Heterogeneous preferences for vehicle-to-grid discharging behavior at home across weekday and weekend temporal contexts

Renewable energy variability necessitates flexible demand-side management to maintain grid stability. Battery electric vehicles (BEVs) can serve as distributed energy resources through vehicle-to-grid (V2G) technology, yet realizing this potential depends critically on user acceptance of home-based discharging. This study investigates BEV users' preferences for home discharging behavior under V2G conditions, systematically comparing weekday and weekend contexts. Choice-based conjoint experiments were conducted with Japanese BEV owners, incorporating four attributes: discharging time slot, electricity selling price, current state of charge (SoC), and guaranteed minimum SoC. Results indicated that all four attributes influenced discharging decisions, with electricity selling price and time slot as the dominant factors. Weekday preferences were sharply concentrated in late evening and overnight periods, whereas weekend preferences were more evenly distributed. Scenario-based simulations using three identified user segments—Price driven, Balanced, and Time slot driven—showed that combining elevated electricity selling prices with higher current SoC during peak hours (17:00–24:00) raised their relative discharging probability by 47.1% on weekdays and 57.1% on weekends (17.6 and 19.8 percentage points) versus the low incentive case. Separate sensitivity analyses revealed electricity selling price as the primary lever and current SoC as a smaller, directionally consistent complement for shifting discharging preferences toward peak hours, both amplified on weekends across all segments. These findings provide a foundation for designing time-varying, day-type-differentiated, and segment-targeted V2G tariff structures that align user preferences for discharging behavior with grid flexibility needs, helping mitigate supply-demand imbalances from variable renewable energy integration.