A back contact photovoltaic module and a method of manufacturing the same

Abstract

The application discloses a back contact photovoltaic module and a preparation method thereof. The method comprises the following steps: providing a cell piece and a solder strip; the cell piece is provided with a main grid; the solder strip is stretched, and tin paste is sprayed on one side surface of the solder strip; the tin paste sprayed on the solder strip is pre-solidified to connect the tin paste and the solder strip; one side of the solder strip, on which the tin paste is sprayed, is attached to the main grid of the cell piece and heated to remove the tin paste, so that the main grid of the cell piece and the solder strip are fixedly connected to form a cell string; and the cell string is encapsulated and laminated to form the back contact photovoltaic module. By pre-solidifying the solder strip with the tin paste, the tin paste is preliminarily solidified, the initial temperature difference between the solder strip and the cell piece is reduced, the welding stress is reduced, the probability of hidden cracks in welding is greatly reduced, and the performance of the photovoltaic module is ensured.

Description

Technical Field

[0001] This invention relates to the technical field of back-contact photovoltaic modules, and more particularly to a back-contact photovoltaic module and its preparation method. Background Technology

[0002] Solar cells have good photoelectric conversion capabilities, therefore, solar cells are a key focus of clean energy development. Fully back-contact solar cells, because both the positive and negative metal electrodes are located on the back of the cell and there is no grid line obstruction on the front of the cell, can eliminate the light-shielding current loss of the metal electrodes and maximize the utilization of incident photons, thus showing good prospects. Therefore, photovoltaic modules constructed using fully back-contact solar cells have good application prospects.

[0003] The conventional soldering process for photovoltaic modules using fully back-contact solar cells involves first printing and curing insulating adhesive on the back of the cell, then printing and curing solder paste on the back of the cell, and finally soldering the cell to the photovoltaic solder ribbon to form a cell string. However, in this approach, the solder paste needs to be pre-cured to prevent contamination from subsequent mechanical structures. Contaminated solder paste can easily fall onto other cells, causing short circuits and defects. Furthermore, direct soldering of the cell to the solder ribbon can lead to stress release in the solder ribbon, potentially causing microcracks in the cell. Summary of the Invention

[0004] This invention provides a back-contact photovoltaic module and its preparation method. By pre-curing the solder ribbon coated with solder paste, the solder paste is initially cured, reducing the initial temperature difference between the solder ribbon and the solar cell, thereby reducing welding stress and significantly reducing the probability of welding microcracks, ensuring the performance of the photovoltaic module. At the same time, spraying solder paste on the solder ribbon can reduce the amount of solder paste used, reduce material costs, and eliminate the risk of solder paste contamination on the surface of the solar cell, thereby reducing the risk of welding short circuits.

[0005] In a first aspect, the present invention provides a method for preparing a back-contact photovoltaic module, comprising:

[0006] Provides solar cells and solder strips; the solar cells are equipped with main grids.

[0007] Stretch the solder strip while simultaneously spraying solder paste onto one side of the solder strip surface;

[0008] Pre-curing is performed on the solder paste sprayed onto the solder strip to ensure the solder paste and solder strip bond.

[0009] The side of the solder ribbon coated with solder paste is attached to the main grid of the solar cell and heated to remove the solder paste, thereby fixing the main grid of the solar cell and the solder ribbon together to form a solar cell string;

[0010] The battery strings are encapsulated and laminated to form a back-contact photovoltaic module.

[0011] Optionally, the solder strip is stretched, and solder paste is sprayed onto one side of the solder strip surface during stretching, including:

[0012] Place the solder ribbon directly below the solder paste sprayer, and spray solder paste onto one side of the solder ribbon surface through the solder paste sprayer while the solder ribbon is being stretched.

[0013] Optionally, the solder paste spraying machine includes an integrally connected spraying pipeline and spraying pinholes. The side of the spraying pinhole closest to the spraying pipeline is the first small hole, and the side of the spraying pinhole furthest from the spraying pipeline is the second small hole. The diameter of the first small hole is smaller than the diameter of the second small hole.

