TAS1 experienced sustained negative pricing across five consecutive intervals from 19:35 to 20:10 on 12 September 2026, with prices ranging from −$8.47/MWh to −$3.60/MWh. The trough price of −$8.47/MWh occurred at 19:40, representing the most severe downward pressure during the event.
The negative pricing was driven by high renewable generation (approximately 640 MW combined hydro and wind capacity) coinciding with low demand during evening shoulder periods, creating oversupply conditions in the region. A binding constraint (F_T+LREG_0050) with marginal values ranging from $14.29/MWh to $18.28/MWh indicates that network or reserve constraints were actively limiting Tasmania's ability to export surplus generation, forcing the region to absorb the excess supply domestically and pushing prices into negative territory.
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.