Solar photovoltaic soldering strip and photovoltaic module prepared thereby

Abstract

The present application relates to the technical field of photovoltaic material, in particular to a photovoltaic solder strip and a photovoltaic module prepared by the same. According to the present application, 35-45% tin, 20-30% lead, 20-30% bismuth and 1-5wt% silver are mixed to obtain a quaternary material solder with a melting point of 140-180 DEG C, which not only meets the low-temperature welding process conditions, but also maintains good welding tension, thereby ensuring that the prepared photovoltaic module has high photoelectric conversion efficiency. In addition, when the photovoltaic solder strip is used to prepare the photovoltaic module, the fluorine-containing monomer is prepared by the reaction of dodecafluoroheptanol and acrylic acid, the benzene-containing crosslinking monomer is obtained by the reaction of pentaerythritol and 4-vinylbenzoic acid, the fluorine-containing monomer and the benzene-containing crosslinking monomer are used to modify the EVA resin, and the EVA encapsulating adhesive layer with strong adhesion and good thermal chemical properties is obtained, thereby prolonging the service life of the photovoltaic module and reducing the repair rate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photovoltaic materials, in particular to a solar photovoltaic solder strip and a photovoltaic module prepared therefrom. BACKGROUND

[0002] The photovoltaic solder strip is an important component of the photovoltaic module, mainly applied to the series or parallel connection of solar cell pieces, and plays an important role in collecting current and conducting electricity, thereby ensuring the stability of the output voltage and power of the photovoltaic module. The solar cell pieces are connected by the photovoltaic solder strip to form a complete circuit loop, and then encapsulated by EVA / POE adhesive film, photovoltaic glass, back film, frame, silicone and other materials to form a photovoltaic module. The photovoltaic solder strip is an important material in the soldering process of solar silicon cell pieces, and its quality directly affects the current collection efficiency of the solar silicon cell pieces, and ultimately affects the power of the photovoltaic module and the efficiency of the photovoltaic power generation system.

[0003] Under the background of the new era of the photovoltaic industry, "reducing cost and improving efficiency" has become the main trend. As the core component of photovoltaic power generation, the photovoltaic module is the basis for reducing the cost of photovoltaic power generation and improving the efficiency of power generation. Therefore, the development of low-cost and high-efficiency photovoltaic modules is the only way for the continuous development of the photovoltaic industry. With the continuous exploration of photovoltaic researchers and production enterprises on the "reducing cost and improving efficiency" technology of photovoltaic modules, high-efficiency photovoltaic modules have emerged in an endless stream. From the cost structure of the photovoltaic module, the proportion of the solder strip in the cost of the module is about 3.2%, but the quality of the solder strip product directly affects the current collection efficiency of the photovoltaic module, and has a greater impact on the power generation of the photovoltaic module. In addition, the EVA encapsulation adhesive layer also has an important application in the photovoltaic module, and is often used as an adhesive to bond the photovoltaic cell pieces with the glass and back plate. Due to the influence of the installation area environment on the solar cell panel, the solar cell panel is often exposed to outdoor environment for many years, and is often exposed to sunlight, rain and wind, which has a bad influence on the adhesion of the EVA encapsulation adhesive layer, thereby reducing the efficiency of the photovoltaic module. SUMMARY

[0004] The purpose of the present application is to provide a solar photovoltaic solder strip and a photovoltaic module prepared therefrom to solve the problems raised in the background.

[0005] In order to solve the above technical problems, the present application provides the following technical scheme: a solar photovoltaic solder strip and a photovoltaic module prepared therefrom, comprising the following steps:

[0006] Step 1: preparing a photovoltaic solder strip:

[0007] Mixing and melting tin, lead, bismuth and silver to obtain a molten liquid; coating the molten liquid on the surface of the conductive copper-based strip to obtain a photovoltaic solder strip;

[0008] Step 2: preparing a modified EVA encapsulation adhesive layer:

[0009] S21: weigh dodecafluoroheptanol, acrylic acid, phenothiazine and cyclohexane, stir uniformly, then add concentrated sulfuric acid, heat to reflux, evaporate the solvent, cool, let the liquid stand and separate the sulfuric acid, wash the organic phase with sodium bicarbonate solution; dry with anhydrous sodium sulfate and then distill under reduced pressure to obtain the fluorine-containing monomer;

[0010] S22: take pentaerythritol and 4-vinylbenzoic acid, add toluene, concentrated sulfuric acid and hydroquinone, stir uniformly, heat under nitrogen protection, constant temperature preheating, continue to heat and react; wash the esterification liquid with lye, salt water and distilled water several times until neutral, then dry the organic phase with anhydrous sodium sulfate overnight, and then distill under reduced pressure to remove impurities to obtain the benzene-containing crosslinking monomer;

[0011] S23: mix EVA resin, crosslinking agent, fluorine-containing monomer, benzene-containing crosslinking monomer, antioxidant and light stabilizer by open mill, then heat and cold press to obtain the modified EVA encapsulation adhesive layer.

