Development of a spatially resolved reflectometer to monitor corrosion of solar reflectors

Abstract

Solar reflectors for Concentrating Solar Power (CSP) concentrators require a high reflectance and high specularity over the whole solar spectrum. During their lifetime of at least 20years, the reflectors must withstand harsh outdoor conditions without loosing their reflective properties. Currently, there are not many devices available to measure the specular reflectance. In this work a prototype of a specular reflectometer with spatial resolution has been developed. The major advantage of the prototype compared to other reflectometers is the possibility of measuring the specular reflectance on an extended measuring spot of more than 5cm in diameter with a spatial resolution of 37pixel/mm. Additionally, measurements can be taken at three different acceptance half angles (φ=3.5,6.0, and 12.5mrad) and at three different wavelengths (λ=410nm, 500nm, and 656nm). This lab scale instrument can be employed to monitor degradation effects, such as corrosion spots, and evaluate their influence on the specular reflectance of solar mirror materials.