South Australia (SA1) experienced sustained negative pricing during the early morning of 29 August 2026, with prices falling to −$31.81/MWh across two settlement intervals. The region's generation mix was dominated by solar (141–222 MW) and wind (78.62 MW) output, alongside significant gas-fired generation (82–82 MW CCGT and minimal OCGT), creating an oversupply condition typical of high renewable penetration periods.
The negative pricing was driven by a binding constraint (F_T+LREG_0050) with marginal values ranging from $43.70 to $63.85/MWh, indicating that this constraint was active and preventing the market from clearing at positive prices. The combination of substantial solar and wind generation during low demand hours (early morning) created excess supply that could not be economically dispatched, forcing the spot price into negative territory as the marginal generator was effectively required to pay to inject energy into the grid.
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.