A multi-main grid battery module with a reflective film and its manufacturing process

Abstract

The present invention discloses a multi-busbar battery module with a reflective film and its preparation process, which includes glass, a battery cell assembly, and a backsheet. The battery cell assembly is disposed below the glass, and the backsheet is disposed below the battery cell assembly. An anti-PID film is disposed between the battery cell assembly and the glass, and an EVA film is disposed between the battery cell assembly and the backsheet. Through the reflective film on the solder tape, the present invention avoids the loss of sunlight in the solder tape area, improves the utilization rate of incident light, and promotes the further improvement of the module power. The microstructures in the reflective film deflect the light incident on the solder tape and then reflect it. After being reflected twice by the glass, the light is finally reflected onto the battery surface and converted into electrical energy, improving the efficiency of the battery module, and is suitable for wide promotion and use.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic cells, and specifically to a multi-busbar cell module with a reflective film and its manufacturing process. Background Art

[0002] At the current stage of the rapid development of technology, it has become a consensus to carry out energy transformation and accelerate the popularization of clean energy. Among them, photovoltaic cells that convert solar light into electrical energy have great advantages, but the cost per kilowatt-hour still needs to be reduced. The optimal solution is to improve the efficiency of the module and reduce the internal losses of the module. Materials are the material basis of photovoltaic cells. In photovoltaic cells, solder ribbons are needed to weld multi-busbar cell wafers. The solder ribbons will block sunlight and prevent the cell wafers from utilizing light, resulting in a loss of cell efficiency. Therefore, we propose a multi-busbar cell module with a reflective film and its manufacturing process. Summary of the Invention

[0003] The purpose of the present invention is to provide a multi-busbar cell module with a reflective film and its manufacturing process to solve the problems in the prior art.

[0004] To achieve the above purpose, the present invention provides the following technical solution: A multi-busbar cell module with a reflective film and its manufacturing process, including glass, a cell wafer assembly, and a backsheet. The cell wafer assembly is disposed below the glass, and the backsheet is disposed below the cell wafer assembly. An anti-PID film is disposed between the cell wafer assembly and the glass, and an EVA film is disposed between the cell wafer assembly and the backsheet. The cell wafer assembly includes multiple groups of cell strings, and adjacent two groups of cell strings are connected by solder ribbons. One group of cell strings includes multiple groups of cell wafers, and adjacent two groups of cell wafers are connected by solder ribbons. A reflective film is disposed on the top of the solder ribbon.

[0005] Further, multiple groups of main grids are disposed on the top of the cell wafer, and the cell strings and the cell wafers are all located in the same plane.

[0006] In the above technical solution, the cell wafers are multi-busbar cell wafers, and the cell wafer assembly is a polycrystalline 12-busbar assembly, which can reduce the surface occlusion of the cell wafers, increase the light-receiving area, shorten the conduction distance of the current on the fine grids, achieve the effect of effectively reducing the series resistance of the module and reducing the resistance loss, thereby improving the efficiency of the cell module.

[0007] Further, the reflective film includes a microstructure, a base layer, and a coating layer. The microstructure is in the shape of a triangular pyramid. The included angle B between the inclined surface of the microstructure and the base layer is 28.4 - 42.1°, the edge length C of the microstructure is 16.5 - 21.0 μm, and the refractive index of the base layer is 1.50 - 1.60.

[0008] In the above technical solution, the addition of the reflective film can improve the utilization rate of incident light and promote the further improvement of the component power. Among them, the angle B between the micro-structured inclined surface and the base layer can deflect the incident light angle, concentrate the sunlight in the vertical direction, so that after the sunlight is incident on the coating layer for reflection, it can be refolded to the interface between the glass and the air for total reflection. The angles of other light rays with the vertical direction are relatively large, and total reflection can directly occur on the bottom surface of the reflective film. The refractive index of the base layer is between 1.50 and 1.60, so that the refractive index of the base layer is lower than that of the micro-structure, improving the reflectivity of the reflective film. The setting of the coating layer can reduce the loss of sunlight on the reflective film, achieving the effect of increasing the total amount of light received by the solar cell and improving the power of the battery component.

[0009] Further, the anti-PID film comprises the following weight components: 64-72 parts of polyolefin resin, 5-15 parts of brominated polyphenylene ether, 6-10 parts of p-chloromethylstyrene, 1-3 parts of 1-methylimidazole, and 0.1-1 part of stabilizer.

