Regional Outlook — SA1: Saturday 12 September 2026
South Australia's spot price sits at -$4.53/MWh at 20:30 AEST, holding in negative territory for the sixth consecutive hour as evening wind generation swamps demand of 1,179 MW. This follows an extremely volatile 24 hours: prices swung from a peak of $96.48/MWh during the 07:25 AEST morning ramp down to a trough of -$223.28/MWh at 04:45 AEST overnight, when several intervals breached -$179/MWh amid a minimum system load event. That MSL1 condition — triggered when operational demand fell below the -40 MW advisory threshold — was cancelled by AEMO at 14:50 AEST once demand recovered, but it underscores how thin overnight demand combined with strong wind output continues to push SA into deeply negative pricing.
Wind is the dominant fuel source this evening at 1,665 MW, comfortably covering total demand alongside 73 MW from gas OCGT and 43 MW from gas CCGT. Solar has dropped to zero post-sunset and battery output is negligible at 0.06 MW. Renewable penetration sits at 93.51%, with carbon intensity at a very low 0.0383 tCO2/MWh. Across the day, intensity ranged from a low of 0.0116 tCO2/MWh at 14:25 AEST (97.64% renewable, coinciding with peak solar) to a high of 0.4178 tCO2/MWh at 04:55 AEST when wind briefly ebbed overnight and gas plant carried more of the load.
Predispatch forecasts show prices staying negative to strongly negative through the overnight period, with troughs of -$60 to -$63/MWh expected between 12:00 and 14:00 AEST tonight (i.e. the 12:00-14:00 UTC window covering early Sunday morning), before recovering through the 07:00-08:00 AEST morning ramp to a forecast $80/MWh plateau from mid-morning into the afternoon, and firming further to $93.65/MWh by 18:00 AEST tomorrow evening. Tomorrow's weather outlook supports this trajectory: cloud cover eases to 37% with average solar potential of 14.3 and wind potential of 8, a moderate improvement on today's overcast, low-wind conditions (64% cloud, 3.2 wind potential currently).
Traders should note AEMO has an active market intervention notice for SA region effective from 05:05 AEST today, with a further foreseeable intervention flagged for voltage support from 08:30 AEST tomorrow (13 September) — AEMO expects insufficient market response by 06:00 AEST and may issue directions to maintain secure operation. This follows a pattern of repeated voltage-related directions to synchronous generation (including AGL's Torrens Island units) over the past week, reflecting the system strength challenges as synchronous generator commitment stays low during high-wind, high-renewable periods. The VIC-SA negative settlement residue constraint (NRM_VIC1_SA1) also remains a live feature, having started and ceased multiple times this week as interconnector flows respond to SA's price volatility.