How your EV could power your cooking, heating and gadgets
The charging box in the Charlton family’s garage not only powers their two electric cars, but turns the vehicles into batteries.
During the day, the plugged-in EV provides some morning heat for the Queenstown house, powers the dishwasher, cooks dinner and still has enough left over for the school run.
Overnight, the car charges on cheaper, cleaner electricity. The setup will likely reduce the family’s power bills by hundreds of dollars.
Engineer Dave Charlton has one of the nation’s first two-way EV chargers. It is the only system installed in a Kiwi home, he said.
“It not only charges the vehicle at a relatively fast rate, but can also draw power back out of the car and into the home. If the house uses less than the car can deliver, it can put it back on the grid.”
The installation of the Wallbox Quasar system is part of a trial by Octopus Energy NZ, a British power company launched in Aotearoa this year. Charlton, who recently arrived in Queenstown, is the head of new energy solutions at Octopus.
Charlton’s experience with the system, which came online a week ago, will test the pros and cons of two-way charging in New Zealand.
“We want to make sure this solution actually works for customers.”
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For example, the trial will look at whether the setup reduces the life of the car’s battery. Charlton suspects it won’t: “The rate at which we’re extracting power is a mere drop in the ocean compared to driving it up a hill.”
While Charlton’s wife was a little nervous about the new system, Charlton is a self-described “energy nerd” and was excited.
“It was like Christmas came early for me,” he said.
“When you plug in the car, the plug itself is not energized until it goes into the car, shuts itself down, checks and then finally turns on the power. They are very safe.”
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So far, the benefits have emerged.
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. That’s relatively small compared to the new EVs on the market today, Charlton said.
Even so, one car holds enough juice to power the house morning and night, and take the kids to and from school. Charlton and his wife work from home.
“During the summer, everything comes out of the car,” he said. “In the middle of winter, we’ll probably find that it can’t do everything.”
With two-way charging, the average home with an EV can cut its power bill by $400 to $500 a year, Charlton said — especially if the power provider offers half-price nighttime rates (Octopus is one).
Smart software controls the two-way charging. Octopus’ Kraken Flex system selects the cheapest times to charge the car. Conversely, it will predict when grid power prices are likely to jump and send power to the home during those hours.
It also ensures that the EV battery does not discharge below a limit set by the customer. (The Charltons keep their car battery at a minimum of 20%.)
While a one-way smart charger is easy to buy and can set you back a few thousand, the two-way Wallbox Quasar isn’t available in New Zealand yet and retails for $10,000 overseas.
Charlton believes the price will have to come down for homeowners to consider buying one. He hoped to see two-way chargers designed and priced for homeowners hitting the market within the next 12 months.
“I suspect the difference between the peak and off-peak [electricity] price will get bigger and bigger. The finances for a battery system will become more and more attractive.”
There can be a sweetener. During grid emergencies like the August event that led to power outages, EV owners with two-way charging can earn a lot 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, replacing the fossil-fueled power plants that typically ramp up generation during periods of high demand.
“Batteries can keep the grid nice and stable and get us to 100% renewable energy.”
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