Vehicle-to-grid charging: could your electric car pay the bills?

With the price of electricity through the roof, buying it at a low price during off-peak times and then selling it back at a higher one when demand returns sounds very appealing.

To do this, you need to be able to store your surplus power until the price is right, which is where electric cars, with their large batteries, are essential. It's why the process is known as vehicle-to-grid or, more modishly, V2G. 

The idea is being hotly debated and is regarded, at least by some, as the answer to smoothing out the peaks and troughs in renewable energy supply, making it more practicable and thus reducing our dependency on fossil fuel. The possibility of consumers selling their unwanted renewable energy for a profit is a welcome side benefit, but the real prize, say many, is accelerating the world's shift to renewables. 

A major step on the road to testing V2G's viability has just been completed, and the results appear to be positive. Electric Nation, a project involving partners including Western Power Distribution (WPD) and Crowd Charge, a demand management provider, equipped the homes of 100 Nissan EV owners with Wallbox Quasar V2G chargers that charged and discharged their cars' batteries and gave them a choice of four energy suppliers offering at least two different tariffs, including off-peak. 

Crowd Charge remotely managed the batteries to take advantage of the changing tariffs, while taking into account each owner's preferences regarding their vehicle's charge state.

Their Nissan battery warranty remained unaffected, while the car maker has said that similar trials haven't revealed any deterioration in battery life. 

Marie Hubbard, one of the trial's participants, reported that by setting her Nissan e-NV200 camper van to charge during the night when electricity prices were lower, she had earned £25 per month selling her electricity back to the grid at peak times.

Because she uses solar panels to charge her EV, she was also able to take advantage of the V2G charger's ability to use the electricity in her car's battery to power her home. This resulted in a halving of her monthly electricity bill from £50 to £25.