Regional Outlook — SA1: Friday 18 September 2026

South Australia's spot price sits at $0.01/MWh at 06:30 AEST, capping off a night of persistently negative and near-zero pricing that began around 21:20 last evening and has held through the overnight trough, with prices as low as -$180/MWh at 12:55 AEST and a cluster of -$35 to -$60/MWh readings through the early hours. Demand has recovered to 1,287 MW from an overnight low near 92 MW, tracking the typical wind-and-demand pattern for the region. Wind is dominant in the generation mix, contributing 1,336 MW against just 42 MW from gas CCGT and negligible battery and OCGT output — solar has yet to ramp up at this hour. Renewable penetration sits at 96.94%, pushing carbon intensity down to 0.015 tCO2/MWh, near the lowest levels seen in the past 24 hours (which ranged from 0.014 to 0.227 tCO2/MWh depending on wind availability and overnight thermal dispatch).

Predispatch forecasts show prices staying negative through the morning, bottoming near -$176/MWh around 13:30 AEST before a sharp reversal: the market flips positive by 17:30 AEST and climbs to a forecast peak of $79.80/MWh around 19:00 AEST as wind potential eases and evening demand builds. This morning's minimum system load event is the key driver of the trough — AEMO has flagged a forecast MSL1 condition for today, with operational demand expected to fall below -178 MW between 11:30 and 14:30 AEST, indicating minimal scheduled demand and heavy renewable oversupply pushing prices deeply negative. Traders with flexible load or storage should note the load-shifting windows identified overnight, with the best opportunity being the 03:00–04:00 AEST window at an average -$147.71/MWh, saving roughly $228/MWh versus peak pricing.

Several active AEMO notices are relevant to today's SA outlook. AEMO issued a foreseeable intervention notice for voltage support in SA effective from 09:00 AEST, and has directed AGL SA Generation's Torrens Island B4 unit to synchronise and follow dispatch targets from 09:00 AEST through to 17:00 AEST today to maintain adequate voltage control — a recurring pattern this month as synchronous generation thins out during high-wind, low-demand periods. This follows a similar direction and subsequent cancellation on 17–18 September, underscoring the frequency of voltage security interventions in SA under current high-renewable, low-demand conditions. Traders should expect continued volatility around the midday trough and the evening price reversal, with grid stress scored at 74 and market conditions at 53.8 reflecting the operational complexity of managing near-zero minimum demand alongside strong wind output today.