Abrasion and Cleaning Tests on Antireflective and Antireflective/Antisoiling Coatings for Solar Glass Glazing

Abstract

The application of antireflective (AR) coatings on glass components for solar thermal collectors and PV modules increases the solar efficiency by increasing the sun energy that reaches the active layer. The low refractive index of this material required to satisfy the condition of producing destructive interference in AR/glass interfaces, makes necessary to deposit porous silica layers which are mechanically weaker than dense silica layers. Soiling of AR coated glass glazing not only can reduce the solar transmittance and increase the scattering but also can deteriorate the surface of the AR coating leading to irreversible damage by abrasion and reducing the long-term performance. The use of an anti-soiling (AS) coating on the top of the AR surface could avoid this yield loss due to soiling and increases the durability of the solar device. This paper describes the effect on the soiling and cleaning of an AS treatment on AR coated glass samples. The effect of the sample soiling, the type of sand applied and the brush used has been studied. The AS coating not only affects the sample soiling but also diminishes the surface damage.