On the analysis of suitable ageing tests of first-surface CSP mirrors in Moroccan outdoor conditions

Desert areas are considered to be the most suitable sites for CSP power plant installations due to their high irradiance, principally the direct normal irradiance (DNI), as well as the flat land scape and lower population densities. However, CSP reflector components are exposed to very harsh weather conditions in desert areas, such as wind storms, strong irradiation flux, scarcity of water needed for the cleaning of the reflectors, as well as sand and dust storms. These degradation factors can seriously affect the specular reflectance, surface morphology and therefore the overall efficiency of the CSP plants. On the other hand, CSP power plants installations can also be sited in coastal areas or industrial areas, which exposes the solar reflectors to salty environment or to Sulfur Dioxide (SO2) due to high levels of pollution in industrial sites. Previous work of the authors has been dedicated to the preparation of several types of highly reflective CSP mirrors, prepared experimentally by the deposition of a metallic layer of Copper (50nm) covered with a reflective layer of Silver (100 nm) protected with layers of Aluminum Oxide (AhO3) and Titanium Dioxide (TiO2) with thicknesses of 1 um and 50 nm, respectively. The aim of this work consists on studying the appropriate ageing tests suitable for the nature of different mirror samples and the particularity of the different potential sites in Morocco where the CSP reflectors can be potentially exposed.