An analysis of surface-soiling and self-cleaning of photovoltaic panel under condensation

Abstract

Dust on the PV surface is well known to cause significant losses in energy yield. Complex physical and chemical interactions occur between dust and condensate on the surface of PV module under condensation, which determine the mode and severity of surface contamination. In this work, dynamic behavior of dust particle on surface is investigated from a microscopic perspective. Dust mainly experiences particle aggregation, dusty droplet coalescence, growth, movement and drying. After condensation & drying, surface transmittance is quantitatively measured to provide an assessment of surface contamination. The results show that for SiO₂ and Al₂O₃ particles, that do not react with condensate, surface transmittance increases after drying, especially for superhydrophobic surface (SHS). However, CaO particle easily react with condensate and atmospheric carbon dioxide to form insoluble substances. After drying, a dense layer of dust is formed on the hydrophilic surface with transmittance of 49.2 %. SHS has excellent ability of self-cleaning and it increases with extension of condensation time. As condensation time is 120 min, transmittance of SiO₂-contaminated SHS can recover to 99.1 % of clean surface. This finding may guide for development of suitable strategies to prevent or mitigate surface-soiling under condensation.