Effects of Capacity Factor on Sizing of Energy Storage Systems for Electric Vehicle Charging Plazas

This paper presents a study on the effects of capacity factor of electric vehicle (EV) charging plazas on sizing of energy storage systems (ESS) for peak load reduction of the charging plazas. The study is based on one year of measurement data from four fast charging stations from southern California, USA. The capacity factor of the charging stations was varied from 10% to 40% by duplicating the measured charging sessions to occur at the same time on a different day of the same type. Moreover, the size of the charging plaza was varied between 4 and 20 charging stations. The results show that the relatively highest ESS capacity is needed, and the utilization rate of the ESS is the largest, for highly utilized small-scale charging plazas. The required grid connection power of an EV charging plaza can be decreased considerably by an ESS with relatively small power and energy capacities.