Old electric vehicle batteries are to be sold to households to store power in their homes under plans announced by Renault.
The company, Europe’s biggest electric carmaker, has struck a deal with the domestic battery provider Powervault to repurpose old batteries when they are no longer fit for use in cars.
Powervault said that using the “second life” batteries would enable it to offer home storage for about £3,000, a 30 per cent discount on new lithium-ion home batteries, and should boost take-up.
Only a few thousand UK households are thought to have installed batteries, but it is considered a fast-growing market as technology costs fall. Batteries are primarily marketed at households with solar panels to allow them to store surplus solar power generated during the day for use when it is dark, reducing the power they need to buy from a supplier.
Powervault said customers could cut electricity bills by up to 35 per cent by using their spare solar power and also charging batteries with cheap night-time economy 7 electricity rates. A typical large family home with solar panels could save up to £210 a year, meaning it would still take at least 15 years to recoup the battery installation cost.
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The Renault-Powervault partnership aims to take advantage of the fact that the energy requirements of car batteries are far greater than those for home storage. Lithium-ion batteries degrade over time as they are recharged, reducing their storage capacity. Most car batteries are expected to have a usable life of eight to ten years. An old electric vehicle battery that is no longer good enough for use in a car can still provide enough capacity to be turned into two home batteries.
Joe Warren, managing director of Powervault, said: “When the battery gets down to about 70 or 80 per cent, it can be reused in a home energy storage application. It’s still got plenty of life left inside it.” The potential drawback is size, as households are buying a big partially depleted battery pack rather than a more compact new one.
The companies are installing the second life batteries in 50 homes from this summer in a trial backed by M&S Energy to check their performance before launching the product more widely. Mr Warren said Powervault had sold about 400 batteries in the UK but was aiming to sell 30,000 by 2020, boosted by the Renault deal.
The number of electric vehicle batteries coming to the end of their usable life is also relatively small, with about 100,000 electric cars on the road in Britain. Renault, which has sold about 7,400 in the UK and 100,000 across Europe, said it expected to have up to 20,000 batteries ready for second life usage by 2020.