TAS1 experienced sustained negative pricing in two consecutive intervals on 28 August 2026 at 23:10 and 23:15, with the minimum price reaching −$3.62/MWh. The negative pricing occurred during a period of elevated renewable generation, with combined hydro and wind output totalling over 1.2 GW across the measured intervals.
The negative pricing was driven by binding constraints with significant marginal values, particularly constraint F_TASCAP_RREG_0220 (marginal values $4.99 and $4.64/MWh) and related network/service constraints, indicating that Tasmania's generation was constrained in its ability to export surplus output. With high hydro and wind generation coinciding with lower demand periods, the inflexibility of dispatchable generation (GAS_OCGT running at ~124 MW) and active binding constraints forced the marginal unit into negative pricing territory to manage oversupply within 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.