A method for welding repair of a photovoltaic module and a welding repair device for a photovoltaic module

Abstract

The application discloses a welding repair method of a photovoltaic module and a welding repair device of the photovoltaic module, and relates to the field of photovoltaic module manufacturing. The welding repair method of the photovoltaic module comprises the following steps: providing a welded photovoltaic module, wherein the photovoltaic module comprises at least one completed-welding battery string; and performing scanning on the solder strip on the photovoltaic cell by using a laser to repair the welding residual stress of the photovoltaic module. In the manner, the application can effectively repair the stress generated by welding of the photovoltaic module.

Description

Technical Field

[0001] This application relates to the field of photovoltaic module manufacturing, and in particular to a welding repair method and a welding repair device for photovoltaic modules. Background Technology

[0002] During the welding process of photovoltaic modules, residual stress is generated after welding, leading to problems such as cell warping and microcracks. This is especially true given the current trend towards thinner and larger solar cells. Thinner solar cells are inherently thinner and more structurally fragile; the heat generated during welding can cause excessive deformation, affecting the flatness of the cell and the assembly precision of subsequent modules. Furthermore, welding residual stress poses a greater threat to the structural integrity of the cells. Even small residual stresses can damage the internal crystal structure of thinner solar cells, thus affecting their electrical performance. Larger solar cells, due to their larger size, exhibit more pronounced uneven heat transfer during welding. Achieving an ideal, even heat distribution during welding is difficult on large cells, resulting in greater welding residual stress and deformation. This can lead to warping, microcracks, and reduced mechanical properties and photoelectric conversion efficiency.

[0003] Annealing heat treatment can reduce post-weld residual stress, welding deformation, and cell warpage. Hot annealing furnaces are an existing method for reducing deformation and stress. However, hot annealing furnaces have several problems. Their annealing uniformity is poor; when annealing larger photovoltaic modules, temperature deviations in different areas can reach ±10℃. This uneven annealing means that deformation and stress in some areas cannot be effectively eliminated. Summary of the Invention

[0004] This application mainly provides a welding repair method and a welding repair device for photovoltaic modules to solve the problem that welding stress in photovoltaic modules cannot be effectively eliminated.

[0005] To solve the above-mentioned technical problems, one technical solution adopted in this application is: to provide a welding repair method for photovoltaic modules, comprising: providing a welded photovoltaic module, the photovoltaic module including at least one string of welded cells; and scanning the solder strips on the photovoltaic cells with a laser to repair the residual welding stress of the photovoltaic module.

[0006] In some embodiments, scanning the solder strip on the photovoltaic cell with a laser includes: irradiating the solder strip with a laser spot and scanning it a preset number of times along the length of the solder strip, with a preset time interval between two adjacent scans, forming a temperature cycle between a preset repair temperature and the ambient temperature for a preset number of times, wherein the preset repair temperature is the highest temperature formed by the laser on the solder strip during the scanning process.

[0007] In some embodiments, the laser scanning parameters include: a preset repair temperature of 50–140°C, a scanning speed of 500–2000 mm / s, a preset number of scans of 5–10, and a preset duration of not less than 1 second.

[0008] In some embodiments, the ratio of the width of the laser spot to the width of the solder strip is 1 to 2.5:1.

[0009] In some embodiments, before scanning the solder ribbons on the photovoltaic cell with a laser, the method further includes: covering the photovoltaic module with a light-transmitting flexible film, evacuating the covered area, and pressing the flexible film tightly against the solder ribbons and the photovoltaic cell.

[0010] In some embodiments, providing a welded photovoltaic module includes: providing a photovoltaic module to be welded, the photovoltaic module to be welded including photovoltaic cells and solder ribbons welded to the photovoltaic cells; covering the photovoltaic module with a light-transmitting flexible film, evacuating the covered area to make the light-transmitting flexible film press the solder ribbons and the photovoltaic cells, and performing laser welding on the photovoltaic module through the light-transmitting flexible film.

