SA1 experienced sustained negative pricing at approximately −$5/MWh across two settlement intervals on 4 September 2026, with prices declining through the period to a minimum of −$5.05/MWh. The negative pricing persisted despite modest load requirements being met by a substantial wind generation fleet (1,375.85 MW) alongside gas-fired plant, indicating structural surplus generation in the region.
The negative pricing resulted from high renewable generation (predominantly wind) exceeding regional demand, creating downward pressure on spot prices. A binding constraint with marginal value of $6.80/MWh (F_TASCAP_RREG_0220) was active across most intervals, suggesting physical transmission or reserve limitations were restricting export of surplus generation, forcing local prices negative to incentivise demand response or generation withdrawal rather than allowing energy to flow unconstrained out of the region.
Causal analysis generated by gridIQ's synthesis model from live AEMO market data: dispatch prices, generation mix, interconnector flows and market notices in the interval surrounding the event.