Photovoltaic coating, photovoltaic cell, photovoltaic module and preparation method of photovoltaic cell

Abstract

The invention discloses a photovoltaic coating, a photovoltaic cell, a photovoltaic module and a preparation method of the photovoltaic cell. The photovoltaic coating is formed by curing a composition comprising the following components in parts by weight: 45-55 parts of a prepolymer; 25 to 35 parts of a reactive diluent; 3 to 5 parts of a photoinitiator; and 2-4 parts of an ultraviolet light absorber. According to the invention, by directly forming the coating with ultraviolet ray isolation and high light transmittance on the surface of the battery piece, excellent ultraviolet ray protection is provided for the battery piece while the performance of the packaging adhesive film is not influenced, and a potential induced degradation (PID) effect induced by ultraviolet ray radiation is synergistically inhibited. The coating composition for forming the photovoltaic coating is optimized and can be quickly cured in an air atmosphere, so that the production efficiency is greatly improved, and the dependence on inert gas is reduced; meanwhile, precise coating processes such as ink-jet printing and the like are adopted, so that the high utilization rate of the material is realized, and the manufacturing cost is remarkably reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photovoltaics, in particular to a photovoltaic coating, a photovoltaic cell, a photovoltaic module and a preparation method of the photovoltaic cell. BACKGROUND

[0002] In the prior art, the packaging materials of photovoltaic modules mainly use ethylene-vinyl acetate copolymer (EVA) adhesive film and POE (polyolefin elastomer) adhesive film to achieve the bonding and sealing between the cell and the glass and backsheet. However, these two kinds of adhesive films have the following disadvantages when facing long-term ultraviolet (UV) radiation:

[0003] 1. EVA adhesive film is prone to photo-oxidation under long-term UV radiation, especially UV-A and UV-B with a wavelength less than 400 nm, which leads to yellowing of the material and a decrease in light transmittance. The decrease in light transmittance reduces the number of photons reaching the cell, thereby reducing the photoelectric conversion efficiency;

[0004] 2. As an alternative material to EVA adhesive film, POE adhesive film provides better UV protection performance, but its cost is significantly higher than that of EVA, which increases the total cost of photovoltaic modules;

[0005] 3. Potential Induced Degradation (PID) effect is an important problem faced by photovoltaic modules during operation. UV radiation can accelerate the aging of the packaging material, produce by-products such as acetic acid, and possibly damage the passivation layer on the surface of the cell, thereby exacerbating the occurrence of PID effect and leading to passivation failure on the surface of the cell;

[0006] 4. Current technologies for UV protection of photovoltaic modules, such as coating an anti-reflective film on the surface of the glass or adding a UV absorber in the adhesive film, not only have complex processes and high costs, but also often cannot effectively block specific wavelength UV, which may affect the spectral transmittance of visible and near-infrared bands, thereby indirectly affecting the power generation efficiency;

[0007] 5. Existing UV protection solutions usually require additional equipment investment and process steps, increasing the complexity of the production process.

[0008] In summary, there is an urgent need for a new solution in the prior art that can effectively block harmful UV light and synergistically suppress the PID effect without affecting the normal operation and appearance quality of the module, while also considering low cost and compatibility with large-scale production lines. SUMMARY

[0009] The present application aims to provide a photovoltaic coating, a photovoltaic cell, a photovoltaic module and a preparation method of the photovoltaic cell, so as to solve the problems of high cost, performance loss and complex process in the prior art UV protection scheme.

[0010] According to one aspect of the present application, a photovoltaic coating is provided, which is cured from a composition comprising the following components by weight: prepolymer: 45-55 parts; active diluent: 25-35 parts; photoinitiator: 3-5 parts; ultraviolet absorber: 2-4 parts.

[0011] Optionally, the composition further comprises 0.1-0.3 parts of a leveling agent.

[0012] Optionally, the prepolymer is selected from at least one of polyurethane acrylate, epoxy acrylate and polyester acrylate; the active diluent is trimethylolpropane triacrylate; and the ultraviolet absorber is 2-(2-hydroxy-5-methylphenyl) benzotriazole.

[0013] According to another aspect of the present application, a photovoltaic cell is provided, comprising a cell substrate and the photovoltaic coating, wherein the photovoltaic coating covers at least one side surface of the cell substrate.

[0014] Optionally, the thickness of the photovoltaic coating is 5-15 μm.

[0015] Optionally, the average light transmittance of the photovoltaic coating in the wavelength range of 400-1100 nm is greater than 95%, and the average ultraviolet light blocking rate in the wavelength range of 280-400 nm is greater than 90%.

[0016] According to another aspect of the present application, a photovoltaic module is also provided, comprising the photovoltaic cell.

[0017] According to another aspect of the present application, a preparation method of the photovoltaic cell is provided, comprising the following steps:

[0018] applying an ultraviolet-resistant coating comprising a prepolymer, an active diluent, a photoinitiator and an ultraviolet absorber to at least one side surface of the cell substrate by an inkjet printing process or a screen printing process; and

[0019] curing the ultraviolet-resistant coating by ultraviolet light in an air atmosphere.

[0020] Optionally, the parameters of the inkjet printing process include: droplet volume of 6-50 pL, and printing resolution of 360-1440 DPI.

[0021] Optionally, the curing energy of the curing is 800-3000 mJ / cm 2 .