[0010] A preparation process of a multi-busbar battery module with a reflective film comprises the following steps:

[0011] 1) Cell sorting: Sort the cells with qualified appearance, and divide the cells with the same color and efficiency into one group. The number of cells in one group is the number required for one group of battery modules.

[0012] 2) Welding: Take the cells and put them into a string welding machine for welding to form a cell module.

[0013] 3) Laminating: Lay the materials in the laying order of glass, anti-PID film, cell module, EVA film, and backsheet to form a module structure.

[0014] 4) Laminating: Place the module structure in a laminator for laminating to form a laminated module.

[0015] 5) Framing: Take the semi-finished battery module after laminating, assemble it with a frame, and install a junction box to obtain a battery module.

[0016] 6) Testing: Conduct tests according to the test standards to obtain the finished battery module.

[0017] 7) Packaging: Take the finished battery module, install the lead-out wire and fix it, put it into a packing box, wrap it with corner protectors, and wind it with a PE film to obtain the product.

[0018] In the above technical solution, when sorting the battery cells in step 1), place the battery cells 30 cm away from the eyes and check each battery cell for defects such as color difference, broken pieces, cracks, missing corners, chipped edges, poor grid line printing, and positive electrode bulging under light, and select qualified products for later use; after framing, there is also a cleaning process, scraping off the residual colloid on the front of the module, wiping the front and the aluminum alloy with alcohol, removing the residual colloid on the backplane, and removing the surface film on the frame to ensure the yield and surface cleanliness of the finished battery module.

[0019] Further, step 2) includes the following steps:

[0020] Take the welding tape and use infrared heating to weld the battery cells one by one to form a battery string, and then weld the battery strings in series to form a battery cell assembly. While welding the battery strings, paste a reflective film on the surface of the welded welding tape to obtain a battery cell assembly, where the temperature of the welding film bottom plate is 100 - 120 °C.

[0021] In the above technical solution, the selected welding tape is a round welding tape, which can effectively reduce the shading area. Combined with the reflective film, sunlight can be reflected onto the battery cells, improving the utilization rate of sunlight in the area of the welding tape and the efficiency of the battery module.

[0022] Further, the lamination process in step 3) is as follows:

[0023] Take the materials and lay them in the order of glass, anti-PID film, battery cell assembly, EVA film, and backplane to form a module structure.

[0024] In the above technical solution, for lamination repair, a manual film pasting station is added, and the temperature requirement of the manual film pasting heating plate is 90 - 110 °C.

[0025] Further, step 4) includes the following steps:

[0026] Place the module structure formed after lamination in a double-chamber laminator, evacuate the module structure and laminate it to form a laminated module;

[0027] Among them, the vacuum degree of the laminator is 90 - 120 Pa. Parameters of chamber one: lamination temperature is 130 - 142 °C, evacuation time is 4 - 7 min, and lamination time is 0.5 - 2 min; parameters of chamber two: lamination temperature is 140 - 152 °C, evacuation time is 0 - 1 min, and lamination time is 6 - 9 min; and the total lamination time of chamber one and chamber two is 7 - 11 min, the primary lamination pressure is 50 - 70 KPa, the secondary lamination pressure is 20 - 60 KPa, and the tertiary lamination pressure is 10 - 30 KPa.

[0028] In the above technical solution, a double-chamber laminator is used to laminate the component structure formed after lamination. It has high production efficiency, and its process and process parameters can be adapted to the anti-PID film in the present invention, preventing bubbles from being generated during the use of the double-chamber laminator, ensuring the incident rate of sunlight, and making fine adjustments within the above parameter range according to the materials of the glass and the backplane.

[0029] Further, the preparation process of the reflective film is as follows:

[0030] a) Prepare the base layer:

[0031] Take polyethylene terephthalate, polyallyl diglycol carbonate, 2,8-di-tert-butyl-4-methylphenol, and sodium dihydrogen phosphate and co-extrude them, cast the film and conduct heat treatment. The heat treatment process is as follows: After maintaining the temperature at 50 - 70°C for 1 - 5 minutes, then raise the temperature to 120 - 140°C, conduct cyclic hot air treatment for 20 - 40 seconds and then slowly cool down to room temperature. The pressure is always 270 - 700 KPa to obtain the base layer;

[0032] b) Prepare the coating layer:

