Comparison of Corrections and Calibration Procedures for Rotating Shadowband Irradiance Sensors.

Rotating Shadowband Irradiance sensors are a relevant alternative to pyrheliometers for measurement of direct beam solar irradiance because they require less maintenance and power. Different calibration procedures are used to compensate the deviating spectral response of the silicon photodiode sensors. An enhanced RSI correction has been developed, accounting for temperature and spectral response of photodiode sensors and further dependencies on incidence angle, air mass and altitude. Furthermore, different calibration methods are examined. The enhanced correction delivers the best performance for RSI correction with an average RMSD of 15 W/m² and annual DNI deviations of typically 0.5%.