Accelerated aging tests and characterizations of solar mirrors: Comparison of combinations of stress factors on degradation

Abstract Solar mirrors for concentrated solar power (CSP) plants are expected to ensure a proper efficiency during 30 years. Due to this long time, accelerated aging tests of solar materials are crucial to estimate the real degradation in-service. However, most publications in the CSP field are based on standardized tests which are not sufficient to reach the durability of products in service on all CSP sites and all the market. The impacts on the material properties of unitary stress factors such as temperature, irradiation and humidity have been studied, and models have been proposed for different kinds of materials. All of these models include one or two stress factors, various magnitudes doses, and material dependent parameters. This study aimed to compare degradation under multifactor of stresses: temperature, humidity and irradiation on solar mirrors, with a focus on verification of two following hypotheses: 1 The coupling hypothesis based on the multiplication of the acceleration factors without synergy between themselves, 2. The initialization hypothesis for these three stress factors where the order of application of these tests does not matter. This last hypothesis was never formulated in the models but it is studied in this article. In this paper, we present the results of four different silvered glass mirrors subjected to several accelerated aging tests. The conclusion of this work will help the manufacturer to compare their technology to the others and to ensure the reproducibility of aging between indoor chambers and outdoor sites.