What is V2G?
Vehicle-to-Grid (V2G) is a technology that enables bidirectional power flow between an electric vehicle's battery and the electrical grid. While conventional EV chargers only draw power from the grid to charge the vehicle battery (unidirectional), V2G-capable chargers can also discharge the vehicle battery back into the grid — effectively turning parked EVs into distributed energy storage assets.
The principle is elegantly simple: most passenger EVs are parked 95% of the time. During those parked hours, their battery packs represent enormous distributed storage capacity that grid operators could theoretically access for grid balancing, peak shaving, and renewable energy integration — if the right hardware and software protocols are in place.
Why V2G matters for grid stability
Modern power grids face a fundamental challenge: electricity supply and demand must balance in real time. As renewable energy penetration increases — solar and wind are inherently intermittent — this balancing challenge intensifies. A grid with 40% solar penetration might see midday demand-supply mismatches measured in gigawatts.
Traditional response mechanisms include:
- Peaker plants — Expensive gas turbines brought online during peak demand; high operating cost and carbon emissions
- Battery storage — Utility-scale BESS installations; effective but capital-intensive ($400-600/kWh installed)
- Demand response — Paying industrial users to reduce consumption; limited scope
V2G offers a fourth mechanism: using the aggregate capacity of parked EVs as a virtual power plant. A fleet of 1,000 EVs with 60kWh batteries each represents 60MWh of distributed storage — without requiring dedicated infrastructure investment.
How V2G works technically
The V2G communication stack is built on ISO 15118, the international standard for plug-in vehicle to grid communication:
- ISO 15118-2 — Defines the handshake and session management for bidirectional power transfer
- ISO 15118-20 — Adds advanced features including Plug & Charge (automatic authentication and billing), bidirectional metering, and scheduled charging/discharging profiles
- OCPP 2.0.1 — The backend protocol enabling charge point operators to manage V2X sessions, set discharge prices, and coordinate fleet-wide energy flows
On the hardware side, V2G requires bidirectional DC-DC converters capable of controlled discharge, plus grid-forming inverter functionality to match grid frequency and voltage specifications. Not all bidirectional chargers are equal — the quality of grid-forming capability determines how stably the charger can island from the main grid and form a stable local AC supply.
V2G, V2H, and V2L: the terminology
The broader "V2X" (Vehicle-to-Everything) family includes:
- V2G (Vehicle-to-Grid) — Discharge back to the utility grid; requires grid operator agreements and revenue metering
- V2H (Vehicle-to-Home) — Discharge to the home during a power outage or peak rate period; simpler regulatory framework
- V2L (Vehicle-to-Load) — powering external devices from the vehicle; available via AC socket or DC output
Commercial deployment: the Wuhan Yangluo Port pilot
The world's first national V2G pilot — and a landmark reference for V2G deployment at scale — launched at Wuhan Yangluo Port in March 2026. The project uses megawatt-class bidirectional charging infrastructure to manage a fleet of electric port vehicles, with surplus battery capacity fed back to the port grid during off-peak periods.
Key learnings from commercial pilots to date:
- Battery cycle impact is manageable — Properly managed V2G cycling adds roughly 5-8% to annual cycle count; within most fleet warranty parameters
- Revenue potential varies by market — Markets with high price volatility (Germany, Australia) offer stronger V2G revenue cases than flat-rate markets
- Grid codes are evolving — Most national grid codes were written before V2G; updated interconnection standards are rolling out in the EU, UK, and China
SUNFULL's V2G product portfolio
SUNFULL offers a complete V2G-certified product range:
- 7-22kW V2G AC chargers — For residential and commercial V2H applications; ISO 15118-20 certified
- 60-240kW V2G DC fast chargers — For fleet and depot applications with grid-forming capability
- Megawatt-class V2G systems — For port, industrial, and utility-scale deployments (as deployed in the Wuhan Yangluo Port pilot)
- All V2G products — OCPP 2.0.1 compliant with ISO 15118 Plug & Charge support
