Back contact battery grid line repairing method and device

Abstract

The invention relates to a back contact cell grid line repairing method and device, and belongs to the technical field of solar cell manufacturing, a laser light source is adopted to process a silver grid line containing silver sulfide of a back contact cell so as to remove the silver sulfide generated by oxidation of sulfide on the silver grid line in the solar cell; and the grid line is repaired through laser equipment without newly adding equipment, and the grid line can be directly integrated to the existing production line, so that the equipment investment cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of solar cell manufacturing, in particular to a back contact cell grid line repair method and device. BACKGROUND

[0002] In a back contact cell, the collection of current mainly depends on the silver grid laid on the back of the cell. In order to ensure the electrical insulation performance, the cell usually sets an insulating glue area between the back electrodes.

[0003] However, during long-term use, the silver grid line and the electrode are easily affected by environmental factors, especially in a humid or sulfur-containing polluted environment, the silver grid line reacts with sulfide to form a sulfide layer. Since the conductivity of sulfide is much lower than that of metallic silver, this reaction will cause the grid line resistance to increase, thereby causing the cell series resistance to rise and the current collection ability to decrease, ultimately resulting in a decrease in photoelectric conversion efficiency and a shortening of service life.

[0004] Based on this, a back contact cell grid line repair method and device are proposed. SUMMARY

[0005] The purpose of the present application is to provide a back contact cell grid line repair method and device for improving the electrical conductivity of the cell and prolonging the service life.

[0006] To solve the above technical problems, the present application is realized by the following technical scheme:

[0007] A back contact cell grid line repair method, comprising the following steps:

[0008] Using a laser light source to process the silver sulfide grid line of the back contact cell to remove the sulfide on the silver grid line of the solar cell.

[0009] Further, the laser irradiation comprises the following specific steps:

[0010] Positioning the sulfidation area that needs to be processed on the cell, avoiding the insulating glue covered area.

[0011] Further, the laser is a nanosecond laser or a picosecond / femtosecond laser with a wavelength of 300-600 nm, a pulse frequency of 10-6000 kHz, a spot size of 10-50 μm, and an energy density controlled within .

[0012] Further, the laser is selected from green light with a wavelength of 532 nm or ultraviolet light with a wavelength of 355 nm.

[0013] Further, the laser repair process is carried out under the protection of inert gas.

[0014] Further, the surface of the grid line is cleaned by low-pressure inert gas after laser irradiation to remove residual sulfur or byproducts.

[0015] Further, the battery insulation glue is one of polyimide, PVDF, silicone resin or epoxy resin.

[0016] Further, the method uses the Mark point of the battery or the pad or other feature patterns on the main grid to accurately position the battery.

[0017] Further, the laser processing width is 3-10 um narrower than the silver grid line containing silver sulfide, and the width of the two sides is uniform.

[0018] A back contact battery grid line repair device, comprising:

[0019] A laser generation module for generating a specific wavelength laser to process the silver sulfide grid line of the back contact battery to remove the sulfide on the silver grid line of the solar cell;

[0020] A battery positioning and movement platform for fixing and moving the battery to be repaired, equipped with a visual recognition system to identify the Mark point or the main grid pad to realize automatic alignment of the processing path;

[0021] An inert gas protection module, including a gas supply device and a nozzle system, for providing inert gas in the laser repair area;

[0022] A byproduct exhaust module, including an exhaust pipeline and a filtration system, for timely exhausting the sulfur vapor and particles generated during the repair process.

[0023] Advantages:

[0024] The present disclosure removes the sulfide on the surface of the silver grid line of the back contact battery by laser, restoring the conductive performance of the grid line.

[0025] The present disclosure uses laser repair, which can avoid irradiating the insulation glue area, thereby avoiding the thermal damage to the insulation glue that may be caused by traditional high-temperature methods, thereby improving the reliability of the repair process and the stability of the battery structure.

[0026] The present disclosure uses precise laser scanning and inert gas protection to avoid damaging the silicon nitride layer and the insulation glue area.

[0027] The present disclosure uses laser equipment for repair without the need for additional equipment, which can be directly integrated into the existing production line, reducing the cost of equipment investment.

[0028] Of course, implementing any product of the present application does not necessarily require all the advantages described above. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed for the description of the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0030] Figure 1 Effect diagram of the embodiment of the present disclosure; DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort belong to the protection scope of the present application.

[0032] In the back contact cell, the electrode grid line usually adopts silver grid line. After the silver grid line is formed by screen printing, in the long-term use process, the silver grid line and the electrode are easily affected by environmental factors to generate sulfide, especially in a humid or sulfur-containing polluted environment, the silver grid line reacts with the sulfide to generate silver sulfide layer. Since the conductivity of silver sulfide is much lower than that of metal silver, this reaction will cause the grid line resistance to increase, thereby causing the battery series resistance to rise and the current collection capacity to decrease, and finally showing the decrease of photoelectric conversion efficiency and the shortening of service life. At the same time, the electrode grid line appears black and yellow, which further causes the appearance of the solar cell to be poor.

