Suitability of PV and Battery Storage in EV Charging at Business Premises

The impact of the electric vehicle (EV) charging on node voltages and feeder currents of an electric grid can be reduced by upgrading its feeder capacity or deploying onsite photovoltaic (PV) and battery energy storage (BES), or their appropriate combination. It, in turn, enhances the quality of service (QoS) of the charging. This paper proposes an approach, which can enable a distribution network operator/business owner in finding the appropriate combination of the solutions above for providing the best QoS at a minimum cost while reducing the grid impact. The developed approach takes into account the previously scarcely incorporated characterization aspects (whether it is a constant power, constant current, or constant impedance load) of the EV charging. It has been applied to an IEEE 37-bus system in conjunction with the parking lots of the University of Queensland for a case study. The numerical results show that the proposed approach can effectively find the appropriate combination of the solutions above and the corresponding optimal sizes of PV and BES for a given EV penetration level or a given QoS.

I. Introduction

Extensive proliferation of electric vehicles (EVs) necessitates the deployment of widespread charging facilities [1]. Resulting charging loads are projected to impact the grids adversely without the appropriate remedial measures [2], such as controlling the charging [3], [4]. Controlling the charging alone, however, reduces the quality of service (QoS) defined as the ratio of charging energy delivered to charging energy demanded [2]. Therefore, EVs are advocated to be charged during the nighttime from lightly-loaded grids at lower prices to improve the QoS and reduce costs involved [5].