Indirect method to determine near-normal sun-conic reflectance

This paper presents an indirect method to estimate the near-normal sun-conic reflectance of solar mirrors, which is considered to be the relevant parameter to describe the reflectance characteristics of reflectors employed for CSP systems. The indirect method has been validated by direct measurements with the Spectral Specular Reflectometer measurement device reported in previous conferences. Good agreement between indirect and direct measurements was found for new and aged mirrors but not for soiled mirrors, where different phenomena seem to occur. The indirect method is thus only applicable for clean mirror surfaces in new and aged condition. The benefit of the indirect method is that it is simple and applicable with commercial equipment, providing a useful tool to determine near-normal sun-conic reflectance for all laboratories which do not own advanced reflectometers.