A back contact solar cell, cell assembly and photovoltaic system

Abstract

The application is suitable for the photovoltaic technical field, and provides a back contact solar cell, a cell assembly and a photovoltaic system.The back contact solar cell comprises a silicon wafer, a back surface of the silicon wafer comprising first soldering areas and second soldering areas which are alternately and spacedly arranged along a first direction; first and second auxiliary grids arranged on the back surface, the first and second auxiliary grids being alternately and spacedly arranged along a second direction, the first direction intersecting the second direction, the first auxiliary grid extending to the first soldering area, and the second auxiliary grid extending to the second soldering area; and an insulating layer arranged on the back surface, the insulating layer covering at least a part of the first auxiliary grid close to the second soldering area, and covering at least a part of the second auxiliary grid close to the first soldering area, the average reflectivity of the insulating layer to light with a wavelength in a range of 800 nm to 1200 nm being 50% to 95%, and the area ratio of the insulating layer to the total area of the back surface being 40% to 60%. The back contact solar cell can reduce the escape of sunlight from the back surface, thereby improving the conversion efficiency of the cell.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, and in particular to a back-contact solar cell, a cell module, and a photovoltaic system. Background Technology

[0002] A solar cell is a semiconductor device that converts solar energy into electrical energy. Under sunlight, a solar cell generates a photocurrent, which is then output as electrical energy through electrodes. In recent years, solar cell manufacturing technology has continuously improved, production costs have decreased, and conversion efficiency has increased. As a result, solar cell power generation has become increasingly widespread and is a crucial energy source for electricity supply.

[0003] In related technologies, the back side of a back-contact solar cell typically includes a first welding area and a second welding area, which are alternately spaced along a first direction and used for mounting solder ribbons. The back side of the back-contact solar cell also has a first sub-grid and a second sub-grid, which are alternately spaced along a second direction, intersecting the first direction. The first sub-grid extends to the first welding area, and the second sub-grid extends to the second welding area. To prevent the solder ribbons in the second welding area from contacting the first sub-grid and to prevent the solder ribbons in the first welding area from contacting the second sub-grid, an insulating layer is needed to cover the portion of the first sub-grid near the second welding area and the portion of the second sub-grid near the first welding area, ensuring reliable insulation between the first and second sub-grids and solder ribbons of opposite polarity. However, typical insulating layers have low reflectivity for long-wavelength (800nm~1200nm) sunlight, and the area of ​​the insulating layer on the back side of the back-contact solar cell is small. The insulating layer cannot reflect long-wavelength sunlight emitted from the back of the silicon wafer back to the silicon wafer, allowing long-wavelength sunlight to easily escape from the back of the solar cell, resulting in low solar energy utilization and poor cell conversion efficiency. Summary of the Invention

[0004] This invention provides a back-contact solar cell, which aims to solve the problem that sunlight easily escapes from the back of the solar cell in the prior art, resulting in low sunlight utilization and poor cell conversion efficiency.

[0005] This invention is implemented by providing a back-contact solar cell, comprising:

[0006] A silicon wafer, the back side of which includes a first welding area and a second welding area alternately spaced along a first direction;

[0007] A first sub-gate and a second sub-gate are disposed on the back side, the first sub-gate and the second sub-gate being alternately spaced along a second direction, the first direction intersecting the second direction, the first sub-gate extending to the first welding area, and the second sub-gate extending to the second welding area; and

[0008] An insulating layer is provided on the back side, the insulating layer at least covers the portion of the first sub-gate near the second soldering area, and the insulating layer at least covers the portion of the second sub-gate near the first soldering area, the insulating layer has an average reflectivity of 50% to 95% for light in the wavelength range of 800nm ​​to 1200nm, and the area of ​​the insulating layer is 40% to 60% of the total area of ​​the back side.

[0009] Preferably, the ratio of the area of ​​the insulating layer to the total area of ​​the back surface is 40% to 50%.

[0010] Preferably, the thickness of the insulating layer is 10 micrometers to 100 micrometers.

[0011] Preferably, the insulating layer comprises organic resin and titanium dioxide, wherein the mass fraction of the titanium dioxide is 20% to 60%.

[0012] Preferred options also include:

[0013] A first pad is provided in the first welding area, the first pad is electrically connected to the first sub-gate, and a first gap is provided between the insulating layer and the first pad.

[0014] Preferred options also include:

[0015] A second pad is provided in the second welding area, the second pad is electrically connected to the second sub-gate, and a second gap is provided between the insulating layer and the second pad.

[0016] Preferably, the width of the first gap is 5 micrometers to 150 micrometers; and / or, the width of the second gap is 5 micrometers to 150 micrometers.

[0017] Preferably, the insulating layer includes a first insulating portion covering the first sub-gate and a second insulating portion covering the second sub-gate, wherein the first insulating portion and the second insulating portion are spaced apart or connected to each other.

[0018] Preferably, the projections of the first insulating portion and the second insulating portion in the second direction overlap.

