Surface azimuth estimation from solar irradiance on tilted surfaces.

Abstract

Azimuth misalignment of receiver surfaces is a frequent source of uncertainty when working with solar irradiance measurements on tilted surfaces (GTI). Two complementary methods to estimate the true azimuth of a tilted surface from GTI data are implemented and evaluated; the first method being a new one, and the second a variation of a previously existing one. Ground data from an arrangement of tilted pyranometers with different azimuths, along with global horizontal, direct normal and diffuse horizontal irradiance (GHI, DNI and DHI) data, are used to validate the methods. The results show good agreement with nominal azimuth values, with typical uncertainties of a few degrees that increase with the nominal azimuth. Both methods are complementary since they have different strengths and weaknesses.