Evaluation of an EDLC-battery hybrid stand-alone photovoltaic power system

We have proposed a stand-alone photovoltaic power system that uses electric double-layer capacitors (EDLCs) and lead acid batteries as power storage devices. We simulated the system´s operating characteristics and evaluated the photovoltaic array mismatching loss, system conversion loss, battery contribution factor, averaged battery state-of-charge, and maximum depth-of-discharge. The results show that the system is effective at reducing the mismatching loss and battery contribution factor, so the system efficiency is improved. Moreover the system can maintain the averaged battery state-of-charge during operation. The maximum depth-of-discharge can be kept higher than in the conventional system. Consequently, the proposed system should have a longer battery lifetime