Commodity Demand — SA1: Saturday 12 September 2026
South Australia's spot price sits at -$4.53/MWh at 06:30 AEST with demand at 1,179 MW, holding in negative territory as wind generation of 1,665 MW comfortably exceeds current load. This is a marked shift from the demand collapse overnight, when total demand plunged to near-zero and briefly negative (-74.67 MW at 13:25 AEST equivalent) between 12:30-14:30 AEST, driving prices as low as -$223.28/MWh. That minimum system load event triggered an AEMO MSL1 advisory around 13:20 AEST before cancellation an hour later, underscoring how thin overnight demand in SA continues to create negative pricing risk even without generation oversupply concerns.
Demand shows strong price sensitivity through the morning ramp: as load climbed from 355 MW at 16:00 AEST (prior day) to over 1,300 MW by 18:30 AEST, prices moved from -$1.10/MWh to a peak of $96.48/MWh at 17:25 AEST. This roughly 1,000 MW swing over three hours produced a price range exceeding $300/MWh peak-to-trough, consistent with SA's typically steep short-run supply curve once wind output plateaus and gas peaking plant sets the marginal price. Demand has since eased back to the 1,250-1,390 MW band through the middle of the trading day, with prices retreating to near-zero or negative as wind supply remains ample relative to load.
Looking at today's forecast trajectory, AEMO's outlook shows demand-driven price strength building from late morning: forecast RRP holds around $80/MWh from 18:00-22:00 AEST (target times 08:00-12:00 local), before easing to the low $60s in early afternoon, then stepping back up to $80/MWh through the evening peak and $93.65/MWh by the final forecast point at 04:00 AEST tomorrow. This pattern reflects the classic solar-trough-then-evening-peak shape, with the trough itself likely staying mild given today's cloud cover (37% average) limiting solar output and keeping wind-plus-gas as the dominant price setters.
Two active market notices are directly relevant to today's demand-price dynamics. AEMO has flagged a foreseeable voltage-related intervention in SA from 08:30 AEST today, with a further direction already issued and in effect from 05:05 AEST — meaning synchronous generation dispatch may be adjusted independent of pure economic merit order, a factor traders should watch for basis risk against forecast prices. Separately, the VIC-SA negative settlement residue constraint that operated for four hours yesterday afternoon (16:00-20:00 AEST) has now ceased, removing one source of interconnector-driven price distortion between the regions for now. With wind sitting at 1,665 MW and renewable penetration at 93.5%, further wind strength could keep suppressing prices below forecast levels through the demand build this morning.