“Remarkable:” Record day of wind and solar curtailment as renewables surge and rooftop PV holds sway

Australia’s main grid saw what energy experts are describing as a “remarkable day” of records on Sunday, as excellent generation conditions and low grid demand results in multiple new records of renewable curtailment.

According to Geoff Eldridge, of GPE NEMWatch, there were a heap of records that tumbled, mostly in the middle of the day, with the most notable being the first time on the National Electricity Market that wind and solar curtailment had totalled more than 10 gigawatts.

It reached a new peak of 10.21 GW, nearly 1.5 GW above the previous record that was set in September, 2024. The remarkable part is that is in itself more than electricity demand at the time, which hit a new low of 9.5 GW just after 1pm.

There were also new highs for individual technologies, with wind curtailment breaking through 5 GW for the first time on the NEM, with Victoria being the most impacted with a new high of 3.5 GW of wind curtailement.

Total curtailment also reached a new peak of 4.6 GW in South Australia and 8.4 GW in Victoria, Eldridge says.

The share of curtailment was also remarkable, with the combination of actual production and curtailment reaching a new peak of 114 per cent of total demand – the highest since October last year when it reached 106 per cent, and a new record in Victoria where it reached 156 per cent.

Eldridge said that the curtailment record of 107 per cent of total grid demand (excluding the demand served by rooftop solar) mentioned earlier shows how far availability exceeds system absorption.

He notes that renewable energy production and curtailment exceeded native demand from 9.15 am to 3.10 pm, underlying how sustained the surplus was through the day.

“The behind the meter rooftop PV is reducing demand for dispatchable generation,” Eldridge tells Renew Economy.

“You can see that, on average, for every 1 MW of fooftop PV output there was 0.8 MW of Wind and Solar Curtailed. Coal will be running on or close to minimums, and there are four units out in Victoria at the moment, along with 3 in each of NSW and Queensland.

It points, he says, to the gap in flexibility – storage, electric vehicles and dynamic tariffs can capture surplus renewables, but not yet in sufficient quantities.

“Some battery charging and pumped hydro reduced the curtailment, but a lot more needed, plus lots of potential to move loads into the sunny/curtailment part of the day.

“The big question is: Which lever — batteries, transmission, demand-shifting, or reform — most reduces next spring’s curtailment?” he asked.

“These records highlight not just how far renewables have come, but how much further system flexibility and integration must go.”