UV degradation of primary mirrors in outdoor exposure and accelerated aging

Abstract

Concentrating solar thermal (CST) energy plays a fundamental role in the energetic transition which is facing our society. The energy generation of these systems hugely depends on the optical behavior of the reflectors. CST plants are installed in zones where the solar irradiance is very high. As it is well known, UV radiation is a main degradation mechanism for some materials. The possible weathering of the solar reflectors provoked by this environmental agent could be fundamental to decide the feasibility of a CST plant in a certain location. In this work, the degradation provoked by UV radiation in a series of different silvered-glass solar reflectors was deeply studied. For that purpose, seven reflector types were exposed for three years in countries of high interest for CST plants such as Chile, Spain and Morocco. An UV aging test based on fluorescent lamps was carried out to reproduce the degradation mechanism observed outdoor. Finally, the acceleration factors between the outdoor sites and the UV test were obtained.