[0019] Preferably, the distance between adjacent first welding area and second welding area is L, and the length of the overlapping area of ​​the projection of the first insulating part and the second insulating part in the second direction along the first direction is D, where 0.5L≤D≤0.8L.

[0020] Preferably, the widths of the first insulating portion and the second insulating portion near the edge of the silicon wafer decrease sequentially from the center of the silicon wafer toward the edge of the silicon wafer.

[0021] Preferably, the first welding area is provided with a first solder joint, and the insulating layer further includes a first blocking portion covering the first sub-gate, the first blocking portion being located outside the first welding area and adjacent to the first solder joint.

[0022] Preferably, the first blocking portion connects to two adjacent second insulating portions, and the first blocking portion and the two adjacent second insulating portions form a first receiving groove.

[0023] Preferably, the distance from the first blocking portion to the first welding area along the first direction is 600 micrometers to 700 micrometers.

[0024] Preferably, the width of the first blocking portion along the first direction is 100 micrometers to 200 micrometers.

[0025] Preferably, the second welding area is provided with a second solder joint, and the insulating layer further includes a second blocking portion covering the second sub-gate, the second blocking portion being located outside the second welding area and adjacent to the second solder joint.

[0026] Preferably, the second blocking portion connects two adjacent first insulating portions, and the second blocking portion and the two adjacent first insulating portions form a second receiving groove.

[0027] Preferably, the insulating layer includes at least one marking portion, the marking portion being located on the first sub-gate and / or the second sub-gate, or the marking portion being located in a region not where the first sub-gate and the second sub-gate are disposed.

[0028] The present invention also provides a battery assembly including the aforementioned back-contact solar cell.

[0029] The present invention also provides a photovoltaic system including the above-described battery module.

[0030] The present invention provides an insulating layer for a back-contact solar cell with an average reflectivity of 50% to 95% for light in the wavelength range of 800nm ​​to 1200nm. This results in a high reflectivity of the insulating layer for long-wavelength (800nm ​​to 1200nm) sunlight, allowing it to effectively reflect long-wavelength sunlight emitted from the back of the silicon wafer back into the wafer, reducing sunlight loss from the back of the solar cell and thus improving sunlight utilization and conversion efficiency. Furthermore, by controlling the ratio of the insulating layer's area to the total area of ​​the back surface to be 40% to 60%, the coverage area of ​​the insulating layer is significantly increased compared to traditional back-contact solar cells. This allows for the reflection of a suitable proportion of long-wavelength sunlight emitted from the back of the silicon wafer back into the wafer. The controlled ratio of the insulating layer's area to the total area of ​​the back surface (40% to 60%) ensures good reflection of long-wavelength sunlight emitted from the back of the silicon wafer while also allowing sunlight to enter the wafer from the back, ensuring good power generation efficiency on the back surface, and maintaining low production costs for the insulating layer. Attached Figure Description

[0031] Figure 1 A schematic diagram of the back side of a back-contact solar cell provided in an embodiment of the present invention;

[0032] Figure 2 for Figure 1 A magnified schematic diagram of part A in the middle;

[0033] Figure 3 for Figure 1 A magnified schematic diagram of part B in the middle;

[0034] Figure 4 for Figure 1 A magnified schematic diagram of part C in the middle;

[0035] Figure 5 for Figure 1 A magnified schematic diagram of part D in the middle;

[0036] Figure 6 for Figure 1 A magnified schematic diagram of part E in the middle. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Examples of 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 the invention, and should not be construed as limiting the invention. Furthermore, it should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0038] In the description of this invention, it should be understood that the terms "upper", "lower", "backlight", "front", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing this invention 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, and therefore should not be construed as a limitation of this invention.

[0039] 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.

[0040] The following disclosure provides numerous different embodiments or examples for implementing various structures of the 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 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.

[0041] Please refer to Figures 1-4 This invention provides a back-contact solar cell, comprising:

[0042] The silicon wafer 1 has a back surface 11 including a first welding area 111 and a second welding area 112 that are alternately spaced along a first direction X.

[0043] A first sub-gate 2 and a second sub-gate 3 are disposed on the back side 11 of the silicon wafer 1. The first sub-gate 2 and the second sub-gate 3 are alternately spaced along the second direction Y. The first direction X intersects the second direction Y. The first sub-gate 2 extends to the first bonding area 111, and the second sub-gate 3 extends to the second bonding area 112.

[0044] An insulating layer 4 is provided on the back side 11. The insulating layer 4 covers at least the portion of the first sub-gate 2 near the second welding area 112, and the insulating layer 4 covers at least the portion of the second sub-gate 3 near the first welding area 111. The average reflectivity of the insulating layer 4 for light with a wavelength range of 800nm ​​to 1200nm is 50% to 95%, and the ratio of the area of ​​the insulating layer 4 to the total area of ​​the back side 11 is 40% to 60%.

