South Australia (SA1) experienced very high renewable penetration of 94.8% during the early morning period of 5 September 2026, driven predominantly by wind generation of 1,461.56 MW. This high renewable contribution resulted in negative regional reference prices ranging from −$6.14/MWh to −$4.04/MWh across consecutive settlement intervals.
The negative pricing reflects excess renewable generation relative to regional demand during a low-demand overnight period. The binding constraint F_T+RREG_0050 with a marginal value of $4.44/MWh indicates an active system constraint limiting further injection or requiring additional drawdown, which—combined with the dominance of wind output (1,461.56 MW) and solar generation (108.52 MW combined)—constrained the market operator's ability to accommodate all available renewable supply, forcing prices negative to incentivise consumption and demand response.
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.