[0014] Optionally, the diameter of the first small hole is d1, and the diameter of the second small hole is d2, where 0.05mm≤d1≤0.07mm and 0.06mm≤d2≤0.08mm.

[0015] Optionally, the solder ribbons coated with solder paste may be pre-cured, including:

[0016] Using an infrared lamp, the solder ribbon coated with solder paste is placed on a preheating platform below the infrared lamp to pre-cure the solder paste and solder ribbon.

[0017] Optionally, the side of the solder ribbon coated with solder paste is attached to the main busbar of the solar cell and heated to remove the solder paste, including:

[0018] Place the side of the solder ribbon without solder paste on the soldering heating platform, and place the main grid side of the cell on top of the solder paste. Heat the solder paste under preset heating conditions to remove it.

[0019] Optionally, before heating the solder paste, the following steps are also included:

[0020] Using a thermal imager to detect the temperature of the welding heating platform;

[0021] The controller receives the temperature and determines the temperature change of the welding heating platform based on the temperature.

[0022] When the temperature change is outside the preset range, adjust the output power of the welding heating platform to keep the welding heating platform within the preset temperature change range.

[0023] Optionally, the preset heating conditions include a heating temperature of 180℃-260℃, a heating time of 1s-5s, and a preset variation range that satisfies: -5℃≤dT≤5℃, where dT is the preset variation.

[0024] Optionally, after placing the side of the solder ribbon without solder paste on the soldering heating platform, the method further includes:

[0025] The position of the weld strip is corrected using a welding correction device;

[0026] The welding strip is adsorbed by a vacuum adsorption device to fix it on the welding heating platform.

[0027] Optionally, the welding heating platform includes multiple parallel through holes, with the welding strip located directly above each through hole. The vacuum adsorption device includes an adsorption structure located on the side of the through holes away from the welding strip, used to adsorb and fix the welding strip through the through holes.

[0028] Secondly, the present invention provides a back-contact photovoltaic module, which is prepared by the above-described back-contact photovoltaic module preparation method.

[0029] The technical solution of this invention involves providing a solar cell and a solder ribbon; a main grid is disposed on the solar cell; the solder ribbon is stretched, and solder paste is sprayed onto one side of the solder ribbon; the solder paste sprayed on the solder ribbon is pre-cured to connect the solder paste and the solder ribbon; the side of the solder ribbon with solder paste sprayed on it is attached to the main grid of the solar cell and heated to remove the solder paste, thereby fixing the main grid of the solar cell and the solder ribbon together to form a solar cell string; the solar cell string is encapsulated and laminated to form a back-contact photovoltaic module. Using the above method, by pre-curing the solder ribbon with solder paste sprayed on it, the solder paste is initially cured, reducing the initial temperature difference between the solder ribbon and the solar cell, thereby reducing welding stress and significantly reducing the probability of welding microcracks, ensuring the performance of the photovoltaic module. Simultaneously, spraying solder paste onto the solder ribbon reduces the amount of solder paste used, lowers material costs, and eliminates the risk of solder paste contamination on the surface of the solar cell, thereby reducing the risk of welding short circuits.

[0030] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a flowchart of a method for preparing a back-contact photovoltaic module according to an embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of a welding strip structure provided in an embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of the structure after solder paste is sprayed onto the solder strip according to an embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of the structure after the battery cell and the solder strip are connected, according to an embodiment of the present invention;

[0036] Figure 5 A flowchart illustrating another method for preparing a back-contact photovoltaic cell module provided in an embodiment of the present invention. Detailed Implementation

[0037] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0038] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0039] In one embodiment, Figure 1 This is a flowchart illustrating a method for fabricating a back-contact photovoltaic module according to an embodiment of the present invention. Figure 2 This is a schematic diagram of a solder strip structure provided in an embodiment of the present invention. Figure 3 This is a schematic diagram of the structure after solder paste is sprayed onto the solder strip according to an embodiment of the present invention. Figure 4 This is a schematic diagram of the structure after the battery cell and solder ribbon are connected according to an embodiment of the present invention. This embodiment can be applied to situations where solder paste contamination on the battery cell can cause short circuits and to reduce soldering stress, thereby reducing the probability of soldering microcracks. Figures 1 to 4 As shown, the method includes:

[0040] S110 provides battery cells and solder strips.

