The development of fluorocarbon coating technology is discussed from the development route of photovoltaic back plate technology

In recent years, environmental pollution caused by the non-renewable energy use of fossils such as coal and oil has attracted more and more attention from all over the world, and governments are actively seeking and developing clean energy sources such as hydro, wind, biomass and solar energy to replace fossil fuels. Solar energy is an important direction for the positive development of renewable energy in all countries because of its environmental protection, safety and abundant sources. With the active advocacy, leadership and policy support of governments, solar photovoltaic applications such as large-scale ground power stations, home rooftop power generation and agricultural photovoltaic multi-purpose power generation will continue to develop rapidly. Solar photovoltaic power generation is expected to account for more than 20% of total energy consumption by 2040, and is likely to reach more than 60% by the end of the 21st century.
solar power generation is mainly achieved through photovoltaic modules formed by silicon wafers and their packaging materials. Photovoltaic modules are mainly composed of glass panels, hot-melt film EVA, battery chips, back plate materials, wiring boxes, etc. , in addition to the battery sheet are package materials. Sunlight shines on photovoltaic modules, which absorb photoelectronics for photoelectric conversion (figure 1), resulting in solar photovoltaic power generation. In addition to the cells themselves, package materials can also affect the efficiency and service life of photovoltaic modules, which in turn affect the cost of generating components. In the packaging material, due to the limitations of the existing technology, the back plate material is still mainly using polymeric polymer materials, its most easily aging and the shortest life, so the quality of the back plate material will directly affect the power generation efficiency and service life of photovoltaic modules, to promote the development of back plate material technology is a common and sustained concern of the solar photovoltaic industry an important topic.
1 Photovoltaic Module Photoelectric Conversion1, back plate product technology development requirements
1.1 back plate for the importance of components
back plate material is the last layer of protection material on the back of the battery sheet, directly facing the UV, low temperature, wet heat, highland sand, salt spray and other environmental erosion, need to have excellent insulation, water vapor barrier and weather resistance and other advantages to meet the component service life >25a requirements. If the quality of the back plate material does not pass, will make the component back plate appear de-layering, cracking, foaming, yellowing and other conditions, resulting in battery module shedding, battery slip, battery effective output power decline and other adverse effects, in low voltage, low current sometimes appear arcing, resulting in back plate and component combustion events and even fire, the components safe power generation and operation has a great impact, so the back plate material needs to have versatility, and a single material difficult to meet the requirements. In addition to the glass back plate, other traditional back plate materials are composed of different single material multi-layer composite structure, under the pressure of cost, at present, domestic and foreign back plate manufacturers are actively seeking ways to improve the back plate material technology.
1.2 back plate technology development trend
solar module packaging structure since the 1980s batch training, after more than 30 years of environmental, application verification phase-out, gradually stereotyped for modern components with glass, battery, welding belt, flexible back plate, packaging film (EVA), aluminum border, wire box, silicone and other 8 major materials, because of its long-term outdoor work characteristics, so long-term application verification and outdoor environmental verification structure is a major factor. The victory of flexible fluorocarbon back plate in long-term application verification and outdoor environment verification is the result of a long selection process and industry application practice. Technological advances and the development of the solar energy industry have put forward higher and broader performance and indicator requirements and expectations for solar modules and their selected materials, some of which are expressed in Figure 2.
Fable 2 Back plate technical indicators development route
From Figure 2, it can be seen that the typical 8 environmental types for flexible back plate put forward different adaptive indicators, back plate from a single protection to long-term protection, long-term electricity cost reduction of the functional direction of the desire to develop increasingly strong. Figure 2 systematically expresses the comprehensive demand for flexible back plate, eliminating the impact of the industry's single index to measure the misunderstanding of back plate awareness brought about by a single environment.
the functionalization of the back plate is becoming more and more obvious, different application environment requirements for the back plate, Table 1 lists the specific back plate products to meet the needs of future trends.
Table 1 Back plate product technical development indicators forecast
As can be seen from Table 1, the future technical development of back plate materials is mainly to improve the reflectivity of back plate materials, increase the efficiency of component power generation, improve the characteristics of environmental tolerance indicators so that the back plate has a longer service life, reduce back plate costs so that components and operators get more profit space, pay attention to back plate materials, especially fluorine material recovery, reduce environmental pollution and so on.
further analysis and prediction of the application of different back plates in this paper, the results are shown in Figure 3.
Figure 3 Percentage Trend of Applications in different back plate markets
As can be seen from Figure 3, the replacement trend of back plate materials is obvious, TPT/KPK type (double-sided dry composite PVF/Acoma VDF) structural back plate material due to cost pressure and single innovative characteristics of the proportion continued to decrease, glass back plate, CPC (double-sided coated fluorocarbons) Coating) back plate, XFB (one side dry composite fluorine film, the other side coated with fluorocarbon coating) back plate and co-extrusion multi-layer structure PET back plate proportion will be more than 85%, due to the agricultural shed and lighting buildings, direct water adjacent areas of the application growth, glass back plate growth trend is obvious, by 2025 will account for 20%; CPC double-sided fluorine back plate due to weather resistance and process technology advantages, in 2020 will account for 20%; The pure PET structure back plate will evolve into a multi-layer co-crowding PET technology, continue to be used in small distributed markets, maintaining the current market share, by 2025 accounted for about 20%.
Table 2 adds indicators to the back plate material testing standards for different environments
at the same time, in terms of back plate testing technology, one or more stringent tests must be carried out to test the reliability of the back plate material (as shown in Table 2, from THET), which will bring new technical challenges to the back plate material.
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