Solar cell manufacturing method, solar cell, stacked cell, and photovoltaic module

Abstract

The application relates to a solar cell preparation method, a solar cell, a laminated cell and a photovoltaic module. The preparation method comprises the following steps: providing a substrate to be processed; identifying a grid line structure on the surface of the substrate; dividing the grid line structure into a plurality of independent processing areas; dividing the grid line structure into an edge area, a transition area and a center area; configuring different laser process parameters for each processing area, the laser process parameters comprising a reverse bias value and a laser power value, and in the radial direction from the edge area to the center area, the laser power value and the reverse bias value both show a decreasing trend; and performing laser processing on each processing area based on the configured laser process parameters. The grid line structure on the surface of the substrate is divided into different processing areas, and different laser process parameters are configured for each processing area, which effectively compensates for the unevenness of the substrate itself, reduces the occurrence rate of EL cloud-like defects in the edge area of the substrate, improves the conversion efficiency of the cell piece, and improves the yield and production efficiency.

Description

Technical Field

[0001] This application relates to the field of solar cell manufacturing technology, and in particular to solar cell preparation methods, solar cells, tandem cells, and photovoltaic modules. Background Technology

[0002] With the development of photovoltaic cell manufacturing technology, laser-enhanced contact optimization (LECO) technology has emerged, which optimizes the contact characteristics of the grid structure on the surface of the substrate through laser action, thereby improving the performance of the cell.

[0003] In related technologies, laser processing graphic design typically employs a design approach where the graphic is the overall structure. For example, in actual mass production, laser processing parameters are uniformly set and processed based on the overall graphic.

[0004] However, due to the inherent non-uniformity of the substrate, the edge region of the grid structure on the surface of the substrate is prone to cloud-like phenomena at the EL edge when using the integrated laser processing pattern design with uniform parameter distribution. This seriously affects the product yield and production efficiency. Summary of the Invention

[0005] Therefore, it is necessary to provide a solar cell fabrication method, a solar cell, a tandem cell, and a photovoltaic module to address the problems caused by the overall patterning of existing laser processing, which results in EL cloud-like phenomena at the edges of the grid structure on the substrate surface and affects product yield.

[0006] A method for preparing a solar cell, comprising:

[0007] Provide the substrate to be processed;

[0008] Identify the grid line structure on the surface of the substrate;

[0009] The grid structure is divided into multiple independent processing areas;

[0010] Different laser process parameters are configured for each processing area, including reverse bias voltage and laser power value;

[0011] Based on the configured laser process parameters, laser treatment is performed on each processing area;

[0012] The step of dividing the grid structure into multiple independent processing areas includes: dividing the grid structure into an edge area, a transition area, and a center area;

[0013] The step of configuring different laser process parameters for each processing area further includes: in the radial direction from the edge area to the center area, both the laser power value and the reverse bias value show a decreasing trend.

[0014] In one embodiment, the central region is the central region of the grid structure; the transition region is the region surrounding the central region; and the edge region is the region between the transition region and the edge of the substrate.

[0015] In one embodiment, the width of the central region is greater than the width of the transition region and the width of the edge region, respectively.

[0016] In one embodiment, the laser power value configured in the edge region is greater than the laser power value configured in the transition region, and the laser power value configured in the transition region is greater than the laser power value configured in the center region;

[0017] The reverse bias value configured in the edge region is greater than the reverse bias value configured in the transition region, and the reverse bias value configured in the transition region is greater than the reverse bias value configured in the center region.

[0018] In one embodiment, the reverse bias voltage ranges from 3V to 50V; the laser power ranges from 5W to 80W.

[0019] In one embodiment, the reverse bias voltage of the edge region is 40V-50V; the laser power of the edge region is 60W-80W.

[0020] In one embodiment, the reverse bias voltage of the transition region is 20V-40V; the laser power of the transition region is 30W-60W.

[0021] In one embodiment, the reverse bias voltage of the central region is 3V-20V; the laser power of the central region is 5W-30W.

[0022] In one embodiment, prior to the step of dividing the grid structure into multiple independent processing areas, the method includes: detecting and locating abnormal areas where EL fog occurs using EL imaging, and classifying the abnormal areas into edge regions.

[0023] In one embodiment, the width of the edge region is 20mm-30mm.

[0024] In one embodiment, the grid structure includes main grids, the number of which is 3 to 20, and the width of the main grids is 10μm-30μm.