[0033] Take the base layer and dry it, coat an aqueous adhesive on the back, and conduct vacuum aluminizing after drying. The vacuum degree is 4.0×10-4 - 1.0×10-2 Pa to obtain the aluminum sheet layer;

[0034] Take copper sulfate, sodium citrate, nickel sulfate, ethylenediaminetetraacetic acid disodium (complexing agent), sodium tetraborate (reducing agent), thiourea, sodium dodecylbenzenesulfonate, 2,2-bipyridine, p-benzoquinone, and deionized water to prepare the copper plating solution. Adjust the pH value of the plating solution to 5.0 - 5.8 with sulfuric acid, raise the temperature to 60 - 70°C, and put the base layer coated with the aluminum sheet layer into it to obtain the copper sheet layer;

[0035] After drying, conduct vacuum aluminizing again to form a secondary aluminum sheet layer and obtain the coating layer;

[0036] c) Prepare the micro-structure:

[0037] Take poly(2-methylallyl benzothiazole mercaptan), silane-modified glass powder, polycaprolactone polyol, isocyanate, sodium ethylenediamine sulfonate, acetone, and antioxidant and blend them. Coat the obtained coating on the front of the base layer, dry it, and then conduct hot pressing with a mold for 3 - 6 minutes. After cooling, remove the mold, adjust the temperature to 70 - 110°C in a nitrogen atmosphere, keep it warm for 20 - 40 minutes, slowly cool down to room temperature, and extract the air in the reaction kettle to form the micro-structure and obtain the reflective film.

[0038] In the above technical solution, polyethylene terephthalate and allyl diglycol carbonate are used as the base resins of the base layer. They have good optical and mechanical properties. Sodium dihydrogen phosphate affects the crystallinity, melting point and glass transition temperature of polyethylene terephthalate, and can increase the initial decomposition temperature of the base layer and improve the thermal stability of the base layer. 2,8-Di-tert-butyl-4-methylphenol improves the antioxidant performance of the prepared base layer, enabling the base layer to have a certain refractive index while meeting the performance requirements of the reflective film, facilitating the combination with the micro-structure and achieving the optical properties required for the reflective film; in the coating preparation process, an aluminum sheet layer-copper sheet layer-aluminum sheet layer structure is formed on the back of the base layer. Aluminum and copper have high reflectivity. The aluminum sheet layer in contact with the base layer provides the ability of the reflective film to reflect sunlight. The copper sheet layer is bonded to the aluminum sheet layer, which can prevent the oxidation of the above-mentioned aluminum sheet layer, avoid affecting its reflectivity, and at the same time improve the heat conduction ability and dimensional stability of the reflective film. Combined with the outermost aluminum sheet layer, while maintaining the flexibility of the reflective film, it is naturally oxidized in an air environment to form a passivation layer, achieving the purpose of isolating the solder strip and protecting the base layer and solder strip of the reflective film; poly(2-methylallyl benzothiazole mercaptan) is used as the base resin and combined with silane-modified glass powder, making the prepared micro-structure have a high refractive index. Under the action of isocyanate, polycaprolactone polyol reacts at a certain temperature condition, improving the toughness, mechanical strength and adhesion of the prepared micro-structure, and promoting the close combination between the micro-structure and the base layer; the combination of the base layer, micro-structure and coating can improve the utilization rate of incident light by the reflective film and promote the improvement of the component power.

[0039] Further, the preparation process of the anti-PID film is as follows:

[0040] Acetone is introduced into trimethylamine, and p-chloromethylstyrene is added, and the reaction is carried out at room temperature for 10-12 h. The reaction product is taken and brominated polyphenylene ether is added, and chlorobenzene and N-methylpyrrolidone are added. Under a nitrogen atmosphere, it is fully stirred, and copper bromide, bipyridine and arsonic acid acetic acid are added. After vacuum pumping, the reaction is carried out at a temperature of 115-125 °C for 42-54 h. The reaction product is vacuum dried at 56-64 °C for 18-30 h, then dissolved in the solvent N-methylpyrrolidone, 1-methylimidazole is added, and the mixture is stirred at a temperature of 40-45 °C for 12-24 h. Polyolefin and stabilizer are added, and a film is formed by casting and the solvent is removed. After heat treatment, the anti-PID film is obtained.

