Commodity Demand — SA1: Saturday 5 September 2026
South Australia's spot price sits at $60.09/MWh at 20:30 AEST with demand at 1,132 MW, capping off a day that swung from deeply negative overnight pricing to a firm evening peak. The 06:00-20:30 window traced the full demand curve: overnight troughs near 400-500 MW pushed prices to -$16/MWh during the 04:30-05:00 low, before the morning ramp lifted demand past 1,700 MW by 08:30-09:00 and prices broke through $30/MWh. Demand has since eased back from that late-morning peak of ~1,720 MW, tracking down through the afternoon to the current 1,130 MW range, with prices holding in the high $50s to low $70s through the evening ramp as solar output fades.
The demand-price relationship today is unusually elastic given SA's thin operating margin. A roughly 20 MW swing between 20:15 and 20:20 (1,108 to 1,158 MW) coincided with a price move from $59.55 to $70.80/MWh, underscoring how tight the region's marginal supply stack is once rooftop and grid-scale solar drop away. Battery output of 436 MW is currently the largest single generation source in the mix, alongside 145 MW wind and 61 MW gas CCGT, with solar at zero — this evening's price firmness reflects the system leaning on batteries and gas to cover the demand that solar no longer serves.
AEMO's forecast curve points to a sharp overnight price collapse, with negative pricing already showing near midnight and a trough around -$4/MWh forecast for 05:00 AEST tomorrow, consistent with weekend minimum demand conditions. But the outlook flips sharply from 07:00 tomorrow: forecast prices jump to $74.44/MWh at 07:00, then climb through the morning to $104-126/MWh across the 08:00-12:00 window, peaking near $126.40/MWh at 12:00. This trajectory reflects tomorrow's demand ramp compounding with a foreseeable AEMO intervention notice flagged for voltage conditions in SA from 11:00 06/09/2026 — a signal that grid stability measures may constrain supply flexibility just as demand and price pressure builds through the late morning peak.
Demand-side factors to watch: AEMO's active intervention notice for SA voltage conditions from 11:00 tomorrow suggests directions to generators are likely if market response is insufficient by 15:00 today, which could tighten available capacity heading into the forecast midday price spike. Weather also supports a subdued demand day — cool conditions (12-15.6°C) with moderate cloud cover (55%) limit both heating load and solar output, keeping the region reliant on wind, gas, and battery dispatch through the low-solar periods that are driving today's price volatility at both ends of the demand curve.