Processing technology of large silicon wafer string photovoltaic module

Abstract

The application discloses a large silicon wafer string type photovoltaic module processing technology and particularly relates to the technical field of photovoltaic modules. The large silicon wafer string type photovoltaic module processed by the processing technology has high light source utilization rate, higher power generation efficiency, can effectively ensure the peeling strength of the light-emitting solder strip, and further strengthens the stability of the light-emitting solder strip; can sort the battery pieces; can weld and connect the battery pieces to form a battery string; can solidify the adhesive on the pretreated solder strip, form uneven prism structures on the surface of the solder strip through the adhesive, then make a metal aluminum layer, form a light-reflecting solder strip, and change the existing solar power light source compensation problem, reasonably and fully maximize the utilization of the light source, thereby increasing the solar power battery piece light intensity and area and reducing the conversion efficiency loss caused by the limitation of external light sources.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic module technology, and more specifically, to the processing technology of large silicon wafer string photovoltaic modules. Background Technology

[0002] Currently, there are three mainstream silicon wafer sizes in the photovoltaic market: 166mm, 182mm, and 210mm. Cost is a key factor in the development of the photovoltaic industry, and the advantages of large silicon wafers are clear in terms of conversion efficiency, investment per GW of equipment, product yield, and mass production data. Existing solar cell strings are connected using busbars, including additional flying wires. That is, the busbars connect the front and back electrodes, which are exposed to light, to form a series circuit. The front of the cell is the area exposed to light. Due to the presence of flying wires, a large amount of blank space is left in the overall layout, resulting in a reduction in the light-receiving area. This prevents the effective utilization of light illuminating the busbar area. The solder strips are designed with a structure at a certain angle relative to the incident light. Light incident on the busbar area is reflected at a certain angle to the interface between the module glass and the air. Glass and air have different refractive indices, causing light to refract and reflect at the interface. Since the refractive index of glass is greater than that of air, glass is a relatively optically denser medium, and air is a relatively optically less dense medium. The reflective busbar has a reflective structure on its surface. Through the directional reflection of the surface structure, the light incident on the busbar surface is reflected to the glass-air interface. Then, through total internal reflection at the glass-air interface, the incident light is reflected to the surface of the adjacent solar cell, thereby generating additional photocurrent. This achieves the reuse of incident light.

[0003] The reflective busbars in existing large silicon wafer string photovoltaic modules have flat structures on both sides, resulting in low reflection efficiency. Summary of the Invention

[0004] To overcome the above-mentioned defects of the prior art, embodiments of the present invention provide a processing technology for large silicon wafer string photovoltaic modules.

[0005] The specific processing steps for large silicon wafer string photovoltaic modules are as follows:

[0006] Step 1: Cell sorting: Sorting cells that meet the appearance requirements, and grouping cells with the same color and efficiency into the required quantity for a module;

[0007] Step 2: Welding: Weld the solder strips to the main grid lines on the surface of the battery cells to connect the cells in series and form a battery string;

[0008] Step 3: Perform surface micro-arc oxidation treatment on the solder strips on the battery string to obtain pretreated solder strips;

[0009] Step 4: Curing the adhesive onto the pre-treated solder strips on the front of the battery string, rolling to form an uneven structure; curing the gaseous and reflective metal onto the solid adhesive to form reflective solder strips;

[0010] Step 5: Electrically connect several battery strings with reflective solder ribbons to form a battery string unit;

[0011] Step Six: Stacking, framing, installing junction boxes, testing, and packaging to obtain large silicon wafer string photovoltaic modules.

