South Australia (SA1) experienced very high renewable penetration of 93.7%, driven by substantial wind generation (985.72 MW) and solar output (303.67 MW combined), with minimal fossil fuel contribution. Spot prices remained near zero for most of the period (21:45–22:00) but spiked to $14.20/MWh at 21:40, indicating a brief dispatch constraint.
The zero and near-zero prices across most settlement periods reflect the high renewable supply relative to demand, typical of low-marginal-cost wind and solar generation. The single price spike to $14.20/MWh at 21:40 corresponds to binding regulatory constraints with marginal values of $11.96 and $10.99, suggesting that dispatch was temporarily constrained by regulation-related obligations (indicated by constraint IDs F_T+LREG_0050), which required dispatch at a premium above the marginal renewable cost. The subsequent return to zero pricing indicates the constraint relaxed and renewable generation resumed setting the price floor.
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.