SA1 experienced sustained negative pricing reaching $-179.67/MWh across three consecutive intervals (03:45–03:50 on 12 September 2026) during overnight low-demand conditions. The region's generation mix was dominated by wind (100.26 MW) and gas (84.8 MW combined), with minimal demand absorption capacity available.
The negative pricing was driven by excess renewable generation (primarily wind at 100+ MW) during low-demand overnight hours, where flexible load and storage had limited ability to absorb output. Multiple binding constraints with modest marginal values (F_TASCAP_RREG_0220 at $4.66/MWh, F_TASCAP_LREG_0210 at $4.62/MWh, and F_MAIN++LREG_0210 at $3.62/MWh) indicate that regional or interconnection constraints were restricting the ability to export or balance supply, forcing the market into negative pricing to curtail generation rather than physical spill.
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.