[0041] In the above technical solution, through the above reaction, the reaction product is positively charged, repelling the cations moving towards the anti-PID film from the outside, and can block the free sodium ions formed by the reaction of sodium-containing substances in the glass with water under the influence of the environment, preventing the cations from moving and aggregating towards the battery chip and affecting the normal operation of the PN junction. Moreover, it dissociates into hydroxide ions in water to be alkaline, which can neutralize the erosion of acidic rain on the film and extend the service life of the anti-PID film. The water vapor transmission rate of polyolefin is relatively low, the volume resistance is relatively high, and it is not easy to generate free radicals when exposed to ultraviolet light. The combination of the two can effectively reduce the deviation of ions towards the battery chip, achieve the purpose of anti-PID effect, and thus improve the battery efficiency.

[0042] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: The multi-busbar battery module with a reflective film and its preparation process of the present invention, through the reflective film on the solder tape, avoid the loss of sunlight in the solder tape area, improve the utilization rate of incident light, and promote the further improvement of the module power. The microstructures in the reflective film deflect the light incident on the solder tape and then reflect it. After being reflected twice by the glass, the light is finally reflected to the battery surface and converted into electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation to the present invention. In the drawings:

[0044] Figure 1 is a top view structural schematic diagram of a group of triangular pyramids of the microstructures in the present invention;

[0045] Figure 2 is a sectional structural schematic diagram of a group of triangular prisms of the embossed structures in the present invention.

[0046] Where B is the angle between the inclined surface of the microstructure and the base layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0047] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0048] Embodiment 1

[0049] Sort the battery chips with qualified appearance, divide the battery chips with the same color and the same efficiency into one group, the number of battery chips in one group is 60 groups, the battery chips are multi-busbar battery chips, and the battery chip module is a polycrystalline 12-busbar module;

[0050] Co - extrude polyethylene terephthalate, allyl diglycol carbonate, 2,8 - di - tert - butyl - 4 - methylphenol, and sodium dihydrogen phosphate, and then cast and heat - treat the film. The heat - treatment process is as follows: keep it at 50°C for 1 minute, then raise the temperature to 120°C, perform cyclic hot - air treatment for 20 seconds, and then slowly cool to room temperature. The pressure is always 270 KPa to obtain the base layer; dry the base layer, coat an aqueous adhesive on the back, and perform vacuum aluminizing after drying. The vacuum degree is 4.0×10 -4 Pa to obtain the aluminum - film layer; prepare a copper - plating solution with copper sulfate, sodium citrate, nickel sulfate, ethylenediaminetetraacetic acid disodium (complexing agent), sodium tetraborate (reducing agent), thiourea, sodium dodecylbenzenesulfonate, 2,2 - bipyridine, p - benzoquinone, and deionized water. Adjust the pH value of the plating solution to 5.0 with sulfuric acid, raise the temperature to 60°C, and put the base layer plated with the aluminum - film layer to obtain the copper - film layer; dry it and then perform vacuum aluminizing again to form a secondary aluminum - film layer to obtain the coating layer; blend poly(2 - methylallyl benzothiazole mercaptan), silane - modified glass powder, polycaprolactone polyol, isocyanate, sodium ethylenediaminosulfonate, acetone, and antioxidant, coat the resulting coating on the front of the base layer, dry it, and then perform hot pressing for 3 minutes using a mold. After cooling, remove the mold, adjust the temperature to 70°C in a nitrogen atmosphere, keep it warm for 20 minutes, slowly cool to room temperature, and extract the air in the reaction kettle to form a microstructure. The microstructure is in the shape of a triangular pyramid. The angle B between the inclined plane of the microstructure and the base layer is 28.4°, the edge length C of the microstructure is 16.5 μm, and the refractive index of the base layer is 1.50 to obtain the reflective film;

[0051] Pass acetone into trimethylamine, add p - chloromethylstyrene, and react at room temperature for 10 hours. Add the reaction product to brominated polyphenylene ether, add chlorobenzene and N - methylpyrrolidone, stir well in a nitrogen atmosphere, add copper bromide, bipyridine, and arsonic acid - based acetic acid, evacuate, and react at 115°C for 42 hours. Vacuum - dry the reaction product at 56°C for 18 hours, then dissolve it in the solvent N - methylpyrrolidone, add 1 - methylimidazole, stir at 40°C for 12 hours, add polyolefin and stabilizer, cast and form a film and remove the solvent, and obtain the anti - PID film after heat - treatment;

