TAS1 experienced sustained negative pricing of -$3.01/MWh across two consecutive intervals (23:50–23:55 on 9 September 2026), representing a sharp reversal from positive pricing of $5–$11/MWh in the preceding four intervals. The region's generation mix was dominated by high hydro output (1,238–1,029 MW across multiple units), with secondary contributions from wind, gas-fired generation, and rooftop solar.
Negative pricing was driven by excess renewable generation outpacing demand, as indicated by the substantial hydro dispatch (particularly the 1,029 MW unit) combined with baseline wind and solar output during a low-demand late-evening period. Binding constraints with marginal values of $4.66–$4.99 (principally F_TASCAP_RREG_0220, with a secondary constraint F_T+RREG_0050 at $4.20) suggest operational or network limitations were active, preventing generators from easily dispatching or exporting surplus supply, forcing marginal units into negative pricing to manage oversupply within Tasmania.
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.