SA1 experienced sustained negative pricing over a 30-minute period from 04:55 to 05:30 on 13 September 2026, with the minimum price reaching −$7.59/MWh across three consecutive intervals. The region had elevated renewable generation (predominantly wind at 990.63 MW and solar at 100.31 MW combined) coinciding with moderate gas generation totalling 191.69 MW, creating an oversupply condition during the early morning period.
Negative pricing in SA1 was driven by binding constraints on regulation services (F_TASCAP_RREG_0220 and F_TASCAP_LREG_0210) with marginal values between $4.64/MWh and $7.23/MWh, indicating supply-side pressure from insufficient flexible regulation capacity to manage the high renewable penetration. The combination of substantial wind and solar output with limited demand in early morning hours forced marginal generation to accept negative prices to remain on-network, with the binding regulation constraints preventing economic dispatch from clearing the surplus generation.
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.