Most Australian EV drivers self-manage charging at home to take advantage of off-peak electricity times, says online financial broker Savvy which looks at the feasibility of EV charging at home and whether the Australian electricity grid will be able to accommodate more EVs on the road.
“There is an unfounded assumption that the demand on the electricity grid by many users charging their EVs at the same time will place the system under pressure,” says Savvy, which studied the latest data from the Electric Vehicle Council (EVC) of Australia, and the Commonwealth Scientific and Industrial Research Organisation (CSIRO).
According to case studies compiled by the EVC, the expected impact of EV charging at times of peak demand will top out at about 250W per EV under the ‘convenience model’ which assumes there are no tariffs controlling or incentivising when to charge – drivers will simply charge when it’s most convenient.
“This is half as much as a small, refrigerated air conditioner (500W) and a quarter of some higher-end desktop computers, assuming 80% or more efficiency (700-1000W). With computers being used during the day by people who work from home this represents a significant cost over EVs, Savvy explains.
It points out that Norway, with 20% EVs vs internal combustion engine (ICE) vehicles on roads, shows negligible increase in peak demand during peak times.
CSIRO models on the ‘current trajectory’ of EV take-up shows parity in short-range EVs vs ICE price by 2030, it adds.
“Did you know that for every 300 vehicles on the road, that one is electric? It doesn’t seem like a lot, but the rate will accelerate as time goes on. Other countries are seeing major upswings in EV uptake which means a lot of people are doing their EV charging at home.”
Savvy says the University of Queensland undertook a study of 239 Tesla EVs over six months, showing the impact per EV at peak times is within the 150-300W range.
“Typically, one kW of charge adds one kilometre of range to an EV every 10 minutes. Put simply, a 10kW charger will give a vehicle 60km of range after charging for an hour. At present, most home chargers are limited to 4.8-7.6kW (20A-32A @ 240V, single phase, depending on location.
“Detailed modelling by the CSIRO says that 250W per EV is about a fifth of the impact forecast under the convenience model. However, the convenience model does not line up with real-world behaviour, as most drivers would charge their vehicles at a charging station during the day (as they’re on the road) and at home at night-time.”
Savvy says the University of Melbourne predicts that 250W per EV is one eighth of the impact forecast under the convenience model. This assumes 80% of drivers will use the 7kW chargers at home, with a typical 2kW excess on the grid during peak times on weekdays.
Most drivers are willing to avoid peak time charging, as it costs less, Savvy says.
“The EVC and Tesla Owner’s Club of Australia ran a survey in 2022 and showed a majority of Tesla owners charged during the nightly off-peak of midnight-2am, and the middle of the day (10am-2pm) when solar production is at its best.”
Both groups also held a recent survey dispelling range anxiety.
About 3000 public EV charging points were in Australia as of January 2022, Savvy says. “This comprises AC ‘trickle’ charging (much like home charging at the moment), with 291 rapid (above 50kW) charging stations and 1580 regular (below 50kW) charging stations available around the country.
Some 700 more fast and ultra-rapid stations (300kW+) are planned for development within the next five years.
“Australians are moving to electric vehicles with ever-increasing enthusiasm, which has been borne out in the number of people seeking green car loans,” says Savvy automotive finance expert Bill Tsouvalas.
“As we’re seeing, this is raising concern over whether the existing electricity grid will be able to handle the increased demand for charging EVs at home.
“For now, it seems that it will be OK, as people are inclined to charge overnight and at off-peak times to save money. Whether or not it becomes a real problem when EV ownership expands to double digits is another story.”
Tips for Ev charging at home include charging during off-peak periods. South Australia Power Networks have introduced an ‘EV Ready’ off-peak tariff on the same low rate as off-peak hot water, with their ‘solar sponge’ tariff establishing a ‘super off-peak’ period during the middle of the day.
Some electricity retailers are also offering ‘super off-peak’ rates between midnight-4am, provided the household has a smart meter installed. Some EV manufacturers allow EV users to schedule charging to take advantage of these off-peak rates, such as the Tesla ‘Scheduled Departure’ feature.
Installing solar panels at home would also reduce the cost of EV charging– and the cost of using appliances and other electricity around the home, Savvy explains.
“However, there are some issues to overcome first. Home charging stations are mostly limited to 20A single phase charging – which means a 12-hour charging cycle to get up to 300km of range. “Some service and installation rules allow for 32A charging, which reduces the cycle to eight hours. Standardising these rules would make charging faster and more accessible during these ‘super off-peak’ times.”
It adds that taking advantage of public chargers at low or no cost is preferable to charging it yourself, Savvy adds.
“Many shopping centres and office complexes not only offer free public charging while you shop or work but a parking spot close to the entrance.
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