[0052] Take the solder strip and use infrared heating to perform single - cell welding on the battery cells to form a battery string, and then perform series welding on the battery strings to form a battery - cell assembly. While welding the battery strings, paste the reflective film on the surface of the already - welded solder strip to obtain the battery - cell assembly, where the temperature of the welding - film bottom plate is 100°C; lay the materials in the order of glass, anti - PID film, battery - cell assembly, EVA film, and backplane to form an assembly structure;

[0053] Place the assembled component structure formed by lamination in a double-chamber laminator, evacuate the component structure and perform lamination to form a laminated component; the vacuum degree of the laminator is 90 Pa, the parameters of one chamber: the lamination temperature is 130 °C, the evacuation time is 4 min, and the lamination time is 1 min; the parameters of the second chamber: the lamination temperature is 140 °C, the evacuation time is 0 min, and the lamination time is 6 min; and the total lamination time of the first chamber and the second chamber is 7 min, the primary lamination pressure is 50 KPa, the secondary lamination pressure is 20 KPa, and the tertiary lamination pressure is 10 KPa; take the semi-finished battery component after lamination, assemble it with a frame, and install a junction box to obtain a battery component.

[0054] Example 2

[0055] Sort out the battery wafers with qualified appearance, divide the battery wafers with the same color and efficiency into a group, the number of battery wafers in a group is 60 groups, the battery wafers are multi-main grid battery wafers, and the battery wafer assembly is a polycrystalline 12-grid assembly;

[0056] Co-extrude polyethylene terephthalate, polyallyl diglycol carbonate with 2,8-di-tert-butyl-4-methylphenol and sodium dihydrogen phosphate, cast a film and perform heat treatment. The heat treatment process is: keep warm at 60 °C for 3 min, then heat up to 130 °C, perform circulating hot air treatment for 30 s and then slowly cool down to room temperature, and the pressure is always 485 KPa to obtain a base layer; dry the base layer, coat a water-based adhesive on the back, and perform vacuum aluminizing after drying, and the vacuum degree is 1.0×10 -3 Pa to obtain an aluminum sheet layer; take copper sulfate, sodium citrate, nickel sulfate, ethylenediaminetetraacetic acid disodium (complexing agent), sodium tetraborate (reducing agent), thiourea, sodium dodecylbenzenesulfonate, 2,2'-bipyridine, p-benzoquinone, deionized water to prepare a copper plating solution, adjust the pH value of the plating solution to 5.4 with sulfuric acid, heat up to 65 °C, and put the base layer plated with an aluminum sheet layer to obtain a copper sheet layer; dry and then perform vacuum aluminizing again to form a secondary aluminum sheet layer to obtain a coating; take poly(2-methylallyl benzothiazole mercaptan), silane-modified glass powder, polycaprolactone polyol, isocyanate, sodium ethylenediamine sulfonate and acetone, antioxidant and blend them to prepare a coating and coat it on the front of the base layer. After drying, perform hot pressing with a mold for 4.5 min, remove the mold after cooling, adjust the temperature to 90 °C in a nitrogen atmosphere, keep warm for 30 min, slowly cool down to room temperature, and extract the air in the reaction kettle to form a microstructure. The included angle B between the inclined plane of the microstructure and the base layer is 35.2°, the edge length C of the microstructure is 18.5 μm, and the refractive index of the base layer is 1.55 to obtain a reflective film;

[0057] Acetone was introduced into trimethylamine, and p-chloromethylstyrene was added. The reaction was carried out at room temperature for 11 h. The reaction product was taken and brominated polyphenylene oxide was added, and then chlorobenzene and N-methylpyrrolidone were added. Under a nitrogen atmosphere, it was fully stirred, and copper bromide, bipyridine, and arsenoacetic acid were added. The vacuum was evacuated, and the reaction was carried out at 120 °C for 48 h. The reaction product was vacuum-dried at 60 °C for 24 h, then dissolved in the solvent N-methylpyrrolidone, 1-methylimidazole was added, and it was stirred at 42 °C for 18 h. Polyolefin and stabilizer were added, and a film was formed by casting and the solvent was removed. After heat treatment, an anti-PID film was obtained;

[0058] The welding tape was taken and the solar cells were welded one by one by means of infrared heating to form a battery string, and then the battery strings were welded in series to form a solar cell module. While the battery strings were being welded, a reflective film was pasted on the surface of the welded welding tape to obtain a solar cell module, where the temperature of the welding film bottom plate was 110 °C; The materials were taken and laid in the order of glass, anti-PID film, solar cell module, EVA film, and backsheet to form a module structure;

