A quick article this morning to sum up one of the more difficult days in forecasting ‘Market Demand’ in South Australia for yesterday (Tuesday 18th November 2025), clearly visualised in this snapshot from the ‘Forecast Convergence’ widget in ez2view, time-travelled back to 19:00 (NEM time) yesterday, when the show was over:
With respect to yesterday in South Australia:
1) As per the annotations,
(a) The AEMO was very consistent in forecasting that the ‘Market Demand’ would drop in the middle of the day
(b) Whereas something happened* and the demand dropped steeply from ~11:30 (NEM time) to bottom out at a low point of only 150MW
(c) Which was 600MW (or 80%) lower than AEMO’s consistent earlier forecasts.
… a challenging day!
2) In terms of the ‘something’ that ‘happened’ during the day to make it so:
(a) the most obvious suspect is the clouds parting to deliver a large dose of unexpected rooftop PV
(b) but perhaps there are other explanations?
Not shown here, but also worth noting that ‘Market Demand’ in QLD for the middle of the day yesterday was considerably (~15-20%) higher than AEMO’s earlier forecast, on the flip side.
Another to the list of Case Studies
We can add this one to the list of Case Studies that we might explore later with respect to the question ‘Is VRE forecastable?’
An unexpected ‘Actual MSL1’
With particular respect to what happened yesterday, this had the impact of triggering an unexpected ‘Actual MSL1’ notice for South Australia in the middle of the day – seen here in MN130753 at 13:02 (NEM time):
——————————————————————-
MARKET NOTICE
——————————————————————-
From : AEMO
To : NEMITWEB1
Creation Date : 18/11/2025 13:02:07
——————————————————————-
Notice ID : 130753
Notice Type ID : MINIMUM SYSTEM LOAD
Notice Type Description : MSL1/MSL2/MSL3
Issue Date : 18/11/2025
External Reference : Actual Minimum System Load MSL1 condition in the SA Region on 18/11/2025
——————————————————————-
Reason :
AEMO ELECTRICITY MARKET NOTICE
Actual Minimum System Load MSL1 condition in the SA Region on 18/11/2025
AEMO has detected that there is an elevated risk of insufficient demand to maintain a secure operating state in the SA on 18/11/2025.
Minimum demand is forecast to be 210 MW at 1300 hrs, and the advisory threshold is:
– MSL1: 245 MW
– MSL2: 96 MW
– MSL3: -256 MW
The demand is below the MSL1 threshold. The actual MSL1 condition is forecast to exist until 1400 hrs.
Forecast demand refers to forecast Operational Demand that excludes contribution from Significant Non-Scheduled Generation: see definitions at https://aemo.com.au/energy-systems/electricity/national-electricity-market-nem/data-nem/operational-demand-data .
Manager NEM Real Time Operations
——————————————————————-
END OF REPORT
——————————————————————-
This was cancelled at 14:33 (NEM time) in MN130757.
Be the first to comment on "The bottom falls out of SA ‘Market Demand’ unexpectedly, on Tuesday 18th November 2025"