[0022] By the present application, the photovoltaic coating is formed by coating the anti-ultraviolet coating on the surface of the cell substrate and curing, for ultraviolet blocking, without affecting the performance of the film itself, while providing excellent ultraviolet protection effect to the cell, by efficiently blocking ultraviolet, slowing down the aging of the packaging system and the decline of the cell surface performance, thereby significantly inhibiting the occurrence of PID effect, and improving the long-term reliability of the module; wherein the components of the photovoltaic coating determine that it has a short curing time, greatly improving the production efficiency; at the same time, the components of the photovoltaic coating have a high utilization rate, only 5-15g of coating is needed per square meter, and the product yield is expected to exceed 99%, significantly reducing the material cost, and the components of the photovoltaic coating can be rapidly cured in an air atmosphere without nitrogen protection, greatly reducing the equipment investment and operating cost, and improving the production efficiency. Experiments show that the photovoltaic coating in the present application can have a light transmittance of more than 95% in the 400-1100nm waveband, an average ultraviolet light blocking rate of more than 90% in the 280-400nm waveband, preferably in the core harmful waveband of 300-380nm, and the blocking rate can be more than 95%; compared with the traditional EVA film module, the power generation and the service life of the module are obviously improved, and the long-term power attenuation of the module is effectively controlled. In addition, the photovoltaic coating in the present application can adopt a solvent-free formula combined with a UV curing process, reducing VOC emissions, saving energy and protecting the environment, and meeting the green manufacturing concept. BRIEF DESCRIPTION OF DRAWINGS

[0023] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and the illustrative embodiments of the present application and their descriptions are used to explain the present application, and do not constitute improper limitations on the present application. In the drawings:

[0024] Figure 1 is a cross-sectional structure schematic diagram of a photovoltaic module provided according to an embodiment of the present application;

[0025] Figure 2 is a flowchart schematic diagram of a preparation method of a photovoltaic cell provided according to an embodiment of the present application.

[0026] Among them, the above drawings include the following reference signs:

[0027] 10, cell substrate; 20, photovoltaic coating; 30, back plate; 40, first film; 50, second film; 60, front plate. DETAILED DESCRIPTION

[0028] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0029] In the following, the technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application, so that those skilled in the art can better understand the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present application.

[0030] It should be noted that the terms "first", "second", and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily have to describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device that includes a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0031] As introduced in the background, the prior art has obvious deficiencies such as high cost, performance loss of materials, and complex process in solving the UV protection problem of photovoltaic modules, and there is an urgent need for a new solution that can effectively block harmful UV light and synergistically inhibit the PID effect without affecting the normal operation and appearance quality of the module, while also considering low cost and compatibility with large-scale production lines. In order to solve the problems of high cost, performance loss and complex process of the UV protection scheme in the prior art, the embodiments of the present application provide a photovoltaic coating, a photovoltaic cell, a photovoltaic module and a preparation method of a photovoltaic cell.

[0032] According to the embodiments of the present application, a photovoltaic coating is provided, which is cured from a composition comprising the following components by weight: pre-polymer: 45-55 parts; active diluent: 25-35 parts; photoinitiator: 3-5 parts; ultraviolet absorber: 2-4 parts.

[0033] By the embodiment of the present application, the photovoltaic coating is formed by coating the anti-ultraviolet coating on the surface of the cell substrate and curing, for blocking ultraviolet rays, without affecting the performance of the film itself, while providing excellent ultraviolet protection effect to the cell, slowing down the aging of the packaging system and the degradation of the cell surface performance by efficiently blocking ultraviolet rays, thereby significantly inhibiting the occurrence of PID effect and improving the long-term reliability of the module; wherein the components of the photovoltaic coating determine that it has a short curing time, greatly improving the production efficiency; at the same time, the components of the photovoltaic coating have a high utilization rate, only 5-15g of coating is needed per square meter, and the product yield is expected to exceed 99%, significantly reducing the material cost, while the anti-ultraviolet coating of the photovoltaic coating can be rapidly cured in an air atmosphere without nitrogen protection, greatly reducing the equipment investment and operating cost, and improving the production efficiency.

[0034] And experiments prove that the photovoltaic coating in the present application can have a light transmittance of more than 95% in the 400-1100nm waveband, an average ultraviolet light blocking rate of more than 90% in the 280-400nm waveband, preferably a blocking rate of more than 95% in the core harmful waveband of 300-380nm; compared with the traditional EVA film module, the power generation and the service life of the module are obviously improved, and the long-term power attenuation of the module is effectively controlled. In addition, the photovoltaic coating in the present application can use a solvent-free formula combined with a UV curing process, reducing VOC emissions, saving energy and protecting the environment, and meeting the green manufacturing concept.

[0035] In the embodiment of the present application, by adjusting the proportions of the prepolymers, active diluents, photoinitiators and ultraviolet absorbers and other components, the balance between efficient UV protection and low optical loss of the photovoltaic coating is achieved. Specifically, the synergistic effect of a lower proportion of active diluents and a higher proportion of base resin ensures that the photovoltaic coating has sufficient mechanical strength and durability, and can maintain good condition even in long-term outdoor environment. The presence of ultraviolet absorbers, especially in the 280-400nm waveband, has high absorption capacity, effectively preventing damage to the film and cell, and greatly reducing the risk of PID effect of the module.

[0036] In the embodiment of the present application, the prepolymer can be selected from at least one of polyurethane acrylate, epoxy acrylate and polyester acrylate; the active diluent is trimethylolpropane triacrylate; and the ultraviolet absorber is 2-(2-hydroxy-5-methylphenyl) benzotriazole.

