What is vehicle-to-grid (V2G) charging?

It won’t be long before your electric car will be able to sell electricity back to the grid from its batteries, helping you save even more money

Nissan Leaf charging

Vehicle-to-grid (V2G) charging is one of the most significant future developments for electric-car owners. Essentially, it'll let them sell electricity stored in their cars' batteries back to the National Grid during times of high demand – potentially making money in the process.

Cheaper energy tariffs during late-night, off-peak hours allow electric-car owners to top up their cars for less than would otherwise be the case. Through the use of 'smart' software and charging points, the transfer of electricity back and forth from the car to the grid can be automatically controlled, ensuring the owner still gets their car charged as much as they wanted, in addition to feeding power back to the grid.

The technology is already being trialled and government bodies such as the Department for Transport are backing it, so before long V2G will become a reality.

How V2G charging works

V2G is based on using electric-car batteries as energy storage devices and being able to both add and take power from them while a car is plugged into a home wallbox charger or public charging station.

New technology allowing cars' batteries to discharge back into the grid is needed in order for V2G to work as envisaged. Energy providers will incentivise customers with a small fee per kWh of electricity returned to the grid. The price difference between that fee and the cost of recharging your electric car during off-peak hours would be the profit made from V2G charging.

When will V2G charging be available in the UK?

Nissan and energy supplier OVO have run a 1,000-unit V2G charging trial in the UK. Participation takes two years and it's currently open to Nissan Leaf-driving OVO customers only, but the company estimates a £305 annual energy bill saving for users.

At the same time, the UK Government has pledged £30 million funding towards V2G charging. The funding is split across 21 different projects, to pay for “research and design and development, with the aim of exploring and trialling both the technology itself and commercial opportunities.” The Government is also working on a separate trial in Oxford using a fleet of 100 vehicles with V2G charging technology.

In June 2020, Western Power Distribution (WPD) launched its trial of V2G charging in the Midlands, South West and South Wales. The programme, run in partnership with CrowdCharge, is recruiting Nissan electric-car owners to take part in the trial, with the offer of free installation of a £5,500 smart charger in those areas. 

The trial, WPD says, will see several different energy suppliers testing their services to these chargers, offering "a more realistic simulation of a future world in which many streets will have a number of EVs using V2G chargers operated by different energy suppliers".

FCA V2G trial

Fiat Chrysler Automobiles (FCA) is the latest car manufacturer to get involved with vehicle-to-grid technology. Working with ENGIE, the Italian firm has announced it has begun development of V2G infrastructure. In May 2020, work began at FCA’s Mirafiori complex on installing V2G points to connect 64 electric cars to the grid; FCA says this will increase to 700 cars by the end of 2021.

While this technology is currently limited to FCA’s own headquarters and its own fleet of vehicles, the project represents a starting point for the technology and can be considered as a sign that big car companies are taking V2G seriously.  It’s most likely that any commercial version of FCA’s V2G technology would first roll out across its native Italy before it made its way to the rest of Europe and the UK.

Audi V2H trial

Audi is the latest manufacturer to turn its attention to the technology as it aims for a CO2-neutral range by 2050. Working in partnership with electrical installation firm Hager Group, Audi is developing a V2H (Vehicle to Home) system, whereby the electric car and its battery serve as a "temporary storage medium" for power produced by domestic solar panels. Audi says that this power can then be fed back into the home when sunlight levels are low, reducing electricity costs and increasing the stability of the wider electricity network

Audi says that this technology could be expanded to include a home electricity storage unit working alongside the electric car, allowing for "near-complete energy independence" and greater security against blackouts. 

During the research project exploring this technology, an Audi e-tron with 'near-series' – close to production – bi-directional charging capability was used along with a 12kW DC wallbox and a 9kWh home storage unit. The overall system, Audi says, is intended to function in homes with solar panels. 

It's not yet clear when this technology will make it to production Audi models, but it doesn't seem to be too far off.