The Battery Energy Storage System (BESS) design option for on-campus Photovoltaic Charging Station (PV-CS)

As the application of Light weight Electric Vehicles (LEVs) increase in communities, Dublin Institute of Technology (DIT) uses these small vehicles for short distance journeys around its 78 acre campus of "Grangegorman" located in inner Dublin city, Ireland. This paper presents an introduction to the campus Photovoltaic Charging Station (PV-CS) that generates clean electricity from the sun and charges the LEVs batteries which can lead to reduction of CO₂ emissions, along with fulfillment of national and international green sustainability targets. Based on the evaluation of possible options for PV-CS design, the optimal design configuration was chosen as a "Battery Energy Storage System (BESS)". The PV generated electricity that is stored in battery banks will serve as the primary source for charging the campus vehicles, with any surplus demand being met by the utility grid. Batteries have been included in the design due to intermittent nature of Irish sunshine and the charge time requirements of campus load. This paper concentrates on the detailed sizing of the BESS via two approaches: BESS with DC generation and BESS with LEV load demand. In the first approach the outputs were normalized and grouped into specified generation categories in MATLAB. To establish the accurate BESS capacity the load demand variations of the LEVs were monitored. Based on DC generation and demand profile, the optimal capacity of BESS was chosen to be in the range of 6-8 kWh, which can accommodate up to 6 LEVs.