltaic glass can be mounted on a metal frame. The metal frame serves as the main external support structure for the entire battery module, providing stable support and installation. For example, the battery module can be installed at the desired location using the metal frame.

[0049] The beneficial effects of the battery module in this embodiment are equivalent to those of the solar cell 100 described above, and will not be repeated here.

[0050] Example 3 This embodiment provides a photovoltaic system, including the aforementioned battery module.

[0051] Photovoltaic systems can be applied in photovoltaic power plants, such as ground-mounted, rooftop, and floating power plants, as well as in equipment or devices that utilize solar energy to generate electricity, such as user solar power supplies, solar streetlights, solar cars, and solar buildings. Of course, it's understandable that the application scenarios of photovoltaic systems are not limited to these; that is, photovoltaic systems can be applied in all fields that require solar energy to generate electricity. Taking a photovoltaic power generation network as an example, a photovoltaic system can include photovoltaic arrays, combiner boxes, and inverters. A photovoltaic array can be a combination of multiple battery modules; for example, multiple battery modules can form multiple photovoltaic arrays. The photovoltaic arrays are connected to combiner boxes, which collect the current generated by the photovoltaic arrays. The collected current flows through an inverter and is converted into AC power required by the mains grid before being connected to the mains grid to achieve solar power supply.

[0052] The beneficial effects of the photovoltaic system in this embodiment are equivalent to the beneficial effects of the battery module described above, and will not be repeated here.

[0053] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A solar cell, characterized in that, include: A silicon substrate, wherein the backlight surface of the silicon substrate includes a plurality of first regions and a plurality of second regions alternately arranged along a first direction, the first regions and the second regions extend along a second direction, the distance between the center line of the first region and the center line of the adjacent second region is the center distance, and the first direction and the second direction intersect. The positions on both sides of the center line extending along the second direction of the silicon substrate are the central region, and the positions near the edge of the silicon substrate are the edge region. There is a transition region between the central region and the edge region. The center distance within the edge region is Lb, the center distance within the transition region is Lzc, and the center distance within the central region is Lz, where Lz < Lzc ≤ Lb or Lz ≤ Lzc < Lb.

2. The solar cell as described in claim 1, characterized in that, Lzc≤1 / 2×(Lz+Lb) 3. The solar cell as described in claim 1, characterized in that, On one side of the centerline of the silicon substrate, the width of the central region, the width of the transition region, and the width of the edge region are the same.

4. The solar cell as described in claim 1, characterized in that, 0.1mm≤Lz, and Lb≤0.8mm.

5. The solar cell as described in claim 4, characterized in that, The value of Lz ranges from 0.1mm to 0.4mm.

6. The solar cell as claimed in claim 1, characterized in that, The value of Lzc ranges from 0.2mm to 0.6mm.

7. The solar cell as claimed in claim 4, characterized in that, The value of Lb ranges from 0.3 mm to 0.8 mm.

8. The solar cell as claimed in claim 1, characterized in that, The first region has a first polar doped layer, and the second region has a second polar doped layer, wherein the polarity of the first polar doped layer is different from that of the second polar doped layer.

9. The solar cell according to claim 1, characterized in that, An interval region is set between the first region and the second region.

10. The solar cell as claimed in claim 9, characterized in that, The widths of the interval regions are the same.

11. A battery assembly, characterized in that, Includes the solar cell described in any one of claims 1 to 10.

12. A photovoltaic system, characterized in that, Includes the battery assembly as described in claim 11.

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