[0012] Step 3: connect the photovoltaic cell pieces by photovoltaic solder strips to obtain a photovoltaic cell piece layer, lay the metal backboard, the first modified EVA encapsulation adhesive layer, the photovoltaic cell piece layer, the second modified EVA encapsulation adhesive layer and the glass cover plate in turn, and perform lamination treatment to obtain a photovoltaic module.

[0013] Further, in step 1, the content of each component in the molten liquid is 35-45% tin, 20-30% lead, 20-30% bismuth and 1-5wt% silver.

[0014] Further, in S21, the preparation method of the fluorine-containing monomer is as follows: weigh dodecafluoroheptanol, acrylic acid, phenothiazine and cyclohexane, stir uniformly, then add concentrated sulfuric acid, heat to 110-130℃, reflux for 1-2h, evaporate the solvent, cool to 30-40℃, let the liquid stand for 2-3h, separate the sulfuric acid, and wash the organic phase with 5% sodium bicarbonate solution until the pH is 7-8; then dry with anhydrous sodium sulfate and distill under reduced pressure to obtain the fluorine-containing monomer.

[0015] Further, in S21, the amount of each component is 33-35 parts by weight of dodecafluoroheptanol, 7.2-8.5 parts of acrylic acid, 2-3 parts of phenothiazine, 8-10 parts of cyclohexane, and 120-150 parts of concentrated sulfuric acid.

[0016] Furthermore, in S22, the preparation method of the benzene-containing crosslinking monomer is as follows: take pentaerythritol, 4-vinylbenzoic acid, toluene, catalyst and hydroquinone, stir evenly, and heat to 70-80℃ under nitrogen protection, preheat at a constant temperature for 30-60 min, raise the temperature to 100-110℃, and react for 3-6 h; then wash the esterification liquid with alkaline solution, brine and distilled water respectively until the pH is 7-8, and then dry the organic phase overnight with anhydrous sodium sulfate and remove impurities by vacuum distillation to obtain the benzene-containing crosslinking monomer.

[0017] Furthermore, in S22, the amounts of each component, by weight, are: 13-15 parts pentaerythritol, 58-60 parts 4-vinylbenzoic acid, 200-250 parts toluene, 300-320 parts concentrated sulfuric acid, and 0.05-0.1 parts hydroquinone.

[0018] Furthermore, the content of each component in S23, by weight, is 100-120 parts EVA resin, 1-2 parts crosslinking agent, 4-6 parts benzene-containing crosslinking monomer, 1-1.5 parts antioxidant, and 1-2 parts light stabilizer; the amount of fluorine-containing monomer is 1-3% of the amount of EVA resin.

[0019] Furthermore, in S23, the antioxidant is any one of antioxidant 1010, antioxidant 168, and antioxidant 1076; the light stabilizer is any one of light stabilizer 770, light stabilizer 944, and light stabilizer 292.

[0020] Furthermore, in S23, the hot pressing temperature is 150–160℃, the hot pressing pressure is 8–10MPa, the hot pressing time is 150–200s, and the holding time is 500–600s.

[0021] Furthermore, in S23, the cold pressing pressure is 8–10 MPa, and the time is 200–240 s.

[0022] Furthermore, in S23, the thickness of the modified EVA encapsulating adhesive layer is 1 to 1.5 mm.

[0023] Compared with existing technologies, the beneficial effects achieved by this invention are as follows: This invention mixes and melts tin, lead, bismuth, and silver to obtain a quaternary solder. The solder's melting point is between 140 and 180°C, meeting the requirements of low-temperature welding processes while maintaining good welding tensile strength. Photovoltaic modules made using the photovoltaic solder ribbon provided by this invention have high photoelectric conversion efficiency.