[0037] In the technical scheme of the embodiment, the prepolymer preferably uses one or a combination of materials such as polyurethane acrylate, epoxy acrylate, polyester acrylate, etc. with excellent weather resistance and adhesion. These materials can form a stable cross-linked network, enhance the physical and chemical properties of the photovoltaic coating, effectively resist ultraviolet radiation, and ensure the long-term stability of the photovoltaic coating. Further, through synergistic action with the reactive diluent, the flowability of the photovoltaic coating can be improved while maintaining the cross-linking degree, ensuring uniform distribution of the photovoltaic coating on the surface of the cell substrate, and further ensuring the optical consistency and mechanical stability of the entire photovoltaic module.

[0038] In the technical scheme of the embodiment, the reactive diluent uses trimethylolpropane triacrylate, which can reduce the viscosity of the base resin, facilitate uniform coating of the anti-ultraviolet coating on the cell substrate, and participate in cross-linking reactions under UV light, enhancing the strength and adhesion of the photovoltaic coating.

[0039] In the technical scheme of the embodiment, the ultraviolet absorber uses 2-(2-hydroxy-5-methylphenyl) benzotriazole, which can efficiently absorb ultraviolet rays, especially UVB and UVA rays in the wavelength range of 280-400 nm, thereby preventing these harmful rays from reaching the surface of the cell substrate, reducing the occurrence of PID effects, and inhibiting the photo-oxidation reaction of the EVA adhesive film. The selected ultraviolet absorber has good chemical stability and can stably exist in the photovoltaic coating without decomposition, ensuring long-term ultraviolet protection performance.

[0040] It should be noted that, in addition to the preferred material types described above, the prepolymer can also be selected from one or more of polyether acrylate, polysiloxane acrylate, vinyl ether acrylate, urethane acrylate, and polyvinyl butyral acrylate; the reactive diluent can also be selected from one or more of dipentaerythritol pentaacrylate, ethoxylated bisphenol A diacrylate, neopentyl glycol diacrylate, dipropylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, and polyethylene glycol / polypropylene glycol block copolymer diacrylate; and the ultraviolet absorber can also be selected from one or more of 2-hydroxy-4-n-octyloxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-hexyloxybenzophenone, 2-hydroxy-4-n-decyloxybenzophenone, 2-hydroxy-4-n-nonyloxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, and 2-hydroxy-4-n-tetradecyloxybenzophenone, which are not limited in the embodiment.

[0041] In the embodiments of the present application, the photoinitiator can be selected from one or more of 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl propan-1-one, 2-benzoyl-2-dimethylamino-1-[4-(morpholinyl)phenyl]butan-1-one, benzil dimethyl ketal, 2,4,6-trimethylbenzoyl-phenyl-1-hydrazyl and Irgacure 184.

[0042] In the technical solutions of the embodiments, the selection of the photoinitiator of the above-mentioned type is conducive to improving the curing rate and effect of the photovoltaic coating. The photoinitiator such as 1-hydroxycyclohexyl phenyl ketone and 2-hydroxy-2-methyl-1-phenyl propan-1-one can rapidly decompose to generate free radicals under ultraviolet light, promote the cross-linking reaction of the prepolymer and the active monomer in the ultraviolet-resistant coating, and form a stable three-dimensional network structure, thereby not only accelerating the curing process of the photovoltaic coating, but also significantly improving the mechanical strength and chemical stability of the photovoltaic coating, especially the resistance to ultraviolet rays.

[0043] In some optional embodiments, the above-mentioned composition further comprises 0.1-0.3 parts of a leveling agent. The addition of the leveling agent improves the surface quality of the photovoltaic coating, reduces the bubble and unevenness phenomenon in the process of the photovoltaic coating, helps the uniform spreading of the photovoltaic coating, reduces the surface defects, and thereby improves the uniformity and overall optical performance of the photovoltaic coating.

[0044] In the embodiments of the present application, the leveling agent can be selected from one or more of an organic silicon surfactant, a fluorocarbon compound leveling agent and a non-ionic surfactant.

[0045] In the technical solutions of the embodiments, the leveling agent of the above-mentioned type is conducive to optimizing the surface tension of the photovoltaic coating, promoting the uniform spreading of the ultraviolet-resistant coating on the surface of the cell substrate, reducing the orange peel effect and pinhole phenomenon of the photovoltaic coating, and thereby improving the optical quality and physical stability of the photovoltaic coating. The addition of the organic silicon surfactant enhances the leveling property and anti-shrinkage ability of the photovoltaic coating, and ensures the uniformity of the photovoltaic coating.

[0046] In the embodiments of the present application, the component ratio and synergistic effect of the prepolymer, the active diluent, the photoinitiator, the ultraviolet absorber and the leveling agent jointly construct a high-efficiency and stable photovoltaic coating system. The system forms a thin and uniform photovoltaic coating on the surface of the cell substrate, realizes effective blocking of ultraviolet rays, significantly reduces the damage of ultraviolet rays to the EVA film and the cell, while maintaining high transmittance in the visible light and near-infrared wave bands, and ensures the maximum utilization of the effective spectrum by the photovoltaic cell. The selection and content control of the leveling agent in the optional scheme promote the uniform formation of the photovoltaic coating, further enhance the weather resistance, optical stability and mechanical strength of the photovoltaic coating, effectively reduce the power attenuation of the assembly, and prolong the service life of the photovoltaic assembly.

