The extraordinary price event unfolded around 3:30pm AEDT on Monday, with prices exceeding $5,000 per megawatt hour in 11 separate five-minute intervals. On Reddit, home battery owners shared screenshots of their earnings, with one user reporting they had made $100 in an hour by selling 30 kilowatt-hours of stored energy. "Hot day shenanigans," another user posted. "Good for us hey!"
The heatwave pushed temperatures into the mid-30s, with Sydney's Observatory Hill recording 34.7 degrees Celsius - more than 12 degrees above the long-term monthly average for October. As demand climbed, four of New South Wales' 12 coal-fired generating units were out of action and two were running at reduced capacity. Several high-voltage transmission lines were also operating below capacity due to maintenance, preventing large amounts of renewable energy and storage capacity from reaching Sydney.
Australian energy intelligence firm GridScout noted that technical curtailment peaked at 2,800 megawatts, with renewables and batteries in southern New South Wales the most heavily affected. "This was all while prices were above $10,000/MWh," the firm said on social media.
Green Energy Markets CEO Tristan Edis said the price spike was a reminder of an underlying vulnerability in the NEM as it manages the transition from ageing coal plants to new generation and storage in a rapidly warming climate. "It's normal for electricity prices to be high when temperatures go noticeably above 30 degrees," Edis said. "What's problematic is that doesn't normally happen in October."