[0024] In the preparation of photovoltaic components, the EVA encapsulating adhesive is modified. The EVA encapsulating adhesive is a hot melt adhesive, which has good adhesion after melting. Fluorine-containing monomers are obtained by esterification of dodecafluoroheptanol and acrylic acid. By introducing fluorine-containing monomers, the performance of the EVA encapsulating adhesive can be effectively improved. Fluorine atoms have high electronegativity, which can effectively improve the corrosion resistance and hydrophobicity of the encapsulating adhesive, ensuring the strength and stability during use. At the same time, the thermal chemical stability of the fluorine-modified EVA encapsulating adhesive is improved, which can maintain adhesion for a long time in a high-temperature environment. At the same time, the pentaerythritol containing four hydroxyl groups is reacted with 4-vinylbenzoic acid to obtain a benzene-containing crosslinking monomer. The benzene ring can improve the mechanical strength of the EVA encapsulating adhesive, and cooperate with the fluorine-containing monomer to modify the thermal chemical properties. The crosslinking monomer not only can graft with EVA resin to form chemical crosslinking, but also has a tree structure itself, which can react with EVA resin to form physical crosslinking, thereby improving the crosslinking strength and adhesion of the encapsulating adhesive.

[0025] In addition, it should be noted that when modifying the EVA encapsulating adhesive, the amount of fluorine-containing monomers needs to be limited. Since the bonding force between fluorine atoms and other atoms in the fluorine-containing monomer is strong and stable, the introduction of fluorine atoms will reduce the surface tension of the encapsulating adhesive and improve the hydrophobicity of the encapsulating adhesive, but too high content will also cause the problem of reduced adhesion. Therefore, the amount of fluorine-containing monomers is controlled at 1-3% of the amount of EVA resin. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be described below. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0027] The materials used in the embodiments of the present application and their sources: EVA resin from Beijing VAE707 emulsion, model EVA14-2; crosslinking agent is di-t-butyl peroxide from Aladdin; antioxidant 1010 from Guangzhou Dayin New Materials; light stabilizer 944 from Liyanlong New Materials.

[0028] Example 1

[0029] Step 1: Preparation of photovoltaic solder strip:

[0030] Mix 45% tin, 20% lead, 30% bismuth and 5% silver by mass percentage and melt to obtain a molten liquid; coat the molten liquid on the surface of the conductive copper-based strip to obtain a photovoltaic solder strip;

[0031] Step 2: Preparation of modified EVA encapsulating adhesive layer:

[0032] S21: 33.2 g of dodecafluoroheptanol, 7.2 g of acrylic acid, 2 g of phenothiazine and 8.4 g of cyclohexane are weighed, stirred uniformly, then 120 g of concentrated sulfuric acid is added, heated to 110°C, refluxed for 1 h, the solvent is evaporated, cooled to 30°C, the liquid is left to stand for 2 h, the sulfuric acid is separated, and the organic phase is washed with a 5% sodium bicarbonate solution until the pH is 7; then dried with anhydrous sodium sulfate and distilled under reduced pressure to obtain the fluorine-containing monomer;

[0033] S22: 13.6 g of pentaerythritol and 58.86 g of 4-vinylbenzoic acid are taken, 200 g of toluene, 300 g of concentrated sulfuric acid and 0.1 g of hydroquinone are added, stirred uniformly, and heated to 70°C under nitrogen protection, preheated for 30 min, then the temperature is raised to 100°C, and reacted for 3 h; then the esterification liquid is washed with lye, salt water and distilled water several times until it is neutral, then the organic phase is dried with anhydrous sodium sulfate overnight, and impurities are removed by distillation under reduced pressure to obtain the benzene-containing crosslinking monomer;

[0034] S23: 100 kg of EVA resin, 1 kg of crosslinking agent, 1.3 kg of fluorine-containing monomer, 4.5 kg of benzene-containing crosslinking monomer, 1.5 kg of antioxidant 1010, and 1 kg of light stabilizer 944 are mixed and then hot-pressed at 150°C and 8 MPa for 150 s, with a holding pressure of 500 s; and cold-pressed at 8 MPa for 200 s to obtain a modified EVA encapsulation adhesive layer with a thickness of 1.5 mm;

[0035] Step 3: The photovoltaic cell layer is obtained by connecting the photovoltaic cell pieces through the photovoltaic solder strips, and the metal back plate, the first modified EVA encapsulation adhesive layer, the photovoltaic cell layer, the second modified EVA encapsulation adhesive layer and the glass cover plate are sequentially laid and laminated to obtain the photovoltaic module.

