South Australia’s gigawatt-scale grid reached zero demand on Sunday 21 November when the combined output of rooftop solar PV and other non-scheduled generators exceeded local customer load demands.
This is the first time that a gigawatt-scale grid has achieved this landmark event, noted RenewEconomy. This event was brought about when minimum operational demand hit a new record low of 104MW, down 45% from the previous record of 188MW on 31 October 2021.
Between 1PM to 1:30PM on Sunday, the estimated rooftop solar PV output was 1,220MW, accounting for 92% of the region’s underlying electricity demand, according to Australian Energy Market Operator (AEMO).
At 1:05PM, AEMO stated that it was directing approximately 120MWs 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 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 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,” he said.
The milestone achieved on Sunday is the latest in a series of achievements in South Australia, a region leading the country in solar and wind energy deployment.