Accelerated aging testing is used in several industries to estimate the lifetime of products and components. Manufacturers of solar reflector materials usually test the durability of their products following standards from automotive and photovoltaic industry. The testing time and the “pass” or “fail” criteria differ from manufacturer to manufacturer which makes it hard for customers to compare the available mirrors on the market and to select the most durable product based on the data sheets.This paper gives an extensive review of the state of the art of currently applied accelerated aging tests for solar reflectors. The testing conditions of relevant tests are summarized. Based on the experience gained over the last years in the aging laboratory of CIEMAT and DLR, a typical testing program to qualify the durability of reflector materials is being proposed. The appearing degradation of glass and aluminum mirrors under accelerated aging is analyzed and compared to outdoor exposure results

Concentrating solar power (CSP) plants are often located near industrial areas typically affected by high concentration of sulfur dioxide (SO2). This paper is focused on the influence of acid atmospheres of SO2 on the durability of solar reflectors, under accelerated aging conditions. A whole test campaign was designed and performed. All types of commercial solar reflectors were included. The accelerated aging tests consisted in applying up to 50 cycles, according to ISO Standard 6988. To quantify the optical degradation, reflectance was measured and a visual assess was done. After exposing the samples to the acid rain atmospheres, the deterioration and reflectance drop was smaller in thick glass mirrors than in the case of thin glass, aluminum and polymer mirrors. The anodized aluminum mirrors showed overall staining and intergranular corrosion, while coated aluminum mirrors did not show any degradation. Although no major reflectance losses were detected in polymer mirrors, a significant degradation, such as pitting corrosion on the reflector and damaged edges, was noticed

In this work, results of the outdoor exposure campaign of a newly developed hydrophilic anti-soiling coating for concentrated solar thermal power (CSP) mirrors are presented. The material was exposed for nearly two years under realistic outdoor conditions and the influence of two different cleaning techniques was evaluated. Mirror samples were analyzed during exposure and their reflectance and cleanliness were measured. The performance of the anti-soiling coated mirror samples was compared to conventional uncoated silvered-glass mirrors. The coatings showed appropriate anti-soiling and easy-to-clean behavior, with a mean cleanliness gain of 1 pp and maximum values under strong soiling conditions of up to over 7 pp. Cleanliness of the coated samples stayed higher throughout the whole campaign before and after cleaning, resulting in lower soiling rate compared to the reference material. Taking into account these values and supposing a threshold for cleaning of 96%, the number of cleaning cycles could be decreased by up to 11%. Finally, the coated material showed negligible degradation, not exceeding the degradation detected for the reference material.