Analytical resolution of the electrical four-parameters model of a photovoltaic module using small perturbation around the operating point

In this paper, a new real-time curve fitting method for photovoltaic (PV) modules is presented. The method solves the four-parameters photovoltaic cell model without scanning the entire I–V curve, without sensing irradiance or temperature and with no need of any manufacturer data. Only six pairs of voltage and current coordinates are needed to obtain the photovoltaic module parameters in any conditions of illumination, temperature or degradation. Once the electrical model is known, a new technique to compute the maximum power point (MPP) of the module is devised. This method is suitable for real time applications where the I–V curve of the module and the MPP can be extracted at any moment without affecting the operation of the system. The theory that supports the estimator and experimental results are presented in this work. ► We provide an analytic resolution of the four-parameters model of the I–V curve. ► We approximate the I–V curve with six voltage–current points near the working point. ► We estimate with a good precision the MPP using the four-parameters model. ► We use the Fix Point Method to compute very quickly and precisely the MPP. ► Information can be used for monitoring or to control the power in a solar array.