[0041] A solar cell is a semiconductor device whose core function is to directly convert sunlight into electrical energy using the photovoltaic effect. The solar cell is the smallest unit that makes up a solar panel (photovoltaic module). The material of a solar cell can include, but is not limited to, silicon. A main grid is installed on the solar cell; the main grid is a wide, silver conductive line on the surface of the solar cell, which serves as the main channel for collecting current. Solder ribbon is a special flat metal strip (usually tin-plated copper strip) used to connect the solar cells. The structure of the solder ribbon can be found in [reference needed]. Figure 2 .

[0042] S120. Stretch the solder strip and spray solder paste onto one side of the solder strip surface.

[0043] Solder paste, also known as soldering paste, is a gray, viscous mixture widely used in the electronics assembly industry. Solder paste is not pure tin, but a composite material made from a precise ratio of various ingredients. The most common component of solder paste is an alloy of tin and silver-copper, which serves as a temporary binder and a medium for permanent conductive connections.

[0044] For details, please refer to Figure 3 The solder strip is stretched, and the stretching method can include, but is not limited to, using the clamps on the soldering machine to hold both ends of the solder strip for stretching. During the solder strip stretching process, solder paste is sprayed onto one side of the solder strip surface to ensure that the solder paste is evenly sprayed onto the solder strip. In this embodiment, the method of solder paste spraying, whether continuous or intermittent spraying, and the width of the solder paste spraying, can be determined according to the actual situation and are not limited here. It should be noted that this embodiment uses a spraying process for the solder paste, which can reduce the amount of solder paste used, thereby reducing the cost of solder paste materials and improving the controllability of solder paste spraying.

[0045] It should also be noted that in this embodiment, solder paste is sprayed onto the surface of the solder strip. In actual applications, in addition to solder paste, other conductive colloids, such as conductive adhesives, can also be sprayed. The specific method can be determined according to the actual situation and is not limited here.

[0046] S130. Pre-curing the solder paste sprayed on the solder strip to bond the solder paste and the solder strip.

[0047] Specifically, after spraying solder paste onto one side of the solder strip, the solder strip with the solder paste sprayed on is pre-cured. The pre-curing method may include, but is not limited to, heating, so that the cured solder paste and the solder strip can be connected.

[0048] S140. The side of the solder ribbon coated with solder paste is attached to the main grid of the battery cell and heated to remove the solder paste, so that the main grid of the battery cell and the solder ribbon are fixedly connected to form a battery string.

[0049] For details, please refer to Figure 4After the solder paste and solder ribbon are pre-cured, the solder ribbon needs to be placed on the main grid of the solar cell. In this embodiment, the side of the solder ribbon without solder paste is first placed on the welding heating platform, and the side of the solder paste facing away from the solder ribbon is left untouched. The main grid of the solar cell is then placed on the solder paste, with the main grid facing the solder paste surface. The solder paste is heated until a preset temperature is reached, at which point heating is stopped. The solder paste melts, and the melted solder paste is used to fix and weld the main grid of the solar cell and the solder ribbon. Multiple solar cells can be connected together using the solder ribbon in this way to form multiple long solar cell strings.

[0050] S150. The battery string is encapsulated and laminated to form a back-contact photovoltaic module.

