Commodity Demand — SA1: Wednesday 19 August 2026
South Australia demand sits at 1,380 MW as of 06:30 AEST, with spot price at $80/MWh — a marked turnaround from overnight conditions where demand troughed near 500 MW and prices collapsed as low as -$496.77/MWh during the 03:30 interval. The overnight period saw eleven separate sub-$-100/MWh prints between 02:00 and 05:00 AEST as wind generation (averaging 85-94% renewable penetration) heavily outstripped low demand, forcing negative pricing to incentivise offtake. That relationship has now inverted sharply: as demand climbed through the 06:00-09:00 AEST ramp from 777 MW to a morning peak above 1,860 MW, prices moved in lockstep, hitting $101-105/MWh through several 08:00-08:30 intervals as solar output remained at zero (heavy 99% cloud cover) and the system leaned on wind, gas OCGT/CCGT, and 241 MW of battery discharge to meet the ramp.
Demand has since eased back to the current 1,380 MW range through the mid-morning, with prices holding a $65-100/MWh band as gas CCGT and OCGT plant (currently contributing 457 MW combined) sit on the margin alongside wind at 505 MW. Carbon intensity has risen accordingly from sub-0.04 tCO2/MWh overnight to 0.223 tCO2/MWh now, with renewable share at 62%, reflecting the shift from wind-dominated overnight supply to a more mixed daytime stack.
AEMO's forecast trajectory points to a firming price profile into this evening and tomorrow: the 20:01 AEST forecast run shows prices climbing from $83.70/MWh at 21:00 AEST tonight to $95/MWh by 23:00 AEST, before easing into low overnight troughs (sub-$15/MWh from 00:30-06:00 AEST), then a sharp re-ramp tomorrow morning to $130/MWh forecast at 10:00 AEST and a sustained $101/MWh band through the tomorrow afternoon peak (14:00-17:00 AEST). This pattern reinforces today's demand-price coupling: SA's price outlook is now tightly bound to the solar recovery, with today's 99% cloud cover and near-zero solar potential (average 12.8% forecast tomorrow) limiting midday relief and keeping thermal and wind plant on the margin through peak hours.
On the demand-side and system security front, AEMO's SA voltage control direction to AGL's Torrens Island B2 unit (issued 18 August, expected duration to 15:00 AEST 19 August) reflects thin synchronous generator coverage in SA overnight — a factor traders should watch given the region's continued reliance on directions to manage voltage during low-thermal-output periods. Separately, the VIC-SA negative settlement residue constraint (NRM_VIC1_SA1) that activated at 17:05 AEST yesterday and was cancelled at 18:00 AEST signals interconnector flow stress was building during yesterday's negative price trough, a pattern likely to recur given tonight's forecast return to negative pricing between 00:30-06:00 AEST.