[0036] Example 2:

[0037] Step 1: Preparation of photovoltaic solder strip:

[0038] 45% tin, 20% lead, 30% bismuth and 5% silver are mixed and melted to obtain a molten liquid; the molten liquid is coated on the surface of the conductive copper-based strip to obtain the photovoltaic solder strip;

[0039] Step 2: Preparation of modified EVA encapsulation adhesive layer:

[0040] S21: 33.2 g of dodecafluoroheptanol, 7.2 g of acrylic acid, 2 g of phenothiazine and 8.4 g of cyclohexane are weighed, stirred uniformly, then 120 g of concentrated sulfuric acid is added, heated to 113°C, refluxed for 1.5 h, the solvent is evaporated, cooled to 35°C, the liquid is left to stand for 2 h, the sulfuric acid is separated, and the organic phase is washed with a 5% sodium bicarbonate solution until the pH is 7; then dried with anhydrous sodium sulfate and distilled under reduced pressure to obtain the fluorine-containing monomer;

[0041] S22: Take 13.6 g of pentaerythritol and 58.86 g of 4-vinylbenzoic acid, add 200 g of toluene, 300 g of concentrated sulfuric acid and 0.1 g of p-phenylenediamine, stir uniformly, and heat to 72°C under nitrogen protection, preheat for 35 min, then increase the temperature to 103°C, and react for 3 h; then wash the esterification liquid with lye, salt water and distilled water several times until it is neutral, then dry the organic phase with anhydrous sodium sulfate overnight, and then remove the impurities by distillation under reduced pressure to obtain a benzene-containing crosslinking monomer;

[0042] S23: Mix 100 kg of EVA resin, 1 kg of crosslinking agent, 1.3 kg of fluorine-containing monomer, 4.5 kg of benzene-containing crosslinking monomer, 1.5 kg of antioxidant 1010, and 1 kg of light stabilizer 944, and then hot-press at 153°C and 8.5 MPa for 180 s, hold for 510 s, and then cold-press at 8 MPa for 210 s to obtain a modified EVA encapsulation adhesive layer with a thickness of 1.5 mm;

[0043] Step 3: Connect the photovoltaic cell pieces by photovoltaic solder strips to obtain a photovoltaic cell piece layer, lay the metal back plate, the first modified EVA encapsulation adhesive layer, the photovoltaic cell piece layer, the second modified EVA encapsulation adhesive layer and the glass cover plate in sequence, and perform lamination processing to obtain a photovoltaic module.

[0044] Example 3:

[0045] Step 1: Prepare the photovoltaic solder strip:

[0046] Mix 45% tin, 20% lead, 30% bismuth and 5% silver by mass percentage and melt to obtain a molten liquid; coat the molten liquid on the surface of the conductive copper-based strip to obtain a photovoltaic solder strip;

[0047] Step 2: Prepare the modified EVA encapsulation adhesive layer:

[0048] S21: Take 33.2 g of dodecafluoroheptanol, 7.2 g of acrylic acid, 2 g of phenothiazine and 8.4 g of cyclohexane, stir uniformly, then add 120 g of concentrated sulfuric acid, heat to 118°C, reflux for 1.4 h, evaporate the solvent, cool to 34°C, and let the liquid stand for 2.4 h; separate the sulfuric acid and wash the organic phase with a 5% mass concentration sodium bicarbonate solution until the pH is 7.5; then dry with anhydrous sodium sulfate and distill under reduced pressure to obtain a fluorine-containing monomer;

[0049] S22: Take 13.6 g of pentaerythritol and 58.86 g of 4-vinylbenzoic acid, add 200 g of toluene, 300 g of concentrated sulfuric acid and 0.1 g of p-phenylenediamine, stir uniformly, and heat to 72℃ under nitrogen protection, preheat for 40 min, then increase the temperature to 103℃, and react for 4 h; then wash the esterification liquid with lye, salt water and distilled water several times until it is neutral, then dry the organic phase with anhydrous sodium sulfate overnight, and then remove the impurities by distillation under reduced pressure to obtain a benzene-containing crosslinking monomer;

[0050] S23: Mix 100 kg of EVA resin, 1 kg of crosslinking agent, 1.3 kg of fluorine-containing monomer, 4.5 kg of benzene-containing crosslinking monomer, 1.5 kg of antioxidant 1010, and 1 kg of light stabilizer 944, and then heat press at 152℃ and 8.4 MPa for 155 s, hold for 540 s, and then cold press at 8.8 MPa for 210 s to obtain a modified EVA encapsulation adhesive layer with a thickness of 1.5 mm;

[0051] Step 3: Connect the photovoltaic cells by photovoltaic solder strips to obtain a photovoltaic cell layer, lay the metal back plate, the first modified EVA encapsulation adhesive layer, the photovoltaic cell layer, the second modified EVA encapsulation adhesive layer and the glass cover plate in sequence, and then perform lamination to obtain a photovoltaic module.

