Vehicle-to-Grid (V2G) Explained

A guide explaining the concept of vehicle-to-grid charging and exploring the benefits and drawbacks of this technology.

Last updated: Mar 06, 2024 4 min read

Vehicle-to-grid (V2G) allows electricity to flow two ways between an electric car battery and the electricity grid. This helps balance supply and demand better and reduce the risk of power cuts, and also offers drivers the ability to sell any excess energy back to the grid.

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V2G for a greener future

The global adoption of renewable energy like wind and solar power as our primary energy source is key to a greener future. However, renewables can be unpredictable at times, with supply fluctuating depending on weather conditions.

But with V2G, energy storage systems consisting of batteries could help maintain a reliable level of available energy to avoid shortages and power cuts when supply is low by selling the energy stored to the grid.

Electric vehicles (EVs) - particularly their batteries - could play a crucial part in this balancing of demand and supply on the grid. Your EV would manage the flow of energy independently using smart features, all while earning you some extra money.

What is V2G?

Vehicle-to-grid, commonly referred to as V2G, is a technology that allows you to supply energy stored in an EV battery to the grid. This is done during times of high demand on the electricity grid, which is called the National Grid in the UK. It helps to balance the supply of electricity to ensure there’s enough for people who need to use it.

A similar technology was first invented for vehicle-to-vehicle (V2V) charging in the early 1990s. The concept of V2G was later explored in academic research in 1997 before the first V2G-capable EV was eventually produced in 2007.

How does V2G work?

When a V2G-capable charger is plugged into a compatible EV, electricity can flow in two different directions. This is also referred to as a bi-directional flow of energy.

For example, an EV could feed energy into the grid during the daytime when there’s more demand and charge overnight when most people are asleep, using little to no energy.

Ideally, the battery only discharges energy when it isn’t needed, so when the car will be stationary for some time. It should then automatically recharge when there’s less demand on the grid, in time for when you need to drive.


Can I use my EV to power my house?

Vehicle-to-house (V2H) charging is based on the same bi-directional principles as V2G. While an EV battery would be capable of powering a home for several days, the technology isn’t available yet.

Benefits of V2G

V2G could offer some real benefits to EV owners and the move to a greener energy grid.

Balancing the grid in a green way

In times of high demand and low supply of renewable energy, we wouldn’t have to rely on the use of fossil fuels like coal to fill the gap if V2G was widely adopted.

A new revenue stream

Both private users and businesses benefit from the ability to sell energy back to the grid when demand and prices are higher.

Environmental benefits

We’ve already mentioned that V2G could remove the need for fossil fuels to deal with high demand on the grid. But it could also help store excess renewable energy in car batteries when demand is low but energy generation is high, so it wouldn’t go to waste.


Drawbacks of using V2G

Implementation cost

The hardware required to support V2G systems will make chargers more expensive. These costs could outweigh the financial benefits to the consumer, or at least make the payback period long.

Standardisation

Currently, only the CHAdeMO DC connector is capable of V2G, which is not typically available for home chargers in the UK. If V2G technology became viable in the mainstream, chargepoint and EV compatibility would need to be standardised.

Impact on battery degradation

It’s currently unclear whether V2G use would increase the rate of battery degradation or have no impact on it. With this uncertainty, EV owners may be hesitant to invest in new technology to use V2G.

Intermittent availability of EV as power source

EVs aren’t always parked and plugged into a charger, so it’s challenging to predict how reliable they’d be as a power source for the grid – unless uptake of V2G is very high in the future.

Easier ways to enjoy the same benefits

Using high-powered devices such as your washing machine, dryer, or charging your EV at night will provide similar savings, with no significant implementation costs. This only works if you’re on a flexible energy tariff, which prices electricity based on demand.

Alternatively, you could install a fixed battery at the home which will provide the same benefits as a V2G system.

Are all EVs compatible with V2G?

A number of carmakers produce V2G-capable cars such as Nissan, Mercedes Benz and Honda. Although the technology is mostly ready, adaptation among EV drivers is low, because V2G technology requires the use of a CHAdeMO plug, which is typically not available for home chargers.