[0011] In some embodiments, each of the photovoltaic cells has multiple parallel welding strips; each welding strip is sequentially laser-scanned and cyclically scanned a preset number of times, with a preset time interval between two adjacent cycles; or, multiple welding strips on the photovoltaic cell are sequentially laser-scanned and cyclically scanned a preset number of times, with a preset time interval between two adjacent cycles and ambient temperature.

[0012] In some embodiments, the photovoltaic cell is a gridless photovoltaic cell.

[0013] In some embodiments, the photovoltaic module is a welded battery string; or, the photovoltaic module includes a photovoltaic substrate and a plurality of welded battery strings disposed above the photovoltaic substrate.

[0014] To address the aforementioned issues, this application also provides a welding repair device for photovoltaic modules, used to implement the welding repair method described above, comprising: a support platform for supporting the welded photovoltaic module, the photovoltaic module including photovoltaic cells and solder strips welded to the photovoltaic cells; and a laser repair module disposed above the support platform for laser scanning of the solder strips.

[0015] The beneficial effects of this application are as follows: Unlike existing technologies, this application discloses a welding repair method and apparatus. A welded photovoltaic module is provided, comprising at least one string of welded cells. A laser scan is used to scan the weld strips on the photovoltaic cells to repair residual welding stress in the photovoltaic module. Only the weld strips are heated, avoiding the propagation of microcracks caused by heating the cells, and the laser energy can be efficiently absorbed by the weld strips. Simultaneously, the rapid laser scanning quickly heats the weld strip area and cools it at intervals, creating a cycle of ambient temperature and repair temperature, effectively removing residual stress. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0017] Figure 1 This is a schematic flowchart of an embodiment of the welding repair method for photovoltaic modules provided in this application;

[0018] Figure 2 Is it like this? Figure 1 A schematic diagram of the position of an embodiment of method one is shown;

[0019] Figure 3 Is it like this? Figure 1 The flowchart of step 10 of the method shown is a schematic diagram of an embodiment. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0021] Unless otherwise stated or limited, the terms "first," "second," and "third" in the embodiments of this application are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. 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 device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.

[0022] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0023] See Figure 1 , Figure 1 This is a schematic flowchart of an embodiment of the welding repair method for photovoltaic modules provided in this application. The welding repair method includes the following steps:

[0024] 10: Provide a welded photovoltaic module, the photovoltaic module comprising at least one string of welded cells.

[0025] As will be understood by those skilled in the art, a welded photovoltaic module can be a string or multiple strings of welded cells, or a whole-panel photovoltaic module. When it is a whole-panel photovoltaic module, it also includes a photovoltaic substrate, which typically includes photovoltaic glass and a heat-sealing layer disposed on top of the photovoltaic glass, such as POE (Polyolefin Elastomer) or EVA (Ethylene Vinyl Acetate). It also includes multiple welded cell strings arranged according to the photovoltaic module layout disposed above the heat-sealing layer. Each cell string consists of photovoltaic cells arranged in a series.

[0026] During the welding process of photovoltaic cells, residual stress is easily generated in the welding area due to differences in the thermophysical properties of materials, temperature changes, and the effects of external mechanical constraints. Residual stress may lead to defects such as cell warping and microcracks. These problems are particularly prominent against the backdrop of the trend towards thinner and larger photovoltaic cells, making effective repair of welded photovoltaic modules especially important.

[0027] 20: Laser scanning is used to scan the solder strips on photovoltaic cells to repair residual welding stress in photovoltaic modules.

[0028] The laser beam used for repair irradiates the surface of the weld strip, covering the width of a single weld strip with a specific laser spot size, and continuously scans along the length of the weld strip at a preset speed. This creates an instantaneous high-temperature zone on the weld strip surface, causing the metal material in the weld strip to rapidly reach a state of thermal expansion, thereby releasing the residual stress generated during welding. A rapid heating-cooling cycle induces thermoplastic deformation of the weld strip material, offsetting the original residual stress.

