TAS1 experienced sustained negative pricing over two intervals on 4–5 September 2026, with prices reaching −$6.61/MWh. The region generated substantial renewable output (approximately 760 MW of combined hydro and wind capacity) alongside baseload gas generation, creating structural oversupply during low-demand overnight periods.
The negative prices were driven by binding constraint F_TASCAP_RREG_0220 with marginal values ranging from $4.66 to $6.80/MWh, indicating that regional capability or export limitations restricted the ability to clear surplus generation into the broader NEM. With high renewable generation and inflexible thermal plant (gas OCGT at ~124 MW) unable to ramp down sufficiently in the low-demand late-night window, generators faced economic incentive to offer at negative prices to avoid forced curtailment or constraint violations.
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.