[0047] According to an embodiment of this application, a photovoltaic cell is also provided, including a cell substrate and a photovoltaic coating, wherein the photovoltaic coating covers at least one side surface of the cell substrate.

[0048] In this embodiment, the proportions of each component in the photovoltaic coating formed on one side of the cell substrate are precisely controlled and the types of materials are optimized. This not only enhances the UV protection performance of the photovoltaic coating and slows down the aging of the encapsulation system and the degradation of the cell surface performance, but also significantly suppresses the occurrence of PID effect, thereby optimizing its optical and mechanical properties and extending the service life of the photovoltaic cell module. At the same time, the proportions of each component in the photovoltaic coating enable it to achieve rapid curing, high material utilization and good batch consistency during the production process, thereby not only increasing the first-year power generation of the module, but also significantly reducing the long-term power decay of the module.

[0049] In some optional embodiments, the thickness of the photovoltaic coating is 5-15 μm. The photovoltaic coating can be applied and cured using an inkjet printing process. By precisely controlling parameters such as droplet volume, printing speed, and substrate temperature, a high degree of control over the thickness of the photovoltaic coating is achieved, ensuring the uniformity and accuracy of the photovoltaic coating.

[0050] In this embodiment, the photovoltaic coating is directly applied to the surface of the solar cell substrate for UV blocking, with a thickness of only 5-15 μm, which is significantly thinner than EVA and POE films. This photovoltaic coating is composed of prepolymers, reactive diluents, photoinitiators, and UV absorbers. By optimizing the component ratios and process conditions, it can provide a blocking rate of >90% in the 280-400 nm wavelength range and maintain >95% transmittance in the 400-1100 nm wavelength range, effectively protecting the solar cell and the film from UV damage.

[0051] According to an embodiment of this application, a photovoltaic module is also provided, including a photovoltaic cell, the photovoltaic cell including a cell substrate and a photovoltaic coating, the photovoltaic coating covering at least one side surface of the cell substrate.

[0052] In some alternative implementations, such as Figure 1 As shown, the photovoltaic module includes a backsheet 30, a first encapsulant film 40, a photovoltaic coating 20, a cell substrate 10, a photovoltaic coating 20, a second encapsulant film 50, and a front panel 60, which are stacked sequentially from bottom to top.

[0053] Specifically, the backsheet 30 is located on the back of the photovoltaic module, and its main function is to provide mechanical protection, waterproofing, and moisture protection, while blocking harmful substances in the environment. For example, the backsheet 30 is a TPT (Tedlar-PET-Tedlar, a polyester film sandwiched between two layers of polyvinyl fluoride film) backsheet or a POE (polyolefin elastomer) backsheet. The above types of backsheets can have good weather resistance and electrical insulation properties.

[0054] Specifically, the first adhesive film 40 is used to bond the cell substrate 10 to the backsheet 30, and the second adhesive film 50 is used to bond the cell substrate 10 to the frontsheet 60. The materials of the first adhesive film 40 and the second adhesive film 50 may include, but are not limited to, EVA (ethylene-vinyl acetate copolymer), which has good adhesion and light transmittance, thereby improving the long-term stability of the module.

[0055] Specifically, the front panel 60 is located on the outermost layer of the photovoltaic module. Its main function is to protect the internal modules from impacts from the external environment while providing good light transmission. The aforementioned front panel 60 can be tempered glass, which has the characteristics of high strength and good impact resistance, providing sufficient mechanical protection while maintaining good optical properties.

[0056] According to an embodiment of this application, a method for preparing photovoltaic cells as described in the above embodiments is provided, comprising:

[0057] A UV-resistant coating comprising a prepolymer, an active diluent, a photoinitiator, and a UV absorber is applied to at least one surface of the solar cell substrate using inkjet printing or screen printing processes; and

[0058] UV-resistant coatings are cured under air.

[0059] In this embodiment, a photovoltaic coating for UV blocking is formed by coating and curing an anti-UV coating on the surface of the solar cell substrate. This does not affect the performance of the encapsulant film itself, while providing excellent UV protection to the solar cell. By efficiently blocking UV rays, the aging of the encapsulation system and the degradation of the cell surface performance are slowed down, thereby significantly suppressing the occurrence of PID effect and improving the long-term reliability of the module. The composition of the photovoltaic coating determines its short curing time, which greatly improves production efficiency. At the same time, the components of the photovoltaic coating have a high utilization rate, requiring only 5-15g of coating per square meter, and the product yield is expected to exceed 99%, significantly reducing material costs. Furthermore, the components of the photovoltaic coating can be rapidly cured in an air atmosphere without nitrogen protection, greatly reducing equipment investment and operating costs and improving production efficiency.

[0060] This application demonstrates a method that involves directly applying a photovoltaic coating to the surface of the solar cell substrate, rather than relying solely on modifications within the encapsulant film or upgrades to the backsheet material. This direct protective effect of the photovoltaic coating is more significant, particularly in suppressing the PID effect, which helps reduce performance degradation of the solar cells caused by ultraviolet radiation, thereby ensuring stable operation and a longer lifespan of the photovoltaic module in harsh environments.

[0061] Exemplary embodiments of the method for fabricating photovoltaic cells according to this application will now be described in more detail. However, these exemplary embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. It should be understood that these embodiments are provided so that the disclosure of this application is thorough and complete, and that the concept of these exemplary embodiments is fully conveyed to those skilled in the art.

