Regional Outlook — SA1: Thursday 17 September 2026
South Australia's spot price sits at $99.74/MWh as at 06:30 AEST, tracking near the middle of a volatile 24-hour band that swung from -$186.96/MWh overnight (06:20 AEST oversupply trough) to an intraday peak of $135.04/MWh during the 08:30 AEST demand ramp. Demand currently sits at 1447 MW. Prices have been grinding down through the evening from a $117.44/MWh spike at 20:25 AEST, consistent with the broader pattern seen through the day: strong wind generation keeps prices low overnight and negative in the small hours, before the morning demand ramp combined with softer wind pushes prices back above $100/MWh through mid-morning and midday.
Generation mix at the current interval is wind-dominated at 902 MW, supplying the bulk of SA's 1156 MW total output, with batteries contributing 129 MW, gas CCGT at 83 MW and gas OCGT at 42 MW. Solar is at zero, reflecting the 20:30 AEST timestamp after sunset. Renewable penetration sits at 89.2%, and carbon intensity is very low at 0.0585 tCO2/MWh, near the cleanest point of the day. This is a sharp contrast to the middle of the day, when intensity peaked near 0.44 tCO2/MWh with renewable penetration down near 22-26% around 07:30-08:30 AEST as wind output dipped and gas plant carried more of the load.
Predispatch forecasts point to a further easing overnight: prices are expected to fall to $78.20/MWh by 21:00 AEST, spike briefly to $138/MWh at 21:30 AEST, then collapse through the early hours, troughing around -$63.25/MWh near 04:00 AEST on 18 September as wind supply outstrips low overnight demand. Prices are forecast to recover only modestly through tomorrow's daytime, hovering in the $37-60/MWh range from 08:00 to 14:00 AEST before easing again into the evening. Low-price windows between 01:00-06:00 AEST tomorrow offer strong load-shifting opportunities, with avg prices around -$57 to -$61/MWh and savings near $195-199/MWh versus peak.
Market notices remain active on voltage support: AEMO has flagged a foreseeable intervention in SA from 23:00 AEST tonight (18/09) due to voltage conditions, continuing a pattern of near-daily voltage-related directions this week, including a direction to AGL's Torrens Island unit to remain synchronised through to 16:30 AEST today. Separately, AEMO has forecast a Minimum System Load (MSL1) event for 19 September between 11:30-14:30 AEST, with minimum demand expected to reach -178 MW at 13:30 AEST — a signal for generators and flexible load to prepare for extended low-demand, high-renewable conditions later this weekend.