[0033] In order to solve the above problems, the present application removes the sulfide on the surface of the silver grid line of the back contact cell by precise laser scanning combined with inert gas protection, restores the conductivity and avoids damage to silicon nitride and insulating glue.

[0034] Specifically, the steps of the back contact cell grid line repair method are as follows:

[0035] Step 1: Position the sulfuration area

[0036] The silver paste area of the cell is determined by the silver fine grid line and the main grid artwork or measurement method, the insulating glue covered area is removed, and the area to be processed is determined.

[0037] Further, the actual width of the silver grid needs to be distinguished when positioning the sulfuration area. The actual width of the silver fine grid is usually about 15um wider than the artwork width.

[0038] Step 2: Laser parameter optimization

[0039] Wavelength selection: 532 nm (green) or 355 nm (UV) is preferred, so that the laser is used Strong absorption in 300-600 nm, while The band gap of silicon nitride is ~ 5 eV, and the insulating glue has weak absorption in this waveband, avoiding thermal damage to the insulating glue.

[0040] Energy density: nanosecond laser Or picosecond / femtosecond laser Avoid thermal diffusion damage to the surrounding material.

[0041] Pulse frequency: 10-6000 kHz, so as to balance efficiency and heat accumulation control.

[0042] Spot size: 10-50 μm, to ensure accurate coverage of the vulcanization area.

[0043] Step 3: Inert gas protection

[0044] Laser repair is carried out in an inert gas environment to prevent the generated sulfur vapor from being oxidized again or deposited on the battery surface. Nitrogen, argon is preferred.

[0045] Step 4: Post-processing cleaning

[0046] Use low-pressure gas flow to remove residual sulfur. Inert gas is preferred.

[0047] It can be understood that when the above steps are carried out, the silicon nitride and the insulating glue need to be protected from damage. The specific measures are as follows:

[0048] Protection of silicon nitride (Si3N4) );

[0049] Wavelength avoidance: 532 nm laser is preferred to avoid the strong absorption region.

[0050] Energy threshold control: the damage threshold of silicon nitride is about , and the actual processing energy is controlled below .

[0051] Thermal management: use pulse interval cooling greater than 10 μs to reduce the effect of heat accumulation.

[0052] Protection of insulating glue;

[0053] Material selection: polyimide, PVDF, silicone resin or epoxy resin can be selected, and high-temperature resistant materials such as polyimide are preferred, which can withstand more than .

[0054] Laser energy control: the carbonization threshold of the insulating glue is about , so the laser energy should be less than or equal to .

[0055] Focus control: the laser focus is strictly locked on the silver grid line, avoiding shifting to the insulating glue area.

[0056] It can be understood that the laser irradiates the silver grid line area containing sulfide on the silver grid line, so that the sulfide undergoes a photo-thermal decomposition reaction to generate metallic silver and sulfur vapor.

[0057] In some embodiments, as shown in FIG. 1, taking a P-type BC battery as an example, the repair process of the silver grid line by the sulfided P-type BC battery is as follows: Figure 1

[0058] S1, select the oxidized battery;

[0059] S2, according to the silver main grid and silver fine grid 1 exposed to air in the oxidized battery, design the pattern formula that needs to be processed, and consider the actual width of the silver fine grid line 1, the main grid width, the position, etc. in detail; the processing area needs to avoid silicon nitride, aluminum grid line 3, insulating glue 2, etc.

[0060] S3, use the Mark point of the battery or the solder pad or other characteristic patterns on the main grid to accurately position the battery;

[0061] S4, use 532 nm (green light) to process the silver main grid and silver fine grid part of the battery, the laser processing width is slightly lower than the grid line, about 3-10 um, and the width of both sides is uniform. Taking the fine grid as an example, if the fine grid is 35 um wide, the laser processing width is 25-32 um, the spot length can be in the range of 25-400 um, the frequency is 10-1000 KHz, the scanning speed is 2-100 m / s, and the power range is 2W-300W;

[0062] S5, the fine grid conducts electricity mainly through the middle part of the grid line, and the height of the silver paste on both sides is low, which has little effect on the conductivity;

[0063] S6, the laser slightly lower than the silver grid line can reduce the damage of the laser to the silicon nitride area of the battery;

[0064] S7, during the processing, nitrogen can be used for purging and blown away by the exhaust system: 1. protection to prevent the silver grid line from being oxidized by oxygen in the air during processing; 2. purging byproducts generated during processing, such as sulfur, etc.