[0012] Furthermore, in step four, a prism structure is formed by rolling on the adhesive surface; in step four, the adhesive application amount is 6–8 g / m². 2 The curing time is 4-5 days; a vacuum pump is used to evacuate the vacuum evaporation machine, and then the aluminum material is heated to 1250℃-1350℃ to deposit gaseous aluminum particles on the surface of the adhesive. After cooling, a continuous and bright metallic aluminum layer is formed, resulting in reflective solder ribbon; in step six, glass, EVA, battery cells, EVA, and backsheet are laid in sequence, and then flow into the next process of lamination; the laminated components are assembled with frames;

[0013] Furthermore, in step two, the solder strip is subjected to surface micro-arc oxidation treatment using an electrolyte solution. The electrolyte solution comprises, by weight percentage: 0.9–1.1% sodium sulfate, 0.16–0.24% sodium hydroxide, and the remainder deionized water. The micro-arc oxidation treatment parameters are: constant current density of 0.15–0.19 A / cm². 2 Frequency: 500-540Hz, duty cycle: 48-52%, processing time: 2-4min;

[0014] Furthermore, in step two, the electrolyte consists of the following by weight percentages: 1.0% sodium sulfate, 0.20% sodium hydroxide, and the remainder deionized water; the micro-arc oxidation treatment parameters are: constant current density of 0.17 A / cm². 2 Frequency: 520Hz, Duty Cycle: 50%, Processing Time: 3min;

[0015] Further, in step four, the adhesive comprises, by weight percentage: 32-38% toluene diisocyanate, 5.6-6.6% 2,2-dimethylolpropionic acid, 3.6-4.6% 1,4-butanediol, 2.4-3.4% trimethylolpropane, 0.9-1.1% epoxy resin, 0.08-0.12% polyamide resin, 0.6-1.0% silane coupling agent, 1.4-1.6% sulfonate chain extender, 0.6-1.0% polylactic acid, 8.3-8.9% dichloromethane, 0.4-0.8% nano zinc oxide, with the remainder being polyether diol; the preparation method of the adhesive specifically includes the following steps:

[0016] S1: Weigh toluene diisocyanate, 2,2-dimethylolpropionic acid, 1,4-butanediol, trimethylolpropane, epoxy resin, polyamide resin, silane coupling agent, sulfonate chain extender, polylactic acid, dichloromethane, nano zinc oxide, and polyether diol according to the above weight ratio.

[0017] S2: Add the polylactic acid from step S1 to dichloromethane, stir for 50-60 minutes, then add the nano zinc oxide from step S1, stir for 10-14 hours to obtain mixture A;

[0018] S3: Mix the toluene diisocyanate and polyether diol from step S1 for 30-40 minutes; then add 2,2-dimethylolpropionic acid, 1,4-butanediol, trimethylolpropane, silane coupling agent, and sulfonate chain extender, and sonicate the mixture for 50-60 minutes to obtain mixture B.

[0019] S4: Add the epoxy resin and polyamide resin from step S1 and mixture A from step S2 to mixture B, blend and sonicate for 30-40 minutes to obtain the adhesive.

[0020] Furthermore, the silane coupling agent is one of KH-550, KH-560, and KH-570; the polyether diol is one or more of PEG2000, PEG3000, and PEG4000.

[0021] Furthermore, the adhesive comprises, by weight percentage: 32% toluene diisocyanate, 5.6% 2,2-dimethylolpropionic acid, 3.6% 1,4-butanediol, 2.4% trimethylolpropane, 0.9% epoxy resin, 0.08% polyamide resin, 0.6% silane coupling agent, 1.4% sulfonate chain extender, 0.6% polylactic acid, 8.3% dichloromethane, 0.4% nano zinc oxide, and the remainder being polyether diol.

[0022] Furthermore, the adhesive comprises, by weight percentage: 35% toluene diisocyanate, 6.1% 2,2-dimethylolpropionic acid, 4.1% 1,4-butanediol, 2.9% trimethylolpropane, 1.0% epoxy resin, 0.10% polyamide resin, 0.8% silane coupling agent, 1.5% sulfonate chain extender, 0.8% polylactic acid, 8.6% dichloromethane, 0.6% nano zinc oxide, and the remainder being polyether diol.