[0051] Specifically, multiple prepared battery strings are precisely and neatly arranged on photovoltaic glass that has already been covered with a lower layer of photovoltaic EVA film, according to the designed circuit layout (usually in parallel or a series-parallel combination). EVA (ethylene-vinyl acetate copolymer) film is a thermosetting adhesive film that melts and flows upon heating, and solidifies upon cooling, firmly bonding the layers together while providing excellent light transmittance and insulation. At this stage, a short section of solder strip is left at both ends of each battery string; this extended solder strip is the protruding copper strip. Next, the photovoltaic busbar is cut. The photovoltaic busbar is a wider, more conductive copper strip (or flat cable), equivalent to the "main power line" of the entire module. According to the circuit design, the photovoltaic busbar is cut to a suitable length and shape. The various branches of the photovoltaic busbar are then connected to the extended solder strips of each battery string by welding. For example, if parallel connection is required, the positive electrode strips of all battery strings are soldered to the positive branch of the photovoltaic busbar, and all negative electrode strips are soldered to the negative branch; if series connection is required, more complex wiring is needed, connecting the negative electrode of the previous battery string to the positive electrode of the next battery string through the photovoltaic busbar, thereby collecting the current of the dispersed battery strings and outputting it uniformly through the photovoltaic busbar.

[0052] After the photovoltaic busbars are welded, a top layer of EVA film is laid. On top of this EVA film, a photovoltaic backsheet or a second photovoltaic glass panel is laid. The backsheet is typically a white TPT / PET composite material, providing insulation, waterproofing, and light reflection. The second photovoltaic glass panel is a double-glass module. Once fabricated, the laminated structure consisting of photovoltaic glass, EVA film, battery string, photovoltaic busbar, EVA film, and backsheet is fed into a photovoltaic laminator. The laminator removes air by vacuuming and then holds the laminate at high temperature (approximately 140℃-150℃) and pressure for a period of time, allowing the EVA film to completely melt, filling all gaps and tightly and firmly bonding the photovoltaic glass, battery string, photovoltaic busbar, and backsheet into a single unit. This process eliminates air bubbles, ensures light transmission and insulation, and forms a robust, sealed, and waterproof "sandwich" that protects the internal, fragile battery cells and solder joints from moisture, dust, and mechanical stress.

[0053] Finally, aluminum alloy frames and welding junction boxes are installed on the laminated structure to complete the fabrication of the photovoltaic modules. The welding junction box is a plastic box installed on the back of the module (usually in a corner of the frame) to enhance mechanical strength and provide electrical connection points, leading the photovoltaic busbars inside the photovoltaic module to external cables.

[0054] The technical solution of this invention involves providing a solar cell and a solder ribbon; a main grid is disposed on the solar cell; the solder ribbon is stretched, and solder paste is sprayed onto one side of the solder ribbon; the solder paste sprayed on the solder ribbon is pre-cured to connect the solder paste and the solder ribbon; the side of the solder ribbon with solder paste sprayed on it is attached to the main grid of the solar cell and heated to remove the solder paste, thereby fixing the main grid of the solar cell and the solder ribbon together to form a solar cell string; the solar cell string is encapsulated and laminated to form a back-contact photovoltaic module. Using the above method, by pre-curing the solder ribbon with solder paste sprayed on it, the solder paste is initially cured, reducing the initial temperature difference between the solder ribbon and the solar cell, thereby reducing welding stress and significantly reducing the probability of welding microcracks, ensuring the performance of the photovoltaic module. Simultaneously, spraying solder paste onto the solder ribbon reduces the amount of solder paste used, lowers material costs, and eliminates the risk of solder paste contamination on the surface of the solar cell, thereby reducing the risk of welding short circuits.

[0055] In another specific embodiment, optionally, Figure 5 This is a flowchart of another method for preparing a back-contact photovoltaic cell module according to an embodiment of the present invention. This embodiment refines the specific implementation of S120 in the above embodiment, which involves stretching the solder strip and spraying solder paste onto one side of the solder strip during stretching, as follows:

[0056] Place the solder ribbon directly below the solder paste sprayer, and spray solder paste onto one side of the solder ribbon surface through the solder paste sprayer while the solder ribbon is being stretched.