[0045] In this embodiment of the invention, the back side 11 of the silicon wafer 1 is the side facing away from sunlight when the back-contact solar cell is working. The insulating layer 4 partially covers the first sub-gate 2 and the second sub-gate 3, and also partially covers the area of ​​the back side 11 where the first sub-gate 2 and the second sub-gate 3 are not located; that is, the total area of ​​the insulating layer 4 is greater than the sum of the areas of the first sub-gate 2 and the second sub-gate 3. In practical applications, the width of the insulating layer 4 at the position of the first sub-gate 2 is greater than the width of the first sub-gate 2, and the width of the insulating layer 4 at the position of the second sub-gate 3 is greater than the width of the second sub-gate 3. This ensures that the insulating layer 4 covers not only a portion of the area of ​​the first sub-gate 2 and a portion of the area of ​​the second sub-gate 3, but also a portion of the area of ​​the back side 11 where the first sub-gate 2 and the second sub-gate 3 are not located. Long-wavelength sunlight emitted from the back side 11 of the silicon wafer 1 strikes the insulating layer 4 from the area where the first sub-gate 2 and the second sub-gate 3 are not located. Utilizing the good reflective properties of the insulating layer 4, the insulating layer 4 reflects the long-wavelength sunlight back into the silicon wafer 1, thereby improving the utilization efficiency of long-wavelength sunlight.

[0046] The present invention provides an insulating layer 4 for a back-contact solar cell with an average reflectivity of 50% to 95% for light in the wavelength range of 800nm ​​to 1200nm. The insulating layer 4 has a high reflectivity for long-wavelength (800nm ​​to 1200nm) sunlight. When long-wavelength sunlight not completely absorbed by the silicon wafer 1 is emitted from the back surface 11 of the silicon wafer 1, the insulating layer 4 can effectively reflect the emitted long-wavelength sunlight back into the silicon wafer 1, reducing sunlight escape loss from the back surface 11 of the solar cell, thereby improving sunlight utilization and thus increasing cell conversion efficiency. Simultaneously, the area ratio of the insulating layer 4 to the total area of ​​the back surface 11 is 40% to 60%, which can... This means that the ratio of the total area of ​​all insulating layers 4 to the total area of ​​the back surface 11 is 40% to 60%, while the area of ​​the insulating layer 4 in traditional back-contact solar cells is usually less than 30%. Therefore, the embodiment of the present invention greatly increases the coverage area of ​​the insulating layer 4, which can reflect a suitable proportion of the long-wavelength sunlight emitted from the back surface 11 of the silicon wafer 1 back into the silicon wafer 1. By controlling the ratio of the area of ​​the insulating layer 4 to the total area of ​​the back surface 11 to 40% to 60%, the good reflection effect of the insulating layer 4 on the long-wavelength sunlight emitted from the back surface 11 of the silicon wafer 1 is ensured, while also taking into account that sunlight can enter the silicon wafer 1 from the back surface 11, ensuring good power generation efficiency of the back surface 11, and ensuring low production cost of the insulating layer 4.

[0047] In this embodiment of the invention, the average reflectance of the insulating layer 4 for light with wavelengths in the range of 800nm ​​to 1200nm is any value between 50% and 95%. For example, the average reflectance of the insulating layer 4 for light with wavelengths in the range of 800nm ​​to 1200nm is any value between 50%, 53%, 55%, 60%, 65%, 70%, 76%, 80%, 84%, 88%, 90%, and 95%.

[0048] In this embodiment of the invention, the ratio of the area of ​​the insulating layer 4 to the total area of ​​the back surface 11 is any value between 40% and 60%. For example, the ratio of the area of ​​the insulating layer 4 to the total area of ​​the back surface 11 can be any value among 40%, 42%, 44%, 45%, 47%, 49%, 50%, 52%, 54%, 56%, 58%, and 60%.

[0049] In this embodiment of the invention, the first direction X and the second direction Y can be arranged perpendicularly or not perpendicularly. Preferably, the first direction X and the second direction Y are arranged perpendicularly. There are multiple first sub-gates 2 and multiple second sub-gates 3, which are alternately arranged along the second direction Y on the back side 11 of the silicon wafer 1. The first welding area 111 and the second welding area 112 are respectively used to set solder strips, which are used to connect multiple back-contact solar cells into a cell string. There are multiple first welding areas 111 and multiple second welding areas 112, which are alternately arranged along the first direction X on the back side 11 of the silicon wafer 1. Specifically, the first sub-gate 2 extends to the first welding area 111 but not to the second welding area 112, and the second sub-gate 3 extends to the second welding area 112 but not to the first welding area 111; this can be understood as the first sub-gate 2 being disconnected at the second welding area 112 and the second sub-gate 3 being disconnected at the first welding area 111.