[0023] Furthermore, in step S2, the stirring speed is 600-800 r / min; in step S3, the stirring speed is 120-180 r / min, the ultrasonic frequency is 1.5-1.7 MHz, and the ultrasonic power is 400-500 W; in step S4, the ultrasonic frequency is 40-60 kHz, and the ultrasonic power is 900-1000 W.

[0024] Furthermore, in step S2, the stirring speed is 700 r / min; in step S3, the stirring speed is 150 r / min, the ultrasonic frequency is 1.6 MHz, and the ultrasonic power is 450 W; in step S4, the ultrasonic frequency is 50 kHz, and the ultrasonic power is 950 W.

[0025] The technical effects and advantages of this invention are as follows:

[0026] 1. The large-silicon wafer string photovoltaic module manufactured using the processing technology of this invention has high light source utilization, resulting in higher power generation efficiency. Simultaneously, it effectively ensures the peel strength of the luminescent solder ribbon, thereby enhancing the stability of the luminescent solder ribbon. In step one, the cells are sorted to effectively ensure their stability and uniformity, thus guaranteeing the stability of the subsequent string photovoltaic module. In step two, the solder ribbon is welded to the main grid lines of the cells to connect them in series, forming a cell string. In step three, the solder ribbon undergoes surface micro-arc oxidation treatment, effectively creating a micro-arc oxidation coating on the solder ribbon surface for protection. In step four, adhesive is cured onto the pre-treated solder ribbon, effectively pre-treating it with adhesive, facilitating subsequent roll forming of the solder ribbon surface. The adhesive forms an uneven prism on the solder ribbon surface. The structure is constructed by first creating a layer of aluminum on the uneven prism surface to form a reflective ribbon. This reflective ribbon addresses the existing problem of light source compensation in solar power generation by maximizing light source utilization and rationally increasing the light intensity and area of ​​the solar cells, thus reducing conversion efficiency losses due to external light source limitations. The refractive reflective ribbon utilizes the principles of absorption, refraction, and reflection to amplify and reflect a single light source into multiple light sources, which are then refracted 180° and dispersed onto the cell surface in a unique way, forming powerful light source compensation to achieve higher conversion efficiency. In step five, several battery strings with reflective ribbons are electrically connected to form a battery string unit. In step six, the battery string units are stacked, framed, fitted with junction boxes, tested, and packaged to form a large silicon wafer string photovoltaic module.

[0027] 2. The micro-arc oxidation coating in this invention grows in situ from the alloy surface inwards and outwards. The inner layer of the micro-arc oxidation coating adjacent to the substrate is a dense layer, which can effectively inhibit corrosion. The outer layer of the micro-arc oxidation coating has micropores and cracks. The adhesive is applied to the micro-arc oxidation coating of the pretreated weld ribbon, and the adhesive can effectively penetrate into the interior of the micro-arc oxidation coating, strengthening the bonding effect between the adhesive and the micro-arc oxidation coating, resulting in higher peel strength. The addition of epoxy resin to the adhesive results in the synthesis of a waterborne polyurethane adhesive with hard segments containing epoxy groups and improved hydrolysis resistance and adhesion properties. This effectively improves the adhesive's bonding performance and water resistance. The addition of polyamide resin, which can be used as a curing agent for epoxy resin, enables the epoxy resin to have... Excellent adhesion, flexibility, toughness, chemical resistance, moisture resistance, and surface smoothness enhance the structural stability of the cured adhesive. The use of silane coupling agents effectively modifies polyurethane, further strengthening the stability of the adhesive. Polylactic acid is dissolved in dichloromethane, then nano-zinc oxide is added and stirred before being added to the adhesive. The nano-zinc oxide fills the porous structure of the micro-arc oxidation coating and the cured adhesive, thereby improving the corrosion resistance of the micro-arc oxidation coating and the adhesive. The addition of nano-zinc oxide alters the surface morphology of the micro-arc oxidation coating and the adhesive, reducing the pore size and increasing the density of the pores on the cured adhesive surface, resulting in a more compact surface structure. This effectively enhances the uniformity and smoothness of the aluminum plating process, ensuring a reflective effect. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 are within the scope of protection of the present invention.

