TAS1 experienced sustained negative pricing across 3 intervals on 15 September 2026 at 04:15–04:40 UTC, with prices ranging from −$15.01/MWh to −$7.31/MWh. The region had high renewable generation (633.62 MW wind, 494.80 MW hydro, 148.68 MW rooftop PV) combined with modest gas-fired output (247.92 MW), creating an oversupply situation during a typically low-demand overnight period.
Negative pricing reflects excess generation that could not be economically curtailed or exported, consistent with the high binding constraint marginal values (up to $104.03/MWh) on constraint F_T+LREG_0050 in the first interval, indicating physical network limitations restricting outflow from the region. The combination of elevated wind and hydro output during low overnight demand, coupled with active constraint binding, forced the dispatch algorithm to accept negative prices to balance supply and demand within the binding constraint envelope.
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.