[0050] In this embodiment, the insulating layer 4 at least covers the portion of the first sub-gate 2 near the second welding area 112, preventing the first sub-gate 2 from making contact with the solder strip on the second welding area 112; the insulating layer 4 at least covers the portion of the second sub-gate 3 near the first welding area 111, preventing the second sub-gate 3 from making contact with the solder strip on the first welding area 111, thereby achieving good insulation between the first sub-gate 2 and the second sub-gate 3 and solder strips of opposite polarity, thereby reducing the risk of short circuit in the solar cell and ensuring normal operation of the cell. In some embodiments, to facilitate the printing of the insulating layer 4, the insulating layer 4 may simultaneously cover the portions of the first sub-gate 2 and the second sub-gate 3 near the first welding area 111, and the insulating layer 4 may not cover the portion of the first sub-gate 2 in the first welding area 111, and the insulating layer 4 may simultaneously cover the portions of the first sub-gate 2 and the second sub-gate 3 near the second welding area 112, and the insulating layer 4 may not cover the portion of the second sub-gate 3 in the second welding area 112.

[0051] In this embodiment of the invention, the back-contact solar cell further includes a first doped layer and a second doped layer alternately spaced along a second direction Y. A first sub-gate 2 is disposed on and in contact with the first doped layer, and a second sub-gate 3 is disposed on and in contact with the second doped layer. The first and second doped layers have opposite doping types. One of the first and second doped layers is a P-type doped layer, and the other is an N-type doped layer. If the first doped layer is a P-type doped layer, the region containing the first doped layer is a P-type doped region; if the second doped layer is an N-type doped layer, the region containing the second doped layer is an N-type doped region. Alternatively, the first doped layer is an N-type doped layer, and the second doped layer is a P-type doped layer. The P-type doped layer contains a P-type element, and the N-type doped layer contains an N-type element, for example, boron for the P-type element and phosphorus for the N-type element.

[0052] In this embodiment of the invention, the back-contact solar cell can be either a back-contact solar cell with a main grid or a back-contact solar cell without a main grid. When the back-contact solar cell is a back-contact solar cell with a main grid, the first welding area 111 and the second welding area 112 are provided with main grids, the solder strips of the first welding area 111 are connected to the main grid of the first welding area 111, and the solder strips of the second welding area 112 are connected to the main grid of the second welding area 111. When the back-contact solar cell is a back-contact solar cell without a main grid, the first welding area 111 and the second welding area 112 are not provided with main grids, the solder strips of the first welding area 111 are directly connected to the first sub-grid 2, and the solder strips of the second welding area 112 are directly connected to the second sub-grid 3.

[0053] As an embodiment of the present invention, the ratio of the area of ​​the insulating layer 4 to the total area of ​​the back surface 11 is 40% to 50%.

[0054] In this embodiment, the ratio of the area of ​​the insulating layer 4 to the total area of ​​the back surface 11 is further controlled to be 40%~50%, so that the area ratio of the insulating layer 4 on the back surface 11 is more appropriate. This allows the insulating layer 4 to better reflect a suitable proportion of the long-wavelength sunlight emitted from the back surface 11 of the silicon wafer 1 back into the silicon wafer 1, ensuring the good optical effect of the insulating layer 4 and ensuring the low production cost of the insulating layer 4.

[0055] As an embodiment of the present invention, the insulating layer 4 includes organic resin and titanium dioxide, wherein the mass fraction of titanium dioxide is 20% to 60%.

[0056] In this embodiment, the insulating layer 4 comprises an organic resin and titanium dioxide, with the titanium dioxide accounting for 20% to 60% of the total weight of the insulating layer 4. Specifically, the organic resin can be epoxy resin, and the titanium dioxide is titanium dioxide. Controlling the mass fraction of titanium dioxide to 20% to 60% ensures that the insulating layer 4 is white and that its average reflectivity for light with wavelengths in the range of 800nm ​​to 1200nm is 50% to 95%. Furthermore, it ensures good insulation performance of the insulating layer 4.

[0057] As an embodiment of the present invention, the thickness of the insulating layer 4 is 10 micrometers to 100 micrometers.

[0058] In this embodiment, the thickness of the insulating layer 4 is controlled to be 10 micrometers to 100 micrometers, which can ensure that the insulating layer 4 has good reflectivity for light with wavelengths in the range of 800nm ​​to 1200nm and good insulation performance.

[0059] For example, the thickness of the insulating layer 4 can be any value among 10 micrometers, 15 micrometers, 18 micrometers, 20 micrometers, 22 micrometers, 28 micrometers, 30 micrometers, 33 micrometers, 37 micrometers, 40 micrometers, 42 micrometers, 46 micrometers, 50 micrometers, 55 micrometers, 60 micrometers, 65 micrometers, 70 micrometers, 72 micrometers, 78 micrometers, 80 micrometers, 81 micrometers, 84 micrometers, 88 micrometers, 90 micrometers, 92 micrometers, 96 micrometers, and 100 micrometers.

[0060] As an embodiment of the present invention, the thickness of the insulating layer 4 is 35 micrometers to 45 micrometers.

