Authorities are moving to gain more control over rooftop solar panels amid a ballooning number of installations that are threatening to overload the grid at certain times.
From today, Western Australia will join South Australia in having the authority to turn off household solar systems at times when the electricity network is deemed to be under severe stress.
The regulations follow the runaway demand for rooftop solar in WA, where more than a third of residential and business customers on the state's main grid have an installation.
Nationally, there are more than three million small-scale solar customers following another year of record uptake in 2021.
WA Energy Minister Bill Johnston said the new rules amounted to taking a "scalpel rather than a shotgun" to the challenges posed by surging solar output.
Under the regulations, customers installing new or upgraded solar panels will be required to have inverters that allow authorities to switch off production in emergency situations.
The minister said such circumstances would only occur a few times a year and would typically last for only a few hours.
Solar 'success with downsides'
According to Mr Johnston, the output from rooftop solar in WA is now so significant the system struggles to cope at particular times.
These typically happened on sunny weekend days during autumn or spring when temperatures were mild, but production from solar panels was "full tilt", he said.
In these instances, he said low demand for electricity collided with a flood of solar energy, which forced other generators such as coal and gas-fired power plants offline.
"The reason that we need to do this is to allow more and more people to have solar energy," Mr Johnston said.
"Solar energy is important to the decarbonisation journey, but at some times of the year and on certain days when there's very low usage of electricity, we'll need to manage the total output from solar panels so that the grid remains stable."
Other states 'to follow suit'
Mr Johnston said while WA was not expected to use the new powers until next year, he predicted other states would soon follow with regulations of their own.
"It's a sensible solution to a new problem. It allows more solar panels to be installed, and it allows that to benefit the whole community."
Katharine McKenzie, the managing director of Macht Consulting and a former ministerial energy adviser, said the pace of the solar wave washing over the energy system had made the new rules imperative.
Ms McKenzie said although solar and renewable energy were overwhelmingly a good thing, fitting them to a system designed to run on fossil fuels was not without its problems.
"While it's an exciting development and helping towards 100 per cent renewable energy on the system, it also creates challenges for the safe and secure operation of the system as well," Ms McKenzie said.
"So when you have cloud cover coming over or when you have the sun going down in the evening, you do need other forms of generation to jump in and fill the gap.
"But they need to be running at a minimum level in order for them to be online and ready to go.
"The issue that WA has now is there is so much rooftop solar connected to the system that there are times where you actually have more electricity generation going into the system than what is needed to meet demand.
"And that creates a lot of issues."
Few other options: expert
Ms McKenzie said that in the absence of powers to switch off — or "curtail" — household solar panels, the bodies that run the system would have to revert to far more draconian measures when the grid came under strain.
"They could turn off electricity lines, and that, of course, means you're managing the generation issue, but you're also turning a bunch of customers off so that they don't have access to any electricity during that period," she said.
"To slow down the rate of this problem, you could say 'sorry, the inn is full, no more connection of rooftop solar to the system'.
"But really, until we get to the point where we have enough battery storage and other options to manage fluctuations, we need to have enough traditional generation online to jump in.
Households would 'want to know'
Tess Bryant, a mother of two teenage boys who lives in Albany on WA's south-coast, said she had mixed feeling about the changes.
Ms Bryant had a 6.6kW system installed on her roof in 2020, and she said that while the new rules will not directly affect her for the time being, they may complicate future decisions.
She said she eventually wanted to buy an electric car and substitute gas-fired appliances with electric ones and would want to know if her panels were ever switched off remotely, forcing her to buy power from the grid.
"I hope that it won't discourage people from taking them up," Ms Bryant said.
"Personally, I would want to know [if her solar panels were curtailed] because I would change my habits if I knew it was coming."
Ms Bryant agreed that it made more sense for households to use their own solar power rather than buy from the grid but noted it wasn't always straightforward.
"It's a lot easier to get someone to put power on your roof.
"But to then actually live with it efficiently and maximise it is a bit harder. And it's habit changing."
