Early solar backsheets had a three-layer structure (PVDF/PET/PVDF). The outer protective layer, PVDF, had good resistance to environmental corrosion; the middle layer, PET polyester film, had good insulation properties; and the inner layers, PVDF and EVA, had good adhesion. Later, to reduce costs and for environmental reasons, some fluorine-free backsheet structures emerged, such as APE structure backsheets.
Applications of solar backsheets
1. High voltage resistance and high insulation performance
2. Excellent weather resistance, with UV aging resistance ≥25 years.
3. Shockproof and effectively protects against battery cell breakage.
Classification of solar backsheets
Solar panel backsheet materials include: TPT solar panel, TPE solar panel, BBF solar panel, APE solar panel, and EVA solar panel;
1. TPT Solar Backsheet: TPT stands for polyvinyl fluoride composite film. Strictly speaking, TPT refers to a three-layer composite film made using DuPont Tedlar, consisting of Tedlar, PET, and Tedlar. DuPont has made significant contributions to the research of fluorides. In addition, Gore, a company that was essentially spun off from DuPont, also has a strong research track record. Tedlar is manufactured exclusively by DuPont.
2. TPE Solar Backsheet: This is a general term. It refers to thermoplastic elastomers. It typically includes block copolymers (styrene-based resins, copolyesters, polyurethanes, and polyamides), as well as thermoplastic elastomer blends and alloys (thermoplastic polyolefins and thermoplastic vulcanized rubbers). Block copolymers are relatively widely used. They include styrene-based resins and hydrogenated resins.
3. BBF Solar Backsheet: A composite material made of EVA, PET, and THV. It is typically produced using a three-layer co-extrusion process. THV resin is a terpolymer of tetrafluoroethylene, hexafluoropropylene, and fluorinated vinylidene. It is the most resilient fluoropolymer and possesses the highest level of optical transparency.
4. APE Solar Backsheet: Layer A is a nylon 12 film with comprehensive and excellent weather resistance. The middle layer is a modified polymer alloy. It has better long-term hydrolysis resistance and water vapor barrier properties than traditional PET middle layers, and also has excellent electrical insulation properties; Layer E is a modified polyolefin material that can bond with the EVA encapsulation film, and has high resistance to ultraviolet radiation aging.
5. EVA solar backsheet: Ethylene vinyl acetate resin. It has good flexibility, is not sticky at room temperature, but exhibits strong adhesion to the backsheet and glass at certain temperatures.
