Portable Solar Spectrum Reflectometer for planar and parabolic mirrors in solar thermal energy plants

This contribution presents a new field Solar Spectrum Reflectometer for solar-weighted specular reflectance characterization of planar, spherical or parabolic mirrors. This reflectometer is designed to provide fast and reliable field measurements and to be valid for any type of mirror currently installed in concentrated solar power systems, including parabolic trough, Stirling dish and central receiver power plants. The optical design of the Solar Spectrum Reflectometer, which includes 6 LEDs in the VIS-NIR band, is described, and its tolerance to variations in the geometrical parameters of the mirrors discussed and evaluated. The contribution of diffuse reflection and its impact on the measured reflectance is also calculated for different concentrated solar power systems.