Solar cell and solar cell module

Abstract

The utility model relates to the technical field of solar cells, in particular to a solar cell and a solar cell module. A solar cell includes: a silicon substrate; the passivation reflecting layer is arranged on the silicon substrate; the auxiliary grids extend in the first direction, the number of the auxiliary grids is multiple, and the auxiliary grids penetrate through the passivation reflection layer; the main grid extends in the second direction, the second direction is perpendicular to the first direction, the main grid is in contact with the passivation reflecting layer and does not penetrate through the passivation reflecting layer, the main grid comprises a first main grid part located between the two auxiliary grids, and the passivation reflecting layer corresponding to the first main grid part in position is in direct contact with the silicon substrate; the passivation contact layer, the passivation reflection layer corresponding to the position of the auxiliary gate and the silicon substrate are separated through the passivation contact layer, and the auxiliary gate penetrates through the passivation reflection layer and is in ohmic contact with the passivation contact layer. And a passivation contact layer at the main grid between the two auxiliary grids is removed, so that the optical loss of the solar cell is greatly reduced, and the illumination absorptivity of the solar cell is improved.

Description

Technical Field

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

[0002] The field of solar cell technology mainly involves technologies that convert solar energy into electrical energy, which is the core of photovoltaic power generation. N-type cell technology, such as passivated contact cells and heterojunction cells, is favored by the market due to its high efficiency and low light decay characteristics, and is rapidly increasing its market share. Passivated contact (TOPCon, Tunnel Oxide Passivated Contact) cells are a high-efficiency solar cell technology that uses a tunnel oxide passivated contact structure based on the principle of selective carriers. The core advantage of passivated contact cells lies in their back passivated contact technology, which effectively reduces surface recombination and interface recombination, increases the open circuit voltage (Voc), and thus improves the overall efficiency of the cell. Passivated contact cells usually use an N-type silicon substrate, and the back structure includes ultra-thin silicon oxide and a doped polysilicon thin layer to form a passivated contact structure, which helps to improve the selective transmission and collection efficiency of carriers.

[0003] A passivated contact layer is fabricated on the back of the cell. This layer, consisting of a dielectric layer and a doped polysilicon layer, effectively reduces surface recombination and metal contact recombination. However, the doped polysilicon layer itself has the ability to extinct light, which increases optical loss and reduces the cell's short-circuit current. Utility Model Content

[0004] The embodiments of the present application disclose a solar cell and a solar cell module, in which the passivation contact layer between the auxiliary grids is completely removed, including the main grid area between two adjacent auxiliary grids, which significantly reduces the optical loss of the solar cell and can also improve the patterning production capacity. This pattern with the passivation contact layer removed is more convenient to produce and increases the completion speed of this process.

[0005] To achieve the above objectives, in a first aspect, embodiments of the present application disclose a solar cell, comprising:

[0006] Silicon substrate;

[0007] A passivation reflective layer, the passivation reflective layer being provided on the silicon substrate;

[0008] A secondary grid, the secondary grid extending along a first direction, the secondary grid being multiple, and the secondary grid penetrating the passivation reflective layer;

[0009] a main gate extending along a second direction perpendicular to the first direction, the main gate contacting the passivation reflective layer and not penetrating the passivation reflective layer, the main gate including a first main gate portion located between the two sub-gates, the passivation reflective layer corresponding to the position of the first main gate portion being in direct contact with the silicon substrate;

[0010] A passivation contact layer is provided, wherein the passivation reflective layer corresponding to the position of the auxiliary gate is separated from the silicon substrate by the passivation contact layer, and the auxiliary gate penetrates the passivation reflective layer and establishes ohmic contact with the passivation contact layer.

[0011] As an optional embodiment, each of the auxiliary gates includes a plurality of auxiliary gate segments arranged at intervals along the first direction, the main gate is arranged through the interval between two adjacent auxiliary gate segments along the first direction, the auxiliary gate segments of two adjacent auxiliary gates correspond one to one in the second direction, and the passivation reflective layer corresponding to the position between the two adjacent auxiliary gate segments along the second direction is in direct contact with the silicon substrate.

[0012] As an optional embodiment, the main gate further includes a second main gate portion located between two adjacent sub-gate segments along the first direction, and the passivation reflective layer corresponding to the position of the second main gate portion and the silicon substrate are also separated by the passivation contact layer.