[0062] In this embodiment, the coating on the surface of the photovoltaic cell substrate includes a prepolymer (polymer base resin), an active diluent, a photoinitiator, and an ultraviolet absorber. The prepolymer, such as polyurethane acrylate, serves as the main structure of the coating, providing excellent weather resistance and mechanical properties, ensuring good adhesion between the coating and the cell substrate surface. The active diluent, such as trimethylolpropane triacrylate, promotes the fluidity of the coating, ensuring uniform deposition during inkjet printing or screen printing, forming a coating with controllable and uniform thickness. The photoinitiator can stimulate polymerization under ultraviolet irradiation, rapidly curing the coating and forming a stable cross-linked network structure. This not only gives the coating excellent UV resistance and optical stability but also shortens the production cycle and improves production efficiency. The addition of an ultraviolet absorber, such as 2-(2-hydroxy-5-methylphenyl)benzotriazole, efficiently absorbs short-wave ultraviolet light, reducing its aging effects on the cell and encapsulant film, effectively reducing the occurrence of potential-induced degradation (PID) and maintaining high power output of the module.

[0063] In some alternative embodiments, the aforementioned UV-protective coating also includes a leveling agent, which optimizes the surface tension of the coating, helps eliminate bubbles and unevenness in the coating, improves the smoothness of the coating, reduces surface defects, and enhances the optical properties of the coating.

[0064] Through the synergistic effect of the components in the aforementioned UV-protective coating, the technical solution of this application forms a highly efficient UV protection layer on the surface of the solar cell substrate. This not only significantly reduces the long-term power degradation of the photovoltaic module but also increases its power generation. Furthermore, it maintains high transmittance in the visible and near-infrared bands, ensuring full utilization of the effective spectrum by the photovoltaic cell. Simultaneously, the combination of coating formulation and coating process enables cost control.

[0065] In a preferred embodiment, to further improve the surface quality and uniformity of the coating, the aforementioned UV-protective coating may further contain 0.1-0.3 parts of a leveling agent. The addition of the leveling agent helps the coating spread evenly and reduces surface defects such as orange peel and pinholes during the curing process. In this case, an exemplary formulation may contain: 45-55 parts of prepolymer; 25-35 parts of reactive diluent; 3-5 parts of photoinitiator; 2-4 parts of UV absorber; and 0.1-0.3 parts of leveling agent.

[0066] In this embodiment, a balance between high-efficiency UV protection and low optical loss in the coating is achieved by adjusting the relative proportions of the components. Specifically, the lower proportion of reactive diluent and the higher proportion of base resin work synergistically to ensure that the coating has sufficient mechanical strength and durability, maintaining good condition even in long-term outdoor environments. The presence of UV absorbers, especially with high absorption capacity in the 280-400nm wavelength range, effectively prevents damage to the encapsulant and solar cells, significantly reducing the risk of PID effects in the module. The addition of leveling agents improves the surface quality of the coating, reduces bubbles and unevenness during the coating process, thereby improving the uniformity and overall optical performance of the coating.

[0067] In this embodiment, the UV-protective coating can be applied using screen printing or inkjet printing. Through inkjet printing or screen printing, the UV-protective coating containing UV absorbers is uniformly coated onto the surface of the solar cell substrate, forming a dense protective film. This not only effectively prevents UV damage to the component materials but also avoids negative impacts on the transmittance of visible and near-infrared light. Furthermore, compared to existing EVA film solutions, the introduction of this coating does not significantly increase cost.

[0068] In some optional embodiments, the surface of the solar cell substrate is subjected to an online rapid pretreatment before the UV-protective coating is applied. In this embodiment, considering the stringent cycle time requirements of large-scale production, the pretreatment step is optional, and an online treatment method with extremely short processing time is preferred. For example, an online atmospheric pressure fluid atomization treatment can be used to rapidly sweep the surface of the solar cell substrate for no more than 2 seconds. This process aims to instantly increase surface energy and effectively remove microscopic contaminants and organic matter from the surface of the solar cell substrate. Alternatively, an atomized spray of deionized water / isopropanol can be used, followed immediately by drying with high-purity compressed air.

[0069] The aforementioned pretreatment measures are characterized by extremely short processing time (seconds), seamless integration into existing conveyor belts without affecting the overall production cycle, and, compared to no treatment, further improved coating adhesion stability under extreme aging conditions, reducing the risk of long-term component performance degradation due to interface issues. In most cases, by optimizing the coating's own adhesion, this application can proceed without any pretreatment steps.

[0070] In the above optional embodiments, the pretreatment of the battery cell substrate surface improves the adhesion of the coating, and precision coating techniques such as inkjet printing or screen printing can accurately control the coating thickness, ensuring its uniformity and optical stability. Ultraviolet curing under inert gas protection not only reduces the influence of oxygen on the photocuring reaction and improves curing efficiency, but also avoids the subsequent high-temperature baking process, reducing energy consumption and VOC emissions.

[0071] In some alternative implementations, an anti-UV coating is uniformly applied to the surface of the solar cell substrate using inkjet printing or screen printing, forming a thin photovoltaic coating of 3-15 μm. Inkjet printing achieves precise control over coating thickness by controlling parameters such as droplet volume, printing speed, and substrate temperature, ensuring coating uniformity and accuracy. Screen printing, by adjusting parameters such as screen size, squeegee hardness, and screen spacing, also achieves precise control over coating thickness, and this process has unique advantages for large-area fabrication.