[0025] The above-described solar cell fabrication method divides the grid structure on the surface of the substrate into different processing areas and configures differentiated laser process parameters according to different processing areas. This effectively compensates for the non-uniformity of the substrate's own characteristics, reduces the occurrence rate of EL cloud-like defects in its edge areas, improves the conversion efficiency of the solar cells, and thus improves the product yield and production efficiency.

[0026] According to another object of the present invention, a solar cell is also provided, which is manufactured using the solar cell fabrication method described above; the solar cell includes a substrate, wherein the difference between the maximum and minimum values ​​of the contact resistivity of the grid structure on the surface of the substrate in a radial direction from the edge of the substrate to the center of the substrate is less than or equal to 20%.

[0027] The aforementioned solar cells, through differentiated laser processing in different regions, effectively eliminate cloud-like defects at the edges of the cells, reduce the contact resistance between the grid structure and the substrate, effectively improve yield and electrical performance, and enhance the conversion efficiency of the solar cells.

[0028] According to another objective of the present invention, a stacked battery is also provided, comprising a top battery and a bottom battery, wherein the bottom battery is a solar cell as described above.

[0029] The aforementioned tandem solar cell, by using a solar cell that has undergone differentiated laser treatment in different regions as the bottom cell and combining it with the top cell, effectively solves the problem of cloud-like defects caused by the uneven characteristics of the bottom cell itself, and improves its conversion efficiency.

[0030] According to another objective of the present invention, a photovoltaic module is also provided, comprising a solar cell as described above or a tandem cell as described above, wherein multiple solar cells or multiple tandem cells are connected to form a cell string; the photovoltaic module further comprises an encapsulation layer covering the surface of the cell string and a cover plate disposed outside the encapsulation layer.

[0031] The aforementioned photovoltaic module is made of solar cells or tandem cells that have undergone differentiated laser treatment in different regions. Compared with traditional cells that have undergone integrated laser treatment, the photovoltaic module has superior optical performance, higher output power, and greater stability. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the process for fabricating solar cells.

[0033] Figure 2 This is a schematic diagram of the grid line structure distribution.

[0034] In the diagram: 10, substrate; 20, grid structure; 30, edge region; 40, transition region; 50, center region. Detailed Implementation

[0035] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0036] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application 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 application.

[0037] Furthermore, where the terms "first" and "second" appear, these terms are 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 with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0038] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; 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, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0039] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0040] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0041] In the manufacturing of photovoltaic cells, laser-enhanced contact optimization (LECO) technology is used to laser process the grid structure on the surface of the cell substrate to optimize the contact characteristics of the grid structure and improve cell performance.

[0042] Currently, the laser processing patterns used in related technologies are typically designed as a single entity, meaning that during mass production, laser processing parameters are uniformly set and processed based on the overall pattern. However, due to the inherent inhomogeneity of the substrate material, the use of a single pattern design and uniform parameter distribution can lead to a cloud-like abnormality at the edge of the EL (electroluminescence) cell due to differences in its own properties. This defect severely affects the yield and production efficiency of the battery.

[0043] One embodiment of this application provides a method for fabricating solar cells, which is applicable to improving the cloud-like problem at the EL edge caused by uneven substrate characteristics in the Laser Enhanced Contact Optimization (LECO) process, thereby improving cell yield and production efficiency.

[0044] like Figure 1 As shown, Figure 1 This is a schematic flowchart of a solar cell fabrication method according to an embodiment of this application. The solar cell fabrication method includes the following steps:

[0045] Step S1: Provide the substrate 10 to be processed;

[0046] Step S2: Identify the grid line structure 20 on the surface of the substrate 10;

[0047] Step S3: Divide the grid structure 20 into multiple independent processing areas;

[0048] Step S4: Configure different laser process parameters for each processing area. The laser process parameters include reverse bias voltage and laser power value.

[0049] Step S5: Perform laser processing on each processing area based on the configured laser process parameters.

[0050] In step S1, a silicon wafer substrate 10 to be processed is provided. The front or back side of the silicon wafer substrate 10 has undergone passivation, coating, and electrode printing and sintering treatment. The substrate 10 is a P-type or N-type single-crystal silicon wafer; wherein, when the substrate 10 is P-type, its doping element is at least one of boron, gallium, and indium; when the substrate 10 is N-type, its doping element is at least one of phosphorus, arsenic, antimony, and bismuth. A gate structure 20 composed of conductive paste has been formed on the surface of the substrate 10, wherein the conductive paste includes silver powder, glass powder, and organic carrier, etc.