[0052] Example 4:

[0053] Step 1: Prepare the photovoltaic solder strip:

[0054] Mix 45% tin, 20% lead, 30% bismuth and 5% silver by mass percentage and melt to obtain a molten liquid; coat the molten liquid on the surface of the conductive copper-based strip to obtain a photovoltaic solder strip;

[0055] Step 2: Prepare the modified EVA encapsulation adhesive layer:

[0056] S21: Take 33.2 g of dodecafluoroheptanol, 7.2 g of acrylic acid, 2 g of phenothiazine and 8.4 g of cyclohexane, stir uniformly, then add 120 g of concentrated sulfuric acid, heat to 118℃, reflux for 2 h, evaporate the solvent, cool to 40℃, and let the liquid stand for 2.5 h; separate the sulfuric acid and wash the organic phase with a 5% mass concentration sodium bicarbonate solution until the pH is 7; then dry with anhydrous sodium sulfate and distill under reduced pressure to obtain a fluorine-containing monomer;

[0057] S22: Take 13.6 g of pentaerythritol and 58.86 g of 4-vinylbenzoic acid, add 200 g of toluene, 300 g of concentrated sulfuric acid and 0.1 g of p-phenylenediamine, stir uniformly, and heat to 75°C under nitrogen protection, preheat for 45 min, then increase the temperature to 108°C, and react for 5 h; then wash the esterification liquid with lye, salt water and distilled water several times until it is neutral, then dry the organic phase with anhydrous sodium sulfate overnight, and then remove the impurities by distillation under reduced pressure to obtain a benzene-containing crosslinking monomer;

[0058] S23: Mix 100 kg of EVA resin, 1 kg of crosslinking agent, 1.3 kg of fluorine-containing monomer, 4.5 kg of benzene-containing crosslinking monomer, 1.5 kg of antioxidant 1010, and 1 kg of light stabilizer 944, and then hot-press at 155°C and 8.8 MPa for 185 s, hold for 550 s, and then cold-press at 9 MPa for 210 s to obtain a modified EVA encapsulation adhesive layer with a thickness of 1.5 mm;

[0059] Step 3: Connect the photovoltaic cell pieces by photovoltaic solder strips to obtain a photovoltaic cell piece layer, lay the metal back plate, the first modified EVA encapsulation adhesive layer, the photovoltaic cell piece layer, the second modified EVA encapsulation adhesive layer and the glass cover plate in sequence, and then perform lamination to obtain a photovoltaic module.

[0060] Example 5:

[0061] Step 1: Prepare the photovoltaic solder strip:

[0062] Mix 45% tin, 20% lead, 30% bismuth and 5% silver by mass percentage and melt to obtain a molten liquid; coat the molten liquid on the surface of the conductive copper-based strip to obtain a photovoltaic solder strip;

[0063] Step 2: Prepare the modified EVA encapsulation adhesive layer:

[0064] S21: Take 33.2 g of dodecafluoroheptanol, 7.2 g of acrylic acid, 2 g of phenothiazine and 8.4 g of cyclohexane, stir uniformly, then add 120 g of concentrated sulfuric acid, heat to 120°C, reflux for 1.5 h, evaporate the solvent, cool to 36°C, and let the liquid stand for 2 h; separate the sulfuric acid and wash the organic phase with a 5% mass concentration sodium bicarbonate solution until the pH is 7.5; then dry with anhydrous sodium sulfate and distill under reduced pressure to obtain a fluorine-containing monomer;

[0065] S22: Take 13.6 g of pentaerythritol and 58.86 g of 4-vinylbenzoic acid, add 200 g of toluene, 300 g of concentrated sulfuric acid and 0.1 g of p-phenylenediamine, stir uniformly, and heat to 76℃ under nitrogen protection, preheat for 53 min, then increase the temperature to 108℃, and react for 5.5 h; then wash the esterification liquid with lye, salt water and distilled water several times until it is neutral, then dry the organic phase with anhydrous sodium sulfate overnight, and then remove the impurities by distillation under reduced pressure to obtain a benzene-containing crosslinking monomer;

[0066] S23: Mix 100 kg of EVA resin, 1 kg of crosslinking agent, 1.3 kg of fluorine-containing monomer, 4.5 kg of benzene-containing crosslinking monomer, 1.5 kg of antioxidant 1010, and 1 kg of light stabilizer 944, and then heat press at 157℃ and 9.4 MPa for 190 s, hold for 580 s, and then cold press at 9.7 MPa for 230 s to obtain a modified EVA encapsulation adhesive layer with a thickness of 1.5 mm;

[0067] Step 3: Connect the photovoltaic cell pieces by photovoltaic solder strips to obtain a photovoltaic cell piece layer, lay the metal back plate, the first modified EVA encapsulation adhesive layer, the photovoltaic cell piece layer, the second modified EVA encapsulation adhesive layer and the glass cover plate in sequence, and then perform lamination treatment to obtain a photovoltaic module.

