Study of hydrophobic coatings and potential water savings in solar power plants

This study explores the challenges related to dust deposition on solar photovoltaic (PV) systems. Review of earlier works suggests solar PV performance is significantly affected by the dust deposition and the power loss can vary from 10% to more than 60% in some cases depending on the location. Hydrophobic coatings can offer a potential pathway for reducing dust deposition and water saving in cleaning operations. This paper presents the comparative study of the four commercially available and one developed silica-based hydrophobic coating to estimate the quantity of the water required for cleaning of the dust. Comparative experimental tests reveal that the developed coating has the highest contact angle (145°), least contact angle hysteresis (5°) and least surface free energy (17.4 mN/m) as compared to the other coatings. The prepared coating slightly decreased the visible light transmittance of the glass from 92.4% to 90.23%. The water saving with the hydrophobic coatings is found to be in the range 28%–55%; the highest water saving is observed with the developed coating as it is almost near to a superhydrophobic coating in behaviour. Furthermore, the scope for future work and challenges related to the development and use of hydrophobic coatings in the solar area are discussed.