Improved photovoltaic MPPT algorithm adapted for unstable atmospheric conditions and partial shading

In this paper, we present and implement an improved maximum power point tracking (MPPT) algorithm for photovoltaic (PV) applications. The proposed algorithm incorporates an online current measurement and periodic interrupts to address certain challenges associated with rapidly changing insolation and partial shading. A new rule for updating the adaptive step-size is introduced for improving dynamic and steady-state responses. This rule exploits the first and second derivatives of power as a function of duty-cycle. The algorithm is implemented on a micro-controller, and the technical issues concerning the hardware design and implementation are discussed. Finally, we present both simulation and experimental results, under different irradiation schemes.