[0059] The formed module structure was placed in a double-chamber laminator, the module structure was evacuated and laminated to form a laminated module; The vacuum degree of the laminator was 105 Pa. Parameters of one chamber: the lamination temperature was 136 °C, the vacuum evacuation time was 5.5 min, and the lamination time was 1.2 min; Parameters of the second chamber: the lamination temperature was 146 °C, the vacuum evacuation time was 0.5 min, and the lamination time was 7.5 min; And the total lamination time of one chamber and the second chamber was 8.7 min, the primary lamination pressure was 60 KPa, the secondary lamination pressure was 40 KPa, and the tertiary lamination pressure was 20 KPa; The laminated semi-finished battery module was taken, assembled with a frame, and a junction box was installed to obtain a battery module.

[0060] Example 3

[0061] The solar cells with qualified appearance were sorted, and the solar cells with the same color and efficiency were divided into one group. The number of solar cells in one group was 60 groups. The solar cells were multi-main grid solar cells, and the solar cell module was a polycrystalline 12-grid module;

[0062] Polyethylene terephthalate, polyallyl diglycol carbonate, 2,8-di-tert-butyl-4-methylphenol, and sodium dihydrogen phosphate were co-extruded, and a film was formed by casting and heat treatment. The heat treatment process was: after holding at 70 °C for 5 min, then heating to 140 °C, circulating hot air treatment for 40 s and then slowly cooling to room temperature, and the pressure was always 700 KPa to obtain a base layer; The base layer was dried, a water-based adhesive was coated on the back, and vacuum aluminization was carried out after drying. The vacuum degree was 1.0×10 -2Take Pa to prepare an aluminum sheet layer; take copper sulfate, sodium citrate, nickel sulfate, disodium ethylenediaminetetraacetate (complexing agent), sodium tetraborate (reducing agent), thiourea, sodium dodecylbenzenesulfonate, 2,2-bipyridine, p-benzoquinone, and deionized water to prepare a copper plating solution. Adjust the pH value of the plating solution to 5.8 with sulfuric acid, heat it to 70 °C, and put in the substrate plated with the aluminum sheet layer to prepare a copper sheet layer; after drying, vacuum plate aluminum again to form a secondary aluminum sheet layer and obtain a coating; take poly(2-methylallyl benzothiazole mercaptan), silane-modified glass powder, polycaprolactone polyol, isocyanate, sodium ethylenediaminosulfonate, acetone, and antioxidant and blend them to prepare a coating, coat it on the front of the substrate, dry it, and then perform hot pressing for 6 min with a mold. After cooling, remove the mold, adjust the temperature to 110 °C in a nitrogen atmosphere, keep it warm for 40 min, slowly cool it to room temperature, and extract the air in the reaction kettle to form a microstructure. The included angle B between the inclined plane of the microstructure and the substrate is 42.1°, the edge length C of the microstructure is 21.0 μm, and the refractive index of the substrate is 1.60 to obtain a reflective film;

[0063] Pass trimethylamine into acetone, add p-chloromethylstyrene, and react at room temperature for 12 h. Take the reaction product, add brominated polyphenylene ether, add chlorobenzene and N-methylpyrrolidone, stir well in a nitrogen atmosphere, add copper bromide, bipyridine, and arsonic acid acetic acid, evacuate, place it at 125 °C and react for 54 h. Take the reaction product, vacuum dry it at 64 °C for 30 h, then dissolve it in the solvent N-methylpyrrolidone, add 1-methylimidazole, stir at 45 °C for 24 h, add polyolefin and stabilizer, cast a film and remove the solvent, and obtain an anti-PID film after heat treatment;

[0064] Take the welding tape and use infrared heating to perform single-piece welding on the battery cells to form a battery string, and then perform series welding on the battery strings to form a battery cell assembly. While welding the battery strings, paste the reflective film on the surface of the welded welding tape to obtain a battery cell assembly, where the temperature of the welding film bottom plate is 120 °C; take the materials and lay them in the order of glass, anti-PID film, battery cell assembly, EVA film, and backplane to form an assembly structure;

[0065] Place the formed assembly structure after lamination in a double-chamber laminator, evacuate and laminate the assembly structure to form a laminated assembly; the vacuum degree of the laminator is 120 Pa, the parameters of one chamber: the lamination temperature is 142 °C, the evacuation time is 7 min, and the lamination time is 2 min; the parameters of the second chamber: the lamination temperature is 152 °C, the evacuation time is 1 min, and the lamination time is 9 min; and the total lamination time of one chamber and the second chamber is 11 min, the primary lamination pressure is 70 KPa, the secondary lamination pressure is 60 KPa, and the tertiary lamination pressure is 30 KPa; take the semi-finished battery assembly after lamination, assemble it with a frame, and install a junction box to obtain a battery assembly.