[0051] In step S2, an optical inspection device is used to scan the surface of the substrate 10 to identify the grating structure 20 on the surface of the substrate 10. The optical inspection device includes a high-resolution CCD camera, which captures high-definition images of the grating structure 20 on the surface of the substrate 10 to identify the distribution location and shape of all grating lines, so as to divide the grating structure 20 into regions.

[0052] In step S3, based on the grid line distribution identified in step S2, the entire grid line structure 20 is divided into multiple independent processing areas. This division can be based on the grid line position; for example, grid lines located in the middle of the substrate 10 are designated as the central processing area, and grid lines within a certain distance of the edge of the substrate 10 are designated as edge processing areas. Alternatively, it can be based on the predicted cloud-like characteristics of the EL edge; for example, based on historical inspection data, areas prone to cloud-like defects are designated as independent processing areas.

[0053] In step S4, differentiated laser process parameters are configured for the different processing areas defined in step S3. The laser process parameters include at least the reverse bias voltage and the laser power value. The laser power value refers to the power actually applied to the grid structure 20 on the surface of the substrate 10.

[0054] For the edge region of the grid structure 20, due to its high sheet resistance and poor slurry contact, EL cloud-like defects are prone to occur. Therefore, a set of laser process parameters is configured for the edge region of the grid structure 20. This set of laser process parameters includes a relatively high reverse bias value and a relatively high laser power value. The laser power value in this region is higher than the standard power value of conventional processing. By using a higher reverse bias value and laser power value for the edge region, stronger laser energy and electric field effects are obtained to optimize the ohmic contact in the edge region and reduce the incidence of cloud-like defects.

[0055] For the central region of the gate structure 20, due to its relatively uniform and stable characteristics, a separate set of laser process parameters is configured. This set of laser process parameters includes a relatively low reverse bias voltage and a relatively low laser power value. By using a lower reverse bias voltage and laser power value in the central region, ohmic contact optimization is ensured while avoiding microcracks or performance degradation caused by over-processing.

[0056] In step S5, laser processing is performed on each processing area based on the laser process parameters configured in step S4. The laser processing equipment includes a nanosecond pulse laser, which is used to perform laser processing in zones according to the laser process parameters configured for each processing area.

[0057] Furthermore, the laser beam of the nanosecond pulsed laser is controlled to sequentially scan and irradiate the edge and center regions, automatically switching process parameters such as reverse bias voltage and laser power value when scanning different regions. Alternatively, the laser beam of the nanosecond pulsed laser is controlled to perform laser processing in a sequential order from the center region to the edge region.

[0058] As shown above, compared to traditional laser processing patterning with uniform parameters, this embodiment divides the grid structure 20 on the surface of the substrate 10 into different processing areas and configures different laser process parameters according to different processing areas. This effectively compensates for the non-uniformity of the substrate 10's own characteristics, reduces the occurrence rate of EL cloud-like defects in its edge areas, improves the conversion efficiency of the solar cells, and thus improves the product yield and production efficiency.

[0059] like Figure 2 As shown, Figure 2 This is a schematic diagram showing the distribution of the gate wire structure 20 in one embodiment of this application. In one embodiment, step S3, which divides the gate wire structure 20 into multiple independent processing areas, includes the following steps:

[0060] Step S31: Divide the grid structure 20 into an edge region 30, a transition region 40 and a central region 50; the central region 50 is the central area of ​​the grid structure 20; the transition region 40 is the area surrounding the central region 50; the edge region 30 is the area between the transition region 40 and the edge of the substrate 10.

[0061] When dividing the processing area, a partitioned processing method of edge area 30, transition area 40 and center area 50 is adopted to achieve gradient compensation of the surface characteristics of substrate 10, so as to optimize the effect of laser processing.

[0062] First, a solar cell with a grid structure 20 is provided, the solar cell comprising an N-type or P-type monocrystalline silicon substrate 10. The grid structure 20 is formed on the surface of the substrate 10 by a conductive paste through a printing and sintering process.

[0063] Secondly, images of the grating structure 20 are captured using optical detection equipment to identify the shape and position distribution of the grating structure 20.

