Soaring power production from households and businesses with rooftop solar panels has sent records tumbling across Australia, with output from fossil fuels falling to all-time lows.
In events described as unprecedented, demand for electricity from the grid plummeted to record lows in Queensland, Victoria, South Australia and Western Australia during the past two months.
The record so-called minimum operational demand excludes the power generated by consumers with their own solar panels, which met 92 per cent of South Australia's overall needs at one point on October 17.
It typically occurs on mild, sunny weekend days when solar output is at its highest but demand for electricity is subdued because many businesses are not open and often air conditioners are not running.
Energy experts say the trend is unlikely to slow down amid the runaway take-up of rooftop solar and highlights the urgent need for new infrastructure and back-up power needed to accommodate more renewable energy.
"We have observed records being broken recently – I think we need to get used to that," said Alex Wonhas, a former electricity system planner.
"Minimum demand records are a little bit like birthdays.
"They will keep coming around and around because our demand stays relatively stable.
"And, as we install more and more in particular behind-the-meter (solar), the residual demand on the system will keep going down and down and down."
'Balance' needed for the grid
Dr Wonhas sits on the board of the Energy Corporation of New South Wales, which is responsible for delivering renewable energy zones in the state.
He said although the rapid rise of rooftop solar was undoubtedly a good thing, it was not without its challenges.
For starters, Dr Wonhas said solar generation needed to be backed up by other sources of power when the sun was not shining – something that could be done with batteries, pumped hydro or even gas-fired plants.
More importantly, however, he said most of Australia's vast fleet of solar panels did not yet provide so-called firming services to help keep the grid stable.
By contrast, he said these were services inherently provided by most conventional forms of power such as coal- and gas-fired plants as well as hydro-electric generators.
To deal with the technical challenges, he noted authorities were bringing on batteries and even kit known as synchronous condensers, which provide many of the firming services without generating electricity.
He said there was a pressing need for more such investments.
"In layman's terms, it's a little bit like when you ride your bicycle," he said.
"When you're riding fast, the rotation of the wheels and the inertia that's caught up in that keep you stable … and keep the fluctuations to a minimum.
"And as you get slower and slower, these fluctuations can get larger and larger.
"And what these [synchronous condensers] can do and batteries can do is keep that bicycle stable so it doesn't wobble around.
"You don't want to have your energy system wobble around."
Fixes 'quite straight forward'
The Australian Energy Market Operator, which runs the national electricity market in the Eastern States and the wholesale market in WA, also has the ability to switch off people's solar panels in the event the grid risks becoming overloaded.
Speaking recently on ABC radio in Perth, the head of AEMO in WA, Kate Ryan, said the agency had yet to invoke the powers and did not envisage doing so within the next six months.
Andrew Blakers from the Australian National University's college of engineering and computer science said events so far this spring showed how Australia was the global leader in the adoption and integration of solar power.
Professor Blakers, who specialises in renewable power and energy systems engineering, agreed that the changes underway were on a one-way track and it was imperative Australia deal with them.
"There are many things that we need to do to make sure that the system remains reliable," Professor Blakers said.
"If we fail to do them, the system will not continue to be reliable.
"But they are quite straightforward.
"And these include ever increasing numbers of batteries and pumped hydro systems, ever stronger transmission so that we can share the energy around.
"So, if it's really sunny and windy in Queensland we can send it south and return the favour the next day."
Consumers must get smarter
According to Professor Blakers, Australia also had to become much smarter about how it consumed energy through measures such as demand management.
This could include providing incentives for households, businesses and industry to pare back their usage or even switch off entirely during periods of stress on the grid.
He said the coming electric vehicle revolution would only add to the requirement for behaviour change, arguing it would be "crazy" to load any more demand on to the system in the evening when solar was not producing.
"So, when it's sunny and windy we charge the electric vehicles and we don't charge them at 7 o'clock on a summer's evening when the sun has gone down and the air conditioning is going," he said.
"Australia is now generating twice as much solar per person as any other country.
"Australia is the global solar pathfinder.
"What we discover in adapting to high levels of solar and wind is directly relevant to the following countries like Germany, Japan, the Netherlands, Chile and others."