[0013] As an optional embodiment, the main gate further includes a second main gate portion located between two adjacent auxiliary gate segments along the first direction, and the passivation reflective layer corresponding to the position of the second main gate portion is in direct contact with the silicon substrate.

[0014] As an optional implementation, the corrosiveness of the slurry of the main grid is less than the corrosiveness of the slurry of the auxiliary grid.

[0015] As an optional implementation manner, the maximum corrosion depth of the slurry of the main grid is less than the thickness of the passivation reflective layer.

[0016] As an optional implementation, both the main grid and the auxiliary grid are made of metal paste.

[0017] As an optional implementation manner, the width of the passivation contact layer corresponding to the position of the auxiliary gate along the second direction is 100-300 μm.

[0018] As an optional implementation manner, the width of the passivation reflective layer corresponding to the position of the first main gate portion along the second direction is 400-800 μm.

[0019] In a second aspect, the present application discloses a solar cell assembly, wherein the cell comprises the solar cell described in any one of the first aspects.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] The solar cell provided in an embodiment of the present application includes a silicon substrate, a passivation contact layer, a passivation reflective layer, a secondary gate, and a main gate. The passivation reflective layer is provided on the silicon substrate. The secondary gate extends along a first direction, the secondary gates are multiple, and the secondary gates penetrate the passivation reflective layer. The main gate extends along a second direction perpendicular to the first direction. The main gate contacts the passivation reflective layer but does not penetrate the passivation reflective layer. The main gate includes a first main gate portion located between two secondary gates. The passivation reflective layer corresponding to the position of the first main gate portion is in direct contact with the silicon substrate. The passivation reflective layer corresponding to the position of the secondary gate is separated from the silicon substrate by a passivation contact layer. The secondary gate penetrates the passivation reflective layer and establishes ohmic contact with the passivation contact layer. In this way, the main gate region between two adjacent secondary gates is not provided with a passivation contact layer, which significantly reduces the optical loss of the solar cell and also improves the patterning production capacity. This patterning without the passivation contact layer is more convenient for production and increases the completion speed of the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 Schematic diagram of the structure of the passivation contact layer in the prior art;

[0024] Figure 2 A schematic diagram of the structure of a passivation contact layer disclosed in an embodiment of the present application;

[0025] Figure 3 This is another schematic diagram of the structure of the passivation contact layer disclosed in the embodiment of the present application;

[0026] Figure 4 A schematic structural diagram of a solar cell disclosed in an embodiment of the present application;

[0027] Figure 5 for Figure 4 Cross-sectional view at AA in the middle;

[0028] Figure 6 for Figure 4 Cross-sectional view at the middle BB;

[0029] Figure 7 for Figure 4 Cross-sectional view at CC;

[0030] Figure 8 for Figure 4 A partial enlarged view of the main grid and auxiliary grid segments in the middle part.

[0031] Description of reference numerals:

[0032] 100-solar cell; a-non-metallized area; b-main gate region; c-sub-gate region; 1-silicon substrate; 2-passivation contact layer; 3-sub-gate; 3a-gap; 31-sub-gate segment; 31a-first sub-gate segment; 31b-second sub-gate segment; 31c-third sub-gate segment; 31d-fourth sub-gate segment; 4-passivation reflective layer; 5-main gate; 51-first main gate portion; 52-second main gate portion; X-first direction; Y-second direction. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0034] In this application, the terms "upper," "lower," and "bottom" indicate positions or locations based on those shown in the accompanying drawings. These terms are primarily intended to better describe this application and its embodiments and are not intended to limit the devices, elements, or components indicated to specific positions, or to their construction or operation in a specific position.

[0035] Furthermore, some of the above terms may be used to express other meanings besides indicating a position or location. For example, the term "on" may also be used to indicate a dependency or connection in certain circumstances. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0036] Furthermore, the terms "installed," "disposed," and "equipped with" should be interpreted broadly. For example, they can refer to fixed connections, removable connections, or integral structures; mechanical connections or electrical connections; direct connections or indirect connections through an intermediary; or internal communication between two devices, elements, or components. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0037] Furthermore, the terms "first," "second," and the like are primarily used to distinguish between different devices, elements, or components (which may or may not be of the same type and configuration), and are not intended to indicate or imply the relative importance or quantity of the devices, elements, or components indicated. Unless otherwise specified, "plurality" means two or more.