[0064] Then, based on the overall outline of the identified grid structure 20, it is divided into three independent processing areas. The processing areas include a central area 50, a transition area 40, and an edge area 30. The processing area is the central area of ​​the grid structure 20; the transition area 40 is the area surrounding the central area 50; and the edge area 30 is the area between the outer edge of the transition area 40 and the edge of the substrate 10.

[0065] In this embodiment, the shape of the substrate 10 can be square or rectangular, etc. The grid structure 20 is formed on the surface of the substrate 10, and its distribution area is adapted to the shape of the substrate 10.

[0066] like Figure 2 As shown, Figure 2 This is a schematic diagram showing the distribution of the grid structure 20 in one embodiment of this application. In one embodiment, the base 10 is square. The central region 50 is located in the middle of the base 10 and is a region with a side length of L1 and an area of ​​L1. 2 A square area.

[0067] The transition zone 40 is a frame-shaped area surrounding the central zone 50. The inner boundary of the transition zone 40 coincides with the boundary of the central zone 50, the outer boundary of the transition zone 40 is L2 from the center of the base 10, and the radial width of the transition zone 40 is L2.

[0068] Edge region 30 is the area between the outer boundary of transition region 40 and the edge of base 10, and the radial width of edge region 30 is L3. The total width of base 10 is L0, where the total width of base 10 L0 is equal to the width of center region 50 L1 plus twice the radial width of transition region 40 L2 plus twice the radial width of edge region 30 L3.

[0069] The aforementioned geometrically based division method, combined with the inherent characteristics of the substrate 10, such as the actual distribution gradient of sheet resistance and doping concentration, helps to form a transition zone. This avoids the impact of abrupt changes in laser parameters at the boundaries of different regions on the cell performance, ensuring the uniformity and stability of the cell performance. Compared to traditional laser processing methods with uniform regions and parameters, this effectively solves the problem of cloud-like defects caused by substrate 10 inhomogeneities. Furthermore, the consistency of the division standard allows for the repeated execution of differentiated laser processing methods targeting substrate 10 inhomogeneities.

[0070] In one embodiment, the width of the central region 50 is greater than the widths of the transition region 40 and the edge region 30, respectively.

[0071] Based on the geometry of the substrate 10, the central region 50 is divided with a width greater than that of the transition region 40 and the edge region 30. Since the characteristics of the edge region of the substrate 10 are non-uniform, it is prone to cloud-like defects, while the characteristics of the central region of the substrate 10 are more uniform and stable. Therefore, dividing the central region 50 into the largest area aligns with the characteristics of the substrate 10, ensuring the laser processing effect while improving processing efficiency. Compared to processing methods that divide the area into uniform regions or regions of equal width, this approach effectively improves the yield of the solar cells.

[0072] In this embodiment, the total width L0 of the base 10 is 183 mm. The central region 50 is located in the center of the base 10 and is a square area. The side length of the central region 50, that is, the radial width L1 of the central region 50, is 63 mm.

[0073] The inner boundary of the transition zone 40 coincides with the boundary of the central zone 50, and the distance between the outer boundary of the transition zone 40 and the boundary of the central zone 50 is 30 mm, that is, the radial width L2 of the transition zone 40 is 30 mm. The inner boundary of the edge zone 30 coincides with the outer boundary of the transition zone 40, and the distance between the inner boundary of the edge zone 30 and the edge of the base 10 is 30 mm, that is, the radial width L3 of the edge zone 30 is 30 mm.

[0074] The radial widths of the aforementioned central region 50, transition region 40, and edge region 30 can be adaptively adjusted according to the width of the base 10.

[0075] In one embodiment, the width L3 of the edge region 30 is 20mm-30mm.

[0076] The edge region 30 is an annular area extending inward from the edge of the substrate 10. This region exhibits significant changes in sheet resistance and is prone to cloud-like defects. Further, the width L3 of the edge region 30 is 20mm-30mm. In this embodiment, the width L3 of the edge region 30 is one of 20mm, 21mm, 22mm, 23mm, 24mm, 25mm, 26mm, 27mm, 28mm, 29mm, or 30mm, and the width L3 of the edge region 30 can be adaptively adjusted according to the width of the substrate 10.

[0077] In one embodiment, step S4, which configures different laser process parameters for each processing area, further includes the following steps:

[0078] Step S41: In the radial direction from the edge region 30 to the center region 50, both the laser power value and the reverse bias voltage value show a decreasing trend.

