Assessing the Reliability of Wind-Powered EV Charging Systems in Poland Based on Long-Term Wind Data

The operational reliability of wind-powered electric vehicle charging systems (WPECS) depends not only on average wind resources but also on their temporal variability and continuity. This paper proposes a reliability engineering approach for assessing WPECS performance using long-term meteorological data and translating wind resource variability into practical engineering indicators. The proposed methodology adapts classical reliability concepts, including operational availability, deficit frequency, and redundancy sizing, to systems where unavailability is driven mainly by energy source variability rather than component failures. Four indicators are introduced: the Operational Availability Index (OAI), Deficit Event Frequency (DEF), Seasonal Load Factor (SLF), and Operational Continuity Index (OCI). The minimum required energy storage capacity (Ered) is also estimated. The method was applied to 15 meteorological stations in Poland using data from 2001 to 2024. The results revealed substantial spatial differences in WPECS reliability. Four locations achieved high operational availability (OAIL2 ≥ 0.83) with low storage requirements (<25 MWh), whereas other locations required large or practically infeasible storage capacities. A negative trend in wind resource availability was observed at most stations, indicating a gradual decline in reliability. The results indicate that temporal continuity of wind availability, rather than average energy level alone, is the dominant factor governing operational feasibility and storage requirements of WPECS. The proposed approach supports site selection, storage sizing, and operational planning of WPECS.