[0061] In this embodiment, the thickness of the insulating layer 4 is further controlled to be 35 micrometers to 45 micrometers, which further ensures the good reflectivity of the insulating layer 4 for light with wavelengths in the range of 800nm ​​to 1200nm, and also ensures the good insulation effect of the insulating layer 4, avoiding leakage.

[0062] Please refer to this again. Figures 1-2 As one embodiment of the present invention, it further includes:

[0063] A first pad 5 is provided in the first welding area 111. The first pad 5 is electrically connected to the first sub-gate 2. A first gap 6 is provided between the insulating layer 4 and the first pad 5.

[0064] In this embodiment, the first pad 5 is used for soldering with the solder strip in the first soldering area 111. The first gap 6 can specifically be a groove formed between the insulating layer 4 and the first pad 5.

[0065] In this embodiment, a first gap 6 is provided between the insulating layer 4 and the first pad 5. The first gap 6 is used to physically isolate the insulating layer 4 and the first pad 5. The first gap 6 is a buffer space reserved for the flow of the slurry of the insulating layer 4 during the battery lamination process, preventing the slurry of the insulating layer 4 from flowing onto the first pad 5 and affecting the welding performance of the first pad 5 and the solder ribbon. Due to the setting of the first gap 6, the slurry of the insulating layer 4 only flows into the first gap 6 and does not flow onto the first pad 5, thus preventing poor welding of the first pad 5 and the solder ribbon and improving the welding performance of the first pad 5 and the solder ribbon.

[0066] As an embodiment of the present invention, the width W1 of the first gap 6 is 5 micrometers to 150 micrometers.

[0067] In this embodiment, the width W1 of the first gap 6 is the dimension of the first gap 6 along the first direction X. By controlling the width of the first gap 6 to be 5 micrometers to 150 micrometers, it can effectively prevent the paste of the insulating layer 4 from flowing above the first pad 5, and allow the insulating layer 4 to better cover the part of the second sub-gate 3 near the first soldering area 111.

[0068] Please refer to this again. Figure 1 and Figure 3 As one embodiment of the present invention, it further includes:

[0069] The second pad 7 is located in the second welding area 112. The second pad 7 is electrically connected to the second sub-gate 3. A second gap 8 is provided between the insulating layer 4 and the second pad 7.

[0070] In this embodiment, the second pad 7 is used for soldering with the solder strip in the second soldering area 112. The second gap 8 can specifically be a groove formed between the insulating layer 4 and the second pad 7.

[0071] In this embodiment, a second gap 8 is provided between the insulating layer 4 and the second pad 7. The second gap 8 is used to physically isolate the insulating layer 4 and the second pad 7. The second gap 8 is a buffer space reserved for the flow of the slurry of the insulating layer 4 during the battery lamination process, preventing the slurry of the insulating layer 4 from flowing onto the second pad 7 and affecting the welding performance of the second pad 7 and the solder ribbon. Due to the setting of the second gap 8, the slurry of the insulating layer 4 can only flow into the second gap 8 and will not flow onto the second pad 7, thus preventing poor welding of the second pad 7 and the solder ribbon and improving the welding performance of the second pad 7 and the solder ribbon.

[0072] As an embodiment of the present invention, the width W2 of the second gap 8 is 5 micrometers to 150 micrometers.

[0073] In this embodiment, the width W2 of the second gap 8 is the dimension of the second gap 8 along the first direction X. By controlling the width of the second gap 8 to be 5~150 micrometers, it can effectively prevent the paste of the insulating layer 4 from flowing to the top of the second pad 7, and allow the insulating layer 4 to effectively cover the part of the first sub-gate 2 near the second soldering area 112.

[0074] Please refer to Figure 1 and Figure 4 As an embodiment of the present invention, the insulating layer 4 includes a first insulating portion 41 covering the first sub-gate 2 and a second insulating portion 42 covering the second sub-gate 3, wherein the first insulating portion 41 and the second insulating portion 42 are spaced apart or connected to each other.

[0075] In this embodiment, a first insulating portion 41 is disposed on the first sub-gate 2, and a second insulating portion 42 is disposed on the second sub-gate 3. The first insulating portion 41 and the second insulating portion 42 can be spaced apart or connected to each other. The first insulating portion 41 covers the portion of the first sub-gate 2 near the second welding area 112 to prevent the first sub-gate 2 from making contact with the solder strip on the second welding area 112. The second insulating portion 42 covers the portion of the second sub-gate 3 near the first welding area 111 to prevent the second sub-gate 3 from making contact with the solder strip on the first welding area 111.

[0076] As an embodiment of the present invention, the projections of the first insulating portion 41 and the second insulating portion 42 in the second direction Y overlap.

[0077] In this embodiment, the projections of the first insulating portion 41 and the second insulating portion 42 on the second direction Y overlap, that is, there is an overlapping area between the projections of the first insulating portion 41 and the second insulating portion 42 on the second direction Y, which can further improve the isolation effect between the first sub-gate 2 and the second sub-gate 3 and reduce the short circuit risk between the first sub-gate 2 and the second sub-gate 3.

