Vehicle-to-grid: using an electric car as a home battery

V2G, V2H, V2X

Three terms, one piece of hardware.

V2G — vehicle-to-grid. The car exports to the network, and you are paid for it, usually through an aggregator or a supplier tariff.

V2H — vehicle-to-home. The same bidirectional charger powers your house instead. No export, so no export payment, but also fewer regulatory complications: you are displacing purchased electricity, which is worth several times what exporting it is.

V2X is the umbrella the government uses for both, plus vehicle-to-load.

For most households, V2H is the more interesting one, for the same reason self-consumption dominates everything in solar: a unit you use is worth far more than a unit you sell.

The size difference, and why it matters

A typical home battery holds a handful of kilowatt-hours. A modern electric car holds several tens. That gap is the reason the idea keeps coming back.

It also creates the reason it is complicated. A home battery is a fixed asset that is always there. A car is a mobile asset whose primary job is to be somewhere else. Any scheme that values your car as storage has to cope with it being driven — which means state-of-charge floors, departure times, and an operator who has to guess right.

What the government has said about the barriers

The Electric vehicle smart charging action plan, published 18 January 2023, is the clearest official statement we have found. Its list of barriers to V2X:

• the cost of V2X systems, and the lack of V2X-compatible vehicles
• a limited range of compatible vehicles
• a lack of revenue certainty for a wide range of consumers
• a connection process for bidirectional charge points that is more difficult than for unidirectional smart charge points

On the last point the plan commits Ofgem to work with distribution network operators through the Energy Networks Association to ensure a consistent connection process for V2X across all regions.

It also names one fiscal item worth knowing about: preventing the double charging of final consumption levies on electricity re-exported by domestic-scale storage, vehicle-to- grid included. Levies are charged on electricity consumed; without a fix, electricity bought, stored and sold back can attract them twice.

Support. The plan set out the Vehicle-to-X Innovation Programme, with up to £12.6 million of funding, phase 1 of which supported 17 projects with over £3.2 million.

What the trials found

Ofgem published a case study on 6 July 2021 covering a programme running since April 2018 that installed 330 V2G devices across the UK.

Its headline: customers could earn as much as £725 a year without needing to do anything except keep their cars plugged in.

The same case study is candid about the constraints of the period: the V2G hardware cost around £3,700 more than a standard smart charger, only one vehicle model was compatible during the trials, and ancillary market access for domestic flexibility was limited by high entry thresholds.

That last barrier is the one that has visibly moved. NESO’s Demand Flexibility Service now operates year-round and, since April 2026, values flexibility in both directions — see grid services.

The connection question

A bidirectional charger can export to the network. That puts it in the same territory as any other generation or storage at the property: the Energy Networks Association’s connection recommendations apply, capacity counts towards the site total, and the 16 A per phase threshold — 3.68 kW single-phase — decides whether you may install and notify, or must ask first.

A V2G charger’s export rating can be substantial, and it stacks on top of any solar and any home battery already at the property. This is a question to settle before ordering the equipment, not after. G98 and G99 sets out which procedure applies.

Should you wait for it?

Our answer is: not as a plan, unless you can name the car, the charger, the tariff and the connection route today.

The capability has been arriving for several years. The government’s own framing puts widespread deployment alongside the 2035 zero-emission vehicle transition, with a significant proportion of new vehicles expected to be V2X-capable by then. That is a reasonable expectation and a long time to hold off on storage that would have been paying for itself.

The more useful version of the question is narrower: if you are buying an EV or a charger anyway, is the bidirectional option worth its premium? That is a live question with a real answer, and it depends on the premium, on whether a tariff exists that will pay you for it, and on what the vehicle manufacturer says about its warranty.