Public charger expansion: Impacts across income classes and beyond regional borders

• Fueling detouring time results in improved service from network densification. • Techno-economic optimization shows moderate spillovers of local roll-out on regional BEV adoption. • Income-based consumer classes are key for planning charging networks by usage patterns. Public charging infrastructure is crucial to meet the charging needs of diverse consumer groups, and anticipating future patterns is essential for electricity system planning. This study examines optimal infrastructure roll-out from two perspectives: (1) how spatial densification strategies influence consumer groups with varying adoption behaviors, and (2) how local charging expansion affects battery-electric vehicle (BEV) adoption in neighboring regions. A techno-economic optimization framework is applied, incorporating intangible costs from charging time across charger types. The method integrates long-term infrastructure planning, BEV adoption by consumer group, allocation of charging processes, and spatial interactions between regions. Using a case study of the Basque Country, results show that charger network density significantly shapes charging behavior across income classes. Additionally, rapid local expansion (+30% to a baseline expansion) has a positive, though modest, spillover effect on BEV adoption in adjacent regions (max. 2.1%).