[0029] The method of this invention differs from the method of reducing thermal stress in existing hot annealing furnaces. Hot annealing furnaces perform a slow, uniform heating, holding, and cooling process on the entire component, reducing residual stress through a single slow heating and cooling cycle. However, this method has limited repair effectiveness and cannot address the differences in repair results caused by temperature differences.

[0030] Furthermore, step 20 also includes irradiating the solder strip with a laser spot and scanning it a preset number of times along the length of the solder strip. A preset time interval is maintained between two adjacent scans, forming a temperature cycle between a preset repair temperature and the ambient temperature. The preset repair temperature is the highest temperature reached by the laser on the solder strip during the scanning process. The ambient temperature is typically room temperature, with approximately 20°C being ideal, and 15-25°C yielding better results. The preset time interval between two adjacent scans refers to the time between the completion of the previous scan and the start of the next scan.

[0031] By precisely controlling the laser scanning and cooling cycle, a uniform thermal stress distribution is gradually formed on and inside the solder strip, thereby reducing residual stress.

[0032] Optionally, the laser scanning parameters include:

[0033] The preset repair temperature is 50–140℃. Optionally, it can be a specific point or a range. The preferred temperature is 110℃–140℃. This achieves excellent repair results.

[0034] The preset interval duration is not less than 1 second. Preferably, the interval is 1 second to 10 seconds, and for point values ​​or range values, a duration of 2 to 5 seconds can achieve good repair results. The ratio of the laser spot width to the weld strip width is 1 to 2.5:1. Optionally, it is a point value or range value.

[0035] It should be noted that the laser spot shape can be circular or rectangular, etc. The width of the laser spot refers to the dimension of the laser beam along the width of the solder strip, while the length of the laser spot refers to the dimension of the laser spot along the length of the solder strip. For example, when the laser spot is circular, its width and length constitute the laser spot diameter. When the laser spot is rectangular, its width is the width of the rectangle, and its length is the length of the rectangle. Generally, the length and width of the laser spot are roughly equal, or the length is greater than the width, but the laser spot length is much shorter than the length of the solder strip. The laser spot must continuously scan along the length of the solder strip to irradiate the entire strip.

[0036] When performing laser scanning, the laser spot width is slightly larger than the solder strip width by 1 to 1.5 times to ensure that the laser energy uniformly covers the solder strip surface. If the spot is too small, the edges will not be effectively covered by the solder strip; if it is too large, it will irradiate the solar cell, which may cause the solar cell to overheat. The laser only heats the solder strip, avoiding the propagation of microcracks caused by overheating of the solar cell, and the laser energy can be efficiently absorbed by the solder strip.

[0037] Preferably, the welding repair method for photovoltaic modules of the present invention has excellent repair effects on photovoltaic modules without main grid cells. Those skilled in the art will know that, to avoid short circuits, insulating adhesive is applied below and around the solder strip on the photovoltaic cell. The present invention sets the width of the laser spot to a ratio of 1 to 2.5:1 to the width of the solder strip. This allows the laser spot to effectively cover the solder strip, achieving a good stress-relieving effect. Furthermore, any excess width is scanned primarily on the insulating adhesive and does not directly affect the photovoltaic cell, thus preventing the spread of microcracks caused by heat in the photovoltaic cell.

[0038] The scanning speed is 500–2000 mm / s. Optionally, it can be either a point value or a range value.

[0039] High-speed scanning can shorten the contact time between the laser and the welding strip, suppressing heat diffusion, while multiple heating and cooling cycles can gradually release residual stress.

[0040] Specifically, the preset number of cycles is 5 to 10. During the multiple heating and cooling cycles, the residual stress from the welding is slowly released. Multiple cyclic scanning of the solder strip is superior to heating the entire photovoltaic module and also superior to a single laser scan of the solder strip for resolving cell warping in photovoltaic modules. Using the method of this embodiment, warping repair is achieved with approximately 10% repair in one cycle, approximately 30% in two cycles, and approximately 50% repair by the fifth cycle.

