Vehicle-to-grid technology explained: Plugging in to the next big EV shift

Our guide to vehicle-to-grid technology, its benefits and drawbacks and what it means for EV owners.

The arrival of electric cars has brought a whole new world of jargon for drivers to get their heads around – from charging curves to kilowatt hours.

But one term that is getting an increasing amount of attention is vehicle-to-grid technology.

More and more car makers are talking about it and its potential to save money and perhaps the environment. So what is it and why should you care?

What is vehicle-to-grid?

In simple terms vehicle-to-grid (V2G) technology allows an electric vehicle to send power stored in its battery back to the energy grid.

A lot of cars already support vehicle-to-load (V2L) charging, known as bi-directional charging. This is where small appliances such as laptops, coffee machines or e-bike chargers can be run from the car’s main high-voltage battery via an adaptor or in-car three-pin socket.

Vehicle-to-grid takes this further, allowing owners to send energy back and forth between their car and the national grid to help balance energy demand.

How does V2G work?

Unlike “normal” EVs which can only draw power to their batteries, cars equipped with V2G systems use special on-board hardware and dedicated chargers to send energy away from the vehicle. This hardware is managed by software which allow EVs, home chargers and the wider energy grid to communicate in real time. Doing this enables the technology to manage cars’ charging and discharging in line with wider energy demands and support the national supply. It can top up batteries when demand is low then send it back to the grid when demand is high.

While it sounds fairly simple, the technical process is very complicated.

At the home user end, the charger has to be able to convert AC from the grid to DC for storage in the EV battery. It then needs to be able to convert this back to AC in order to send it back to the grid. This requires very precise synchronisation with the grid. It also requires the car and charger to be in constant communication with the grid via complex software to make sure energy flow is matched to demand from both the grid and the car.

What are the benefits of V2G?

There are a few major benefits of V2G technology both financial and environmental.

Financially, V2G allows EV owners to charge their cars when demand and prices are low, then sell the energy back to the grid when demand and prices are high. It is thought that drivers could cut energy costs by 70% and make up to £320 per year by charging their cars at off-peak times then selling the energy back at peak periods.

For homeowners with solar panels, the benefits could be even greater – generating free energy from their home array then selling it on to the grid when needed.

V2G is also good for the environment as it means excess renewable energy can be stored in EVs for use later. This means wind and solar energy generation in low-demand times isn’t wasted or curtailed. It also means that the grid can draw on stored energy at peak times rather than placing more demand on fossil fuel power stations.

Widespread V2G use could also help stabilise the grid, smoothing out supply fluctuations and reducing the likelihood of power cuts.

What are the drawbacks of V2G?

Although V2G has clear benefits, there are issues around its adoption.

The first obstacle is the limited availability of compatible vehicles and chargers.

Beyond that, setting up V2G infrastructure and connecting it correctly with the national energy supply is nowhere near as simple or cheap as a regular single-direction home charger.

There are some concerns that an increase in charging cycles could accelerate battery degradation. However, it’s not clear how much effect this might have and some studies have suggested that cycles which keep the battery in its optimal charging window might help prolong battery life.

There’s also the issue of cost. While some systems use AC technology like current home chargers others use DC technology. These units are up to six times more expensive than a standard home wallbox, are far larger and more complex to install.

How far along is the UK in adopting it?

Despite lots of talk around V2G and various pilot schemes, the technology is still in its infancy in the UK.

Several manufacturers build cars that are V2G compatible, including Renault, Nissan, Volkswagen, Kia and Polestar, and some already offer it in other countries. However, most haven’t said when it will be offered on UK models or what hardware will be needed to make it work.

There’s also not much in the way of charging hardware. Just four companies in the UK offer chargers that can support V2G operations, and only three of them – Humax, Quasar and Zaptec – are compatible with domestic single-phase supplies.

V2G tariffs are also still under development. Octopus Energy trialled a bespoke V2G tariff in 2024 and plans to launch its “Power Pack” leasing bundle later this year. This will offer an EV lease deal on a BYD Dolphin, a Zaptec Pro home charger and free home charging for the duration of the vehicle lease.

Beyond that there’s not much on offer for drivers looking to explore V2G.

However, with the potential financial and environmental benefits and the number of brands exploring the technology, it seems likely that we’ll hear a lot more about vehicle-to-grid in the coming years.