[0057] Furthermore, the specific implementation method of S130, which pre-cures the solder ribbons coated with solder paste, is refined as follows:

[0058] Using an infrared lamp, the solder ribbon coated with solder paste is placed on a preheating platform below the infrared lamp to pre-cure the solder paste and solder ribbon.

[0059] Furthermore, the specific implementation method of removing the solder paste by heating the side of the solder ribbon coated with solder paste and attaching it to the main grid of the battery cell in S140 is detailed as follows:

[0060] Place the side of the solder ribbon without solder paste on the soldering heating platform, and place the main grid side of the cell on top of the solder paste. Heat the solder paste under preset heating conditions to remove it.

[0061] For details not covered in this embodiment, please refer to the above embodiments, which will not be repeated here.

[0062] refer to Figure 5 As shown, the method includes:

[0063] S210 provides battery cells and solder strips.

[0064] S220. Place the solder ribbon directly below the solder paste spraying machine, and spray solder paste onto one side of the solder ribbon surface through the solder paste spraying machine while the solder ribbon is being stretched.

[0065] Optionally, the solder paste spraying machine includes an integrally connected spraying pipeline and spraying pinholes. The side of the spraying pinhole closest to the spraying pipeline is the first small hole, and the side of the spraying pinhole furthest from the spraying pipeline is the second small hole. The diameter of the first small hole is smaller than the diameter of the second small hole.

[0066] Optionally, the diameter of the first small hole is d1, and the diameter of the second small hole is d2, where 0.05mm≤d1≤0.07mm and 0.06mm≤d2≤0.08mm.

[0067] In this embodiment, solder paste can be applied using a solder paste spraying machine. By placing the solder ribbon directly below the solder paste spraying machine, and as the machine stretches the ribbon at an angle, the machine sprays solder paste onto one side of the ribbon. Since the solder paste is not solid, it will spread slightly on the ribbon. To prevent the solder paste from flowing outside the ribbon and creating edge solder paste, the machine should spray the solder paste onto the center of the ribbon as much as possible during the application process to reduce the risk of short circuits caused by edge solder paste.

[0068] It should be noted that the solder paste spraying machine includes an integrated spraying pipeline and spraying pins. Depending on different needs, different specifications of spraying pins can be used to achieve different amounts of solder paste sprayed. Different pin diameters result in different solder paste spraying volumes. In this embodiment, the side of the spraying pin closest to the spraying pipeline is the first small hole, and the side furthest from the spraying pipeline is the second small hole. The diameter of the first small hole is smaller than the diameter of the second small hole; that is, the spraying pin is funnel-shaped, i.e., a "smaller at the top, larger at the bottom" structure. Under these conditions, when spraying solder paste onto the center of the solder strip, the solder paste on the surface of the solder strip can have a trapezoidal cross-section that is "thicker in the middle and thinner at the edges." This prevents excessive solder paste at the edges of the solder strip, which could cause short circuits in subsequent battery cells due to edge solder paste, and also saves on solder paste usage.

[0069] Furthermore, the diameter of the first small hole is d1, where 0.05mm ≤ d1 ≤ 0.07mm. For example, the diameter of the first small hole can be 0.05mm, 0.055mm, 0.06mm, 0.065mm, or 0.07mm, and can be determined according to the actual situation; no limitation is imposed here. The diameter of the second small hole is d2, where 0.06mm ≤ d2 ≤ 0.08mm. For example, the diameter of the second small hole can be 0.06mm, 0.065mm, 0.07mm, 0.075mm, or 0.08mm, and can be determined according to the actual situation; no limitation is imposed here.

[0070] It should also be noted that solder paste spraying machines can control the spraying of solder paste on the solder ribbon using air pressure control, enabling continuous or intermittent spraying to regulate the spraying spacing and distance between solder paste particles. Specifically, a constant air pressure on the solder paste spraying machine allows for continuous spraying. When the air pressure drops to zero, the machine stops spraying and resumes spraying at the next solder ribbon position, achieving intermittent spraying. Furthermore, the amount of solder paste sprayed can be controlled by varying the traction speed of the solder ribbon. A higher traction speed results in less solder paste being sprayed at the same spraying speed, while a slower traction speed results in more solder paste being sprayed. Besides these methods, other techniques can also be used to control the amount of solder paste sprayed and the spacing between solder paste particles; specific settings can be implemented according to actual conditions and are not limited here.

