Commodity Demand — SA1: Tuesday 8 September 2026
South Australia's spot price sits at -$3.61/MWh at 06:30 AEST, with demand at 1470 MW — negative pricing driven by wind output of 1714 MW, well above current consumption. Wind alone is supplying more than 100% of instantaneous demand, with the surplus exported via interconnectors, pushing the price below zero for the fifth consecutive interval. Battery storage is discharging 183 MW, adding to supply rather than absorbing it, which reinforces the oversupply condition.
The overnight and early morning data show a textbook demand-price relationship: as demand collapsed from 1630 MW at 07:30 AEST yesterday evening down to a trough of 58 MW at 13:30 AEST (03:30 local), prices fell in near lockstep from the $80-100/MWh range down to single digits and negative territory by 13:00-13:30 AEST. Demand then rebuilt through the early morning ramp, climbing from under 300 MW at 04:00 AEST to over 1800 MW by 08:55 AEST, and price responded sharply — spiking to $153.54/MWh at 08:00 AEST as wind generation temporarily lagged the demand ramp and gas (CCGT/OCGT) was called on to fill the gap. This confirms SA's price sensitivity remains acute at the margin: every 100-200 MW swing in demand during low-wind periods can move price by $20-50/MWh.
Today's forecast trajectory points to a demand-driven price collapse persisting through the day. AEMO's forward curve shows prices staying deeply negative from 07:00 AEST through to at least 18:00 AEST, bottoming near -$45/MWh around 15:00 AEST, before a brief recovery to $65-71/MWh forecast for the 18:30-21:00 AEST window as evening demand builds and solar drops away. Peak price risk today is concentrated in that early evening window (18:00-21:00 AEST) when rooftop and grid solar taper off simultaneously with the evening demand ramp — the same pattern that drove yesterday's peak of $177.78/MWh at 22:50 AEST (12:50 local settlement). Weather data supports continued strong wind (10.7 potential, 19 km/h) and negligible solar potential today (cloud cover 42%), reinforcing the wind-dominant, price-suppressed profile through the bulk of the trading day.
Demand-side factors to watch: AEMO has an active direction on AGL's Torrens Island B4 unit to remain synchronised for voltage support until 16:00 AEST today, and a foreseeable intervention notice flags possible further directions from 11:00 AEST due to voltage conditions — this reflects thin synchronous generation cover during high-wind, low-demand troughs rather than a supply shortfall, but it adds cost pressure via direction payments that sit outside the spot price. Grid stress score reads moderate at 46.3, consistent with a market oversupplied on energy but managing minimum system strength requirements.