[0065] It can be understood that the method can also be applicable to N-type BC batteries. Specifically, it can be TOPCon battery or HJT battery structure.

[0066] Meanwhile, the disclosure also proposes a back contact battery grid line repair device, which comprises:

[0067] ​Laser generating module; for generating laser of specific wavelength, preferably 532nm green laser or 355nm ultraviolet laser. The module can adjust the output power range 2W~300W, and support pulse frequency 10~6000 kHz, to meet the repair needs of different grid line width and sulfurization degree.

[0068] Battery positioning and motion platform; the platform is used to fix and move the battery piece to be repaired, and the visual identification system realizes the automatic alignment of the processing path and the actual grid line by identifying the Mark point, main grid pad or other characteristic patterns of the battery, to ensure the accuracy of the laser scanning position.

[0069] Inert gas protection module; including gas supply device and nozzle system, for providing inert atmosphere in the laser repair area. Prevent fresh silver generated during laser action from being oxidized by air, and at the same time, the sulfur vapor and particulate matter generated by decomposition are promptly purged.

[0070] By-product exhaust module; including exhaust pipeline and filtration system, for timely removing sulfur vapor, particulate matter and other by-products generated during the repair process, to avoid their accumulation on the battery surface, and to ensure the cleanliness and stability of the processing area.

[0071] The device has the following advantages; since the back contact battery is configured with laser equipment during the production process, the repair method does not need to add additional hardware, and can be directly integrated into the existing production line, reducing the equipment investment cost.

[0072] During the laser repair process, the insulating glue area can be avoided from being irradiated, thereby avoiding the thermal damage to the insulating glue that may be caused by the traditional high temperature method, thereby improving the reliability of the repair process and the stability of the battery structure.

[0073] In the description of the present specification, the description of the terms "one embodiment", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0074] The preferred embodiments of the application disclosed above are only to facilitate the elucidation of the application. The preferred embodiments do not describe all the details of the application and limit the application to the specific embodiments described. Obviously, many modifications and variations can be made in light of the teachings above. The description is chosen and described in order to best explain the principles of the application and its practical application to thereby enable others skilled in the art to best utilize the application and get the best results from the application. The application is only limited by the claims and their full scope and equivalents.

Claims

1. A method for repairing back contact battery grid lines, characterized in that, Includes the following steps: A laser light source is used to process the silver sulfide grid lines of the back contact battery in order to remove the sulfides on the silver grid lines in the solar cell.

2. The method for repairing back contact battery grid lines according to claim 1, characterized in that, Laser irradiation includes the following specific steps: Locate the sulfated areas on the battery that need treatment, avoiding areas covered by insulating adhesive.

3. The method for repairing back contact battery grid lines according to claim 1, characterized in that, The laser is a nanosecond laser (0.1–0.5 J / cm²) or a picosecond / femtosecond laser (0.01–0.1 J / cm²), with a wavelength of 300–600 nm, a pulse frequency of 10–6000 kHz, a spot size of 10–50 μm, and an energy density controlled within the range of 0.01–0.5 J / cm².

4. The method for repairing back contact battery grid lines according to claim 3, characterized in that, The laser used is either green light with a wavelength of 532nm or ultraviolet light with a wavelength of 355nm.

5. The method for repairing back contact battery grid lines according to claim 1, characterized in that, The laser repair process is carried out under the protection of an inert gas.

6. The method for repairing back contact battery grid lines according to claim 1, characterized in that, After laser irradiation, the surface of the grid line is cleaned with low-pressure inert gas to remove residual sulfur or by-products.

7. The method for repairing back contact battery grid lines according to claim 2, characterized in that, The insulating adhesive is one of polyimide, PVDF, silicone resin or epoxy resin.

8. The method for repairing back contact battery grid lines according to claim 1, characterized in that, The method utilizes the battery's Mark points or pads on the main grid or other feature patterns to accurately locate the battery.

9. The method for repairing back contact battery grid lines according to claim 1, characterized in that, The laser-processed width is 3-10 μm narrower than the silver grid line containing silver sulfide, and the blank width on both sides is uniform.

10. A back contact battery grid line repair device, characterized in that, include A laser generating module is used to generate a laser of a specific wavelength to process the silver sulfide grid lines of the back contact battery in order to remove sulfides from the silver grid lines in the solar cell. A battery positioning and motion platform is used to fix and move the battery cells to be repaired. It is equipped with a vision recognition system to identify Mark points or main grid pads and realize automatic alignment of the processing path. An inert gas protection module, including a gas supply device and a nozzle system, is used to provide inert gas in the laser repair area; The byproduct extraction module, including exhaust ducts and a filtration system, is used to promptly remove sulfur vapors and particles generated during the repair process.

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