TAS1 experienced sustained negative pricing of approximately $-5/MWh across two consecutive settlement intervals (00:25 and 00:30 on 4 September 2026), with the minimum price reaching $-4.62/MWh. The event occurred during a period of elevated renewable generation, with hydro and wind contributing 821–1121 MW combined output and gas generation offline.
The negative pricing was driven by an excess of inflexible renewable supply relative to regional demand, with Tasmania unable to export surplus generation due to a binding constraint (F_TASCAP_RREG_0220) that carried positive marginal values ranging from $4.67 to $6.99/MWh throughout the event window. The constraint's tight binding indicates transmission or system strength limitations prevented efficient dispatch of the available hydro and wind generation, forcing negative pricing as the marginal cost of reducing output.
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.