Sol–gel processed silica based highly transparent self-cleaning coatings for solar glass covers

In order to enhance performance and reliability of photovoltaic modules (PV), it is very essential to keep the PV modules clean. Although there are good number of available technologies to clean the glass covers of solar panels, however, self-cleaning coatings, with extreme wettability, is emerging as one of the most reliable solution which can be easily applied and at the same time comes with low cost. Such coatings should be not only good at keeping the PV modules clean but at the same time should maintain the transparency of solar glass covers so as to allow maximum light to enter the surface of encapsulated solar panels. Most importantly such self-cleaning glazing structures have become very much useful in diverse field of solar energy application areas, such as solar radiation transmission, building integrated photovoltaics (BIPV), solar panels, concentrated solar power (CSP) systems. Here we havedeveloped a facile sol–gel based highly transparent and self-cleaning coatingwith tunable wetting property, by synthesizing single component silane modified base and acid catalyzed mixed silica sol. The sol is coated by following dip-coating approach on glass substrates. A static contact angle (WCA) as high as 150° and contact angle hysteresis (CAH) of ∼2° has been achieved with these coatings. The maximum transmission of glass used in solar glass cover has been found to increase from 91.8% to 95.5% and concomitantly minimum reflectance has been found to reduce from 8.7% to 3.2%. Such antireflection behavior has been further investigated by making ellipsometry studies, where we found the refractive index of the coating to be 1.35 and film thickness 103.54 nm.