Tasmania experienced sustained negative pricing reaching −$58.91/MWh across three consecutive intervals during the early morning of 20 September 2026, with prices fluctuating between −$24.90 and −$58.91/MWh across the wider period. The negative pricing occurred during a period of elevated hydro and wind generation totalling approximately 480–540 MW.
The binding constraints with significant marginal values—particularly F_T+LREG_0050 at $49.97 and $35.79, and F_I+RREG_0220 at $3.80 and $3.10—indicate that Tasmania's dispatch was constrained by regulation services or inter-regional requirements rather than energy-only constraints. The combination of high renewable generation (hydro and wind) with active binding constraints that carry negative shadow prices suggests an oversupply situation in which must-run renewable generation exceeded minimum load requirements, forcing negative pricing to clear the market as dispatchable gas generation remained offline.
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.