South Australia has once again reached a negative electricity demand, with its solar photovoltaic (PV) network causing the minimum operational demand to hit a new record low of 104MW.
The record was set on 21 November 2021, down 45 per cent from the previous record of 188MW on 31 October 2021.
Between 1pm and 1:30pm (ACDT) on the 21 November, estimated rooftop solar PV output was 1,220MW, accounting for 92 per cent of the region’s underlying electricity demand.
At 1:05pm, the Australian Energy Market Operator (AEMO) was directing approximately 120MW of gas to maintain power system stability in South Australia with the high proportion of renewable energy generation.
In addition to the 120MW of directed gas generation, a further 16MW of gas, 130MW of wind and 46MW of grid solar generation in South Australia was bidding into the National Electricity Market (NEM).
All of this electricity, and 38MW of excess rooftop solar PV, was exported into Victoria via the two interconnectors into Victoria for consumption in the NEM.
This resulted in a scheduled demand of -38MW and a total demand of -46MW, when accounting for interconnector electricity losses, as displayed through AEMO’s NEMDE market management system.
AEMO Executive General Manager Operations, Michael Gatt, said, “South Australia had negative electricity demand on Sunday for several five-minute trading intervals, which is a first for the NEM.
“This happened because the combined volume of surplus rooftop solar PV and non-scheduled solar and wind generation was greater than electricity consumed in South Australia.
“The NEM performed as expected during this unique event, made possible by directing gas plants to maintain system strength and capacity available via the Victoria-South Australia interconnectors to spill the excess rooftop solar and dispatch the 350MW of electricity sold into the NEM.”
AEMO uses and reports three key demand measurements, as described in the AEMO Demand Terms in EMMS Data Model.
AEMO calculates operational minimum demand over a 30-minute period rather than every five minutes as it’s more accurate with current systems.