​Longer-duration BESS are capturing a greater share of the NEM’s available trading value, as price spreads narrow and become less predictable.

​Four- and eight-hour batteries have led capture rates in New South Wales, Queensland and Victoria since they went live. Realised price spreads were similar across durations, challenging the expectation that longer discharge windows mean accepting lower returns per MWh.

Bidding helps explain why. More stored energy lets them offer capacity cheaply across more hours, increasing their chance of catching unexpected peaks. Meanwhile, the growing battery fleet is driving actual prices to diverge from forecasts.

Executive summary

• Four- and eight-hour batteries achieved higher capture rates than shorter-duration peers since building in New South Wales, Victoria, and Queensland.
• Longer-duration assets realised a similar spread, despite lower revenue potential per MWh: assets across durations all earned a $60-65/MWh spread since March 2026.
• The timing of peak prices has diverged from AEMO near-term forecasts. Actual daily peaks were within an hour of forecast for 33% of Q3 2026, down from 48% a year earlier.
• Longer-duration batteries spread competitive bids over wider daily windows, relying less on precisely-timed dispatch.
• As a result, they’ve captured a greater share of the highest prices each day, while cycling similarly to short-duration peers.

Four- and eight-hour BESS capture more of the available spread

The available price spread per MWh is lower for longer-duration BESS, as charging and discharging opportunities extend beyond the cheapest and most expensive hours of each day. Yet they traded more energy while achieving spreads similar to shorter batteries through Winter and Spring 2026.