[0071] S230. Using an infrared lamp, place the solder ribbon coated with solder paste on a preheating platform below the infrared lamp to pre-cur the solder paste and solder ribbon so that they can be connected.

[0072] Infrared lamps are tubular electrothermal devices designed and made of materials that allow them to radiate primarily invisible infrared radiation when powered on, enabling efficient and targeted heating of objects. Infrared radiation can pass directly through the air to the target object without physical contact. This is crucial in photovoltaic welding, preventing mechanical damage. A preheating platform is a device or workbench used to preheat workpieces (such as solder ribbons, solar cells, or PCB boards) uniformly before the main heating / welding process.

[0073] Specifically, after the solder paste is sprayed onto the solder ribbon, the ribbon is transferred to a preheating platform. Infrared lamps are positioned above the preheating platform. These lamps pre-cur the solder paste and ribbon within a preset heating time, achieving the connection between them. The preset heating time can be 1-30 seconds, and the infrared lamps can achieve a heating temperature range of 90℃-180℃. In practical applications, the relationship between heating temperature and heating time can be preset. After setting, the infrared lamps begin heating according to the required pre-curing temperature and automatically stop heating when the preset time corresponding to the preset temperature is reached, requiring no manual intervention and improving pre-curing efficiency and effectiveness. Alternatively, manual observation of the pre-curing process and monitoring of the heating time or temperature is possible. Once the preset pre-curing effect is confirmed manually, the infrared lamps are turned off to stop heating. The specific method can be determined based on actual conditions and is not limited here.

[0074] It should be noted that, in addition to the above-mentioned technical solution of first spraying solder paste onto the solder ribbon and then placing the solder paste and solder ribbon on a preheating platform for pre-curing the solder paste and solder ribbon, this embodiment can also first place the solder ribbon on a preheating platform, then use a solder paste spraying machine to spray solder paste onto the solder ribbon on the preset platform, and then pre-cur the solder paste and solder ribbon after spraying to achieve the connection between the solder paste and solder ribbon.

[0075] S240. Place the side of the solder ribbon without solder paste on the soldering heating platform, and place the main grid side of the cell on top of the solder paste. Under preset heating conditions, heat the solder paste to remove it, so that the main grid of the cell and the solder ribbon are fixedly connected to form a cell string.

[0076] Among them, the soldering heating platform is the equipment or workbench that realizes the heating of solder paste.

[0077] Specifically, after pre-curing the solder ribbon and solder paste, the battery cells and solder ribbon need to be connected. In this embodiment, the side of the solder ribbon without solder paste is placed on the soldering heating platform, and the main grid side of the battery cell is placed above the solder paste. At this time, the solder paste is between the solder ribbon and the main grid of the battery cell. By setting preset heating conditions for the soldering heating platform, including a heating temperature of 180℃-260℃ and a heating time of 1s-5s, the solder paste is heated and melted, thereby removing the solder paste. The melted solder paste can then fix the main grid of the battery cell and the solder ribbon in place. By connecting each main grid of the battery cell with solder ribbon, multiple battery strings are formed.

[0078] S250: Encapsulate and laminate the battery string to form a back-contact photovoltaic module.

[0079] The technical solution of this invention involves placing the solder ribbon directly below a solder paste spraying machine. While the solder ribbon is being stretched, solder paste is sprayed onto one side of the ribbon using the machine. Using an infrared lamp, the solder ribbon with the solder paste sprayed is placed on a preheating platform below the lamp for pre-curing of the solder paste and the ribbon. The side of the solder ribbon without solder paste is placed on a welding heating platform, and the main busbar side of the solar cell is placed above the solder paste. Under preset heating conditions, the solder paste is heated to remove it. This method achieves pre-curing of the solder paste and ribbon, as well as effective connection between the solder ribbon and the main busbar of the solar cell, preventing short circuits in the solar cell due to edge solder paste, saving solder paste usage, and improving module filling efficiency.

