V2G turns electric vehicles into mobile energy storage assets. This guide covers bidirectional chargers, BS 7671 regulations, G99 DNO applications, compatible vehicles, grid services revenue, and the installation and certification process.
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Vehicle to Grid — commonly referred to as V2G — is a technology that allows electric vehicles to feed stored energy back into the home electrical installation or the wider electricity grid. Instead of an EV being a passive load that only consumes electricity, V2G turns it into a distributed energy storage asset.
A typical electric vehicle has a battery capacity of 60 to 80kWh — significantly larger than any domestic battery storage system (which are typically 5 to 13kWh). Even using a fraction of this capacity for grid services or home backup represents a substantial energy resource.
V2G requires a bidirectional charger (sometimes called a bi-directional EVSE) that can convert AC from the grid to DC for charging the vehicle, and convert DC from the vehicle battery back to AC for export. The charger communicates with the vehicle via ISO 15118 to manage the power flow, state of charge limits, and scheduling.
For electricians, V2G represents a significant upskilling opportunity. The installation is more complex than a standard EV charger, commands a higher price point, and positions you in a rapidly growing market. This guide covers the regulations, DNO requirements, compatible vehicles, installation process, and certification requirements.
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A bidirectional charger contains an inverter that can operate in two directions. In charging mode, it converts grid AC to DC and pushes it into the vehicle battery. In discharging mode, it draws DC from the vehicle battery, converts it to AC, and feeds it into the home circuits or exports it to the grid.
The EV battery powers the home circuits directly. The charger island-disconnects from the grid (if the grid is down) or supplements grid supply (if the grid is live). Useful for peak shaving — running the home from the EV during expensive peak hours and recharging overnight at off-peak rates. Also provides emergency backup power during grid outages.
The EV battery exports power beyond the home and into the distribution network. This enables participation in grid services — frequency response, demand-side response, and capacity market programmes. An aggregator platform manages the export scheduling and revenue. V2G requires G99 DNO approval because power is being exported.
Both modes require the bidirectional charger to include anti-islanding protection — the system must automatically disconnect from the grid if the grid supply fails, to prevent back-feeding that could endanger DNO engineers working on the network.
V2G installations must comply with BS 7671:2018+A4:2026 including several regulations specifically relevant to bidirectional energy flows and energy management systems:
Additionally, the IET Code of Practice for EV Charging provides detailed guidance on bidirectional charger installations. The charger itself must comply with the relevant product standards and carry a UKCA or CE mark.
Because a V2G charger can export power to the distribution network, it falls under Engineering Recommendation G99 — not G98. This is a critical distinction from standard EV charger installations.
If the property already has solar PV with an existing G98 or G99 notification, the V2G charger must be included in an updated application — the total export capacity of all connected generation and storage must be assessed together.
Not all electric vehicles support bidirectional charging. The vehicle must have an onboard charger and battery management system that supports reverse power flow, and the vehicle firmware must implement the ISO 15118-20 communication protocol.
Always confirm V2G compatibility with both the vehicle manufacturer and the charger manufacturer before quoting. Vehicle software updates can enable or disable V2G support, and not all trim levels or battery options within a model range may be compatible.
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One of the key selling points of V2G is the ability to earn revenue by providing services to the electricity grid. This is managed through aggregator platforms that pool many V2G chargers into a virtual power plant.
Combined, V2G revenue and savings of £500 to £1,000 per year are realistic. At a V2G charger cost of £3,000 to £5,000 (including installation), the payback period is 3 to 7 years — competitive with domestic battery storage.
A V2G installation follows a similar process to a standard EV charger but with additional steps for the bidirectional capability, DNO application, and grid services setup.
The electrical installation must be tested and certified in accordance with BS 7671. The scope includes:
An Electrical Installation Certificate (EIC) must be issued for the new circuit. The certificate should note the V2G charger, the G99 reference number, and the anti-islanding protection. The G99 commissioning confirmation form must also be submitted to the DNO after testing.
V2G installation is a premium service with strong margins. A typical domestic V2G installation (charger, dedicated circuit, CT clamp, commissioning, DNO application, and certification) is worth £3,000 to £5,000 for the electrical package. Combined with the charger hardware (which you can supply and mark up), the total project value can exceed £7,000.
The market is growing rapidly as more vehicles support bidirectional charging and grid services platforms mature. Electricians who upskill now will be well positioned as V2G moves from early adopter to mainstream.
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