[0038] The field of solar cell technology primarily involves converting solar energy into electrical energy, which is the core of photovoltaic power generation. Solar cells, also known as photovoltaic cells, achieve this conversion process by utilizing the photovoltaic effect of semiconductor materials. The working principle of solar cells is that when photons (particles of light energy) shine on semiconductor materials, they transfer energy to electrons, causing electrons to be excited from the valence band to the conduction band, thereby generating electron-hole pairs. Under the action of an electric field, the electrons and holes are separated, with electrons flowing to one side of the cell and holes flowing to the other side, forming an electric current. The efficiency and performance of solar cells depend on the materials used, the cell structure design, and the manufacturing process.

[0039] N-type cell technologies, such as passivated contact cells and heterojunction cells, are favored by the market due to their high efficiency and low light decay characteristics, and are rapidly increasing their market share. The passivated contact (TOPCon, Tunnel Oxide Passivated Contact) cell is a high-efficiency solar cell technology that uses a tunnel oxide passivated contact structure based on the principle of selective carriers. The core advantage of the passivated contact cell lies in its back-side passivated contact technology, which effectively reduces surface and interface recombination, increases the open circuit voltage (Voc), and thus improves the overall efficiency of the cell. Passivated contact cells typically use an N-type silicon substrate, and the back-side structure includes an ultra-thin silicon oxide and a doped polysilicon thin layer to form a passivated contact structure, which helps to improve the selective transport and collection efficiency of carriers.

[0040] The back of the passivated contact cell is prepared with a silicon substrate, a passivated contact layer, and a passivated reflective layer. The three are arranged in sequence. The passivated contact layer includes a dielectric layer and a doped polysilicon layer, which effectively reduces surface recombination and metal contact recombination. However, the doped polysilicon layer itself has the ability to extinct light, which will increase optical loss and reduce the short-circuit current of the cell. In order to reduce optical loss and improve short-circuit current and cell conversion efficiency, the industry has developed technologies such as back-doped polysilicon thinning and localized doped polysilicon etching, but the extent of reducing the optical loss of the cell is relatively low.

[0041] In order to solve the above problems, the inventors have further improved the solar cell and designed the following Figure 1The passivation contact layer structure shown in the figure. Specifically, the main gate region b and the auxiliary gate region c are metallized areas. Because the metal paste of the main gate and auxiliary gate is corrosive, in order to prevent it from corroding the silicon substrate, the passivation contact layer cannot be removed from the main gate region b and the auxiliary gate region c. The passivation contact layer is only removed from the non-metallized region a.

[0042] Based on this, an embodiment of the present application discloses a solar cell in which the passivation contact layer between the sub-grids is completely removed, including the main grid area between two adjacent sub-grids, which greatly reduces the optical loss of the solar cell and can also improve the graphic production capacity. This graphic with the passivation contact layer removed is more convenient to produce and increases the completion speed of this process.

[0043] The technical solution of the present application will be further described below with reference to the embodiments and drawings.

[0044] See also Figure 2 、 Figure 4 and Figure 6 , Figure 2 Schematic diagram of a structure of the passivation contact layer 2 disclosed in the embodiment of this application, Figure 4 This is another structural diagram of the passivation contact layer 2 disclosed in the embodiment of this application. Figure 6 for Figure 4 The embodiment of the present application discloses a solar cell 100, which includes:

[0045] The silicon substrate 1, as the substrate of the solar cell 100, has a low recombination rate and a long carrier lifetime, providing a high-quality semiconductor platform;

[0046] A passivation reflective layer 4 is provided on the silicon substrate 1. This layer is made of materials such as silicon nitride and not only has good passivation properties, but also serves as an anti-reflection layer to reduce light reflection and improve the light capture efficiency of the battery.

[0047] A secondary gate 3 is used to collect photogenerated carriers. The secondary gate 3 extends along the first direction X. There are multiple secondary gates 3. The secondary gates 3 penetrate the passivation reflective layer 4.

[0048] The main gate 5 mainly collects the current of the auxiliary gates 3 and connects them in series. The main gate 5 extends along the second direction Y, which is perpendicular to the first direction X. The main gate 5 contacts the passivation reflective layer 4 and does not penetrate the passivation reflective layer 4. The main gate 5 includes a first main gate portion 51 located between the two auxiliary gates 3. The passivation reflective layer 4 corresponding to the position of the first main gate portion 51 is in direct contact with the silicon substrate 1.