[0079] In this embodiment, the edge region 30 is prone to cloud-like defects. Therefore, the edge region 30 is configured with a fixed laser power value and a fixed reverse bias voltage value. The laser power value and reverse bias voltage value configured in the edge region 30 are the maximum. That is, the laser power value configured in the edge region 30 is greater than the laser power value configured in the transition region 40, and the reverse bias voltage value configured in the edge region 30 is greater than the reverse bias voltage value configured in the transition region 40.

[0080] The transition region 40 is configured with a fixed laser power value and a fixed reverse bias value. The laser power value configured in the transition region 40 is greater than the laser power value configured in the central region 50, and the reverse bias value configured in the transition region 40 is less than the reverse bias value configured in the central region 50.

[0081] The substrate 10 in the central region 50 has relatively uniform characteristics, and the laser power and reverse bias values ​​configured in the central region 50 are the smallest.

[0082] The laser power and reverse bias values ​​remain constant within each region, but undergo a step change at the boundary between different regions, resulting in a step-like decrease.

[0083] In one embodiment, the reverse bias voltage ranges from 3V to 50V; the laser power ranges from 5W to 80W.

[0084] Each processing area is configured with different reverse bias voltage and laser power values. The reverse bias voltage ranges from 3V to 50V. Furthermore, the reverse bias voltage value is one of 3V, 5V, 10V, 15V, 20V, 25V, 30V, 35V, 40V, 45V, or 50V, and can be adjusted to suit different processing areas.

[0085] Furthermore, the laser power value ranges from 5W to 80W. The laser power value is one of 5W, 10W, 20W, 30W, 40W, 50W, 60W, 70W, or 80W, and the laser power value can be adjusted to suit different processing areas.

[0086] In one embodiment, the reverse bias voltage of the edge region 30 is 40V-50V; the laser power of the edge region 30 is 60W-80W. The reverse bias voltage of the transition region 40 is 20V-40V; the laser power of the transition region 40 is 30W-60W. The reverse bias voltage of the center region 50 is 3V-20V; the laser power of the center region 50 is 5W-30W.

[0087] First, a solar cell with a grid structure 20 is provided, the solar cell comprising an N-type or P-type monocrystalline silicon substrate 10. The grid structure 20 is formed on the surface of the substrate 10 by a conductive paste through a printing and sintering process. The grid structure 20 on the substrate 10 is laser-processed to optimize the grid contact and reduce the occurrence of edge cloud-like defects.

[0088] Secondly, based on the distribution of the identified grid lines and the characteristics of the substrate 10 itself, three processing areas are divided: edge area 30, transition area 40, and center area 50.

[0089] Then, due to the non-uniform characteristics of the substrate 10 corresponding to the edge region 30, cloud-like defects are prone to occur. Therefore, the reverse bias voltage value configured for the edge region 30 is 40V-50V. Further, the reverse bias voltage value configured for the edge region 30 is one of 40V, 41V, 42V, 43V, 44V, 45V, 46V, 47V, 48V, 49V, or 50V. The reverse bias voltage value configured for the edge region 30 can be adaptively adjusted according to the characteristics of the substrate 10.

[0090] The laser power value configured in the edge region 30 is 60W-80W. More specifically, the laser power value configured in the edge region 30 is one of 60W, 62W, 64W, 66W, 68W, 70W, 72W, 74W, 76W, 78W, or 80W. The laser power value configured in the edge region 30 can be adaptively adjusted according to the characteristics of the substrate 10.

[0091] Because the substrate 10 corresponding to the central region 50 has relatively uniform characteristics, the reverse bias voltage configured for the central region 50 is 3V-20V. Further, the reverse bias voltage configured for the central region 50 can be one of 3V, 5V, 8V, 10V, 13V, 15V, 18V, or 20V. The reverse bias voltage configured for the central region 50 can be adaptively adjusted according to the characteristics of the substrate 10.

[0092] The laser power configured in the central region 50 is 5W-30W. More specifically, the laser power configured in the central region 50 can be one of 5W, 10W, 15W, 20W, 25W, or 30W. The laser power configured in the central region 50 can be adaptively adjusted according to the characteristics of the substrate 10.

[0093] Since the transition region 40 is located between the edge region 30 and the center region 50, the reverse bias voltage configured for the transition region 40 is 20V-40V. Further, the reverse bias voltage configured for the transition region 40 can be one of 20V, 22V, 24V, 26V, 30V, 32V, 34V, 36V, 28V, or 40V. The reverse bias voltage configured for the transition region 40 can be adaptively adjusted according to the characteristics of the substrate 10.

