Cost and Availability Optimization for Electric Vehicle Charging Infrastructure via Redundancy‐Spares‐Repair Integration

Redundancy allocation and spare parts logistics are among the primary strategies to achieve high operational availability of capital equipment. These methods are often implemented independently, with limited attention to their combined effect on system's lifetime cost. This paper proposes an integrated redundancy‐spares‐repair allocation model to maximize the availability and minimize the cost of electric vehicle (EV) supply equipment. The decision variables include the number of redundant chargers, the spare parts inventory, and the regular and the emergency repair capacity. When the spares inventory is depleted, failed EV chargers are immediately repaired through an expedited process to reduce downtime. Erlang‐B and Erlang‐C queueing models are used to characterize random parts demand and repair turnaround time. The levelized cost of EV chargers is used to compare the return on investment for redundant units versus spares stocking. The proposed model is demonstrated using Tesla's supercharger fleet, which consists of 17,004 DC fast chargers. The result shows that spare parts stocking, combined with regular repair, is a cost‐effective approach to achieving high availability of EV supply equipment. However, both redundancy and emergency repairs are essential when extremely high availability is required. Our analysis also reveals that inventory capital and holding cost have a limited impact on the levelized cost of the EV chargers.