Scientific System for High-resolution Measurement of the Circumsolar Radiation

We developed a camera based system for measurements of the circumsolar radiation with a high angular resolution of 0.1 mrad. Subsequent measurements may be taken at intervals as short as 15 s. In this publication we describe the optical system in detail and discuss some aspects of the measurement method. First results from two days of measurement at Freiburg i. Br., Germany, are presented and compared to data from literature. The good results encourage us to perform longer measurement campaigns in future to better understand the influence of circumsolar radiation on the power yield of concentrating photovoltaic systems.