The role of unidirectional charging flexibility in the planning and operation of the future Swiss electricity system

Electrification of passenger transport is central to decarbonization, yet the growing demand for electric vehicle charging presents challenges for electricity system planning. Because charging is inherently flexible, it can support cost-effective system operation when coordinated with system-level decisions. Here, we couple location-specific charging flexibility boundaries with transmission-level generation and network optimization to examine how a central planner deploys unidirectional charging flexibility in Switzerland’s 2050 electricity system. Scenarios reflect different policy priorities, i.e., cost minimization versus renewable targets, and varying levels of cross-border market integration. The 2050 horizon represents Switzerland’s carbon-neutral target, with widespread rooftop solar, capped hydropower, high electrification of heating and transport, and diverse cross-border exchanges. Results show that unidirectional charging flexibility, implemented during idle parking with minimal user disruption, reduces total system costs by up to 4.5 % and electricity supply prices by over 6 %. Flexibility improves renewable utilization, reduces curtailment, and increases the value of cross-border trade by shifting imports and exports to more favorable times. Seasonal effects are key: flexibility supports Alpine PV and reduces gas reliance in winter, while aligning with rooftop PV and mitigating evening peaks in summer. These findings highlight charging flexibility as a cost-effective resource for decarbonized systems and call for targeted policy signals, simple daytime incentives in summer, and dynamic, weather-sensitive tariffs in winter.