Rooftop solar supplied 99.9% of South Australia's power demand on 1.30 pm August 31, cutting grid-scale generation to just 2 MW and setting a new winter record, the Australian Energy Market Operator (AEMO) said on September 1.

The result coincided with a new winter minimum operational demand record across the National Electricity Market of 12 GW, surpassing the previous low set in August 2024. High rooftop output and negative wholesale prices also saw batteries charging at above-average rates, absorbing excess renewable electricity for use during the evening peak period, the market operator said. 

At the time of the record low, rooftop solar was contributing close to 54% of underlying demand, with all renewables including grid-scale solar and wind accounting for 71% of generation. Battery charging represented about 10.5% of total generation, with just over 2% used for hydro pumping.

AEMO said the records demonstrate how rapidly the electricity system is changing, with high renewable generation increasingly balanced in real time by batteries, hydro and gas. The conditions reinforce the need to plan for a more dynamic power system with flexibility, storage, transmission and operational capability to maintain secure supply as the energy transition accelerates.

Australia leads the world in rooftop PV penetration, with 41% of premises hosting systems delivering 28.3 GW of capacity. In South Australia, 57% of rooftops have solar arrays, equivalent to 2.92 GW.