[0029] Example 1:

[0030] This invention provides a processing technology for large silicon wafer string photovoltaic modules, and the specific processing steps are as follows:

[0031] Step 1: Cell sorting: Sorting cells that meet the appearance requirements, and grouping cells with the same color and efficiency into the required quantity for a module;

[0032] Step 2: Welding: Weld the solder strips to the main grid lines on the surface of the battery cells to connect the cells in series and form a battery string;

[0033] Step 3: Perform surface micro-arc oxidation treatment on the solder strips of the battery string. The surface micro-arc oxidation treatment is performed using an electrolyte solution. The electrolyte composition by weight percentage is: 0.9% sodium sulfate, 0.16% sodium hydroxide, and the remainder is deionized water. Micro-arc oxidation treatment parameters: constant current density 0.15 A / cm². 2 Frequency: 500Hz, duty cycle: 48%, processing time: 2min; pretreated solder strips were obtained.

[0034] Step 4: Apply the adhesive to the pre-treated solder strips on the front side of the battery string. The amount of adhesive applied is 7g / m². 2 The curing time is 5 days. A prism structure is formed by roller pressing onto the adhesive surface. A vacuum pump is used to evacuate the vacuum evaporation machine, and then the aluminum material is heated to 1300℃, causing gaseous aluminum particles to deposit on the adhesive surface. After cooling, a continuous and bright metallic aluminum layer is formed, resulting in a reflective solder ribbon. The adhesive, by weight percentage, comprises: 32% toluene diisocyanate, 5.6% 2,2-dimethylolpropionic acid, 3.6% 1,4-butanediol, 2.4% trimethylolpropane, 0.9% epoxy resin, 0.08% polyamide resin, 0.6% silane coupling agent, 1.4% sulfonate chain extender, 0.6% polylactic acid, 8.3% dichloromethane, 0.4% nano zinc oxide, and the remainder being polyether diol. The preparation method of the adhesive specifically includes the following steps:

[0035] S1: Weigh toluene diisocyanate, 2,2-dimethylolpropionic acid, 1,4-butanediol, trimethylolpropane, epoxy resin, polyamide resin, silane coupling agent, sulfonate chain extender, polylactic acid, dichloromethane, nano zinc oxide, and polyether diol according to the above weight ratio.

[0036] S2: Add the polylactic acid from step S1 to dichloromethane, stir for 55 minutes, then add the nano zinc oxide from step S1, stir for 12 hours to obtain mixture A; the stirring speed is 600 r / min;

[0037] S3: The toluene diisocyanate and polyether diol from step S1 are blended and stirred for 35 minutes; then 2,2-dimethylolpropionic acid, 1,4-butanediol, trimethylolpropane, silane coupling agent, and sulfonate chain extender are added, and the mixture is blended and ultrasonically treated for 55 minutes to obtain mixture B; the stirring speed is 120 r / min, the ultrasonic frequency is 1.5 MHz, and the ultrasonic power is 400 W;

[0038] S4: Add the epoxy resin and polyamide resin from step S1 and the mixture A from step S2 to the mixture B, blend and sonicate for 35 minutes to obtain the adhesive; the ultrasonic frequency is 40KHz and the ultrasonic power is 900W.

[0039] Step 5: Electrically connect several battery strings with reflective solder ribbons to form a battery string unit;

[0040] Step Six: After laying glass, EVA, battery cells, EVA, and backsheet in sequence, the product flows into the next process of lamination; the laminated components are assembled with frames; junction boxes are installed, tested, and packaged.

