South Australia (SA1) experienced very high renewable penetration of 96.5% on 28 June 2026, with wind generation dominating at 1662.7 MW and minimal thermal generation. Regional reference prices (RRP) declined sharply over the five-minute period from $60.26/MWh to $33.77/MWh, reflecting the low-cost renewable supply.
The steep price decline is primarily attributable to the high volume of low-marginal-cost wind generation displacing higher-cost thermal units and suppressing overall demand curves. The binding constraint F_MAIN+RREG_0220 maintained marginal values between $4.99–$8.54/MWh across the settlement period, indicating system limitations that moderated but did not prevent downward price pressure from the renewable generation surplus.
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.