Tasmania experienced sustained negative pricing in TAS1, with prices reaching -$6.79/MWh during the 22:10 interval on 2 September 2026. The negative pricing occurred across 2 intervals following a period of very low positive prices (below $0.10/MWh). High wind and hydro generation totalling approximately 1,200-1,300 MW during this period created an oversupply condition in the region.
The negative pricing was driven by binding regional constraints with significant marginal values (up to $7.34/MWh), indicating physical limitations preventing efficient energy dispatch. The combination of elevated wind generation (480-498 MW) and substantial hydro output (326-353 MW) during a low-demand evening period created surplus generation that could not be economically exported or curtailed, forcing prices negative to incentivise consumption or generation withdrawal. The constraint binding at high marginal values suggests transmission or network limitations were preventing TAS1 from exporting excess renewable generation, resulting in local oversupply.
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.