Estimator of local solar irradiation based on a PV model

In this paper, we propose a concept for estimating solar irradiation by measuring the current, the voltage and the temperature of a photovoltaic cell. The estimation of the solar irradiation is obtained by processing these measurements using a mathematical model of a photovoltaic cell, combined with a PI controller. Since the PV cell current is very sensitive to the irradiance level, the principle of the method is to force the photovoltaic model to reproduce the same current as that measured on the cell by applying an appropriate irradiance as input, for measured temperature and voltage. The appropriate irradiance, which is the output of the estimator, is provided by the PI controller in such way that the estimated current by the model follows exactly the measured current. The PI controller also ensures the self-calibration of the photovoltaic reference-cell depending on the temperature changes. The effectiveness of the proposed approach has been validated in simulation and on an experimental platform.