[0041] The silane coupling agent is KH-550; the polyether diol is PEG2000.

[0042] Example 2:

[0043] Unlike Example 1, in step two, the electrolyte consisted of 1.1% sodium sulfate, 0.24% sodium hydroxide, and the remainder deionized water by weight percentage; the micro-arc oxidation treatment parameters were a constant current density of 0.19 A / cm². 2 Frequency: 540Hz, duty cycle: 52%, processing time: 4min; in step S2, the stirring speed is 800r / min; in step S3, the stirring speed is 180r / min, the ultrasonic frequency is 1.7MHz, and the ultrasonic power is 500W; in step S4, the ultrasonic frequency is 60KHz, and the ultrasonic power is 1000W.

[0044] Example 3:

[0045] Unlike Examples 1-2, in step two, the electrolyte, by weight percentage, consisted of 1.0% sodium sulfate, 0.20% sodium hydroxide, and the remainder deionized water; the micro-arc oxidation treatment parameters were a constant current density of 0.17 A / cm². 2 The ultrasonic frequency was 520 Hz, the duty cycle was 50%, and the processing time was 3 min. In step S2, the stirring speed was 700 r / min. In step S3, the stirring speed was 150 r / min, the ultrasonic frequency was 1.6 MHz, and the ultrasonic power was 450 W. In step S4, the ultrasonic frequency was 50 kHz and the ultrasonic power was 950 W.

[0046] Example 4:

[0047] Unlike Example 3, the adhesive, by weight percentage, comprises: 38% toluene diisocyanate, 6.6% 2,2-dimethylolpropionic acid, 4.6% 1,4-butanediol, 3.4% trimethylolpropane, 1.1% epoxy resin, 0.12% polyamide resin, 1.0% silane coupling agent, 1.6% sulfonate chain extender, 1.0% polylactic acid, 8.9% dichloromethane, 0.8% nano zinc oxide, and the remainder being polyether diol.

[0048] Example 5:

[0049] Unlike Example 3, the adhesive, by weight percentage, comprises: 35% toluene diisocyanate, 6.1% 2,2-dimethylolpropionic acid, 4.1% 1,4-butanediol, 2.9% trimethylolpropane, 1.0% epoxy resin, 0.10% polyamide resin, 0.8% silane coupling agent, 1.5% sulfonate chain extender, 0.8% polylactic acid, 8.6% dichloromethane, 0.6% nano zinc oxide, and the remainder being polyether diol.

[0050] Comparative Example 1:

[0051] Unlike Example 5, no rolling process was performed.

[0052] Comparative Example 2:

[0053] Unlike Example 5, step three is not performed.

[0054] Comparative Example 3:

[0055] Unlike Example 5, the adhesive does not contain polylactic acid, dichloromethane, or nano zinc oxide.

[0056] Comparative Example 4:

[0057] Unlike Example 5, in step S2, all the raw materials of the adhesive are directly mixed and stirred for 2 to 3 hours to obtain the adhesive.

