Commodity Demand — SA1: Wednesday 2 September 2026
South Australia's spot price sits at $9.83/MWh at 6:30am AEST, with demand at 1,351 MW — a level that has kept prices pinned near zero for most of the past 24 hours as wind generation (1,409 MW) comfortably exceeds underlying demand. Renewable penetration is running at 97.1%, with carbon intensity down at 0.0142 tCO2/MWh. This overnight and early-morning pattern reflects a familiar SA dynamic: strong wind output routinely pushes price well below $20/MWh whenever demand tracks under roughly 1,400 MW, as seen through yesterday evening's slide from $76/MWh at 6:35pm down to negative pricing (-$4.36/MWh) by mid-afternoon.
The price-demand relationship in SA today is highly non-linear and wind-dependent rather than purely demand-driven. Looking at yesterday's trading, price spikes above $80/MWh coincided with demand climbing through 1,700-1,830 MW during the 9am-11am period, while price consistently collapsed to sub-$1/MWh whenever demand fell below 1,300 MW into the afternoon and evening trough. This tells traders that SA's price sensitivity is asymmetric: moderate demand increases trigger sharp price responses once wind output can't keep pace, but demand pulling back below the 1,300-1,400 MW mark reliably produces near-zero or negative pricing regardless of time of day, given current wind strength.
AEMO's forecast trajectory for today points to a pronounced price escalation through the morning and into midday. Forecast RRP holds negative to flat through the 11am-4pm AEST window (overnight into early morning) before surging to $80.44/MWh by 5pm AEST, then $120-$196/MWh through the 6-8pm window, and peaking near $215/MWh around 10pm AEST. This is consistent with today's weak solar outlook (avg solar potential just 9.9%, cloud cover 60%) constraining rooftop and grid-scale PV contribution during the day, while wind potential is forecast to soften to 3.8% on average — a marked step down from the current 11.4% wind potential reading. Traders should treat the afternoon build into evening peak as the key risk window, with the combination of fading wind and negligible solar tightening the supply margin materially.
On the demand-side and system security front, AEMO's Minimum System Load (MSL) notices through late August show a pattern of extreme midday demand troughs in SA — including a forecast of -62 MW net demand on 30 August and an actual near-zero reading around 2pm on several days this week — reflecting rooftop solar's growing offset to grid demand at midday even under cloud. The now-cancelled SA intervention event (voltage-related, cancelled 1345 hrs 2 September) and prior directions to Torrens Island and Barker Inlet units for voltage control underline that synchronous generator commitment remains a live constraint independent of pure demand levels, and could recur if wind drops away faster than forecast during today's evening ramp.