Quantitative analysis of the angular dependence of photovoltaic radiometers signal. Modeling and experimental validation

Abstract

Photovoltaic (PV) radiometers based on crystalline silicon sensors are widely used as low cost instruments for solar irradiance monitoring in photovoltaic systems. However, their response depends on the angle of incidence (AOI) of incoming radiation, which introduces measurement uncertainties under real operating conditions. Although this effect is well recognized, its quantitative analysis remains limited. This work investigates the influenceof AOI on the signal of a PV radiometer through a combined optical and electronic modeling approach. The optical response of the multilayer structure of the radiometer is first simulated using a matrix based method to determine the spectral transmittance as a function of AOI. These results are incorporated into PC1D simulations to obtain the angular-dependent spectral response of a crystalline silicon sensor. The radiometer signal is then calculated by integrating the simulated spectral response with solar spectra generated using the SMARTS (Simple Model of the Atmospheric Radiative Transfer of Sunshine) model for atmospheric masses from AM1 to AM10. Simulations show that the spectral response varies only slightly up to approximately 50◦, followed by a marked change at larger angles. The solar spectrum also changes with atmospheric mass, introducing an additional dependence of the radiometer signal on AOI. Comparison with field measurements obtained using a PVradiometer shows good agreement with the simulated trends. The results demonstrate that the radiometer signal is determined by the combined effects of angle-dependent optical transmission and spectral variations in solar radiation.