[0058] The sources of the above raw materials are as follows: soldering strip was purchased from Suzhou Bonide Photovoltaic Technology Co., Ltd. (lead-free tinned copper strip); sodium sulfate was purchased from Sigma-Aldrich (Shanghai) Trading Co., Ltd. (item number: V900052); sodium hydroxide was purchased from Wuhan Jixin Yibang Biotechnology Co., Ltd. (item number: R031); toluene diisocyanate was purchased from Hubei Xinmingtai Chemical Co., Ltd. (grade: industrial); 2,2-dimethylolpropionic acid was purchased from Taian Jiangzhou Biotechnology Co., Ltd. (item number: 111); 1,4-butanediol was purchased from Sigma-Aldrich (Shanghai) Trading Co., Ltd. (item number: V900243); trimethylolpropane was purchased from Shanghai Yuanye Biotechnology Co., Ltd. (item number: S50717); epoxy resin was purchased from Jinan Chuangshi Chemical Co., Ltd. (epoxy resin E51, purity 99%); polyamide resin was purchased from Hubei Ri Shengchang New Materials Technology Co., Ltd., item number: 63428-84-2; silane coupling agent KH-550 was purchased from Wuhan Prof Biotechnology Co., Ltd., item number: 0002; sulfonate chain extender was purchased from Hubei Xinrunde Chemical Co., Ltd., AAS salt / waterborne polyurethane sulfonate chain extender (34730-59-1), purity 50%; polylactic acid was purchased from Sigma-Aldrich (Shanghai) Trading Co., Ltd., item number: 38534; dichloromethane was purchased from Sigma-Aldrich (Shanghai) Trading Co., Ltd., item number: PHR1557; nano zinc oxide was purchased from (Klamar) Shanghai Puzhen Biotechnology Co., Ltd.; polyether diol PEG2000 was purchased from Chongqing Ruiya Biotechnology Co., Ltd., polyethylene glycol PEG2000 (25322-68-3), item number: 25322-68-3;

[0059] The large silicon wafer string photovoltaic modules in the embodiments and comparative examples of this invention were tested. (1) The power generation of the large silicon wafer string photovoltaic modules in the embodiments and comparative examples was tested under the same environment. The power generation improvement rate of the embodiments and comparative examples was calculated based on the power generation of the large silicon wafer string photovoltaic modules in Comparative Example 1 (100%). (2) The T-type peel strength of the reflective solder strips in the embodiments and comparative examples was measured according to GB / T2791-1995 standard. The results are shown in Table 1.

[0060] Table 1:

[0061]

[0062]

[0063] As shown in the table above, the large silicon wafer string photovoltaic modules processed by the process of the present invention have high light source utilization, resulting in higher power generation efficiency. At the same time, it can effectively ensure the peel strength of the light-emitting solder ribbon, thereby enhancing the stability of the light-emitting solder ribbon.

[0064] In step one, the solar cells are sorted to ensure their stability and uniformity, thereby guaranteeing the stability of the subsequent string photovoltaic modules. In step two, the solder ribbons are welded to the main grid lines of the solar cells to connect them in series, forming a battery string. In step three, the solder ribbons undergo micro-arc oxidation treatment to create a micro-arc oxidation coating on their surface, providing protection. In step four, adhesive is cured onto the pre-treated solder ribbons, effectively pre-treating them for adhesion and facilitating subsequent roll forming. The adhesive forms an uneven prism structure on the surface of the solder ribbon, which is then used to create a prism structure. A metallic aluminum layer forms a reflective solder ribbon. This reflective solder ribbon addresses the existing problem of light source compensation in solar power generation by focusing on light source compensation and maximizing light source utilization. It rationally and fully utilizes the light source, thereby increasing the light intensity and area of ​​the solar cells and reducing conversion efficiency losses caused by external light source limitations. The refractive reflective solder ribbon utilizes the principles of absorption, refraction, and reflection to amplify and reflect a single light source into multiple light sources, which are then refracted 180° and dispersed onto the cell surface in a unique way, forming powerful light source compensation to achieve higher conversion efficiency. In step five, several battery strings with reflective solder ribbons are electrically connected to form a battery string unit. In step six, the battery string unit is further processed... The process involves stacking, framing, installing junction boxes, testing, and packaging to form large-wafer string photovoltaic modules. The micro-arc oxidation coating grows in situ from the alloy surface inwards and outwards. The inner layer of the micro-arc oxidation coating adjacent to the substrate is a dense layer, effectively inhibiting corrosion. The outer layer of the micro-arc oxidation coating has micropores and cracks. Adhesive is applied to the micro-arc oxidation coating on the pre-treated solder ribbon, allowing the adhesive to effectively penetrate the interior of the micro-arc oxidation coating, enhancing the bonding effect between the adhesive and the micro-arc oxidation coating, resulting in higher peel strength. The combined action of toluene diisocyanate and polyether polyol effectively provides basic raw materials for polyurethane materials, ensuring the normal synthesis of polyurethane materials. Further addition of 2,2-dimethylolpropionic acid and 1,4-butanediol... Trimethylolpropane effectively ensures the stability and bonding strength of polyurethane adhesives. Adding epoxy resin to the adhesive results in the synthesis of a waterborne polyurethane adhesive with hard segments containing epoxy groups, improved hydrolysis resistance and adhesion. This effectively enhances the adhesive's bonding and water resistance. The addition of polyamide resin, which acts as a curing agent for epoxy resin, imparts excellent adhesion, flexibility, toughness, chemical resistance, moisture resistance, and surface smoothness to the epoxy resin, thereby strengthening the structural stability of the cured adhesive. The use of silane coupling agents effectively modifies the polyurethane, further enhancing the adhesive's stability.Polylactic acid is dissolved in dichloromethane, then nano-zinc oxide is added and stirred before being added to the adhesive. The nano-zinc oxide fills the porous structure of the micro-arc oxidation coating and the cured adhesive, thereby improving their corrosion resistance. The addition of nano-zinc oxide alters the surface morphology of the micro-arc oxidation coating and the adhesive, reducing the pore size and increasing the density of the pores on the cured adhesive surface, resulting in a more compact surface structure. This effectively enhances the uniformity and smoothness of the aluminum plating process, thus ensuring a reflective effect.

