Study and Comparison of Naturally-Aged and As-Received Silvered-Glass Reflectors

Abstract

Back-silvered glass mirrors exposed in Abu Dhabi outdoor conditions for 7 years along with corresponding as-received mirrors from the same manufacturing batch which were preserved in a warehouse are analyzed in the present study. The availability of both the as-received mirrors and the exposed ones over a time longer than that in previous studies presents an opportunity to validate accelerated aging tests through comparison with naturally aged mirrors. The exposed mirrors showed substantial reflectance degradation. Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) was used to characterize both as-received and exposed samples and compare the as-received sample to a reference mirror from the state-of-the-art commercial solar mirrors. The analyses identified 5 possible causes of the rapid degradation observed for the mirrors in question in comparison to the lifetime expectation for commercial solar mirrors. The findings will serve to guide ongoing and future accelerated-aging studies on the same mirrors.