[0068] Example 6:

[0069] Step 1: Prepare the photovoltaic solder strip:

[0070] Mix 45% tin, 20% lead, 30% bismuth and 5% silver by mass percentage and melt to obtain a molten liquid; coat the molten liquid on the surface of the conductive copper-based strip to obtain a photovoltaic solder strip;

[0071] Step 2: Prepare the modified EVA encapsulation adhesive layer:

[0072] S21: Take 33.2 g of dodecafluoroheptanol, 7.2 g of acrylic acid, 2 g of phenothiazine and 8.4 g of cyclohexane, stir uniformly, then add 120 g of concentrated sulfuric acid, heat to 130℃, reflux for 2 h, evaporate the solvent, cool to 40℃, and let the liquid stand for 3 h; separate the sulfuric acid and wash the organic phase with a 5% sodium bicarbonate solution until the pH is 8; then dry with anhydrous sodium sulfate and distill under reduced pressure to obtain a fluorine-containing monomer;

[0073] S22: Take 13.6 g of pentaerythritol and 58.86 g of 4-vinylbenzoic acid, add 200 g of toluene, 300 g of concentrated sulfuric acid and 0.1 g of hydroquinone, uniformly stir, and heat to 80°C under nitrogen protection, preheat for 60 min, then increase the temperature to 110°C, react for 6 h; then the esterification liquid is washed with lye, salt water and distilled water several times until it is neutral, then the organic phase is dried with anhydrous sodium sulfate overnight, and then the impurities are removed by distillation under reduced pressure to obtain a benzene-containing crosslinking monomer;

[0074] S23: After mixing 100 kg of EVA resin, 1 kg of crosslinking agent, 1.3 kg of fluorine-containing monomer, 4.5 kg of benzene-containing crosslinking monomer, 1.5 kg of antioxidant 1010, and 1 kg of light stabilizer 944, hot pressing is performed at 160°C and 10 MPa for 200 s, pressure maintaining for 600 s, and cold pressing at 10 MPa for 240 s to obtain a modified EVA encapsulation adhesive layer with a thickness of 1.5 mm;

[0075] Step 3: Connect the photovoltaic cell pieces by photovoltaic solder strips to obtain a photovoltaic cell piece layer, lay the metal back plate, the first modified EVA encapsulation adhesive layer, the photovoltaic cell piece layer, the second modified EVA encapsulation adhesive layer, and the glass cover plate in sequence, and perform lamination treatment to obtain a photovoltaic module.

[0076] Comparative Example 1: Modify the EVA encapsulation adhesive layer without adding benzene-containing crosslinking monomer, and the other parameters are the same as in Example 1.

[0077] Step 1: Prepare photovoltaic solder strips:

[0078] Mix 45% tin, 20% lead, 30% bismuth, and 5% silver by mass percentage and melt to obtain a molten liquid; coat the molten liquid on the surface of a conductive copper-based strip to obtain a photovoltaic solder strip;

[0079] Step 2: Prepare a modified EVA encapsulation adhesive layer:

[0080] S21: Take 33.2 g of dodecafluoroheptanol, 7.2 g of acrylic acid, 2 g of phenothiazine, and 8.4 g of cyclohexane, stir uniformly, then add 120 g of concentrated sulfuric acid, heat to 110°C, reflux for 1 h, evaporate the solvent, cool to 30°C, and let the liquid stand for 2 h. Separate the sulfuric acid and wash the organic phase with a 5% mass concentration sodium bicarbonate solution until the pH is 7; then dry with anhydrous sodium sulfate and distill under reduced pressure to obtain a fluorine-containing monomer;

[0081] S22: After mixing 100 kg of EVA resin, 1 kg of crosslinking agent, 1.3 kg of fluorine-containing monomer, 1.5 kg of antioxidant 1010, and 1 kg of light stabilizer 944, hot pressing is performed at 150°C and 8 MPa for 150 s, pressure maintaining for 500 s, and cold pressing at 8 MPa for 200 s to obtain a modified EVA encapsulation adhesive layer with a thickness of 1.5 mm.

