Photovoltaic maximum power point tracking battery charge controller

Photovoltaic generators exhibit nonlinear I-V characteristics that vary with solar insolation. This paper describes a technique for real time tracking of the maximum power point (MPPT) of a solar panel charging a battery. A step down switching regulator is used where the duty cycle is varied to attain the desired MPPT level. Performance of the MPPT is evaluated theoretically using ORCAD SPICE. A prototype of the MPPT is built using ATmega 32 microcontroller and tested to charges a 70Ah lead acid battery with a 40W solar panel. Both simulation and experimental results validates capability of the proposed technique to track the maximum power at different solar insolation.