[0049] The passivation contact layer 2 separates the passivation reflective layer 4 corresponding to the position of the auxiliary gate 3 from the silicon substrate 1. The auxiliary gate 3 penetrates the passivation reflective layer 4 and establishes ohmic contact with the passivation contact layer 2. The passivation contact layer 2 is composed of an ultra-thin dielectric layer and a doped polysilicon layer, achieving selective carrier transmission, allowing electrons to pass while blocking holes, thereby reducing carrier recombination losses. The dielectric layer uses the quantum tunneling effect to allow electrons to pass, while the doped polysilicon layer provides a region of high doping concentration, creating a field passivation effect, further reducing carrier recombination.

[0050] In this way, the passivation contact layer 2 at the main grid 5 between the two sub-grids 3 is removed, which greatly reduces the optical loss of the solar cell 100, increases the effective use of light, improves the light absorption rate of the solar cell 100, and can also improve the graphic production capacity. This pattern of removing the passivation contact layer 2 is more convenient for production and improves the completion speed of this process.

[0051] As an optional implementation, combined with Figure 4 、 Figure 5 、 Figure 7 and Figure 8 Each auxiliary grid 3 includes a plurality of auxiliary grid segments 31. Figure 5 for Figure 4 The cross-sectional view at AA in the middle, Figure 7 for Figure 4 Cross-sectional view at CC, Figure 8 for Figure 4 A partial enlarged view of the central portion of the main gate 5 and the auxiliary gate segments 31. Each auxiliary gate 3 includes multiple auxiliary gate segments 31 spaced apart along the first direction X. The main gate 5 is disposed between two adjacent auxiliary gate segments 31 along the first direction X. The auxiliary gate segments 31 of two adjacent auxiliary gates 3 correspond one-to-one in the second direction Y. The passivation reflective layer 4 corresponding to the position between two adjacent auxiliary gate segments 31 along the second direction Y is in direct contact with the silicon substrate 1.

[0052] Specifically, combined Figure 8 One auxiliary gate 3 includes a first auxiliary gate segment 31a and a second auxiliary gate segment 31b, and another adjacent auxiliary gate 3 includes a third auxiliary gate segment 31c and a fourth auxiliary gate segment 31d. The first auxiliary gate segment 31a and the third auxiliary gate segment 31c correspond to each other in the second direction Y, and the second auxiliary gate segment 31b and the fourth auxiliary gate segment 31d correspond to each other in the second direction Y. A gap 3a is formed between the first auxiliary gate segment 31a and the second auxiliary gate segment 31b, and a gap 3a is also formed between the third auxiliary gate segment 31c and the fourth auxiliary gate segment 31d. The main gate 5 extends along the second direction Y through the gap 3a.

[0053] In this way, the passivation contact layer 2 is also removed between two adjacent sub-grid segments 31 along the second direction Y, so that only the passivation contact layer 2 under the sub-grid 3 is retained on the solar cell 100, which greatly reduces the optical loss of the solar cell 100, increases the effective use of light, improves the light absorption rate of the solar cell 100, and also improves the graphic production capacity. This method of removing the passivation contact layer 2 is more convenient and faster, and improves the process production efficiency.

[0054] In some embodiments, combined Figure 7 The main gate 5 also includes a second main gate portion 52 located between two adjacent auxiliary gate segments 31 along the first direction X. The passivation reflective layer 4 corresponding to the position of the second main gate portion 52 is also separated from the silicon substrate 1 by the passivation contact layer 2. Only the passivation contact layer 2 in the area between the two auxiliary gates 3 needs to be removed. When removing the passivation contact layer 2, there is no need to produce complex patterns (which require removing portions of the passivation contact layer 2 under the main gate 5), which can improve patterning production capabilities. This patterning method of removing the passivation contact layer 2 is more convenient to produce and increases the completion speed of this process.

[0055] Optionally, combined Figures 3 to 7 , Figure 3 This is another structural schematic diagram of the passivation contact layer 2 disclosed in an embodiment of the present application. The main gate 5 also includes a second main gate portion 52 located between two adjacent sub-gate segments 31 along the first direction X, and the passivation reflective layer 4 corresponding to the position of the second main gate portion 52 is in direct contact with the silicon substrate 1.

[0056] In this way, the passivation contact layer 2 corresponding to the position of the main grid 5 is completely removed, which greatly reduces the optical loss of the solar cell 100, increases the effective use of light, and improves the light absorption rate of the solar cell 100.