[0066] Comparative Example 1

[0067] Compared with Example 2, the cell in Comparative Example 1 was replaced with a conventional cell.

[0068] Comparative Example 2

[0069] Compared with Example 2, the anti-PID film in Comparative Example 2 was replaced with an EVA film.

[0070] Comparative Example 3

[0071] Compared with Example 2, the reflective film was not added in Comparative Example 3.

[0072] Experiment:

[0073] Take the battery modules prepared in Examples 1-3 and Comparative Examples 1-3, conduct DH2000 damp heat aging test, UV60kWh ultraviolet aging test, and TC200 thermal cycling aging test, respectively test the short-circuit current and open-circuit voltage before and after the test, record the test results, compare with the data before the experiment, and obtain the following data:

[0074]

[0075] According to the data in the above table, the following conclusions can be clearly obtained:

[0076] The battery modules prepared in Examples 1-3 and Comparative Examples 1-3 form a control experiment before and after aging. From the test results, it can be seen that the initial short-circuit current, open-circuit voltage and power of the battery modules in Examples 1-3 are significantly increased compared with Comparative Examples 1 and 3, and the change before and after aging is not obvious. It can be seen that the setting of multi-main grid cells and reflective film promotes the improvement of its power; the initial short-circuit current, open-circuit voltage and power of the battery module in Comparative Example 2 are lower compared with Example 2, and the numerical change after aging is more obvious. It can be seen that the setting of the anti-PID film promotes the improvement of its power, and the anti-aging performance of the anti-PID film is better. This fully shows that the present invention can effectively improve the utilization rate of solar energy of the battery module and has high practicability.

[0077] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprises", "comprising" or any other variation thereof is intended to cover a non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not expressly listed, or elements inherent to such process, method, article or device.

[0078] Finally, it should be noted that the above are only 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 perform equivalent replacements for some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A multi-main grid battery module with a reflective film, comprising glass, a battery cell assembly, and a backplane, characterized in that: A battery cell assembly is disposed below the glass, a backplane is disposed below the battery cell assembly, an anti-PID film is disposed between the battery cell assembly and the glass, an EVA film is disposed between the battery cell assembly and the backplane. The battery cell assembly includes multiple groups of battery strings, and adjacent two groups of battery strings are connected by a solder strip. One group of battery strings includes multiple groups of battery cells, and adjacent two groups of battery cells are connected by a solder strip. A reflective film is disposed on the top of the solder strip; The preparation process of the reflective film is as follows: a) Preparation of the base layer: Take polyethylene terephthalate, allyl diglycol carbonate, 2,8-di-tert-butyl-4-methylphenol, and sodium dihydrogen phosphate and co-extrude them, cast the film and perform heat treatment. The heat treatment process is: keep warm at 50 - 70 °C for 1 - 5 min, then heat up to 120 - 140 °C, perform cyclic hot air treatment for 20 - 40 s and then slowly cool to room temperature. The pressure is always 270 - 700 KPa to obtain the base layer; b) Preparation of the coating layer: Take the base layer and dry it, apply water-based adhesive on the back, and then vacuum-plate aluminum after drying. The vacuum degree is 4.0×10 -4 ~1.0×10 -2 Pa, aluminum sheet is obtained; Take copper sulfate, sodium citrate, nickel sulfate, disodium ethylenediaminetetraacetate, sodium tetraborate, thiourea, sodium dodecylbenzenesulfonate, 2,2-bipyridine, p-benzoquinone, and deionized water to prepare a copper plating solution. Adjust the pH value of the plating solution to 5.0 - 5.8 with sulfuric acid, heat up to 60 - 70 °C, and put the base layer plated with an aluminum sheet layer to obtain a copper sheet layer; After drying, vacuum plate aluminum again to form a secondary aluminum sheet layer to obtain the coating layer; c) Preparation of the micro-structure: Take poly(2-methylallyl benzothiazole mercaptan), silane-modified glass powder, polycaprolactone polyol, isocyanate, sodium ethylenediamine sulfonate, acetone, and antioxidant and blend them. Coat the obtained coating on the front of the base layer, dry it, and then perform hot pressing with a mold for 3 - 6 min. After cooling, remove the mold, adjust the temperature to 70 - 110 °C in a nitrogen atmosphere, keep warm for 20 - 40 min, slowly cool to room temperature, and extract the air in the reaction kettle to form a micro-structure to obtain the reflective film; The preparation process of the anti-PID film is as follows: Pass trimethylamine into acetone, add p-chloromethylstyrene, and react at room temperature for 10 - 12 h. Take the reaction product, add brominated polyphenylene ether, add chlorobenzene and N-methylpyrrolidone, fully stir in a nitrogen atmosphere, add copper bromide, bipyridine, and arsonic acid acetic acid, evacuate the air, and react at a temperature of 115 - 125 °C for 42 - 54 h. Take the reaction product and vacuum dry it at 56 - 64 °C for 18 - 30 h, then dissolve it in the solvent N-methylpyrrolidone, add 1-methylimidazole, stir at a temperature of 40 - 45 °C for 12 - 24 h, add polyolefin and stabilizer, cast the film and remove the solvent, and obtain the anti-PID film after heat treatment.

