Composition and function of each component of a solar cell module:
1. Tempered glass: Its function is to protect the main body of power generation (such as solar cells). There are requirements for its selection: 1. The light transmittance must be high (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, thus affecting the light transmittance of the module and consequently the power generation quality. Besides the quality of the EVA itself, the lamination process of the module manufacturer also has a significant impact. For example, substandard EVA bonding, or insufficient adhesion strength between EVA and tempered glass/backsheet, will cause premature aging of the EVA and affect the module's lifespan. It is mainly used to bond and encapsulate the main power generation components and the backsheet.
3. Solar Cells: Their main function is to generate electricity. The mainstream types in the market are crystalline silicon solar cells and thin-film solar cells, each with its own advantages and disadvantages. Crystalline silicon solar cells have relatively low equipment costs and high photoelectric conversion efficiency, making them suitable for generating electricity outdoors in sunlight, but their consumption and cell costs are high. Thin-film solar cells have very low consumption and cell costs, excellent low-light performance, and can generate electricity even under ordinary light, but their equipment costs are relatively high, and their photoelectric conversion efficiency is slightly more than half that of crystalline silicon solar cells, as seen in the solar cells on calculators.
4. Backsheet: Its functions include sealing, insulation, and waterproofing (generally, materials such as TPT and TPE are used, which must be resistant to aging. Most module manufacturers offer a 25-year warranty. Tempered glass and aluminum alloy are generally fine. The key is whether the backsheet and silicone can meet the requirements).
5. The aluminum alloy protective layer provides a certain degree of sealing and support.
6. Junction Box: Protects the entire power generation system and acts as a current transfer station. If the module is short-circuited, the junction box will automatically disconnect the short-circuited battery string to prevent the entire system from burning out. The most critical part of the junction box is the selection of diodes. The corresponding diodes are different depending on the type of battery cells in the module.
7. Silicone: Used for sealing, specifically at the junctions between components and the aluminum alloy frame, and between components and the junction box. Some companies use double-sided tape or foam as substitutes for silicone, but silicone is widely used in China due to its simple, convenient, and low-cost process.
