Issue date

The Australian Energy Regulator (AER) today published a report into energy prices exceeding $5,000 per megawatt hour (MWh) in the National Electricity Market (NEM) over October, November and December 2023.

During this period, 30-minute prices exceeded $5,000 per MWh 5 times – 3 times in South Australia and 2 times in Queensland. This compares to 10 high prices in the previous quarter and 5 high prices over the same period in 2022. 

A common driver across the high price events was reduced access to cheaper generation from a neighbouring region due to network outages or network constraints to maintain system security:

  • On 9 November in South Australia, flows over the interconnectors were limited due to a planned network outage and a constraint to maintain system security.
  • On 8 December in South Australia, flows were limited to protect system security during severe storms in the region.
  • In the last week of December in Queensland, as temperatures climbed above 36 degrees, Queensland was importing cheaper generation from New South Wales to meet periods of very high demand. Flows from New South Wales, however, were limited by a constraint on the Bayswater to Liddell lines to maintain system security.

Other drivers that contributed to high prices in the quarter included a reduced supply of low-priced capacity and rebidding by market participants


The AER is required to report into significant price outcomes in the NEM.

A high price may occur due to a variety of factors, including outages that adversely affect supply-demand conditions in the wholesale market.

The AER’s role in monitoring wholesale energy markets and reporting on high price events helps to enhance market transparency and compliance.

Our analysis provides a foundation to detect non-compliance, market irregularities, inefficiencies, and consumer harm. We draw on this work to advise stakeholders and market bodies on wholesale market issues.

The AER has published a Guideline for how we report into significant price outcomes.