[0065] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A processing technology for large silicon wafer string photovoltaic modules, characterized in that: The specific processing steps are as follows: Step 1: Cell sorting: Sorting cells that meet the appearance requirements, and grouping cells with the same color and efficiency into the required quantity for a module; Step 2: Welding: Weld the solder strips to the main grid lines on the surface of the battery cells to connect the cells in series and form a battery string; Step 3: Perform surface micro-arc oxidation treatment on the solder strips on the battery string to obtain pretreated solder strips; Step 4: The adhesive is cured onto the pre-treated solder strips on the front side of the battery string, and rolled to form an uneven structure; a gaseous, reflective metal is cured onto the solid adhesive to form a reflective solder strip; the adhesive, by weight percentage, comprises: 32-38% toluene diisocyanate, 5.6-6.6% 2,2-dimethylolpropionic acid, 3.6-4.6% 1,4-butanediol, 2.4-3.4% trimethylolpropane, 0.9-1.1% epoxy resin, 0.08-0.12% polyamide resin, 0.6-1.0% silane coupling agent, 1.4-1.6% sulfonate chain extender, 0.6-1.0% polylactic acid, 8.3-8.9% dichloromethane, 0.4-0.8% nano zinc oxide, and the remainder is polyether diol; the preparation method of the adhesive is detailed below. Includes the following steps: S1: Weigh toluene diisocyanate, 2,2-dimethylolpropionic acid, 1,4-butanediol, trimethylolpropane, epoxy resin, polyamide resin, silane coupling agent, sulfonate chain extender, polylactic acid, dichloromethane, nano zinc oxide, and polyether diol according to the above weight ratio. S2: Add the polylactic acid from step S1 to dichloromethane, stir for 50-60 minutes, then add the nano zinc oxide from step S1, stir for 10-14 hours to obtain mixture A; S3: Mix the toluene diisocyanate and polyether diol from step S1 for 30-40 minutes; then add 2,2-dimethylolpropionic acid, 1,4-butanediol, trimethylolpropane, silane coupling agent, and sulfonate chain extender, and sonicate the mixture for 50-60 minutes to obtain mixture B. S4: Add the epoxy resin and polyamide resin from step S1 and the mixture A from step S2 to the mixture B, blend and sonicate for 30-40 minutes to obtain the adhesive. Step 5: Electrically connect several battery strings with reflective solder ribbons to form a battery string unit; Step Six: Stacking, framing, installing junction boxes, testing, and packaging to obtain large silicon wafer string photovoltaic modules.

