Vehicle-to-Grid (V2G) explained: What it is and how it works

30 November 2023 | Celia Topping

Please note, this article was originally written in February 2021 when OVO were doing V2G trials with Kaluza. This initial trial period is now over. If you'd like to find out when we're doing further trials – on this or other products – please register your interest and we'll keep you informed.

Imagine a huge battery pack on wheels sitting outside on your driveway. It can drive you wherever you want, power your home, then make you money by selling excess power back to the grid. Sounds like science-fiction? It’s not, it’s happening right now. And it’s called vehicle-to-grid (V2G) technology. 

What’s vehicle-to-grid (V2G) technology?

Vehicle-to-grid technology – also referred to as 'V2G' – is the process of feeding the energy stored in an electric vehicle’s (EV) battery back into the National Grid. Why bother? To help boost the Grid’s energy supply at times of peak demand. Oh, and it’s a nice little earner too. V2G is a game-changing new technology that, along with smart charging, has the potential to transform the energy system as we know it. 

What is V2G charging?

V2G charging refers to the 2-way flow of electrical energy from the grid, through a specially-built charger into an EV, and back again. As an EV owner, you can choose to charge your car up from the grid – or sell stored energy in your car back to the grid. 

Why is OVO’s V2G technology smart? 

OVO’s V2G chargers are connected to Kaluza, an intelligent software platform, that enables EV smart charging. This pioneering platform allows you to schedule your EV charging through the Web-app. It decides when to import and export your EV’s energy through the V2G charger, at the best times for you and the grid.

This means there’s no need for our customers to worry about when to charge – Kaluza’s smart system does it all for you. So your car always charges on greener and cheaper energy, and is ready to drive whenever you need it. 

What can I do on the Kaluza Web-app?

Through the Web-app, V2G users are able to:

  • Set charging schedules, with the option to override them for unexpected journeys
  • Set minimum charge levels
  • See live charging updates (i.e. when your car is discharging or charging)
  • Keep a close eye on things by viewing your historical charging data

What is the V2G trial?

Over the last few months, OVO has been running a nationwide V2G trial. It’s funded by the Office for Low Emission Vehicles (OLEV) and the Department for Business Energy and Industrial Strategy (BEIS), in partnership with Innovate UK.

Along with Kaluza, we’ve installed 320 bi-directional EV chargers, manufactured in the UK by Indra Renewable Technologies. With OVO's V2G tariff, EV drivers have saved up to £800 a year on their bills. Not a bad return for just letting your car sit on your drive!

One trialist, David from Luton, said, “90% of the time my car is sat doing nothing. You have a huge energy storage device sitting on your drive. You’ve invested all that money in a car, so why not use it more of the time, rather than have it sitting doing nothing.” Spot on, David!

On a typical day, David charges his car when the grid is off-peak, at 15p/kWh. He drives to work and back, then plugs in again at home. In the evening, David and his family use the car battery to power the lights and various appliances and devices in his home for a few hours.

Then at bedtime, any excess power is exported from his vehicle back to the grid when prices are at a premium, 31p/kWh. David has made a profit of almost £900 in a year. Seems it’s not only his charger that’s smart! 

Why should you care about V2G?

V2G vehicle to grid

Good question! If you care about fighting climate change, then understanding why V2G is important is just the beginning. V2G tech is just one cog in a huge wheel of decarbonisation and the electrification of our energy system. Bit of a mouthful? Basically, fossil fuels are bad. We know this. So we want to cut down the use of carbon-emitting fossil fuels and decarbonise the grid, by using more renewable energies, like solar and wind

The challenge with these energies is that the power they produce is not always available. The sun doesn’t always shine, and the wind doesn’t always blow. So the electricity needs to be used immediately, or stored for later use.

And, as luck would have it, EV batteries are an abundant and cost-effective way of storing that energy. When the grid gets a bit low on energy, at times of peak demand, it can be easily topped up from all those cars. 

It’s actually estimated that there’ll be around 140-240 million EVs on the road globally by 20301. So that’s up to 240 million batteries on wheels, ready to balance the grid when we need it. 

What do we mean by “balancing the grid”?

There are peak times and off-peak times for energy use, just like there’s rush hour traffic in the morning and in the evening. 

Balancing the grid is about making sure there’s enough electricity on the network when we need it in peak times, so the country doesn’t black out. And it also stops power surges, which could damage domestic appliances, or cause electrical fires. 

As mentioned above, more renewable energy sources are being used to create electricity for the grid. This is a key part of the nation’s move towards a zero carbon future, and a cleaner, greener country for us all. But it makes balancing the grid more tricky – as solar and wind can’t be produced on demand in the same way as fossil fuel energy can. 

With technology like EV smart charging, we’re far more in control of when we charge our vehicles. And with V2G, we can also make money from feeding energy back into the grid, to “balance” it in times of need. 

Want to get more information about how to use the grid to create greener energy? We've put everything together in our useful guide.

How does V2G work?

What’s most important to EV owners is having enough energy in their car battery when they need to drive their car. This can be easily controlled through an app on the owner’s phone. But because a car spends 90%2 of its time parked, it makes sense to use the battery when it’s not in use. So with V2G, grid balancing is possible for the whole time an EV is plugged into the smart charger. But always with a (smart) eye on battery levels. 

It makes most sense for an EV owner to charge overnight, when the grid is in less demand, and electricity is cheaper. Then they can sell it back at peak times, at a higher rate. 

What are the key benefits of Vehicle-to-grid?

V2G is a game-changer as we move towards an intelligent, zero carbon grid. Here’s why: 

  • Simplicity of control for EV owners
  • Ability to reduce stress and add stability for the grid 
  • Helps reduce carbon emissions by contributing clean, green energy
  • Greater flexibility for owner and grid
  • Energy-efficient, low cost driving for EV owners
  • Cashback for EV owners – selling surplus energy back to grid

A great example of how V2G can be beneficial was in November 2020. Low wind speeds and high demand meant potential power shortages – so OVO’s V2G members were mobilised  to plug in. 150 vehicles fed power back into the grid, and the shortage was averted3 – and our V2G EV heroes saved the day! 

Why is V2G important for a greener future?

V2G is supporting our mission to power human progress with clean, affordable, renewable energy. A smarter, stable, yet flexible grid, supported by V2G means we don’t need to rely on fossil fuels any more. This brings us one step closer to the government's zero-carbon target, and a cleaner environment. 

Can V2G become mainstream?

The technology is pretty much ready to go, but there are still a few tweaks needed before V2G can hit the market in a major way. And in terms of vehicles, currently, only Nissan are making V2G-compatible cars, but other manufacturers are hot on their heels.

Vehicle-to-Grid FAQs