South Australia recorded very high renewable penetration of 95.6% during the early morning period on 10 April 2026, driven almost entirely by wind generation totalling approximately 1,573 MW across the region. Spot prices remained negative throughout the observed interval, ranging from approximately -$3.48/MWh to near zero, consistent with a classic oversupply scenario. Only a small amount of gas-fired combined cycle generation (around 41–43 MW) remained online, likely for system security purposes.
The negative prices are characteristic of strong overnight and early morning wind output coinciding with low demand, where renewable generators with near-zero marginal costs continue to bid into the market, pushing prices below zero to avoid curtailment and maintain revenue from certificate schemes. The binding constraints — particularly F_T+NIL_MG_RECL_R6 with high marginal values — suggest interconnector or network limitations are restricting the export of surplus South Australian generation to Victoria, trapping excess supply within the region and amplifying the price suppression. The residual gas CCGT output likely reflects minimum generation requirements or FCAS (frequency control ancillary services) obligations necessary to maintain system strength and inertia given the very low synchronous generation levels.
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.