Solar cells, also known as "solar chips" or "photovoltaic cells," are thin photovoltaic semiconductor wafers that generate electricity directly from sunlight. A single solar cell cannot be used directly as a power source; to use it as a power source, several individual solar cells must be connected in series or parallel and tightly packaged into a module.
Solar panel composition and functions of each component
1. Tempered glass: Its function is to protect the main power generation components (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 unit (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 of the module. 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 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, but high consumption and cell costs. However, they also have high photoelectric conversion efficiency and are more suitable for generating electricity outdoors under sunlight.
Thin-film solar cells have relatively high equipment costs, but low consumption and battery costs. Their photoelectric conversion efficiency is only slightly more than half that of crystalline silicon solar cells, but 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 are sealing, insulation, and waterproofing. It is generally made of materials such as TPT and TPE, which 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 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 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, 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.