2. The multi-main grid battery module with a reflective film according to claim 1, characterized in that: Multiple groups of main grids are disposed on the top of the battery cell, and the battery strings and the battery cells are located in the same plane.

3. A multi-main grid battery module with a reflective film as claimed in claim 1, characterized in that: The reflective film includes a micro-structure, a base layer, and a coating layer. The micro-structure is in the shape of a triangular pyramid. The included angle B between the inclined surface of the micro-structure and the base layer is 28.4 - 42.1 °, the edge length C of the micro-structure is 16.5 - 21.0 μm, and the refractive index of the base layer is 1.50 - 1.

60.

4. The multi-main grid battery module with a reflective film as claimed in claim 1, wherein: The anti-PID film comprises the following components by weight: 64 to 72 parts of polyolefin resin, 5 to 15 parts of brominated polyphenylene ether, 6 to 10 parts of p-chloromethylstyrene, 1 to 3 parts of 1-methylimidazole, and 0.1 to 1 part of stabilizer.

5. The preparation process of a multi-main grid battery module with a reflective film according to any one of claims 1-4, characterized in that, It includes the following steps: 1) Cell sorting: Sort the cells with qualified appearance, group the cells with the same color and efficiency, and the number of cells in one group is the number required for one group of battery modules. 2) Welding: Take the cells and put them into a string welding machine for welding to form a cell assembly. 3) Laminating: Lay the materials in the order of glass, anti-PID film, cell assembly, EVA film, and backsheet to form an assembly structure. 4) Laminating: Place the assembly structure in a laminator for laminating to form a laminated assembly. 5) Framing: Take the semi-finished battery module after laminating, assemble it with a frame, and install a junction box to obtain a battery module. 6) Testing: Conduct tests according to the test standards to obtain the finished battery module. 7) Packaging: Take the finished battery module, install the lead-out wire and fix it, put it into a packing box, wrap it with corner protectors, and wind it with PE film to obtain the product.

6. The preparation process of a multi-busbar battery module with a reflective film according to claim 5, characterized in that, Step 2) includes the following steps: Take the welding tape and use infrared heating to weld the cells one by one to form a cell string, and then weld the cell strings in series to form a cell assembly. While welding the cell strings, paste a reflective film on the surface of the welded welding tape to obtain the cell assembly, where the temperature of the welding film bottom plate is 100 to 120°C.

7. The preparation process of a multi-busbar battery module with a reflective film according to claim 5, characterized in that, Step 4) includes the following steps: Place the assembly structure formed after laminating in a double-chamber laminator, evacuate the assembly structure and conduct laminating to form a laminated assembly. Among them, the vacuum degree of the laminator is 90 to 120 Pa. Parameters of the first chamber: laminating temperature is 130 to 142°C, evacuation time is 4 to 7 min, and laminating time is 0.5 to 2 min. Parameters of the second chamber: laminating temperature is 140 to 152°C, evacuation time is 0 to 1 min, and laminating time is 6 to 9 min. And the total laminating time of the first chamber and the second chamber is 7 to 11 min, the first laminating pressure is 50 to 70 KPa, the second laminating pressure is 20 to 60 KPa, and the third laminating pressure is 10 to 30 KPa.

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