Commodity Demand — SA1: Saturday 22 August 2026
South Australia's spot price sits at $113.07/MWh at 06:30 AEST with demand at 1,237 MW, down sharply from today's overnight peak. The overnight trading window tells the demand-price story clearly: prices spiked to $264/MWh when demand climbed toward 1,686 MW around 09:35-09:40 AEST (18:35-19:40 UTC), then eased back toward the $100-120/MWh band as demand settled into the 1,230-1,280 MW range through the evening. This is a demand-elastic market today — every 100-200 MW swing is moving price by $50-150/MWh, reflecting a thin supply stack once wind and rooftop solar contributions fluctuate.
The AEMO forecast trajectory points to further softening overnight, with forecast prices falling from $101/MWh at 07:00 AEST to near zero and even negative by 12:00-14:00 AEST (forecast_rrp of -$6.02/MWh around 13:00 AEST), consistent with minimum overnight demand and continued wind generation. Wind is currently contributing 702 MW against total generation of roughly 1,238 MW, with gas OCGT providing 428 MW of flexible capacity — the mix that's kept renewable penetration at 62% and carbon intensity at 0.242 tCO2/MWh this evening. Demand is forecast to trough overnight before rebuilding through tomorrow morning, with AEMO's forecast showing prices climbing back to $82-99/MWh by 07:30-09:00 AEST tomorrow as morning demand ramp resumes.
A key factor shaping today's price outlook is AEMO's active market intervention in SA — a direction issued to a generator at 16:05 AEST today for voltage support, with a further foreseeable intervention flagged from 10:30 AEST tomorrow (23 August) also for voltage control. These interventions signal the region is operating with reduced synchronous generation margin, which can amplify price volatility during demand ramps even though intervention pricing itself doesn't apply. Traders should note the five low-price windows identified between 11:00 AEST and 16:00 AEST tomorrow, with average prices at or below -$5/MWh, offering strong load-shifting value of over $100/MWh versus today's peak pricing.
Weather adds context for tomorrow: cool conditions (9-17°C) with moderate cloud cover (58%) will keep both heating demand and solar output modest, meaning tomorrow's demand curve is likely to closely track today's shape, with the pre-dawn trough and mid-morning ramp remaining the key price-sensitive periods to watch.