A new kind of charger that allows an electric vehicle (EV) to be used as a giant home battery is close to going on sale in Australia, with the first commercial shipment to arrive within weeks.

Unlike standard one-way EV chargers, bidirectional chargers can also discharge energy from an EV, which means they can be used to power a home (known as vehicle-to-home or V2H) and its appliances, or to export energy to the grid (vehicle-to-grid or V2G).

This may sound simple, but bringing them to Australia has proven difficult.

For years, a mix of regulatory and engineering hurdles have repeatedly pushed back the technology’s rollout date.


Now it appears the date is almost here, with Melbourne-based EV charging company JET Charge expecting a delivery this month, and a second in April.

So how does a bidirectional charger compare with a standalone home battery, and when are they likely to be available to EV owners?

Is a biodirectional charger cheaper than a home battery?

Bidirectional chargers will cost about $10,000, or a bit less than a standard home battery.

JET Charge chief executive officer Tim Washington expects that price will fall by more than half within a few years, as they become more common.

EVs have three to four times the capacity of a home battery, so on a cost per storage basis, buying a bidirectional charger is a lot cheaper.

The downside, of course, is that when the car isn’t home, there’s no battery available for powering the dishwasher or storing excess rooftop solar.

That said, ABS data shows that most cars spend the majority of the day parked at work or home.

On top of this, the average car-owner drives about 35 kilometres per day, or about a 10th the range of an EV.

What this means is that EVs should have plenty of time to moonlight as general-purpose batteries for energy storage and dispatch.

Who will get the first chargers?

Interest in the new chargers appears to be high among the small subset of EV owners whose cars are already compatible (more on that below).

Some have been directly contacting university-led vehicle-to-grid (V2G) trials, asking “when can they buy the charger”, said Bjorn Sturmberg, research leader at ANU’s Battery Storage and Grid Integration Program.

Mr Washington said “limited quantities” would be available for homes in April.

The first batch, however, will go to major projects, including a trial run by utility company Engie, which will partner with a commercial fleet operator to test V2G charging in Australia

V2G is a step beyond using an EV to simply power a home (V2H).

With V2G, the EV also helps stabilise the electricity grid.

EVs have very large, powerful batteries, so the combined power of many vehicles is massive.

If enough EVs are plugged into the mains with bidirectional chargers, and linked by software in a network known as a virtual power plant (VPP), they can be used like a very large commercial-scale battery.

At times of day when there’s lots of cheap solar and wind power available, the VPP directs the EVs to charge their batteries and soak up this excess energy.

When demand is high, it directs them to export this energy back to the grid.

In return, EV owners are paid for making their car’s battery available for general energy storage and dispatch.

Engie has wind farms in South Australia, including this one at Canunda.(Flickr: David Clarke)

For organisations that own lots of cars, this represents an opportunity to make money from idle engines.

“What we’re looking at with V2G is fleets that stay stationary for long periods of time,” Engie’s technical director for green mobility Christopher Munnings said.

“Say we have 100 cars that are used for 9-5, but then after 5 o’clock we leave them parked somewhere and connected to a charging station overnight.

“We can discharge during a peak event and avoid having to turn on a gas turbine — we can just use energy from the car’s battery.

“Then we charge it up overnight when our wind assets are cranking.

“V2G offers the potential to be a very low-cost battery.”

Do I need a special kind of EV?

Unfortunately, not all EVs are compatible with bidirectional chargers.

In fact, if you already own an EV, there’s a good chance you won’t be able use it for V2G or V2H.

But that probably won’t be the case for anyone buying an EV in a few years’ time.

The only cars sold in Australia that offer V2G right now are the Nissan Leaf and the Mitsubishi plug-in hybrids.

A standard Nissan Leaf has about three times the energy storage of a Tesla Powerwall home battery.(Getty Images: John Walton)

Volkswagen says the cars it sells this year onwards will be V2G compatible.

The Hyundai Ioniq 5, which is being sold in Australia, offers vehicle-to-load (V2L), which allows owners to run 240-volt power tools, appliances and so on directly off the car’s battery (handy for camping).

Ford’s new F-150 Lightning utility vehicle will include V2H, but is not being sold yet in Australia.

It’s expected V2G will be standard on all new EVs by 2025.

What do EV owners get paid for V2G?

A three-year trial of V2G chargers in the UK, completed mid-2021, found that the technology could help EV owners reduce electricity bills by up to 725 pounds ($,1375) per year.

That was about three times more than what the owners would have earned using one-way smart charging (i.e. charging the car when power is cheap).

But the cost of the bidirectional charger was still too high, the study concluded.

Even after three years, hardware and installation costs still exceeded the energy savings.

(Though there are other benefits to having a big home battery, including being able to run the fridge during a blackout.)

The Engie trial will work out how much Australian EV owners need to be reimbursed to make them want to take part in V2G, rather than simply doing V2H, Mr Munnings said.

“When looking to sell the business model to customers, you really need the data to determine in dollars and cents what benefit your product will bring,” he said.

“That’s a lot of the trial — getting those details and information and demonstrating the technology.”

Why did regulatory approval take so long?

The process of getting the Spanish-made bidirectional charger certified in Australia was a long and winding one.

First, it had to be certified to Australian safety standards. This required a hardware tweak, which meant the charger had to be re-certified with the association that oversees the plug standard.

That done, there was a final hurdle.

The Clean Energy Council (CEC) maintains a database of smart inverters, which is used by distribution networks and other installers as a quick way to determine what’s been certified as safe.

But the CEC is still deliberating over how to classify the charger and hasn’t yet added it to the database, Mr Washington said.

JET Charge has decided to sell the charger without CEC approval.

A CEC spokesperson confirmed CEC approval was not required for the chargers to be sold in Australia, but added that customers should check with their distribution network before having one installed.

Are EVs more useful as cars or batteries?

Mr Washington says he expects V2G and V2H charging will change the way we think about cars.

Right now, EVs are cars that can sometimes double as home batteries, but if they end up spending more time pumping electrons about the grid than clocking kilometres on the road, maybe that’ll change.

Are EVs most useful as cars, or as energy storage?(Getty Images: Bloomberg)

We may end up thinking of EVs primarily as batteries, Mr Washington said.

“A vehicle will become an energy asset first because it’s parked 90 per cent of the time,” he said.

Having a big battery that’s easily transportable can also be handy, he said.

Employees could charge their cars with free electricity at work and then feed the power into their homes in the evening.

Multi-storey carparks fitted with thousands of bidirectional chargers would double as energy banks for the grid.

“I have no doubt the market for residential batteries is going to decline quite heavily as they’re replaced by cars,” he said.