[0078] As an embodiment of the present invention, the distance between adjacent first welding area 111 and second welding area 112 is L, and the length of the overlapping area of ​​the projection of the first insulating part 41 and the second insulating part 42 in the second direction Y along the first direction X is D, where 0.5L≤D≤0.8L.

[0079] In this embodiment, the length D of the overlapping area of ​​the projections of the first insulating part 41 and the second insulating part 42 in the second direction Y along the first direction X satisfies 0.5L≤D≤0.8L. This ensures a good isolation effect between the first sub-gate 2 and the second sub-gate 3, and avoids the area of ​​the insulating layer 4 being too large, which helps to reduce costs.

[0080] As an embodiment of the present invention, the widths of the first insulating portion 41 and the second insulating portion 42 near the edge of the silicon wafer 1 decrease sequentially from the center of the silicon wafer 1 toward the edge of the silicon wafer 1.

[0081] In this embodiment, since the widths of the first insulating portion 41 and the second insulating portion 42 near the edge of the silicon wafer 1 decrease sequentially from the center of the silicon wafer 1 to the edge of the silicon wafer 1, the width of the insulating layer 4 is smaller at the edge of the silicon wafer 1. This ensures the insulation performance of the insulating layer 4 while reducing material loss of the insulating layer 4 and reducing the risk of cell warping. The first insulating portion 41 and the second insulating portion 42 can narrow in a stepped manner or in a diamond shape at the edge of the silicon wafer 1.

[0082] Please refer to Figure 1 and Figure 5 As an embodiment of the present invention, the first welding area 111 is provided with a first solder joint 9, and the insulating layer 4 further includes a first blocking part 43 covering the first sub-gate 2. The first blocking part 43 is located outside the first welding area 111 and is adjacent to the first solder joint 9.

[0083] In this embodiment, the first solder joint 9 is used for soldering solder strips, and the specific number of the first solder joint 9 is not limited. The insulating layer 4 includes a first blocking portion 43 covering the first sub-gate 2. The first blocking portion 43 can block the solder paste of the first solder joint 9 in the first soldering area 111 from flowing to the second sub-gate 3, so as to prevent the solder paste of the first solder joint 9 from flowing to the first sub-gate 2 when the insulating layer 4 does not cover the second sub-gate 3 well. This further improves the insulation reliability between the first sub-gate 2 and the second sub-gate 3, especially to prevent the solder paste of the first solder joint 9 from flowing to the first sub-gate 2 during the lamination process, which would cause a short circuit between the first sub-gate 2 and the second sub-gate 3.

[0084] As an embodiment of the present invention, the first blocking part 43 connects two adjacent second insulating parts 42, and the first blocking part 43 and the two adjacent second insulating parts 42 form a first receiving groove 410.

[0085] In this embodiment, due to the arrangement of the first receiving groove 410, the first receiving groove 410 can play the role of collecting solder paste. Even when the solder paste of the first solder joint 9 flows, the solder paste of the first solder joint 9 will only flow into the first receiving groove 410 and will not flow to the top of the adjacent second sub-gate 3. Thus, it prevents short circuit between the first sub-gate 2 and the second sub-gate 3 and improves the insulation reliability between the first sub-gate 2 and the second sub-gate 3.

[0086] In some possible embodiments, the surface of the first insulating portion 41 near the first welding area 111 and the first receiving groove 410 is configured in an arc shape.

[0087] In this embodiment, the surface of the first insulating part 41 near the first soldering area 111 and the first receiving groove 410 is arranged in an arc shape. The arc shape can better guide the solder paste of the first solder joint 9 into the first receiving groove 410, further improving the insulation reliability between the first sub-gate 2 and the second sub-gate 3.

[0088] As an embodiment of the present invention, the distance d1 from the first blocking part 43 to the first welding area 111 along the first direction X is 600 micrometers to 700 micrometers.

[0089] In this embodiment, controlling the distance d1 from the first blocking part 43 to the first soldering area 111 to be 600 micrometers to 700 micrometers can effectively prevent the solder paste of the first solder joint 9 from flowing to the adjacent second sub-gate 3, thus ensuring the reliability of the insulation between the first sub-gate 2 and the second sub-gate 3.

[0090] As an embodiment of the present invention, the width d2 of the first blocking portion 43 along the first direction X is 100 micrometers to 200 micrometers.

[0091] In this embodiment, the width d2 of the first blocking part 43 along the first direction X is controlled to be 100 micrometers to 200 micrometers, which can better prevent the solder paste of the first solder joint 9 from flowing to the adjacent second sub-gate 3, and further ensure the insulation reliability between the first sub-gate 2 and the second sub-gate 3.

[0092] Please refer to Figure 1 and Figure 6 As an embodiment of the present invention, the second welding area 112 is provided with a second solder joint 10, and the insulating layer 4 further includes a second blocking part 44 covering the second sub-gate 3. The second blocking part 44 is located outside the second welding area 112 and is disposed adjacent to the second solder joint 10.

