The WEM WA1 region experienced a moderate price spike to $281.07/MWh in the 12:50 trading interval on 20 September 2026, representing a sharp 21% increase from the previous interval. Prices had been elevated for the preceding two intervals ($239–$240/MWh) before this final spike, suggesting sustained tight supply conditions.
The price spike was driven by binding constraints with material marginal values, most notably constraint F_T+LREG_0050 contributing $28.56/MWh to the spot price, indicating a significant limitation on system capability. The generation mix shows substantial reliance on gas-fired generation (OCGT and CCGT combining for 1,015.4 MW) and coal (430.3 MW), with wind and solar providing only 101.1 MW of support, suggesting limited low-cost generation availability during this period and elevated dependence on more expensive marginal plant to meet demand.
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.