V2H

Vehicle-to-home (V2H) is a system that allows a battery electric vehicle (BEV) to discharge stored electrical energy back into a building's power supply. The car functions as a mobile battery pack, drawing current from its high-voltage pack (typically 40 to 100 kWh in passenger vehicles) through a bidirectional charger, an inverter, and the home's electrical panel to supply AC power to household circuits. A 2020 Nissan Leaf with a 62 kWh battery, for example, can theoretically supply a typical home for 2 to 3 days before depletion.

V2H requires three key components working together: a bidirectional on-board charger or off-board DC-DC converter in the vehicle, a compatible home charging station equipped with bidirectional power electronics, and a vehicle compatible with the relevant communication protocol. The system communicates between car and charger via CAN bus or proprietary signals to manage power flow direction and magnitude. Implementations vary by market: CHAdeMO-equipped vehicles in Japan and some European models can already discharge; vehicles using the Combined Charging System (CCS) standard in North America are only now gaining this capability, starting with the 2024 Hyundai Ioniq 5.

Practical scenarios and limitations

V2H serves two distinct roles: backup power during grid outages and demand-side management during peak pricing periods. A homeowner can discharge during expensive evening peak hours (typically 4 PM to 9 PM in regions with time-of-use billing) and recharge during cheaper off-peak hours, often reducing electricity bills 15 to 25 percent depending on rate structure. The system requires a modern electrical panel with capacity for reverse power flow, typically costing USD 3,000 to 8,000 for installation, plus the charger itself.

Technical constraints limit adoption. The vehicle's battery capacity must exceed typical daily household consumption (15 to 30 kWh in most homes); continuous discharge at high power (over 6 kW AC) accelerates battery degradation, so systems usually limit discharge rates and duration; and the charger must support vehicle-to-grid (V2G) protocols, which remain incompatible across regional standards (CHAdeMO in Japan, GB/T in China, CCS in Europe and North America). Battery state-of-charge targets, temperature thresholds, and calendar aging all affect how much energy a vehicle can safely export over its warranty period.

V2H is distinct from V2G (vehicle-to-grid), which supplies power to the broader utility network rather than a single building. It is also different from onboard backup systems: V2H requires intentional discharge via a home charger, not passive support during an outage. Grid operators view V2H primarily as a tool for reducing peak demand and absorbing excess renewable generation during low-demand periods, not as emergency infrastructure, because a vehicle's availability is unpredictable and its state of charge is managed by the owner, not the utility.