Improved Durability Hydrophobic Self-Cleaning Coating Based on OTES-Modified SiO ₂ /PVDF for Photovoltaic Module Protection

The hydrophobic self-cleaning coatings had broad prospects in PV glass and precision instruments, but poor mechanical durability and environmental issues of fluorine-containing modifiers limited their practical use. This work developed an eco-friendly, good mechanical durability, hydrophobic self-cleaning coating. Nano-SiO2 was nonfluorinated and modified with OTES, combined with PVDF, and an OTES-SiO2/PVDF composite coating was prepared on glass via simple spraying. Results showed OTES grafted hydrophobic alkyl groups on SiO2, while PVDF enhanced coating mechanical strength by encapsulating SiO2. At OTES-SiO2 solution, PVDF volume ratio 3:7.5, the coating had optimal comprehensive performance, water contact angle (CA) up to 115.9°, pencil hardness 6H, and visible light transmittance 75%. Characterization confirmed a good self-cleaning effect, while the coating obviously reduced visible light transmittance and initial photovoltaic conversion efficiency but did not impair the core power generation performance and could significantly recover efficiency after self-cleaning. This work reveals the intrinsic mechanism of “covalent grafting-interface entanglement-micronano structure” for fluorine-free coating performance enhancement and provides a low-cost, scalable solution tailored to the extreme arid-sandy environment of northwest China. Its superior dust resistance and moderate UV stability effectively lower the maintenance demand of PV modules, showing more practical value than general-purpose hydrophobic coatings in long-term outdoor dusty environments.