Victoria experienced sustained negative pricing during two intervals on 10 September 2026, with the lowest spot price reaching -$4.41/MWh. The negative pricing occurred during a period of high renewable generation (over 1,600 MW of solar and wind combined) with thermal plant remaining online at approximately 3,800 MW.
The negative pricing reflects an oversupply condition where low-marginal-cost renewable generation exceeded immediate demand, requiring some generators to pay for dispatch. This condition was reinforced by binding constraints (F_TASCAP_RREG_0220 and F_T+RREG_0050) with marginal values of $4.99 and $4.16 respectively, which restricted the ability to balance supply through interconnector flows, forcing local thermal units to remain committed despite weak local demand and forcing prices into negative territory to clear the market.
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.