[0057] The production steps of passivated contact cells usually include texturing, light expansion, laser, oxidation, alkaline polishing, amorphous silicon layer preparation, passivation layer preparation, electrode preparation, testing and sorting. Potassium hydroxide (KOH) is used to treat silicon wafers to remove saw marks caused by the cutting process, and a pyramid-shaped surface structure is formed through chemical texturing to reduce light reflection and increase light absorption; the silicon wafers are thoroughly cleaned to remove organic matter and metal impurities on the surface to ensure the quality of subsequent processes; boron diffusion treatment is performed on the front side of the silicon wafer to form a P-type doping layer to form a PN junction; the borosilicate glass (BSG) on the back side of the silicon wafer is removed, and a dielectric layer is formed on the front side; phosphorus diffusion treatment is performed on the back side of the silicon wafer to form an N-type doping layer for forming a PN junction on the back side; an amorphous silicon layer is grown on the back side of the silicon wafer using plasma-enhanced chemical vapor deposition technology and converted into a polycrystalline silicon layer through high-temperature annealing; a passivation layer is prepared on the front and back sides of the silicon wafer to reduce carrier recombination losses; metal electrodes are prepared on the front and back sides of the silicon wafer, usually using screen printing technology, and a good ohmic contact is formed through a sintering process; finally, the passivated contact cells are performance tested, including IV characteristic tests, and sorted according to the test results.

[0058] The present application adds a laser film opening step to remove part of the passivation contact layer 2, thereby reducing the optical loss of the solar cell 100, increasing the effective use of light, and improving the light absorption rate of the solar cell 100.

[0059] In some possible embodiments, the corrosiveness of the slurry for the main grid 5 is less than that of the slurry for the auxiliary grid 3. During the manufacturing process of the solar cell 100, metal slurry is used to form the main grid 5 and the auxiliary grid 3. These metal grid lines serve as electrodes to collect and transmit current. Corrosiveness refers to the ability or degree of reaction of the metal slurry to erode the passivation reflective layer 4 during high-temperature sintering. Because there is only one passivation reflective layer 4 at the position corresponding to the main grid 5, while there are two layers of passivation contact layer 2 and passivation reflective layer 4 at the position corresponding to the auxiliary grid 3, when the corrosiveness of the slurry for the main grid 5 is less than that of the slurry for the auxiliary grid 3, the corrosion depth of the main grid 5 will be less than the corrosion depth of the auxiliary grid 3. In this way, after the passivation contact layer 2 under the main grid 5 area is removed, the main grid 5 is prevented from penetrating the silicon substrate 1 and affecting the performance of the solar cell 100.

[0060] In some embodiments, the maximum corrosion depth of the busbar 5 slurry is less than the thickness of the passivation reflective layer 4. The corrosion depth refers to the extent to which the metal slurry of the gate line etches the passivation reflective layer 4 when in contact with the passivation reflective layer 4, specifically the vertical distance the metal slurry penetrates the passivation reflective layer 4 during the sintering process. This ensures that the corrosion depth of the busbar 5 slurry is within a safe range, preventing the busbar 5 from excessively eroding into the silicon substrate 1 after the passivation contact layer 2 beneath the busbar 5 region is removed, thereby protecting the cell performance and maintaining the normal operation of the solar cell 100.

[0061] As an optional embodiment, metal paste is used for both the main grid 5 and the auxiliary grid 3. The main grid 5 and the auxiliary grid 3 in the solar cell 100 are important structures for collecting and transmitting current. The metal paste is made of a material with good conductive properties to ensure efficient current collection and transmission of the main grid 5 and the auxiliary grid 3.

[0062] It is understood that the main grid 5 and the auxiliary grid 3 can be made of metal materials such as silver, copper, aluminum, and alloy materials. In a first possible implementation, silver has excellent electrical conductivity and is a common material for preparing solar cell electrodes. Sometimes silver is combined with other metals, such as copper, to optimize cost and performance. In a second possible implementation, copper is also a commonly used conductive material that can be used alone or in composite materials with other metals such as silver. The cost of copper is generally lower than that of silver, so it can be used as a cost-effective alternative in certain applications. In a third possible implementation, aluminum is another economical and efficient conductive material that is commonly used in the back electrode of solar cells. The use of aluminum can help reduce costs while maintaining sufficient conductivity. In a fourth possible implementation, various alloy materials are used, such as silver-aluminum-platinum alloy, copper-nickel alloy, and copper-silver alloy. These materials are intended to combine the advantages of different metals, such as reducing costs, improving conductivity and corrosion resistance, and this embodiment is not limited to this.

