A bunch of rooftop solar power systems in South Australia could be knocked offline for a bit today. But don’t panic – the curtailment event (if it occurs) will be a feature, not a bug.
Uptake of commercial and home solar in South Australia has been phenomenal, with more than 355,000 PV systems installed across the state to date. The impact of all this solar energy goodness was very apparent on the weekend, when on Sunday afternoon at 1PM, rooftop solar alone met 92% of South Australia’s electricity needs.
Events such as this will become increasingly common, particularly during spring when mild temperatures and clear skies combine with reduced home and building heating and air-conditioning demand.
But sometimes you can have too much of a good thing. Excessive generation or too low grid demand can cause electricity system instability – and that is a Very Bad Thing. This is why there has been a requirement since September 28, 2020 that all new solar installations in South Australia can be remotely disconnected (and reconnected) if the need arises, meaning most of these households will be sourcing their electricity from the mains grid during such an event.
The introduction of remote solar disconnection – to be used as a last-resort measure – created some angst and misinformation, which SolarQuotes Founder Finn addressed in his explanation of remote solar shutdowns here.
“Elevated Risk” Of Solar System Disconnection Today
As far as I’m aware, the capability has been barely used since it was introduced. But that brings us to today when it may be called into play.
The situation was flagged last night by WattClarity’s Paul McArdle after the Australian Energy Market Operator (AEMO) published a notice at around 8.30PM warning of the potential.
Market notice 102367 states there is an elevated risk of the ” contingent disconnection of Distributed PV (DPV)” from 10.30 this morning until 2 this afternoon. The notice states:
“Maximum DPV generation forecast by the Australian Solar Energy Forecasting System 2 (ASEFS2) is 1307 MW at 1230 hrs and the secure ASEFS2 generation limit for the forecast operating conditions is 1181 MW.”
.. and this could mean among the actions:
“… an instruction to maintain DPV generation below a secure DPV generation threshold.”
This would mean remotely disconnecting a bunch of rooftop solar systems from the grid, which will be remotely reconnected once the situation has passed.
This actually happening isn’t a done deal – the latest weather report indicates “mostly sunny” conditions; so there may be a bit of cloud around or other factors avoiding the need to do so. And if remote disconnection does happen, it shouldn’t be for long – not necessarily the full 10.30AM – 2PM timeframe.
As mentioned, the remote disconnect potential only applies to new systems installed since September 28, 2020. Even in the event of a solar shutdown instruction being issued, perhaps not all systems will be remotely disconnected.
As far as I’m aware, solar owners who have installed systems since this requirement was introduced to be least affected would be those with home batteries featuring “level 3” backup capabilities. Their solar power systems should disconnect from the grid but continue to supply the home and charge the battery.
As an owner of one of the potentially affected systems (and not having a battery), I’ll be keeping a close eye on my solar system monitoring today during the 10.30AM to 2PM timeframe. I’ll update this post if I spot anything unusual, or with any AEMO updates on the situation.
UPDATE 8.10AM: AEMO’s latest notice still indicates potential for remote disconnection today.
UPDATE 10.45AM: At this point, all appears to be well – but I noticed on OpenNEM that wind generation in SA has dropped off dramatically in the last couple of hours. Whether wind power is being curtailed, or it’s just dropped off due to conditions isn’t clear.
UPDATE 11.18AM: AEMO has cancelled the Distributed PV Contingency 2 (DPVC2) [and Distributed PV Contingency 1 (DPVC1)] in SA. All over, red rover.
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Good writeup. The potential curtailment today wasn’t actually to deal with overall minimum demand – instead it was a different aspect of the “too much of a good thing” issue. There’s always a risk of a large number of PV systems tripping off if a fault somewhere in the system (probably close to Adelaide) were to cause a large voltage dip or other disturbance on the grid. If PV production were too high when this happened, the loss of generation on the system when systems all trip at once gets too large to be managed securely. This risk was amplified today by an outage on the Heywood interconnector to Victoria which would limit capability to swing imports into SA. So AEMO was looking to curtail PV production in order to limit the maximum possible generation loss.
However the Heywood outage finished early so AEMO was then able to call off the potential PV curtailment.
Thanks for that explanation Allan, greatly appreciated.
Kind of amusing that SA is (was?) worried about an excess of solar energy. It’s the reverse problem here – basically need to switch the lights on to see, and solar generation’s been sub kilowatt for a while.
Total generation for today is roughly two-thirds below the average, and the average daily generation this month is looking roughly a fifth below the monthly average supplied by my solar installer – which was a lowballed figure.
Of the 19 days this month only 5 have exceeded the average and 3 have been less than half the average.
Thanks to a negative Indian Ocean Dipole plus La Nina, solar’s even less reliable than usual!!! :-C
will Snowy 2.0 be able to absorb excess power from SA, or is it limited to just excess in Vic?
SA can contribute through existing interconnectors with Victoria. But there are times when they have no spare capacity and some clean SA generation goes to waste. But the large new interconnector with NSW should be completed by the end of 2024 and that will also be able to contribute.
in Adelaide my solar was disconnected yesterday for 30 minutes approx after 3pm on 8/11/2022. I don’t mind but wish to be advised via sms in advance so I can turn off my air conditioners etc
Hi
My Solar has been ‘down’ now for 3 days. The display shows ‘waiting PAC=0’.
Contacted my Tech Advisory team and they assured me that this is common practice under the current circumstances. We have a Fox ESS inverter system, installed Sept 2021.
Anyone else experiencing similar problems?