Online fractional open-circuit voltage maximum output power algorithm for photovoltaic modules

An efficient maximum power point tracking technique is developed, which realises the fractional open-circuit voltage (FOCV) algorithm through a unique on-line procedure. The proposed method continuously estimates the open-circuit voltage by measuring instantaneous voltage, current, and temperature of the photovoltaic module without disconnecting the power flow to the load. Simultaneously, the open-circuit voltage ($V_{{\rm oc}}$Voc) value can be measured at any operating point of the I-V curve and does not require any perturbation to the specific point. Three methods i.e. proposed algorithm, analytical FOCV, and conventional offline FOCV are modelled in Matlab/Simulink environment and also the numerical computations are carried out. Finally, the proposed FOCV and the conventional offline FOCV are tested through the experimental setup. The comparative analysis indicates the following advantages: (i) interruption-free output power; (ii) accurate measurement of $V_{{\rm oc}}$Voc under any weather condition, especially variable temperature condition; and (iii) continuous measurement and tracking of maximum power point (MPP). Owing to the aforementioned advantages, the proposed method exhibits better MPP tracking and superior dynamic plus steady-state efficiencies as compared to the analytical FOCV and conventional offline FOCV methods.