[0082] Step 3: connecting the photovoltaic cells by the photovoltaic soldering ribbon to obtain a photovoltaic cell layer, laying a metal back plate, a first modified EVA encapsulant layer, the photovoltaic cell layer, a second modified EVA encapsulant layer and a glass cover plate in sequence, and performing lamination treatment to obtain a photovoltaic module.

[0083] Comparative Example 2: increasing the amount of fluorine-containing monomer in step S23, and the remaining parameters are the same as those in Example 2.

[0084] Step 1: preparing a photovoltaic soldering ribbon:

[0085] Mixing 45% tin, 20% lead, 30% bismuth and 5% silver by mass percentage and melting to obtain a molten liquid; coating the molten liquid on the surface of a conductive copper-based strip to obtain a photovoltaic soldering ribbon;

[0086] Step 2: preparing a modified EVA encapsulant layer:

[0087] S21: weighing 33.2 g of dodecafluoroheptanol, 7.2 g of acrylic acid, 2 g of phenothiazine and 8.4 g of cyclohexane, stirring uniformly, then adding 120 g of concentrated sulfuric acid, heating to 113℃, refluxing for 1.5 h, evaporating the solvent, cooling to 35℃, and then separating the sulfuric acid and washing the organic phase with a 5% mass concentration sodium bicarbonate solution until the pH is 7; then drying with anhydrous sodium sulfate and distilling under reduced pressure to obtain a fluorine-containing monomer;

[0088] S22: taking 13.6 g of pentaerythritol and 58.86 g of 4-vinylbenzoic acid, adding 200 g of toluene, 300 g of concentrated sulfuric acid and 0.1 g of hydroquinone, stirring uniformly, and heating to 72℃ under nitrogen protection, and preheating at a constant temperature for 35 min, then increasing the temperature to 103℃, and reacting for 3 h; then washing the esterification liquid with lye, salt water and distilled water several times until it is neutral, and then drying the organic phase with anhydrous sodium sulfate overnight and distilling under reduced pressure to remove impurities to obtain a benzene-containing crosslinking monomer;

[0089] S23: mixing 100 kg of EVA resin, 1 kg of crosslinking agent, 5 kg of fluorine-containing monomer, 4.5 kg of benzene-containing crosslinking monomer, 1.5 kg of antioxidant 1010 and 1 kg of light stabilizer 944, and hot pressing at 153℃ and 8.5 MPa for 180 s, holding for 510 s, and then cold pressing at 8 MPa for 210 s to obtain a modified EVA encapsulant layer with a thickness of 1.5 mm;

[0090] Step 3: connecting the photovoltaic cells by the photovoltaic soldering ribbon to obtain a photovoltaic cell layer, laying a metal back plate, a first modified EVA encapsulant layer, the photovoltaic cell layer, a second modified EVA encapsulant layer and a glass cover plate in sequence, and performing lamination treatment to obtain a photovoltaic module.

[0091] Experiment:

[0092] The photovoltaic soldering strips prepared in Examples 1-6 and the battery pieces were welded by using an automatic welding machine, the welding table temperature was 120℃, the welding tension of the photovoltaic soldering strips and the battery pieces was tested, and the experimental results are shown in Table 1.

[0093] Table 1

[0094]

[0095]

[0096] The EVA encapsulation adhesive layers in Examples 1-6 and Comparative Examples 1-2 were tested, and the experimental results are shown in Table 2.

[0097] Wherein:

[0098] Adhesion performance test: under the condition of 140℃ and 100Pa vacuum for 5min, then laminated under the pressure of 50kPa for 15min, the peel strength of the composite film after lamination and bonding was tested by using a universal material testing machine, the test condition was a peel speed of 0.05m / min and a peel angle of 180°;

[0099] Hydrophobic performance test: the surface contact angle of the EVA encapsulation adhesive layer was tested;

[0100] Table 2

[0101]

[0102]

[0103] Conclusion: the data in Table 1 shows that the photovoltaic soldering strips prepared by the application have good welding effect with the battery pieces, the data in Table 2 shows that the peel strength of the EVA encapsulation adhesive layer prepared by the application reaches 7.5N / cm, the adhesion performance is strong; at the same time, the EVA encapsulation adhesive layer has excellent hydrophobic performance, which can improve the service time and reduce the repair rate when used for the packaging of photovoltaic modules. The data of Example 1 and Comparative Example 1 shows that the addition of the benzene-containing crosslinking monomer can effectively improve the adhesion performance of the EVA encapsulation adhesive layer; the data of Example 2 and Comparative Example 2 shows that too high fluorine-containing monomer can reduce the adhesion performance of the EVA encapsulation adhesive layer.

