The charging box in the Charlton family’s garage doesn’t just power up their two electric cars, but transforms the vehicles into batteries.
During the day, the plugged-in EV provides some morning heat for the Queenstown home, powers the dishwasher, cooks the evening meal and still has enough left for the school run.
Overnight, the car charges up on cheaper, cleaner electricity. The set-up will likely reduce the family’s power bills by hundreds of dollars.
Engineer Dave Charlton has one of the country’s first two-way EV chargers. It’s the only system to be installed into a Kiwi home, he said.
“It not only charges the vehicle at a relatively fast rate but can also pull power back out of the car and into the home. If the home’s using less than the car can output, it can put it back into the grid.”
The installation of the Wallbox Quasar system is part of a trial by Octopus Energy NZ, a UK power company that launched into Aotearoa this year. A recent arrival to Queenstown, Charlton is the head of new energy solutions at Octopus.
Charlton’s experience with the system, which came online a week ago, will test the benefits and drawbacks of two-way charging in New Zealand.
“We want to make sure this solution is actually going to work for customers.”
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For example, the trial will look at whether the set-up reduces the lifetime of the car’s battery. Charlton suspects it won’t: “The rate at which we’re pulling power out is a mere drop in the ocean compared with driving it up a hill.”
While Charlton’s wife was a bit nervous about the new system, Charlton is a self-described “energy nerd” and was excited.
“It was like Christmas had come early for me,” he said.
“When you plug the car in, the plug itself isn’t energised until it goes into the car, locks itself in, does checks and then finally turns the power on. They are very safe.”
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So far, the benefits have come to the fore.
The family owns a plug-in-hybrid – a Mitsubishi Outlander with a 20 kilowatt-hour battery – and a Nissan Leaf, with a 24 kilowatt-hour battery. These are relatively small compared to the new EVs on the market today, Charlton said.
Even so, one car holds enough juice to power the home during the morning and evening, plus take the kids to and from school. Charlton and his wife work from home.
“During summer, everything is coming from the car,” he said. “In the middle of winter, we’ll probably find it can’t do all of it.”
Octopus Energy/Supplied
After powering the home in the morning and evening, the EV has plenty of juice left for the school run.
With two-way charging, the average home with an EV could reduce its power bill by $400 to $500 per year, Charlton said – particularly if the power provider offers half-priced night rates (Octopus is one).
Smart software governs the two-way charging. Octopus’ Kraken Flex system picks the cheapest times to charge the car. Conversely, it’ll predict when grid power prices are likely to jump and send power to the home during those hours.
It also ensures the EV battery doesn’t discharge below a limit set by the customer. (The Charltons keep their car battery at a 20% minimum.)
While a one-way smart-charger is easy to buy and might cost you a couple of thousand, the two-way Wallbox Quasar isn’t yet available in New Zealand and retails for $10,000 overseas.
Charlton thinks the price will need to come down for homeowners to consider purchasing one. He hoped to see two-way chargers designed and priced for homeowners arrive on the market within the next 12 months.
“I suspect the difference between the peak and off-peak [electricity] price will become bigger and bigger. The financials for a battery system will become more and more appealing.”
There may be a sweetener. During grid emergencies such as the event in August that led to power cuts, EV owners with two-way charging could earn a chunk of cash for putting power back into the grid, Charlton said.
At scale, EV batteries could become a reliable source of electricity during peak times, Charlton said, to replace the fossil-fuelled power stations that typically ramp up generation during high-demand periods.
“Batteries can keep the grid nice and stable and let us get to 100% renewables.”
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