Tasmania (TAS1) experienced sustained negative pricing at −$0.56/MWh across two consecutive intervals (16:30–16:35) on 18 September 2026, with prices near zero throughout the preceding period. The region maintained elevated wind and hydro generation (approximately 495–509 MW wind and 251–312 MW hydro) whilst gas generation remained offline.
The negative pricing reflects excess renewable generation relative to regional demand, creating downward pressure on spot prices. A binding constraint (F_T+LREG_0050) with a high marginal value of approximately $89.85/MWh was active throughout the period, indicating a tight constraint was limiting further supply adjustment or network utilisation, forcing generators to accept negative prices rather than reduce output or face constraint breach penalties.
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.