[0094] The laser power value configured in the transition region 40 is 30W-60W. More specifically, the laser power value configured in the transition region 40 is one of 30W, 35W, 40W, 45W, 50W, 55W, or 60W. The laser power value configured in the transition region 40 can be adaptively adjusted according to the characteristics of the substrate 10.

[0095] Finally, based on the laser process parameters configured above, laser treatment is performed on each processing area.

[0096] The reverse bias voltage or laser power values ​​for each of the aforementioned processing areas exhibit a gradient pattern, which effectively improves the yield of solar cells compared to traditional laser processing using fixed values. Furthermore, these gradient laser process parameters are applicable to substrates 10 or grid structures 20 of different sizes, thus enhancing their applicability.

[0097] In one embodiment, prior to step S4 of dividing the gate structure 20 into multiple independent processing regions, the following steps are included:

[0098] S40. Locate the abnormal area where EL fog occurs through EL imaging detection, and classify the abnormal area into the edge area 30.

[0099] Before dividing the processing areas, an EL imaging inspection is first performed on the substrate 10. First, the substrate 10 is placed in an EL inspection device, and a certain amount of forward bias current is injected into it in a dark room environment. An infrared camera sensitive to the emission wavelength of the silicon wafer is used to acquire the emitted infrared image. Next, the acquired EL image is processed and analyzed to identify areas with cloud-like features, i.e., abnormal areas where EL clouding occurs, and these are classified into the edge region 30. The edge region 30 is then laser-scanned using a higher reverse bias voltage and laser power value to eliminate the influence of cloud-like defects.

[0100] In one embodiment, the gate structure 20 includes a main gate, the number of which is 3 to 20, and the width of the main gate is 10μm-30μm.

[0101] The grid structure 20 includes multiple main grids for collecting and transmitting current and fine grids for collecting photogenerated carriers. The number of main grids ranges from 3 to 20. Specifically, the number of main grids can be one of 3, 5, 8, 10, 12, 15, 18, or 20. The number of main grids can be adjusted adaptively according to the battery layout design.

[0102] The width of the main gate is 10μm-30μm. Specifically, the main gate width can be one of the following: 10μm, 12μm, 14μm, 16μm, 18μm, 20μm, 22μm, 24μm, 26μm, 28μm, or 30μm. The main gate width can be adjusted to suit the printing process.

[0103] In one embodiment, a solar cell is also provided, which is manufactured using the solar cell manufacturing method described above.

[0104] The solar cell includes a silicon wafer substrate 10 and a grid structure 20 formed on the surface of the substrate 10. The grid structure 20 includes multiple main grids for collecting and transporting current and fine grids for collecting photogenerated carriers.

[0105] The main grid can have a harpoon section to increase the contact area with the fine grid and improve the current collection capability.

[0106] The grid structure 20 of the solar cell undergoes the aforementioned regional laser processing. The laser processing area is the interface region where the fine grid and / or main grid of the grid structure 20 contacts the substrate 10. When the fine grid is being processed, the laser energy is used to optimize the ohmic contact between the fine grid and the emitter of the substrate 10, improving current collection efficiency and reducing series resistance. When the main grid is also being processed, the laser energy can similarly optimize the contact characteristics between the main grid and the substrate 10 or between the main grid and the fine grid, ensuring that current can efficiently flow from the fine grid to the main grid.

[0107] Partitioned laser processing specifically includes the following steps:

[0108] First, the grid structure 20 is divided into multiple independent processing areas, including the edge area 30, the transition area 40, and the center area 50.

[0109] Secondly, different laser process parameters are configured for each processing area, including reverse bias voltage and laser power value, and both reverse bias voltage and laser power value show a decreasing trend in the radial direction from the edge area 30 to the center area 50.

[0110] Finally, based on the configured laser process parameters, laser treatment is performed on each processing area.

[0111] After regional laser processing, the aforementioned solar cells show no obvious edge-clouding defects in EL imaging, and their conversion efficiency is effectively improved compared to the traditional method of processing a uniform area. Simultaneously, it effectively reduces the contact resistance between the grid lines and the substrate 10, improving the fill factor and energy conversion efficiency.

