Impact of Inferring Atmospheric Parameters on Solar Irradiance Estimation

This study focuses on the estimation of clear-sky solar irradiance available in a specific location using a parametric model. The challenge is to estimate solar irradiance at a higher resolution than the resolution at which the atmospheric parameters applied to the model input are measured. Two methods were tested to increase the resolution of the input data: hourly arithmetic averaging of measurements and linear interpolation between two measurements. The influence of averaging and interpolation of the atmospheric parameters on the clear-sky solar irradiance model accuracy was assessed. The analysis was performed on a dataset comprising ground-based measurements from the Solar Platform of the West University of Timisoara, complemented by atmospheric parameters obtained from the Aerosol Robotic Network (AERONET). Particular attention is given to the influence of Ångström turbidity coefficient, which is known to play a critical role in the attenuation of solar radiation when passing through the atmosphere. The results indicate that the use of hourly mean atmospheric parameters does not significantly compromise the overall accuracy of the solar irradiance estimates. However, due to the sensitivity of the model to aerosol-related parameters, it is advisable to employ interpolated values for the Ångström turbidity coefficient to enhance the accuracy of irradiance estimations under fast varying atmospheric conditions.