Low complexity MPPT technique exploiting the effect of the PV cell series resistance

This paper proposes a method for estimating the maximum power point (MPP) of a photovoltaic (PV) module through a simple linear equation, exploiting the relation existing between the values of module voltage and current at the maximum power point (MPP locus). The analytical study of the electrical model shows that this relation tends to be linear for the higher irradiation conditions due to the effect of the PV cell series resistance. Based on that, a linear approximation of the MPP locus is derived, whose parameters are simply related to those of the electrical parameters of a PV cell. The proposed solution presents the same complexity but higher effectiveness when compared to other estimation MPPT methods. Furthermore, the estimation is inherently compensated for temperature variations by periodically sensing the module open circuit voltage (V_oc). The proposed method is suitable for low cost PV systems and was successfully tested in a solar powered 55 W battery charger circuit.