Bidirectional Charging Architecture
Standard EV charging is unidirectional: grid AC → onboard charger → battery. Bidirectional charging (V2G, V2H, V2L) reverses this: battery DC → onboard inverter → AC output for home or grid use. Technically, this requires an onboard charger with a bidirectional inverter stage — more complex and expensive than a standard rectifier-only charger. The vehicle must also support the ISO 15118-20 communication protocol (the 'Plug & Charge' and 'smart charging' standard) which allows the vehicle and grid operator to negotiate power flow direction, rate, and scheduling over the SECC-EVCC communication layer. Alternatively, CHAdeMO was the first standard to support V2G (since 2012), which is why the Nissan Leaf and Mitsubishi Outlander PHEV pioneered bidirectional use. Ford F-150 Lightning with its 9.6 kW Pro Power Onboard system and 15 kW V2H capability became the first mass-market V2H-capable US EV in 2022. General Motors committed all Ultium-based vehicles to V2H support by 2026. Hyundai/Kia's E-GMP platform (Ioniq 5, EV6) supports V2L via an adapter at up to 3.6 kW. The 2025 Nissan Leaf supports V2G at 6 kW bidirectionally via ISO 15118-20 CHAdeMO.