[0112] The grid structure 20 on the surface of substrate 10 has a maximum and minimum difference of contact resistivity of less than or equal to 20% in the radial direction from the edge of substrate 10 to the center of substrate 10. This makes the contact resistivity of the solar cell uniformly distributed in the radial direction from the edge of substrate 10 to its center. Compared with the uneven distribution of contact resistivity and high contact resistance in the edge area of ​​traditional solar cells, the overall contact resistance of the solar cell after the above-mentioned regional laser treatment is reduced, effectively improving the fill factor and energy conversion efficiency.

[0113] The contact resistivity between the gate structure 20 and the substrate 10 is measured using a transmission line model (TLM). First, at least one test point is selected on each of the edge region 30, transition region 40, and central region 50 defined by the gate structure 20. A standard transmission line model (TLM) test pattern is fabricated near the test point using laser ablation or photolithography. This test pattern includes a long, thin gate line with a length greater than its width, and contact pads parallel to the gate line with the same width but different spacing.

[0114] Next, using a probe station and semiconductor parameter analyzer, the total resistance between two contact pads in TLM test patterns with different spacings was measured. The measured total resistance value was then linearly fitted to the corresponding contact pad spacing. The total resistance is equal to twice the single-sided contact resistance plus the ratio of the sheet resistance (sheet resistance) of the substrate 10 to the gate line width, multiplied by the spacing. From the linear fitting of the measurement data, the slope of the straight line represents the ratio of the sheet resistance to the gate line width, and the intercept on the vertical axis represents twice the single-sided contact resistance. Therefore, the contact resistivity is equal to the square of the single-sided contact resistance divided by the ratio of the sheet resistance to the square of the gate line width. The percentage difference in contact resistivity is equal to the maximum contact resistivity minus the minimum contact resistivity, divided by the minimum, and then multiplied by 100%.

[0115] As shown above, compared with solar cells prepared by traditional integral laser processing patterning, this solar cell effectively eliminates cloud-like defects at the edge of the cell and improves the yield by regional differentiated laser processing; at the same time, it reduces the contact resistance, making the difference in contact resistivity between the substrate 10 and the grid structure 20 smaller and the contact resistance more uniform, effectively improving the conversion efficiency and electrical performance of the solar cell.

[0116] In one embodiment, a tandem battery is also provided, including a top battery and a bottom battery, wherein the bottom battery is a solar cell as described above.

[0117] Stacked solar cells are double-junction or multi-junction solar cells, consisting of a top cell and a bottom cell. The top cell is a perovskite solar cell used to absorb high-energy photons, and includes a perovskite light-absorbing layer, an electron transport layer, a hole transport layer, and corresponding electrode structures.

[0118] The bottom cell is used to absorb low-energy photons. The bottom cell is any one of an HJT cell, TOPCon cell, PREC cell, or BC cell fabricated using the aforementioned solar cell fabrication method. The bottom cell includes a silicon wafer substrate 10 and grid electrodes formed on its surface, which have undergone partitioned laser-enhanced contact optimization treatment.

[0119] When the base cell is an HJT cell, it includes a silicon substrate 10, an intrinsic amorphous silicon layer, a doped amorphous silicon layer, a transparent conductive oxide (TCO) layer, and a gate electrode.

[0120] When the base cell is a TOPCon cell, it includes a silicon substrate 10, a tunneling oxide layer, a doped polysilicon layer, a passivation layer, and a gate electrode.

[0121] When the bottom cell is a PERC cell, it includes a silicon substrate 10, a front surface passivation layer and an anti-reflection layer, a partial back contact structure, a back surface passivation layer, and a gate electrode.

[0122] The top and bottom cells are combined through mechanical stacking or integration. In mechanical stacking, the top and bottom cells are bonded together with optical adhesive. In integration, the top cell is deposited on the bottom cell and connected via a tunnel junction.

[0123] The aforementioned tandem solar cell, by using a solar cell that has undergone differentiated laser treatment in different regions as the bottom cell and combining it with the top cell, effectively solves the problem of cloud-like defects caused by the uneven characteristics of the bottom cell itself, and improves its conversion efficiency.

[0124] In one embodiment, a photovoltaic module is also provided, including the solar cells or the stacked cells as described above, wherein multiple solar cells or multiple stacked cells are connected to form a battery string; the photovoltaic module also includes an encapsulation layer covering the surface of the battery string and a cover plate disposed outside the encapsulation layer.

[0125] A photovoltaic module consists of multiple interconnected solar cells or tandem cells. Multiple solar cells or multiple photovoltaic cells are connected in series by interconnecting strips to form multiple cell strings.