[0041] Furthermore, the photovoltaic cell has multiple parallel welding strips.

[0042] like Figure 2 The laser can be used to scan the first solder strip, and then scan the other solder strips in sequence. During this process, the temperature of the scanned solder strips will drop to ambient temperature. Then, the laser can be used to scan the solder strips in the same order as before, until the preset number of scans is reached. In this way, the interval between two adjacent scans is parallel to the scanning process of other solder strips, thus saving laser repair time.

[0043] In other words, when performing laser scanning on all the solder strips of the entire photovoltaic module, one solder strip can be scanned at preset intervals, and then scanned again until the preset number of scans is reached. Alternatively, multiple solder strips can be laser scanned sequentially and cycled for a preset number of scans, with each cycle spaced at a preset interval, which can be equal to the aforementioned interval. The solder strips on the entire photovoltaic module can be divided into multiple groups, each group including the preceding solder strips, and one group can be scanned at a time until the welding repair of the entire photovoltaic module is completed.

[0044] Optionally, before step 10, the process further includes covering the photovoltaic module with a light-transmitting flexible film, evacuating the covered area, and pressing the light-transmitting flexible film tightly against the solder ribbon and photovoltaic cells.

[0045] Before laser scanning repair, a transparent flexible film is placed over the photovoltaic module. A vacuum is then created in the area covered by the film, pressing the solder ribbons and solar cells together. During solder ribbon repair, the vacuum pressure from the flexible film is used to press the solar cells firmly, ensuring they remain flat throughout the repair process and preventing bending. This allows residual welding stress to be released without damaging the cell structure.

[0046] Optionally, see Figure 3 Step 10 also includes the following steps:

[0047] 11: Provide a photovoltaic module to be welded, the photovoltaic module to be welded comprising at least one string of cells to be welded.

[0048] 12: The photovoltaic module is covered with a light-transmitting flexible film, the covered area is evacuated, the light-transmitting flexible film presses the welding strip and photovoltaic cell together, and the photovoltaic module is laser welded through the light-transmitting flexible film.

[0049] The welding temperature is 250℃~350℃, the laser power is 40~60W, and the scanning speed is 30~100mm / s.

[0050] Before welding repair, laser welding is performed using a laser coating process. After welding, the coating is not removed, and laser repair is performed directly. Thus, throughout the entire welding and repair process, the solar cells and solder strips remain flat, which is beneficial for improving the quality and performance of the photovoltaic modules. In this invention, both welding and repair are performed using laser irradiation scanning. The repair temperature is set appropriately based on the welding temperature, and the welding scanning speed is much higher than the welding scanning speed. Furthermore, the welding repair process employs multiple temperature cycles, which effectively repairs residual stress caused by laser welding.

[0051] This application also provides a welding repair device for photovoltaic modules, used to implement the welding repair method described above, including:

[0052] A support platform is used to support the welded photovoltaic module, which includes photovoltaic cells and solder strips welded to the photovoltaic cells.

[0053] The laser repair module, located above the support platform, is used to perform laser scanning on the weld strip to eliminate residual welding stress.

[0054] Furthermore, the laser repair module includes a galvanometer, a field mirror, and a laser.

[0055] The galvanometer controls the laser beam emitted by the laser to scan along the direction of the welding strip, while the field lens is responsible for adjusting the defocus of the laser to ensure that the laser beam is precisely focused on the area to be repaired.

[0056] Specifically, the defocusing amount of the field lens is controlled between -2mm and 2mm to optimize the focusing effect of the laser.

[0057] Optionally, the welding repair device also includes a pressing mechanism with a light-transmitting flexible membrane for pressing the edge of the flexible membrane onto the support platform. Alternatively, a negative pressure adsorption hole can be provided on the support platform to adsorb the edge of the flexible membrane onto the support platform.

