Comparative Assessment of the Durability of Glass and Polymer Mirrors for Concentrated Solar Thermal Technologies

This paper describes experimental work that has been carried out to assess the durability of glass and polymer mirrors against erosion and soiling phenomena. Both outdoor and indoor tests have been performed and the results show that polymer mirrors are quickly degraded in comparison to glass. Soiling deposition has been simulated using a soiling test rig developed for laboratory use. Results show that polymer mirrors, due to their high roughness and their surface energy properties, can accumulate more soiling on their surface generating a higher drop in specular reflectance compared to glass mirrors. Contact cleaning processes have also been simulated on polymer mirrors and the results show that using a hard brush, even at low speed with rotational motion, causes significantly more degradation than a soft brush.