[0072] Furthermore, in this embodiment, the application of UV-resistant coating using inkjet printing technology may include: using a piezoelectric printhead with an aperture of 50-80μm for inkjet printing, and inkjet printing parameters may include: droplet volume of 6-50pL, printing resolution of 360-1440DPI, printing speed of 0.4-1.0m / s, and substrate temperature of 40-50℃.

[0073] In the optional embodiment, a piezoelectric printhead with an aperture of 50μm to 80μm is used for inkjet printing, ensuring precise deposition and uniformity of the photovoltaic coating. The droplet volume is controlled between 6pL and 50pL. Combined with a printing resolution of 360DPI to 1440DPI, highly accurate material distribution can be achieved. The printing speed of 0.5m / s to 2.0m / s and the substrate temperature of 40℃ to 60℃ further improve the coating efficiency and coating quality. The precise control of these parameters ensures the thickness and uniformity of the coating, thereby enhancing the blocking effect against ultraviolet rays while maintaining high transmittance of visible and near-infrared light.

[0074] Furthermore, in this embodiment, the application of UV-resistant coating using screen printing technology may include: screen printing using a 350-400 mesh polyester screen, with screen printing parameters including: a squeegee with a hardness of 75-85 Shore A, a squeegee pressure of 2-4 N / cm, a squeegee speed of 200-700 mm / s, and a screen distance of 2-3 mm.

[0075] In this embodiment, the optional screen printing process uses a 350-400 mesh polyester screen to ensure the fineness and uniformity of the photovoltaic coating. A squeegee with a hardness of 75 Shore A to 85 Shore A is selected, along with an appropriate squeegee pressure of 2 N / cm to 4 N / cm and a reasonable squeegee speed of 200 mm / s to 700 mm / s, achieving efficient and stable coating transfer. A reasonable screen spacing of 2 mm to 3 mm further ensures the continuity and thickness consistency of the coating. These precise process parameters work together to allow the UV-resistant coating to form a protective coating that meets technical requirements on the surface of the solar cell substrate, effectively blocking harmful ultraviolet rays while minimizing the impact on the transmittance of visible and near-infrared light.

[0076] An alternative approach, incorporating screen printing technology, offers a different coating preparation route. This technique utilizes a screen and squeegee to evenly distribute and transfer the prepared UV-blocking coating onto the surface of the solar cell substrate. Compared to inkjet printing, screen printing allows for continuous coating over a larger area, making it suitable for solar cells of various sizes and shapes, thus offering greater versatility. By controlling screen specifications, squeegee hardness, printing pressure, printing speed, and screen spacing, the preferred approach achieves precise adjustment of the coating thickness, thereby enhancing the UV-blocking performance of the coating while maintaining good optical properties. Furthermore, the introduction of screen printing reduces the precision requirements of the equipment, facilitating large-scale production and further controlling production costs.

[0077] In some optional embodiments, UV curing technology is used to cure the UV-resistant coating. The use of a dual-wavelength LED-UV light source and a nitrogen atmosphere with controlled oxygen concentration during the curing process ensures efficient and deep curing of the coating, avoiding secondary curing or over-curing, thereby maintaining the coating's excellent properties, such as high light transmittance, low haze, and high UV blocking rate. In the above optional embodiments, the curing energy can be 800-3000 mJ / cm². 2 .

[0078] In this embodiment, the introduction of inkjet printing technology greatly improves the precision and efficiency of the coating compared to traditional coating methods. The use of UV curing technology ensures that the coating reaches the ideal curing state in a very short time, reducing the production cycle. At the same time, the curing process under a nitrogen protective atmosphere effectively avoids the interference of oxygen on the curing reaction, ensuring the crosslinking degree and anti-aging performance of the coating.

[0079] Specifically, such as Figure 2 As shown, the above-mentioned method for preparing photovoltaic cells may include the following process flow:

[0080] S1. Prepare an anti-UV coating by weighing 45-55 parts of prepolymer, 25-35 parts of reactive diluent, 3-5 parts of photoinitiator, 2-4 parts of UV absorber, and 0.1-0.3 parts of optional leveling agent. Stir the above materials evenly at room temperature to form a stable coating solution.

[0081] S2, Pre-treatment of the solar cell substrate:

[0082] Online atmospheric pressure dual-fluid atomization spraying and other methods are used to rapidly treat the surface of the battery cell substrate for no more than 2 seconds to further improve the long-term stability of coating adhesion.

[0083] S3, with UV-resistant coating applied using inkjet printing or screen printing, has a coating thickness of 5-15μm.

[0084] In inkjet printing, a piezoelectric printhead is used with an aperture set to 50-80μm to ensure the fineness and uniformity of the droplets; the print droplet volume is adjusted to 20-50pL to ensure coating coverage while controlling thickness; the print resolution is set to 360-1440DPI to achieve high precision and uniformity of the coating; the print speed is controlled at 0.4-1.0m / s to balance production efficiency and coating quality; and the substrate temperature is maintained at 40-50℃, which is beneficial for the flow and uniform distribution of the UV-resistant coating.