[0104] Finally, it should be noted that: the above only describes the preferred embodiments of the application, and is not used to limit the application, although the application has been described in detail with reference to the foregoing embodiments, for those skilled in the art, the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced equivalently. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the application shall be included in the protection scope of the application.

Claims

1. A method for preparing a photovoltaic module, characterized in that: Includes the following steps: Step 1: Preparation of modified EVA encapsulating adhesive layer: S1: Weigh dodecafluoroheptanol, acrylic acid, phenothiazine and cyclohexane, stir and mix, add concentrated sulfuric acid, heat to 110-130℃, reflux for 1-2 hours, remove solvent by evaporation, cool to 30-40℃, let the liquid stand for 2-3 hours, separate and remove sulfuric acid, and wash the organic phase with sodium bicarbonate solution until pH is 7-8; then dry with anhydrous sodium sulfate and distill under reduced pressure to obtain fluorine-containing monomers. S2: Take pentaerythritol, 4-vinylbenzoic acid, toluene, concentrated sulfuric acid and hydroquinone, stir evenly, and heat to 70-80℃ under nitrogen protection, preheat at constant temperature for 30-60 min, raise the temperature to 100-110℃, and react for 3-6 h; then wash the esterification solution with alkaline solution, brine and distilled water respectively until the pH is 7-8, and then dry the organic phase overnight with anhydrous sodium sulfate and remove impurities by vacuum distillation to obtain the benzene-containing crosslinked monomer; S3: After open mixing of EVA resin, crosslinking agent, fluorinated monomer, benzene-containing crosslinking monomer, antioxidant, and light stabilizer, the modified EVA encapsulation layer is obtained by hot pressing and cold pressing. The content of each component in S3, by weight, is 100-120 parts EVA resin, 1-2 parts crosslinking agent, 4-6 parts benzene-containing crosslinking monomer, 1-1.5 parts antioxidant, 1-2 parts light stabilizer, and the amount of fluorine-containing monomer is 1-3% of the amount of EVA resin. Step 2: Connect the photovoltaic cells with photovoltaic ribbons to obtain the photovoltaic cell layer. Then, lay the metal backsheet, modified EVA encapsulant layer, photovoltaic cell layer, modified EVA encapsulant layer and glass cover in sequence, and perform lamination to obtain the photovoltaic module.

2. The method for preparing a photovoltaic module according to claim 1, characterized in that: The amounts of each component in S1, by weight, are: 33–35 parts dodecafluoroheptanol, 7.2–8.5 parts acrylic acid, 2–3 parts phenothiazine, 8–10 parts cyclohexane, and 120–150 parts concentrated sulfuric acid.

3. The method for preparing a photovoltaic module according to claim 1, characterized in that: The amounts of each component in S2, by weight, are: 13-15 parts pentaerythritol, 58-60 parts 4-vinylbenzoic acid, 200-250 parts toluene, 300-320 parts concentrated sulfuric acid, and 0.05-0.1 parts hydroquinone.

4. The method for preparing a photovoltaic module according to claim 1, characterized in that: In S3, the antioxidant is any one of antioxidant 1010, antioxidant 168, and antioxidant 1076; the light stabilizer is any one of light stabilizer 770, light stabilizer 944, and light stabilizer 292.

5. The method for preparing a photovoltaic module according to claim 1, characterized in that: In S3, the hot pressing temperature is 150-160℃, the hot pressing pressure is 8-10MPa, the hot pressing time is 150-200s, and the holding time is 500-600s; the cold pressing pressure is 8-10MPa, and the time is 200-240s; the thickness of the modified EVA encapsulation adhesive layer is 1-1.5mm.

6. The method for preparing a photovoltaic module according to claim 1, characterized in that: The photovoltaic solder ribbon is prepared by mixing and melting tin, lead, bismuth and silver to obtain a molten liquid; coating the molten liquid onto the surface of a conductive copper base strip to obtain a photovoltaic solder ribbon.

7. A method for preparing a photovoltaic module according to claim 6, characterized in that: The content of each component in the molten liquid, by weight percentage, is 35-45% tin, 20-30% lead, 20-30% bismuth, and 1-5 wt% silver.

8. A photovoltaic module prepared by any one of the methods for preparing a photovoltaic module according to any one of claims 1 to 7.

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