Functional surfaces for solar cover glass

Replacing fossil fuel electricity with energy generated from renewable sources such as hydro, wind and solar is essential. It is forecast that Solar will become the most important electricity generation technology worldwide by 2027. Over 200GWp of solar photovoltaics was manufactured in 2022 and the current installed base already exceeds 1TWp. Despite the incredible rate of expansion, solar is a young technology and much can be done to improve its performance. This project addresses the significant losses that occur at the solar glass cover sheet used to protect the solar absorber.
Losses occur due to reflection from the glass outer surface and also occur due to soiling of the cover sheet causing attenuation of the light into the absorber. Currently, a single layer porous silica anti-reflection (AR) coating is applied to the outer glass surface. This coating is optically effective, but is vulnerable to abrasion during module cleaning. It is now apparent that its useful life is only about 6 years even in a benign climate such as the UK where panels are cleaned twice per annum. In addition, these coatings are hydrophilic. Their high surface energy causes increased adhesion to soiling. The increased soiling can outweigh the benefits of the lower reflection.
This project will develop a new approach to the problem. We have discovered a polymer that is UV resistant, has a low refractive index and is hydrophobic. Laminating a thin film of this polymer to glass combines the benefits of the structural strength and impermeability of glass with the low reflectance and hydrophobic character of the polymer. The project is aimed at developing an efficient laminating process that results in good polymer/glass adhesion that retains the material advantages of the polymer sheet.