TAS1 experienced sustained negative pricing at -$0.57/MWh across two consecutive intervals (15:30 and 15:35) on 19 September 2026, with prices remaining at or near zero in the preceding four intervals. The region's generation mix was dominated by renewable sources, with hydro and wind collectively representing the entire supply during the negative pricing period.
The negative pricing reflects an oversupply condition in TAS1 driven by high renewable generation (hydro and wind totalling approximately 990–1,240 MW) relative to regional demand, requiring generation to be curtailed or exported. A binding constraint with marginal values ranging from 26.8–27.6 (constraint_id: F_T+LREG_0050) was active during and preceding the negative price intervals, indicating a physical or operational limit that prevented efficient dispatch of excess generation, forcing the price mechanism to incentivise load or discourage further supply.
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.