2. The processing technology for large silicon wafer string photovoltaic modules according to claim 1, characterized in that: In step four, a prism structure is formed on the adhesive surface by roller pressing; in step four, the adhesive application amount is 6-8 g / m2 and the curing time is 4-5 days; a vacuum pump is used to evacuate the vacuum evaporation machine, and then the aluminum material is heated to 1250℃-1350℃ to deposit gaseous aluminum particles on the surface of the adhesive, and then cooled to form a continuous and bright metallic aluminum layer, resulting in reflective solder ribbon; in step six, after laying glass, EVA, battery cells, EVA, and backsheet in sequence, it flows into the next process for lamination; the laminated components are assembled with frames.

3. The processing technology for large silicon wafer string photovoltaic modules according to claim 2, characterized in that: In step two, the solder strip is subjected to surface micro-arc oxidation treatment using an electrolyte solution. The electrolyte solution consists of 0.9–1.1% sodium sulfate, 0.16–0.24% sodium hydroxide, and the remainder deionized water by weight. The micro-arc oxidation treatment parameters are: a constant current density of 0.15–0.19 A / cm². 2 Frequency: 500-540Hz, duty cycle: 48-52%, processing time: 2-4min.

4. The processing technology for large silicon wafer string photovoltaic modules according to claim 3, characterized in that: In step two, the electrolyte consists of 1.0% sodium sulfate, 0.20% sodium hydroxide, and the remainder deionized water by weight percentage; the micro-arc oxidation treatment parameters are: constant current density of 0.17 A / cm². 2 Frequency: 520Hz, Duty Cycle: 50%, Processing Time: 3min.

5. The processing technology for large silicon wafer string photovoltaic modules according to claim 1, characterized in that: The silane coupling agent is one of KH-550, KH-560, and KH-570; the polyether diol is one or more of PEG2000, PEG3000, and PEG4000.

6. The processing technology for large silicon wafer string photovoltaic modules according to claim 1, characterized in that: The adhesive comprises, by weight percentage: 32% toluene diisocyanate, 5.6% 2,2-dimethylolpropionic acid, 3.6% 1,4-butanediol, 2.4% trimethylolpropane, 0.9% epoxy resin, 0.08% polyamide resin, 0.6% silane coupling agent, 1.4% sulfonate chain extender, 0.6% polylactic acid, 8.3% dichloromethane, 0.4% nano zinc oxide, and the remainder being polyether diol.

7. The processing technology for large silicon wafer string photovoltaic modules according to claim 1, characterized in that: The adhesive comprises, by weight percentage: 35% toluene diisocyanate, 6.1% 2,2-dimethylolpropionic acid, 4.1% 1,4-butanediol, 2.9% trimethylolpropane, 1.0% epoxy resin, 0.10% polyamide resin, 0.8% silane coupling agent, 1.5% sulfonate chain extender, 0.8% polylactic acid, 8.6% dichloromethane, 0.6% nano zinc oxide, and the remainder being polyether diol.

8. The processing technology for large silicon wafer string photovoltaic modules according to claim 1, characterized in that: In step S2, the stirring speed is 600-800 r / min; in step S3, the stirring speed is 120-180 r / min, the ultrasonic frequency is 1.5-1.7 MHz, and the ultrasonic power is 400-500 W; in step S4, the ultrasonic frequency is 40-60 kHz, and the ultrasonic power is 900-1000 W.

9. The processing technology for large silicon wafer string photovoltaic modules according to claim 8, characterized in that: In step S2, the stirring speed is 700 r / min; in step S3, the stirring speed is 150 r / min, the ultrasonic frequency is 1.6 MHz, and the ultrasonic power is 450 W; in step S4, the ultrasonic frequency is 50 kHz, and the ultrasonic power is 950 W.

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