[0126] An encapsulation layer covers the front or back of the battery string. The encapsulation layer is made of ethylene-vinyl acetate copolymer (EVA) film, polyolefin (PO) film, or other transparent encapsulation films. The encapsulation layer is melted and laminated to form a single unit from multiple battery strings, a cover plate, and a backplate. The cover plate, made of tempered glass, is placed on the outside of the front encapsulation layer of the battery string. The backplate, with a multi-layered composite structure such as TPT or TPE, is placed on the outside of the back encapsulation layer of the battery string.

[0127] The frame covers the edge of the laminate and is made of aluminum alloy. The junction box is mounted on the outside of the back panel and connects to the output terminal of the battery string via leads.

[0128] The aforementioned photovoltaic module is made of solar cells or tandem cells that have undergone differentiated laser treatment in different regions. Compared with traditional cells that have undergone integrated laser treatment, the photovoltaic module has superior optical performance, higher output power, and greater stability.

[0129] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. The above embodiments only illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent application. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for preparing a solar cell, characterized in that, include: Provide the substrate to be processed; Identify the grid line structure on the surface of the substrate; The grid structure is divided into multiple independent processing areas; Different laser process parameters are configured for each processing area, including reverse bias voltage and laser power value; Based on the configured laser process parameters, laser treatment is performed on each processing area; The step of dividing the grid structure into multiple independent processing areas includes: dividing the grid structure into an edge area, a transition area, and a center area; The step of configuring different laser process parameters for each processing area further includes: in the radial direction from the edge area to the center area, both the laser power value and the reverse bias value show a decreasing trend.

2. The method for preparing a solar cell according to claim 1, characterized in that, The central region is the central area of ​​the grid structure; the transition region is the area surrounding the central region; and the edge region is the area between the transition region and the edge of the substrate.

3. The method for preparing a solar cell according to claim 2, characterized in that, The width of the central region is greater than the width of the transition region and the width of the edge region, respectively.

4. The method for preparing a solar cell according to claim 1, characterized in that, The laser power value configured in the edge region is greater than the laser power value configured in the transition region, and the laser power value configured in the transition region is greater than the laser power value configured in the center region. The reverse bias value configured in the edge region is greater than the reverse bias value configured in the transition region, and the reverse bias value configured in the transition region is greater than the reverse bias value configured in the center region.

5. The method for preparing a solar cell according to claim 4, characterized in that, The reverse bias voltage ranges from 3V to 50V; the laser power ranges from 5W to 80W.

6. The method for preparing a solar cell according to claim 5, characterized in that, The reverse bias voltage of the edge region is 40V-50V; the laser power of the edge region is 60W-80W.

7. The method for preparing a solar cell according to claim 5, characterized in that, The reverse bias voltage of the transition region is 20V-40V; the laser power of the transition region is 30W-60W.

8. The method for preparing a solar cell according to claim 5, characterized in that, The reverse bias voltage of the central region is 3V-20V; the laser power of the central region is 5W-30W.

9. The method for preparing a solar cell according to claim 1, characterized in that, Before the step of dividing the grid structure into multiple independent processing areas, the method includes: detecting and locating abnormal areas where EL fog occurs through EL imaging, and classifying the abnormal areas into edge areas.

10. The method for preparing a solar cell according to claim 9, characterized in that, The width of the edge area is 20mm-30mm.

11. The method for preparing a solar cell according to claim 1, characterized in that, The grid structure includes main grids, the number of which is 3 to 20, and the width of the main grids is 10μm-30μm.

12. A solar cell, characterized in that, The solar cell is manufactured using the solar cell fabrication method according to any one of claims 1-11; the solar cell includes a substrate, wherein the difference between the maximum and minimum values ​​of the contact resistivity between the grid structure on the surface of the substrate and the substrate in a radial direction from the edge of the substrate to the center of the substrate is less than or equal to 20%.

13. A stacked battery, comprising a top battery and a bottom battery, characterized in that, The bottom cell is the solar cell according to claim 12.

14. A photovoltaic module, characterized in that, The photovoltaic module includes the solar cell as described in claim 12 or the tandem cell as described in claim 13, wherein multiple solar cells or multiple tandem cells are connected to form a cell string; the photovoltaic module further includes an encapsulation layer covering the surface of the cell string and a cover plate disposed outside the encapsulation layer.

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