Regional Outlook — SA1: Tuesday 18 August 2026
South Australia's spot price sits at -$4.24/MWh at 06:30 AEST, deep in negative territory as strong wind output continues to outpace overnight and early morning demand of 1,412 MW. Prices have been sub-zero or single-digit for most of the past 12 hours, a sharp contrast to yesterday evening's peak of $55.91/MWh around 07:30 AEST (07:00-07:30 UTC) when demand climbed above 1,600 MW. This overnight collapse reflects the now-familiar SA pattern: abundant wind generation combined with low demand pushes prices negative, while evening peak demand periods with less wind support see prices swing back into the $30-55/MWh range.
Generation mix is heavily wind-dominated: wind is contributing 1,158.6 MW, easily the largest source, against gas CCGT at 82.7 MW, battery output at 16.8 MW, and negligible gas OCGT and solar (solar sits at zero given the pre-dawn hour). Renewable penetration reads 93.4% and carbon intensity is 0.0323 tCO2/MWh — both have drifted slightly from the day's best readings of ~98% renewables and 0.0099 tCO2/MWh recorded around 11:00 AEST yesterday, as wind eased off through the evening and gas ramped to cover the demand ramp.
Predispatch forecasts point to a sharp reversal ahead. Prices are expected to stay negative to flat through the early hours (-$8 to -$5/MWh from 09:00-14:00 AEST), before surging as the morning demand ramp arrives without matching solar support given today's overcast outlook (52% average cloud cover, only 14.1% solar potential). Forecast RRP climbs to $80/MWh by 18:00 AEST, spikes to $189/MWh around 20:00 AEST, and holds near $101/MWh through the middle of the day before easing to $55.90/MWh by 04:00 AEST tomorrow. Traders should treat the overnight negative-price window (currently showing average prices of -$6 to -$8/MWh) as the day's best load-shifting opportunity, with load windows between 11:00 AEST and 16:00 AEST offering savings of roughly $195-197/MWh versus peak.
On notices, AEMO issued a direction to AGL SA Generation's Torrens Island B2 unit to synchronise and follow dispatch targets from 00:00 AEST today, addressing a voltage control shortfall flagged in yesterday's foreseeable intervention notice — the risk being that synchronous generation in SA is otherwise inadequate to maintain secure voltage support. This directed generation, expected to run through 15:00 AEST today, will affect a small volume of dispatch outcomes but doesn't attract intervention pricing. Separately, AEMO's MT PASA update flags a Low Reserve Condition risk for SA in July 2028, a longer-term reliability signal rather than a near-term operational concern. The Basslink interconnector also remains under a technical transfer limit constraint (invoked 07:00 AEST yesterday), worth monitoring for any secondary effect on Victorian-SA price convergence today.