Advanced Measurement Techniques to Characterize the Near-Specular Reflectance of Solar Mirrors

Abstract

The precise measurement of the reflected energy form a solar reflector to the Receiver is a challenging Task because of ist dependency on three different Parameters: the wavelength of the incident lieght, ist incidence angle and the acceptance angle of the Receiver. Up to today, the commonly empleyed measurement Equipment is not able to fully characterize the mirrors in the required range of Parameters which is relevant for CSP. Within this work, four reflectometers were upgraded to overcome the current drawbacks. A Round Robin test among the different characterization methods has been carried out on four reflector materials. The conclusions drawn from the comparison of the measurement results help to improve the current SolarPACES Reflectance Guideline.