South Australia (SA1) experienced high renewable energy penetration of 92.3% during the early morning period of 4 June 2026, with wind generation dominating at 1,441 MW and solar contributing 429 MW combined. Negative wholesale prices ranging from −$3 to −$2/MWh were recorded across six consecutive 5-minute settlements, indicating an oversupply of renewable generation relative to demand.
The negative prices reflect excess renewable generation during a low-demand period (early morning), where wind and solar output significantly exceeded system requirements. Multiple binding constraints with substantial marginal values (constraint F_S++HYSE_R60 at $25/MWh marginal value being the highest) indicate transmission network limitations were constraining the export or redistribution of surplus generation, forcing local prices downward as renewable generators competed to clear their output within the constrained region.
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.