Efficient photovoltaic charging of electric vehicles

The University of South Florida in Tampa, USA, has initiated operation of a photovoltaic (PV) system capable of a 6 kW (peak) output that can be used for simultaneous computer controlled direct DC-DC charging and utility interconnection. The PV DC-DC system is part of the 20 kW (peak), 12 bay Electric Vehicle/Photovoltaic Demonstration and Evaluation Program being conducted at the University and consists of a four bay portion of the parking facility equipped with roof mounted PV panels. These panels not only provide power for charging, but also help protect vehicles from damage caused by solar radiation. The program has been created to evaluate the potential contribution of photovoltaics as a method for offsetting the fuel cost of electric vehicles while reducing air pollution generated by power plants that are fueled by nonrenewable sources. The DC-DC charger controls the charging current of a battery pack with minimal parasitic power waste, by computer on/off control of each of four source circuits. It provides superior efficiency over DC-AC-DC charging and its cost and maintenance requirements are lower.