[0080] In another specific embodiment, optionally, before heating the solder paste in S240, the method further includes: detecting the temperature of the soldering heating platform using a thermal imager; receiving the temperature using a controller and determining the temperature change of the soldering heating platform based on the temperature; and adjusting the output power of the soldering heating platform when the temperature change is outside a preset range, so that the soldering heating platform is maintained within the preset temperature change range.

[0081] A thermal imager is an instrument that can detect infrared radiation (heat) from the surface of an object and convert it into a visual image. It does not "see" visible light, but rather the thermal signal emitted by the object. Different colors or grayscale values ​​in the image represent different temperatures.

[0082] Specifically, when placing the solar cell onto the solder paste, the solder paste needs to be heated. During the heating process, a thermal imager scans the connection area between the solder ribbon and the main busbar of the solar cell. The thermal imager generates a real-time temperature distribution map of this area, accurately measuring the temperature of the welding heating platform during the heating process, and sends this temperature to a controller electrically connected to the thermal imager. After receiving the temperature, the controller determines the temperature change based on the current temperature and the previously received temperature. When the temperature change is within a preset range, it indicates that the welding heating platform is operating normally. If the controller determines that the temperature change is outside the preset range, it indicates that the welding result under these heating conditions may have issues such as cold solder joints or poor contact. Therefore, the controller will activate temperature compensation, controlling the output power of the welding heating platform. By adjusting the output power, the heating temperature is varied to ensure that the heating temperature of the welding heating platform always remains within the preset temperature change range, thus ensuring welding reliability.

[0083] The preset variation range satisfies: -5℃ ≤ dT ≤ 5℃, where dT is the preset variation. In other words, the temperature difference between the two measurements must always be maintained within a variation range of ±5℃ to ensure welding reliability.

[0084] In another specific embodiment, optionally, after placing the side of the solder ribbon without solder paste on the soldering heating platform in S240, the method further includes: using a soldering correction device to correct the position of the solder ribbon; and using a vacuum adsorption device to adsorb the solder ribbon so that the solder ribbon is fixed on the soldering heating platform.

[0085] Optionally, the welding heating platform includes multiple parallel through holes, with the welding strip located directly above each through hole. The vacuum adsorption device includes an adsorption structure located on the side of the through holes away from the welding strip, used to adsorb and fix the welding strip through the through holes.

[0086] Among them, welding alignment devices refer to mechanical or automated mechanisms used to ensure precise alignment of welded components (such as weld strips and solar cell main grids). These can be standalone devices or part of a welding heating platform. Vacuum adsorption devices are devices that use vacuum negative pressure (pressure below atmospheric pressure) to firmly adsorb and fix objects. They typically include a vacuum pump, pipes, valves, and suction cups (or nozzles) with suction holes.

[0087] Specifically, after the welding strip is placed on the welding heating platform, its position can be corrected using a welding correction device. In this embodiment, the welding correction device includes multiple column structures arranged in two parallel rows. When setting the welding strip, it is positioned in the middle of the two rows of column structures and locked in place, preventing the welding strip from shifting left or right, thus achieving the correction of the welding strip's position. After correction, a vacuum adsorption device is used to adsorb and fix the welding strip on the welding heating platform, ensuring that the welding strip does not change position during the heating process of the welding strip and the battery cell, thereby improving welding efficiency and welding reliability.