[0058] Optionally, the support platform is also provided with vacuum adsorption holes to evacuate the space covered by the light-transmitting flexible film, so that the light-transmitting flexible film presses tightly against the photovoltaic module.

[0059] A vacuum is created between the transparent flexible film, photovoltaic module, and support platform through vacuum adsorption holes to achieve closer contact, increase the pressure in the welding area, and ensure welding quality.

[0060] Unlike existing technologies, this application uses laser scanning to scan the solder strip position after welding the photovoltaic module, creating a temperature cycling environment between the preset repair temperature and the ambient temperature at the solder strip position. This repeatedly removes residual stress and effectively repairs the stress generated by welding in the photovoltaic module. Furthermore, by vacuum-pressing the photovoltaic module with a transparent flexible film, the flatness of the photovoltaic substrate and solder strip is maintained during welding and laser repair. This facilitates precise completion of multiple laser irradiations, ensuring the flatness of the cells and thus improving the quality and performance of the photovoltaic module.

[0061] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A welding repair method for photovoltaic modules, characterized in that, include: A welded photovoltaic module is provided, the photovoltaic module comprising at least one string of welded cells; Laser scanning is used to scan the solder strips on the photovoltaic cells to repair residual welding stress in the photovoltaic module.

2. The welding repair method for photovoltaic modules according to claim 1, characterized in that, The process of scanning the solder strips on the photovoltaic cell with a laser includes: The laser spot is irradiated onto the solder strip and scanned a preset number of times along the length of the solder strip. The interval between two adjacent scans is a preset time, forming a temperature cycle between the preset repair temperature and the ambient temperature for a preset number of times. The preset repair temperature is the highest temperature formed by the laser on the solder strip during the scanning process.

3. The welding repair method according to claim 2, characterized in that, The scanning parameters of the laser include: The preset repair temperature is 50-140℃, the scanning speed is 500-2000mm / s, the preset number of scans is 5-10, and the preset duration is not less than 1s.

4. The welding repair method according to claim 2, characterized in that, The ratio of the width of the laser spot to the width of the welding strip is 1 to 2.5:

1.

5. The welding repair method according to claim 1, characterized in that, Before scanning the solder ribbons on the laser photovoltaic cell, the process also includes: The photovoltaic module is covered with a light-transmitting flexible film, and the covered area is evacuated to press the light-transmitting flexible film tightly against the welding ribbon and photovoltaic cells.

6. The welding repair method according to claim 1, characterized in that, The provision of a welded photovoltaic module includes: Provide a photovoltaic module to be welded, the photovoltaic module to be welded comprising at least one string of cells to be welded; The photovoltaic module is covered with a light-transmitting flexible film. The covered area is evacuated to make the light-transmitting flexible film press the welding strip and the photovoltaic cell together. The photovoltaic module is then laser-welded through the light-transmitting flexible film.

7. The welding repair method according to claim 2, characterized in that, The photovoltaic cell has multiple parallel welding strips; Each of the weld strips is sequentially laser-scanned and the process is repeated a preset number of times, with a preset time interval between two adjacent cycles; Alternatively, multiple solder strips on the photovoltaic cell can be laser scanned sequentially and the scan can be repeated a preset number of times, with a preset time interval between two adjacent scans.

8. The welding repair method according to claim 1, characterized in that, The photovoltaic cell is a busbarless photovoltaic cell.

9. The welding repair method according to claim 1, characterized in that, The photovoltaic module is a welded battery string; Alternatively, the photovoltaic module may include a photovoltaic substrate and a plurality of welded cell strings disposed above the photovoltaic substrate.

10. A welding repair apparatus for photovoltaic modules, used to implement the welding repair method as described in any one of claims 1-9, characterized in that, include: A support platform for supporting the welded photovoltaic module, the photovoltaic module including photovoltaic cells and solder strips welded to the photovoltaic cells; A laser repair module is mounted above the support platform and is used to perform laser scanning on the welding strip.

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