[0093] In this embodiment, the insulating layer 4 includes a second blocking portion 44 covering the second sub-gate 3. The second blocking portion 44 can block the solder paste of the second solder joint 10 of the second soldering area 112 from flowing to the first sub-gate 2, thus preventing the solder paste of the second solder joint 10 from flowing to the first sub-gate 2 when the insulating layer 4 does not cover the first sub-gate 2 properly, and further improving the insulation reliability between the first sub-gate 2 and the second sub-gate 3.

[0094] As an embodiment of the present invention, the second blocking part 44 connects two adjacent first insulating parts 41, and the second blocking part 44 and the two adjacent first insulating parts 41 form a second receiving groove 420.

[0095] In this embodiment, due to the provision of the second receiving tank 420, the second receiving tank 420 can collect solder paste. Even when the solder paste of the second solder joint 10 flows, the solder paste of the second solder joint 10 flows into the second receiving tank 420 and does not flow to the top of the adjacent first sub-gate 2, thus preventing short circuit between the first sub-gate 2 and the second sub-gate 3 and improving the insulation reliability between the first sub-gate 2 and the second sub-gate 3.

[0096] As an embodiment of the present invention, the distance d3 from the second blocking part 44 to the second soldering area 112 is 600 micrometers to 700 micrometers, which can better prevent the solder paste of the second solder joint 10 from flowing to the adjacent first sub-gate 2, and ensure the insulation reliability between the first sub-gate 2 and the second sub-gate 3.

[0097] As an embodiment of the present invention, the width d4 of the second blocking portion 44 along the first direction X is 100 micrometers to 200 micrometers, which can better prevent the solder paste of the second solder joint 10 from flowing to the adjacent first sub-gate 2, and further ensure the insulation reliability between the first sub-gate 2 and the second sub-gate 3.

[0098] Please refer to this again. Figure 1 As an embodiment of the present invention, the insulating layer 4 includes at least one marking portion 45, which is located on the first sub-gate 2 and / or the second sub-gate 3, or the marking portion 45 is located in the area where the first sub-gate 2 and the second sub-gate 3 are not disposed.

[0099] In this embodiment, the specific number of marking portions 45 is not limited; it can be one, two, or more. The placement of the marking portions 45 is also not limited; for example, they can be placed diagonally or in the middle of the solar cell. The specific shape of the marking portions 45 is not limited; for example, they can be cross-shaped or circular. For example, there can be 2 to 4 marking portions 45, each placed diagonally on the solar cell. The marking portions 45 assist in the identification and positioning of the solar cells during the battery assembly manufacturing process. Since the marking portions 45 have an average reflectivity of 50% to 95% for light in the wavelength range of 800nm ​​to 1200nm, they can also reflect long-wavelength sunlight emitted from the back surface 11 of the silicon wafer 1 back into the silicon wafer 1, improving sunlight utilization. Therefore, in addition to their marking function, the marking portions 45 of the insulating layer 4 also achieve good optical effects, which is beneficial for improving battery efficiency.

[0100] This invention also provides a battery assembly including the back-contact solar cell described in the above embodiments. It should be noted that this battery assembly has the same or similar beneficial effects as the back-contact solar cell, and the related aspects between the two can be referred to each other; to avoid repetition, they will not be repeated here.

[0101] In this embodiment, multiple back-contact solar cells in the battery module can be connected in series to form a battery string, thereby achieving series current output. For example, the battery cells can be connected in series by setting solder strips (busbars, interconnecting strips), conductive backplates, etc.

[0102] It is understood that in such embodiments, the battery assembly may further include a metal frame, a backsheet, photovoltaic glass, and an encapsulating film. The encapsulating film may be filled between the front and back surfaces of the back-contact solar cells, the photovoltaic glass, adjacent cells, etc. As a filler, it may be a transparent colloid with good light transmittance and aging resistance. For example, the encapsulating film may be an EVA film or a POE film, and the specific choice can be made according to the actual situation, without limitation.

[0103] Photovoltaic glass can be applied to the encapsulating film on the front side of the back-contact solar cell. This photovoltaic glass can be ultra-clear glass, possessing 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 back-contact solar cell while minimizing impact on its efficiency. Simultaneously, the encapsulating film bonds the photovoltaic glass and the back-contact solar cell together, providing sealing, insulation, and waterproofing / moisture protection for the back-contact solar cell.

[0104] The backsheet can be attached to the adhesive film on the back side of the back-contact solar cell. The backsheet protects and supports the back-contact solar cell, providing 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, back-contact solar cell, 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.

[0105] This invention also provides a photovoltaic system, which includes the battery module described in the above embodiments. It should be noted that this photovoltaic system has the same or similar beneficial effects as the back-contact solar cell described above, and the related aspects between the two can be referred to each other; to avoid repetition, they will not be repeated here.