[0085] In the screen printing process, the following parameters are considered: Screen selection: Use 350-400 mesh polyester screen to ensure that the UV-protective coating paste can pass evenly through the mesh; Squeegee hardness: Use an elastic squeegee with a Shore A hardness of 75-85 to ensure stability during the printing process; Squeegee pressure: 2-4 N / cm; Squeegee speed: Set to 200-700 mm / s to maintain coating consistency and production efficiency; Screen distance: Controlled at 2-3 mm to prevent the screen from contacting the surface of the battery cell substrate and avoid scratches; Printing environment: Maintain the relative humidity in the workshop between 30-50% and the temperature between 22-25℃ to reduce the evaporation of the UV-protective coating and avoid surface defects.

[0086] S4, UV curing of the UV-resistant coating: UV curing is performed in a nitrogen-containing gas environment. Concentration <100ppm to reduce oxygen interference with curing; UV lamp type: LED-UV light source with dual wavelengths of 365nm + 395nm to improve curing efficiency; Curing energy: set to 800-3000mJ / cm². 2 To ensure the UV-resistant coating is fully cured; lamp distance: controlled at 2-15mm to ensure even light distribution across the entire coating surface; conveyor speed: set at 0.1-0.7m / s to meet the speed requirements of the production line.

[0087] The above technical solution involves depositing a photovoltaic coating on the surface of a photovoltaic cell substrate, effectively blocking ultraviolet rays in the 280-400nm wavelength range while maintaining high light transmittance in the 400-1100nm wavelength range. Specifically, a UV-blocking coating with a specific formulation is applied uniformly to the cell substrate surface using precise inkjet printing or screen printing processes. During the curing process, the UV photoinitiator is excited by light to generate free radicals, promoting a cross-linking reaction between the prepolymer and the active monomer, forming a dense cross-linked network. This coating not only possesses excellent UV blocking performance but also effectively suppresses the PID effect, preventing a decrease in module power due to UV damage. Furthermore, optimized process parameters ensure the uniformity and high quality of the coating, enabling the module to maintain stable power generation efficiency over a long service life.

[0088] The above-described coating and its preparation method will be further explained below with reference to embodiments.

[0089] To further illustrate this application, the following detailed description is provided with reference to embodiments. It should be understood that these embodiments are merely for illustrating the technical solutions of this application more clearly, and are not intended to limit the scope of protection of this application. Unless otherwise specified, the curing steps in all embodiments are performed in a standard workshop atmosphere.

[0090] Example 1

[0091] The method for preparing photovoltaic cells provided in this embodiment includes the following steps:

[0092] S01, Coating Preparation: Weigh out 50 parts by weight of polyurethane acrylate, 31.8 parts by weight of trimethylolpropane triacrylate, 5 parts by weight of 1-hydroxycyclohexylphenyl ketone, 3 parts by weight of 2-(2-hydroxy-5-methylphenyl)benzotriazole, and 0.2 parts by weight of silicone leveling agent. Stir evenly at room temperature and in the dark, and measure its viscosity at 45℃ as 18 cP.

[0093] S02, no preprocessing.

[0094] S03, Coating: The coating is applied to the surface of the solar cell substrate using inkjet printing. A piezoelectric printhead with a 60μm aperture, a droplet volume of 30pL, a resolution of 800DPI, a printing speed of 0.8m / s, and a substrate temperature of 45℃ is used.

[0095] S04, Curing: UV curing is performed in an air atmosphere. An LED-UV dual-wavelength light source (365nm + 395nm) is used; the curing energy is set to 2500 mJ / cm². 2 The lamp spacing is 12mm.

[0096] Example 2 (Formulation Endpoint - Low Prepolymer)

[0097] The difference from Example 1 is that in step S01, the formulation was adjusted by weight to: 45 parts prepolymer, 35 parts reactive diluent, 5 parts photoinitiator, 4 parts ultraviolet absorber, and 0.1 parts leveling agent. Its viscosity at 45°C was measured to be 12 cP.

[0098] Example 3 (Process Endpoint - Low Ink Volume Thin Coating)

[0099] The difference from Example 1 is that in step S03, the process parameters are adjusted to: droplet volume 6 pL, resolution 360 DPI, and printing speed 1.0 m / s.

[0100] Example 4 (Process endpoint - high ink volume thick coating)

[0101] The difference from Example 1 is that in step S03, the process parameters are adjusted to: droplet volume 50 pL, resolution 1440 DPI, and printing speed 0.4 m / s.

[0102] Example 5 (Optional process - nitrogen atmosphere curing)

[0103] The difference from Example 1 is that in step S04, curing is carried out in a nitrogen atmosphere ( The curing process was carried out at a concentration of <100ppm, with the curing energy reduced to 1200mJ / cm. 2 .

[0104] Comparative Example 1 (No Coating)

[0105] In this comparative example, the uncoated solar cells were used directly for subsequent packaging and testing.

[0106] Comparative Example 2 (Insufficient curing energy)

[0107] This comparative example uses the same steps as Example 1, but in step S04, the curing energy is reduced to 500 mJ / cm. 2 .

[0108] Comparative Example 3 (without UV absorbers)

[0109] This comparative example uses the same steps as Example 1, but in step S01, 2-(2-hydroxy-5-methylphenyl)benzotriazole is not added, and its amount is made up by reactive diluent (TMPTA).

[0110] Table 1

[0111]

[0112] The coatings prepared in Examples 1-5 above were subjected to the following performance tests:

[0113] 1) Thickness uniformity: The coating thickness was detected online using a laser confocal microscope, and measurements were taken at 5 different points to calculate the percentage of thickness deviation.

