South Australia (SA1) experienced two intervals of negative pricing reaching −$4.10/MWh during the 01:00 settlement period on 1 August 2026. The event occurred in a low-demand off-peak window with substantial renewable generation (840 MW combined wind and solar output) and minimal load absorption capacity.
The negative pricing resulted from a structural oversupply of renewable generation relative to demand during the early morning period, with wind and solar collectively representing the dominant supply source. Multiple binding constraints with positive marginal values (F_MAIN++RREG_0220 at $4.67/MWh and F_T+RREG_0050 at up to $4.55/MWh) indicate network or service limitation constraints restricted further generation dispatch or flows, forcing the market into a corner solution where negative pricing was required to balance supply and demand.
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.