Is it plugged in? Impact of Vehicle-to-grid and the Connecting Behavior on the European Power System

Electric vehicles (EVs) are expected to become a major source of flexibility in decarbonized power systems, yet most energy-system studies assume that parked vehicles are always plugged in. This assumption lacks empirical foundation and may bias estimates of vehicle-to-grid (V2G) potential. Here, we combine large-scale survey data on plug-in behavior with a Markov Chain Monte Carlo framework to generate time-resolved availability profiles for Europe’s future EV fleet. We integrate these profiles into the open-source E2M2s optimization model to assess impacts on renewable integration, system adequacy, grid expansion, and costs. We find that realistic plug-in probabilities peak at only about 25%, substantially reshaping the optimal generation mix, reducing solar PV value, and weakening V2G-based peak shaving. While high availability yields short-term benefits (€5.7 billion in 2030), these are constrained by limited technological readiness and decline as the EV fleet expands. Our results highlight the central role of user behavior in power system transformation and provide a benchmark for future modeling and policy design.