Renault promises half-price home electricity with new tech

Renault's bi-directional charging is claimed to make home charging a lot cheaper

Bi-directional charging will become available to the masses for the first time with the new Renault 5 EV

The cost of charging an EV at home is about to get a lot cheaper, in theory. Renault is pioneering a service that promises to cut electricity bills in half.

Meanwhile, UK energy provider Octopus is now offering a new tariff with the hook that customers can essentially charge their electric car at home for free.

How is this possible? The EV technology enabling the savings is called bi-directional charging, and it will be rolled out at scale for the first time with the new Renault 5

The retro-futuristic supermini will become the first car to both offer the tech and allow users to access it – including in the UK from next year.

Bi-directional charging allows electricity not just into your car's battery but out again through the same cable. Which means that, if you agree, the grid can extract energy back from your car when it's needed at peak times. 

Peak-time electricity is worth a lot more than off-peak electricity, so you will be storing cheap energy in your car and selling it back later at a higher rate.

“Depending on what statistic you read, a car is parked 90-95% of its total lifetime,“ Alex Schoch, global director of flexibility for Octopus, told Autocar. “In a combustion-engine world, the car is really just a single-purpose asset. But now with EVs, you have a possible secondary use case.”

Octopus has just launched its Power Pack tariff, which it says will save an EV customer driving 10,000 miles annually around £800, thanks to bi-directional charging. 

“Essentially you charge for free. If you plug in for six hours per day, we say all your charging costs are covered by us,” said Schoch.

Customers can of course opt out on days when they need maximum range by alerting the relevant app.

Octopus has around 130,000 customers on its EV-angled Go tariff, which offers very cheap energy off-peak to incentivise charging but penalises energy use at peak times with surge pricing.

The company’s Kraken technology platform figures out charging optimisation and energy market needs and then juggles the demands.

The pieces missing for Octopus as it rolls out Power Pack on top of Go are on the automotive side, both with car and charger technology. 

This is where Renault and its mobility arm Mobilize reckon they can win customers. Mobilize has assembled what it believes is the full package to make bi-directional work. 

It has teamed up with Germany energy provider The Mobility House to offer energy tariffs tailored to bi-directional charging. It has partnered with American charging tech company Iotecha to build the Mobilize Powerbox wall charger. And it has whipped up the software to control it with France’s Software République. And then of course it supplies the cars, starting with the 5 and all subsequent Renault Group EVs.

French and German customers will be able to take advantage from later this year and Brits will join them in 2025.

If this works, Renault will be able to do what few car makers have been able to do and monetise a non-core aspect of car ownership to the mutual benefit of both itself and the customer. 

The company is currently discussing how it will work – whether customers will pay a subscription or not.

“Most relevant is that we need to guarantee to the customer a saving on the bill,” Mobilize CEO Gianluca de Ficchy told Autocar.

Ziad Dagher, Mobilize's smart energy team leader, added: “We will with our partner buy electricity at the best moment and sell it at the best moment. And thanks to the spread, we generate the value."

Bi-directional charging has been trialled in the UK before, but it has only been compatible with the now pretty much defunct Chademo charging protocol, as used by Nissan on the Leaf. 

The sheer cost of the direct current (DC) wallboxes with inbuilt inverters to switch to alternating current (AC) was another barrier to cost.

However, Renault has incorporated this into the 5. “The disruptive part of the game was to use AC technology,” said Dagher.

That significantly drops the cost of the charger you need to install. Mobilize has yet to reveal the cost of its Powerbox Verso bi-directional wall charger, but it’s unlikely to be anywhere near the price of DC-AC versions, such as the Wallbox Quasar 2, which costs up to €6000 (£5130).

Other companies are also investigating the technology, including British charger provider Indra, which has been running a trial using about 420 Leafs.

“It actually works. Energy companies will pay you between £600 and £800 a year to be able to extract energy at the time they want,” Indra founder Mike Schooling told us back in 2022. The company has yet to offer its charger to the public.

Indra is also investigating vehicle-to-home technology, whereby you power your house with cheap night-time electricity stored in your car. Indra reckons the average UK house uses about 10kWh of electricity a day, which could easily be handled by even a smaller, 50kWh EV. 

In this scenario, the car cuts the need to buy separate battery storage systems by using its spare capacity. As with vehicle-to-grid technology, though, it does require a driveway to allow a constant connection.

Other car companies are joining Renault in building EVs compatible with vehicle-to-grid technology.

Volkswagen, for example, is installing bi-directional capability on all new MEB-based EVs with the 77kWh battery and the ID 3.5 Software or later.

Currently the cars can only be connected via chargers from Hager Energy in Germany. Volkswagen told Autocar it was “evaluating other systems” with a view to rolling out the technology beyond its initial trial.

Meanwhile, Hyundai and Kia models are already available with vehicle-to-load technology, meaning you use the car's battery to power plugged-in electrical equipment.

Hurdles remain, including the potential delays in getting approvals for connecting your car to the grid, according to Octopus's Schoch.

Also, Mobilize can’t for the moment incorporate home solar capacity, which might be a deal-breaker for some early adopters of the technology.

There are also a lot of question marks around how the energy market might change with the potential influx of a cheap method of storage coming on stream.

“There’s a new energy ecosystem value chain developing, and I think we're going to see a lot of people wanting to get in,” said Schoch. “However, if everyone tries to be incredibly greedy because they've got a business plan that says ‘I need to achieve x’, then I think those companies will be in for a rude surprise.”