[0114] 2) Curing degree: Fourier transform infrared spectroscopy (FTIR) was used to detect the 810c content in the coating. The change in the characteristic absorption peak of the C=C double bond of acrylate at position ¹ was used to calculate the double bond conversion rate.

[0115] 3) Optical performance: The average transmittance of the coating in the 400-1100nm wavelength range and the average blocking rate in the 280-400nm wavelength range were examined using an ultraviolet-visible spectrophotometer with an integrating sphere.

[0116] 4) PID effect test: The treated solar cells are packaged into single-cell modules and subjected to PID test according to IEC62804 standard (85℃ / 85%RH, -1000V, 96h), and the power decay is recorded.

[0117] Validity of this application: Compared with Comparative Example 1 (without coating), the PID attenuation rate of Examples 1-5 was significantly reduced from >15.0% to <4.5%, proving that the coating of this application has a significant anti-PID effect.

[0118] Feasibility and required energy for air curing: Example 1: In an air atmosphere, using 2500 mJ / cm 2The energy achieved >95% full curing and excellent performance. Comparative Example 2 shows that the energy in air is too low (500 mJ / cm). 2 This can lead to incomplete curing and performance degradation. This demonstrates that the formulation and process of this application can achieve curing in air and defines a reasonable energy range.

[0119] Synergistic inhibition of PID by UVA: In Comparative Example 3, even with good coating curing, the PID attenuation was still as high as >12.0% when UVA was not present. This strongly proves that ultraviolet radiation is one of the important factors that induce the PID effect, and the ultraviolet absorber of this application is the key to achieving the synergistic anti-PID function.

[0120] Correlation between thickness and performance: Comparing Example 3 (5.2 μm) and Example 4 (14.8 μm), it is clear that as the thickness increases, the UV blocking rate and anti-PID performance are significantly improved, but the visible light transmittance decreases slightly. This demonstrates that the thickness range of 5-15 μm is the optimal range for balancing optical performance and reliability performance.

[0121] With a light transmittance exceeding 99%, and a transmittance of over 95% in the 400-1100nm visible and near-infrared bands, the UV resistance of photovoltaic cells is significantly improved, reducing long-term power degradation of the modules and extending their lifespan. It also exhibits excellent environmental adaptability.

[0122] Wet adhesion (85℃ / 85%RH / 1000h) and thermal cycling adhesion (-40℃~+85℃×200 times) tests were conducted under standard conditions. The test results showed that the bonding strength between the coating and the battery cell met the standard of ≥4B.

[0123] As can be seen from the above description, the embodiments of this application achieve the following technical effects:

[0124] 1. Significantly enhances the module's resistance to UV radiation. By forming a thin and dense photovoltaic coating on the surface of the cell substrate, it not only effectively blocks harmful UV rays but also maintains high transmittance of visible and near-infrared light, ensuring the conversion efficiency of the photovoltaic module.

[0125] 2. By precisely controlling the coating thickness and uniformity, effective material utilization and cost savings are achieved. It is estimated that only 5-15g of coating is needed per square meter of battery cell, which greatly improves economic efficiency.

[0126] 3. It adopts an environmentally friendly solvent-free and UV curing process, which reduces VOC emissions and conforms to the concept of green manufacturing;

[0127] 4. The use of inkjet printing or screen printing technology enables precise coating deposition, improving production efficiency and facilitating online inspection and quality control, thus ensuring high product yield and consistency.

[0128] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0129] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A photovoltaic coating, characterized in that, It is formed by curing a composition comprising the following components in parts by weight: Prepolymer: 45-55 parts; Reactive diluent: 25-35 parts; Photoinitiator: 3-5 parts; UV absorber: 2-4 parts.

2. The photovoltaic coating according to claim 1, characterized in that, The composition also contains 0.1-0.3 parts of a leveling agent.

3. The photovoltaic coating according to claim 1 or 2, characterized in that, The prepolymer is selected from at least one of polyurethane acrylate, epoxy acrylate and polyester acrylate; the reactive diluent is trimethylolpropane triacrylate; and the ultraviolet absorber is 2-(2-hydroxy-5-methylphenyl)benzotriazole.

4. A photovoltaic cell, characterized in that, It includes a solar cell substrate and a photovoltaic coating according to any one of claims 1 to 3, wherein the photovoltaic coating covers at least one side surface of the solar cell substrate.

5. The photovoltaic cell according to claim 4, characterized in that, The thickness of the photovoltaic coating is 5-15 μm.

6. The photovoltaic cell according to claim 4, characterized in that, The photovoltaic coating has an average transmittance of more than 95% in the 400-1100nm wavelength band and an average ultraviolet light blocking rate of more than 90% in the 280-400nm wavelength band.

7. A photovoltaic module, characterized in that, Including the photovoltaic cell according to any one of claims 4 to 6.

8. A method for preparing a photovoltaic cell according to any one of claims 4 to 6, characterized in that, Includes the following steps: An anti-UV coating comprising a prepolymer, an active diluent, a photoinitiator, and an ultraviolet absorber is applied to at least one side of the surface of the battery cell substrate using inkjet printing or screen printing. as well as The UV-resistant coating is cured under ultraviolet light in an air atmosphere.

9. The preparation method according to claim 8, characterized in that, The parameters of the inkjet printing process include: droplet volume of 6-50 pL and printing resolution of 360-1440 DPI.

10. The preparation method according to claim 8, characterized in that, The curing energy is 800-3000 mJ / cm². 2 .

Images