[0088] It should be noted that the welding heating platform includes multiple parallel through holes arranged side by side, with the welding strip positioned directly above each through hole. The vacuum adsorption device includes an adsorption structure, which comprises a suction cup and other structural components with strong adsorption force. In this embodiment, the adsorption structure is located on the side of the through hole away from the welding strip. That is, the welding strip and the adsorption structure are located on opposite sides of the through hole, and the size of the adsorption structure is larger than the diameter of the through hole. Thus, the adsorption structure uses negative pressure to adsorb and non-destructively fix the welding strip, ensuring that its position does not change and providing a stable foundation for the subsequent welding process.

[0089] Based on the same inventive concept, the present invention provides a back-contact photovoltaic module, which is prepared by the above-described back-contact photovoltaic module preparation method and has the corresponding functional modules and beneficial effects of the method.

[0090] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0091] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method of fabricating a back contact photovoltaic module, characterized by, include: Provides battery cells and solder strips; The battery cell is provided with a main grid; The solder strip is stretched while solder paste is sprayed onto one side of the solder strip surface; The solder paste sprayed onto the solder strip is pre-cured to bond the solder paste to the solder strip; The side of the solder ribbon coated with solder paste is attached to the main grid of the battery cell and heated to remove the solder paste, thereby fixing the main grid of the battery cell and the solder ribbon together to form a battery string; The battery string is encapsulated and laminated to form the back-contact photovoltaic module.

2. The production method according to claim 1, characterized by, Stretching the solder strip and spraying solder paste onto one side of the solder strip during stretching includes: The solder ribbon is placed directly below the solder paste spraying machine, and the solder paste is sprayed onto one side of the solder ribbon by the solder paste spraying machine while the solder ribbon is stretched.

3. The preparation method according to claim 2, characterized in that, The solder paste spraying machine includes an integrally connected spraying pipeline and spraying needle holes. The side of the spraying needle hole closest to the spraying pipeline is a first small hole, and the side of the spraying needle hole furthest from the spraying pipeline is a second small hole. The diameter of the first small hole is smaller than the diameter of the second small hole.

4. The preparation method according to claim 3, characterized in that, The diameter of the first small hole is d1, and the diameter of the second small hole is d2, where 0.05mm≤d1≤0.07mm and 0.06mm≤d2≤0.08mm.

5. The preparation method according to claim 1, characterized in that, Pre-curing the solder ribbons coated with the solder paste includes: Using an infrared lamp, the solder ribbon coated with the solder paste is placed on a preheating platform below the infrared lamp to pre-cure the solder paste and the solder ribbon.

6. The preparation method according to claim 1, characterized in that, The solder paste is sprayed onto the side of the solder ribbon and attached to the main grid of the battery cell, then heated to remove the solder paste, including: The side of the solder ribbon not coated with solder paste is placed on the soldering heating platform, and the main grid side of the battery cell is placed above the solder paste. Under preset heating conditions, the solder paste is heated to remove it.

7. The preparation method according to claim 6, characterized in that, Before heating the solder paste, the method further includes: The temperature of the welding heating platform was detected using a thermal imager. The controller receives the temperature and determines the temperature change of the welding heating platform based on the temperature. When the temperature change is outside the preset range, the output power of the welding heating platform is adjusted so that the welding heating platform is maintained within the preset temperature change range.

8. The preparation method according to claim 7, characterized in that, The preset heating conditions include a heating temperature of 180℃-260℃ and a heating time of 1s-5s. The preset variation range satisfies: -5℃≤dT≤5℃, where dT is the preset variation.

9. The preparation method according to claim 6, characterized in that, After placing the side of the solder ribbon not coated with solder paste on the soldering heating platform, the process further includes: The position of the weld strip is corrected using a welding correction device; The welding strip is adsorbed using a vacuum adsorption device to fix the welding strip on the welding heating platform.

10. The preparation method according to claim 9, characterized in that, The welding heating platform includes multiple parallel through holes, with the welding strip located directly above each through hole. The vacuum adsorption device includes an adsorption structure located on the side of the through hole away from the welding strip, for adsorbing and fixing the welding strip through the through hole.

11. A back-contact photovoltaic module, characterized in that, It is prepared by the method of any one of claims 1-10 for back-contact photovoltaic modules.

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