Self-cleaning and photovoltaic characteristics for solar cell with FEP film in curved building

This study addresses the demand for lightweight, flexible, highly transparent, and self-cleaning cover materials in curved-building integrated photovoltaics, proposing fluorinated ethylene-propylene film as an alternative to glass. Based on wetting-state mechanism and surface-energy theory, we investigated outdoor dust accumulation, photovoltaic performance, and city-specific power generation prediction, defining the suitable application scope of FEP across regions. Results show that FEP's low adhesion and hydrophobicity reduce soiling density by up to 52.6% compared to glass. Under rain, snow, or wind, self-cleaning is more effective at low tilt angles due to surface properties; under other weather conditions, higher angles become superior mainly due to gravity. Moreover, FEP-covered cells exhibit anti-reflection effects, increasing maximum power by 4.28–6.03% and achieving faster voltage stabilization. Using experimental data, a random forest model was built to predict power generation for eight cities across four solar resource zones in China. In regions with annual total irradiation ≥7000 MJ/m2, the gain from FEP is relatively low due to Auger recombination; in areas with irradiation ≤3600 MJ/m2 and lower outdoor temperatures, the gain is more pronounced (≈6.4%) owing to excellent moisture resistance. FEP film is particularly suitable for Class IV solar resource zones.