Vehicle-to-Grid (V2G)
Bidirectional charging technology that enables electric vehicles to return digitally managed energy from their batteries back to the power grid during peak demand periods.
Technical Details
Requires ISO 15118-20 compliant chargers and vehicles. Uses inverters capable of bidirectional power flow (AC to DC and DC to AC). Communication involves high-level protocols for grid authentication and session management.
Fleet Applications
Bus depots can generate revenue by selling excess energy back to the grid when buses are parked. It also provides essential frequency containment reserves (FCR) to stabilize the local grid.
Related Terms
Smart Charging
Intelligent management of EV charging sessions to optimize energy consumption based on grid constraints, energy prices, and vehicle schedule requirements.
Energy Arbitrage
The practice of purchasing energy when prices are low (off-peak) and using or selling it when prices are high (peak).
ISO 15118 (Plug & Charge)
Family of standards for high-level communication between an electric vehicle (EV) and a charging station (EVSE), enabling certificate-based "Plug & Charge" and advanced charging control (including bidirectional charging in newer editions).
Bidirectional Power Transfer (BPT)
ISO 15118 concept for charging and discharging where an EV and EVSE coordinate power flow in both directions (V2G/V2B), not just charging.
Generator Mode (Grid-Following vs Grid-Forming)
ISO 15118-20 BPT parameter describing the inverter behavior during discharge: following the grid voltage/frequency (grid-following) or actively forming them (grid-forming).
Islanding Detection (Active vs Passive)
Techniques to detect an unintentional “island” where a site keeps energizing a local grid segment after it is disconnected from the main grid.
Smart Grid
A modernized electricity grid that uses digital control and two-way communication to balance supply and demand.
Bidirectional Charging
Charging that allows energy to flow both into the vehicle and back out to a building or the grid.