South Australia (SA1) experienced brief negative pricing at $-1.02/MWh across two intervals (00:00 and 00:10 on 24 September 2026), with prices ranging from zero to mildly negative during an overnight period. The region was generating substantial renewable output, with wind at 408 MW and solar at 183–186 MW, alongside gas generation totalling approximately 41–42 MW.
The negative prices occurred despite moderate total generation, suggesting demand was constrained relative to supply in the dispatch interval. Multiple binding constraints with marginal values of $3.12–$3.43/MWh indicate transmission or system service limitations were active, preventing efficient export or load-matching and forcing the market to price generation out. The persistence of zero and negative prices across consecutive intervals points to binding constraint conditions that persisted over the period, requiring financial incentives (negative pricing) to reduce or shift renewable output rather than curtail it.
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.