Photovoltaic modules generally refer to solar cell modules. As the end product of the photovoltaic industry, photovoltaic modules utilize a wide variety of raw materials, and the selection of different materials directly affects the module's performance. So, what are the main materials used in photovoltaic modules?
Material composition and function of photovoltaic modules
Photovoltaic modules consist of high-efficiency crystalline silicon solar cells, ultra-white textured tempered glass, EVA, transparent TPT backsheet, and aluminum alloy frame. They are characterized by long service life and strong mechanical resistance to external pressure. The material composition and functions of photovoltaic modules are as follows:
1. Tempered glass: Its function is to protect the main body of power generation (such as solar cells). The requirements for light transmission are: 1) High light transmittance (generally above 91%); 2) Ultra-white tempered treatment.
2. EVA: Used to bond and fix tempered glass and the main power generation components (such as solar cells). The quality of transparent EVA material directly affects the lifespan of the module. EVA exposed to air is prone to aging and yellowing, which affects the light transmittance of the module and thus the power generation quality. In addition to the quality of the EVA itself, the lamination process of the module manufacturer also has a great impact. For example, if the EVA adhesiveness is not up to standard, or if the bonding strength between EVA and tempered glass and backsheet is insufficient, it will cause the EVA to age prematurely and affect the lifespan of the module.
3. Solar Cells: Their main function is to generate electricity. The mainstream solar cells on the market are crystalline silicon solar cells and thin-film solar cells. Each has its advantages and disadvantages. Crystalline silicon solar cells have relatively low equipment costs, but high consumption and cell costs. However, they also have high photoelectric conversion efficiency and are more suitable for generating electricity under outdoor sunlight. Thin-film solar cells have relatively high equipment costs, but very low consumption and cell costs. However, their photoelectric conversion efficiency is only slightly more than half that of crystalline silicon solar cells. They have excellent low-light performance and can generate electricity even under ordinary light, such as the solar cells on calculators.
4. Backsheet: Its functions include sealing, insulation, and waterproofing. Materials such as TPT and TPE are generally used and must be resistant to aging. Most module manufacturers offer a 25-year warranty. Tempered glass and aluminum alloy are generally fine; the key lies in whether the backsheet and silicone sealant meet the requirements.
5. Aluminum alloy: Protective laminate, providing a certain degree of sealing and support.
6. Junction Box: Protects the entire power generation system, acting as a current relay station. If a module short-circuits, the junction box automatically disconnects the short-circuited battery string to prevent damage to the entire system. The most critical component of the junction box is the selection of diodes; different diodes are required depending on the type of battery cells within the module.
7. Silicone: Used for sealing, sealing the junction between components and aluminum alloy frames, and between components and junction boxes. Some companies use double-sided tape or foam to replace silicone, but silicone is widely used in China because the process is simple, convenient, easy to operate, and the cost is very low.
Photovoltaic module materials mainly consist of the seven parts mentioned above. Each part requires careful attention, as small details can have a significant impact.
