The WEM experienced a moderate price spike in WA1 on 18 May 2026, with the RRP rising sharply to $263.34/MWh during the 10:10 trading interval, representing a 104% increase from the previous interval's $129.05/MWh. This spike was isolated to a single trading interval before prices stabilised, suggesting a temporary supply-demand imbalance or constraint breach.
The spike likely resulted from binding transmission constraints in the network, as evidenced by multiple marginal constraint values indicating F_MAIN and F_T constraints were actively limiting available generation capacity. Despite substantial generation from gas OCGT (690 MW), black coal (627 MW), and gas CCGT (568 MW), plus battery support (392 MW), the network constraints restricted supply availability to meet demand in that specific interval, forcing the market to clear at the elevated price ceiling.
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.