This report presents a photovoltaic (PV) back-up battery bank charge controller design. It analyzes the characteristics of high penetration rooftop PV system and proposes adequate back-up battery bank charge controller according to the requirements. This paper aims at designing and carrying out the simulation of a simple but effective charge controller with maximum power point tracker for photovoltaic system. It provides theoretical studies of photovoltaic systems and modeling techniques using equivalent electric circuits. As the system employs the maximum power point tracker (MPPT), it consists of various MPPT algorithms and control methods. Proteus simulations verify the DC-DC converter design and hardware implementation. The results validate that MPPT can significantly increase the efficiency and the performance of PV system.