[0106] In this embodiment, the photovoltaic system can be applied in photovoltaic power plants, such as ground-mounted power plants, rooftop power plants, and floating power plants. It can also be applied to 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 is understood that the application scenarios of the photovoltaic system are not limited to these; that is, the photovoltaic system can be applied in all fields that require solar energy to generate electricity. Taking a photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a combiner box, and an inverter. The photovoltaic array may be an array combination of multiple battery modules; for example, multiple battery modules can form multiple photovoltaic arrays. The photovoltaic array is connected to the combiner box, which can collect the current generated by the photovoltaic array. The collected current flows through the inverter and is converted into AC power required by the mains power grid before being connected to the mains power grid to achieve solar power supply.

[0107] In the description of this specification, references to terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0108] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A back-contact solar cell, characterized in that, include: A silicon wafer, the back side of which includes a first welding area and a second welding area alternately spaced along a first direction; A first sub-gate and a second sub-gate are disposed on the back side, the first sub-gate and the second sub-gate are alternately spaced along a second direction, the first direction intersects the second direction, the first sub-gate extends to the first welding area, and the second sub-gate extends to the second welding area; and An insulating layer is provided on the back side, the insulating layer at least covers the portion of the first sub-gate near the second soldering area, and the insulating layer at least covers the portion of the second sub-gate near the first soldering area, the insulating layer has an average reflectivity of 50% to 95% for light in the wavelength range of 800nm ​​to 1200nm, and the area of ​​the insulating layer is 40% to 60% of the total area of ​​the back side.

2. The back-contact solar cell according to claim 1, characterized in that, The ratio of the area of ​​the insulating layer to the total area of ​​the back surface is 40% to 50%.

3. The back-contact solar cell according to claim 1, characterized in that, The thickness of the insulating layer is 10 micrometers to 100 micrometers.

4. The back-contact solar cell according to claim 1, characterized in that, The insulating layer comprises organic resin and titanium dioxide, wherein the mass fraction of titanium dioxide is 20% to 60%.

5. The back-contact solar cell according to claim 1, characterized in that, Also includes: A first pad is provided in the first welding area, the first pad is electrically connected to the first sub-gate, and a first gap is provided between the insulating layer and the first pad.

6. The back-contact solar cell according to claim 5, characterized in that, Also includes: A second pad is provided in the second welding area, the second pad is electrically connected to the second sub-gate, and a second gap is provided between the insulating layer and the second pad.

7. The back-contact solar cell according to claim 6, characterized in that, The width of the first gap is 5 micrometers to 150 micrometers; and / or, the width of the second gap is 5 micrometers to 150 micrometers.

8. The back-contact solar cell according to claim 1, characterized in that, The insulating layer includes a first insulating portion covering the first sub-gate and a second insulating portion covering the second sub-gate, wherein the first insulating portion and the second insulating portion are spaced apart or connected to each other.

9. The back-contact solar cell according to claim 8, characterized in that, The projections of the first insulating portion and the second insulating portion in the second direction overlap.

10. The back-contact solar cell according to claim 9, characterized in that, The distance between adjacent first welding area and second welding area is L, and the length of the overlapping area of ​​the projection of the first insulating part and the second insulating part in the second direction along the first direction is D, where 0.5L≤D≤0.8L.

11. The back-contact solar cell according to claim 8, characterized in that, The widths of the first insulating portion and the second insulating portion near the edge of the silicon wafer decrease sequentially from the center of the silicon wafer toward the edge of the silicon wafer.

12. The back-contact solar cell according to claim 8, characterized in that, The first welding area is provided with a first solder joint, and the insulating layer further includes a first blocking portion covering the first sub-gate. The first blocking portion is located outside the first welding area and is adjacent to the first solder joint.

13. The back-contact solar cell according to claim 12, characterized in that, The first blocking part connects to two adjacent second insulating parts, and the first blocking part and the two adjacent second insulating parts form a first receiving groove.

14. The back-contact solar cell according to claim 12, characterized in that, The distance from the first blocking portion to the first welding area along the first direction is 600 micrometers to 700 micrometers.

15. The back-contact solar cell according to claim 12, characterized in that, The width of the first blocking portion along the first direction is 100 micrometers to 200 micrometers.

16. The back-contact solar cell according to claim 8 or 12, characterized in that, The second welding area is provided with a second solder joint, and the insulating layer further includes a second blocking portion covering the second sub-gate. The second blocking portion is located outside the second welding area and is adjacent to the second solder joint.

17. The back-contact solar cell according to claim 16, characterized in that, The second blocking part connects to two adjacent first insulating parts, and the second blocking part and the two adjacent first insulating parts form a second receiving groove.

18. The back-contact solar cell according to claim 1, characterized in that, The insulating layer includes at least one marking portion, which is located on the first sub-gate and / or the second sub-gate, or the marking portion is located in a region not where the first sub-gate and the second sub-gate are disposed.

19. A battery assembly, characterized in that, Including the back-contact solar cell as described in any one of claims 1 to 18.

20. A photovoltaic system, characterized in that, Includes the battery assembly as described in claim 19.

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