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Sep 28, 2023

The dumb rules stopping Australian EV owners from charging with their own solar

Archaic rules are preventing electric vehicles owners in at least one state from

Archaic rules are preventing electric vehicles owners in at least one state from being able to use their own rooftop solar panels to charge their cars, and risks cruelling efforts to introduce "smart charging" capabilities considered essential for a future grid based powered renewables.

In Queensland, the official rules state that EV owners are only allowed to connect dedicated home EV chargers – rated at 7 kilowatt (kW), 32 amp – to the grid during off-peak pricing periods via a special circuit that quarantines their car from their rooftop solar system.

The situation means EV owners who want to use their ‘free’ solar power to charge their car must either use a trickle charger, which delivers power at the slow-slow rate of 1.4-2.4 kW/h through a regular wall socket, or have the higher powered charger down-rated to a slower speed of 4.2 kW, or 20 amps.

The state owned Energex defended the rule, saying it has "evolved" since 2011 and is in place to ensure "both the power network and private dwellings are not negatively impacted in the short and long term", a spokesman told The Driven.

Energex and Ergon, the other state-owned network servicing regional areas, are currently consulting on the rules to decide whether they are still fit-for-purpose, with public decisions due in the next few weeks.

"We are currently working on the regulatory and technical impacts to allow customers to utilise primary tariffs and the solar they have connected to them," the spokesman said.

But the data suggests Queenslanders are getting around these rules.

Policing whether a smaller 7 kW charger is connected to a controlled (off-peak) tariff or the general network is difficult, says EV Charging Australia director David Nyambuya.

Indeed, Ergon's and Energex's own EV SmartCharge Queensland Insights report showed more than three quarters of 197 EV owners surveyed had rooftop solar and 19 per cent also had a battery.

Rooftop solar penetration in Queensland is 33 per cent and battery adoption stands at 0.49 per cent.

These figures suggest EV owners have figured out a work-around to the Queensland charging rules, but one that will ensure the state's residential energy infrastructure remains dumb in the long term, says RACQ head of public policy Dr Michael Kane.

"If you go to a Level 2 charger, you can put in a 7kw charger and have it rated down to 4.6 kW and that will give you access to your solar," he told RenewEconomy

"Our concern is people are investing in ‘dumb’ 20 amp, 4.6 kW wall chargers, and spending $2000. They won't want to come back and spend another $3000 on a smart charger. This rule is encouraging people not to engage with a smart future.

"Just get rid of that rule and bring in a suite of smart options."

Kane says the tech problem lies in Queensland's reliance on ripple control technology.

Energy industry bodies recently slammed the technology as "mid-20th Century" after Energy Queensland revealed last year that all rooftop solar and battery systems must be fitted with the generation signalling device, in order to allow the state's network operators to switch these PV systems off, remotely, if needed.

Ripple control is how Queensland plans to deal with the problem of daytime rooftop solar exports threatening system security, but it is also part of the controlled circuit system EV owners are required to put their 7 kW chargers through.

It cuts the power supply to that circuit during peak periods, and only switches it back on during off-peak tariff periods. The smart option would be to empowering consumers to make their own decisions by giving them real-time pricing information as in a virtual power plant system, and through smart controls that allow charging to be timed.

"The actual story here is the controlled circuit is using some old ripple control technology. That's the not the future of orchestration of solar and batteries and EVs," Kane says.

"The Queensland government is also working on a dynamic operating envelope initiative. So we have a progressive approach being considered, with a regressive approach delivered and with the consumer in the middle."

Rachel Williamson is a science and business journalist, who focuses on climate change-related health and environmental issues.