As the global energy situation tightens, solar photovoltaic power generation, as a sustainable energy alternative, has developed rapidly in recent years and has been widely promoted and applied first in countries with abundant solar energy resources (such as Germany and Japan). After nearly ten years of rapid development, China's photovoltaic industry has also entered the forefront of world development. Driven by the international market and domestic policies, a large number of outstanding photovoltaic companies such as Wuxi Suntech, Changzhou Trina and Tianwei Yingli have emerged, driving the development of upstream and downstream companies, and China's photovoltaic power generation industry chain is taking shape.
Solar photovoltaic cells, an important component of solar photovoltaic power generation, are composed of high conversion efficiency monolithic solar cells, ethylene vinyl acetate copolymer (EVA) film, low-iron tempered glass, fluorine plastic, and polyester composite back film (TPT). The components are heated and laminated under vacuum to form a whole, and finally the anti-corrosion aluminum alloy frame and junction box are installed to become the finished photovoltaic cell module. In order to prevent water and oxygen in the air from entering the solar photovoltaic module and oxidizing the silicon cells in the module, resulting in a reduction in the conversion rate of the silicon cells, the frame of the photovoltaic module (i.e. the glass plate on the sun-facing side of the solar panel and the TPT plate on the reverse side) must be The gap between the aluminum frame and the aluminum frame is sealed with a sealant with good bonding sealing and weather aging resistance; sealant must also be used around the power conversion box (i.e. junction box) shell for bonding, fixation and sealing to protect the circuit board. Extended service life.
Compared to other types of sealants, silicone sealants are particularly durable under harsh conditions. It also has excellent resistance to ultraviolet light and atmospheric aging. It can remain in harsh environments such as sunlight, rain, snow and seasonal climate changes for more than 30 years without cracking, brittleness or deterioration in a wide temperature range. It has ±50% resistance to deformation and displacement. Photovoltaic cell modules must be used outdoors in an unprotected environment and must withstand low temperatures in winter (-30°C), high temperatures in summer (up to 80°C or more in the sun), rain and snow erosion, and ultraviolet aging. Architectural practice has proven that silicone sealant can withstand the test and is therefore the most suitable sealant for solar photovoltaic modules.
The common silicone sealant on the market is condensation room temperature vulcanized silicone rubber. When this type of sealant is vulcanized, small molecule by-products are released. According to the type of by-products, condensation room temperature vulcanized silicone rubber can be divided into types such as dealcoholization, deketoxime, deacetic acid, deamidation, and deacetone.
Deacetic silicone sealant is the largest-selling sealant on the market. The by-product released during vulcanization is acetic acid, and acetic acid is corrosive to metals. Therefore, it is mainly used for sealing building glass and ceramics. It is commonly known as glass glue. It is rarely used in industry; the amide small molecule by-product removed during vulcanization of deamidated silicone sealant has a normal pressure boiling point as high as about 200 oC. It is difficult to volatilize to form a clean rubber material. Its application is limited and there are few commercial products. ;Deacetone silicone sealant releases neutral and non-corrosive small molecule by-products during vulcanization, which is most suitable for use in the field of electronic appliances. However, due to the technical difficulty of synthesizing the cross-linking agent of deacetone silicone rubber, the cost is also relatively high. It is relatively high, which limits the application of the dealcoholized silicone sealant; low molecular alcohol is removed during the vulcanization of the dealcoholized silicone sealant. Substances (methanol, ethanol), have low toxicity, and especially have no corrosive effect on metals. Therefore, they are widely used in the construction field (especially building curtain walls) and industry; deoxime silicone sealants remove ketones during vulcanization Oxime (methyl ethyl ketone oxime) is an alkaline substance with certain toxicity and corrosive effect on metals. However, due to its fast vulcanization speed and good performance, it is also widely used in construction and industrial fields.
The cost and performance advantages of dealcoholization and deoxime types make them the most common silicone sealants used in photovoltaic modules on the market.