[0063] Optionally, the width of the passivation contact layer 2 corresponding to the position of the auxiliary gate 3 along the second direction Y is 100-300 μm. By controlling the width of the passivation contact layer 2, efficient current transmission from the silicon substrate 1 to the auxiliary gate 3 is ensured. A width of 100-300 μm not only ensures sufficient contact area to reduce resistance, but also minimizes the area of ​​the passivation contact layer 2, reducing optical losses of the solar cell 100, increasing the effective use of light, and improving the light absorption rate of the solar cell 100.

[0064] In some optional embodiments, the width of the passivation reflective layer 4 corresponding to the location of the first main gate portion 51 along the second direction Y is 400-800 μm. The width of the passivation reflective layer 4 corresponding to the location of the first main gate portion 51 along the second direction Y can be adjusted accordingly to the width of the passivation contact layer 2 along the second direction Y. When the portion of the passivation contact layer 2 corresponding to the location of the first main gate portion 51 is removed, the area of ​​the passivation contact layer 2 is reduced, the optical loss of the solar cell 100 is reduced, the effective utilization of light is increased, and the light absorption rate of the solar cell 100 is improved. At the same time, a reasonable width design helps to enhance the mechanical strength of the solar cell 100, reduce the risk of damage during production, transportation, and installation, and ensure the structural integrity and reliability of the solar cell 100.

[0065] In a second aspect, the present application also discloses a solar cell module, comprising the solar cell 100 described in the first aspect. The solar cell module comprises a plurality of solar cells 100, and minimizes the passivation contact layer 2 structure in the metal region, significantly reducing optical losses in the solar cell module, increasing the effective utilization of light, and improving the solar cell module's light absorption rate.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A solar cell, characterized in that: include: Silicon substrate; A passivation reflective layer, the passivation reflective layer being provided on the silicon substrate; A secondary grid, the secondary grid extending along a first direction, the secondary grid being multiple, and the secondary grid penetrating the passivation reflective layer; a main gate extending along a second direction perpendicular to the first direction, the main gate contacting the passivation reflective layer and not penetrating the passivation reflective layer, the main gate including a first main gate portion located between the two sub-gates, the passivation reflective layer corresponding to the position of the first main gate portion being in direct contact with the silicon substrate; A passivation contact layer is provided, wherein the passivation reflective layer corresponding to the position of the auxiliary gate is separated from the silicon substrate by the passivation contact layer, and the auxiliary gate penetrates the passivation reflective layer and establishes ohmic contact with the passivation contact layer.

2. The solar cell according to claim 1, characterized in that Each of the auxiliary gates includes a plurality of auxiliary gate segments spaced apart along the first direction, the main gate is arranged through the interval between two adjacent auxiliary gate segments along the first direction, the auxiliary gate segments of two adjacent auxiliary gates correspond one to one in the second direction, and the passivation reflective layer corresponding to the position between the two adjacent auxiliary gate segments along the second direction is in direct contact with the silicon substrate.

3. The solar cell according to claim 2, characterized in that The main gate further includes a second main gate portion located between two adjacent auxiliary gate segments along the first direction, and the passivation reflective layer and the silicon substrate corresponding to the position of the second main gate portion are also separated by the passivation contact layer.

4. The solar cell according to claim 2, characterized in that The main gate further includes a second main gate portion located between two adjacent auxiliary gate segments along the first direction, and the passivation reflective layer corresponding to the position of the second main gate portion is in direct contact with the silicon substrate.

5. The solar cell according to claim 1, wherein The corrosiveness of the slurry of the main grid is less than that of the slurry of the auxiliary grid.

6. The solar cell according to claim 5, characterized in that The maximum corrosion depth of the slurry of the main grid is less than the thickness of the passivation reflective layer.

7. The solar cell according to claim 1, wherein The main grid and the auxiliary grid are both made of metal paste.

8. The solar cell according to claim 1, wherein The width of the passivation contact layer corresponding to the position of the auxiliary gate along the second direction is 100-300 μm.

9. The solar cell according to claim 1, wherein The width of the passivation reflective layer corresponding to the position of the first main gate portion along the second direction is 400-800 μm.

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

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