​In May 2026, grid-scale battery revenues in the National Electricity Market (NEM) fell 45% month-on-month to $29k/MW/year. This was the lowest monthly outcome since Modo Energy began tracking the index in July 2022. It is also one-seventh of May 2024 revenues and one-third of May 2025.

A mix of structural and weather-driven factors sits behind the fall. The grid-scale battery fleet grew 2.6x over the past 12 months. Home batteries added 5.2 GW, exceeding the grid-scale additions over the same period, and absorbing midday solar and reducing evening demand. Less negative midday price intervals and more wind also pushed charging prices up and evening prices down. Together, these factors compressed spreads across all four mainland states.

Rising variable renewable supply also makes pre-dispatch signals harder to predict and optimise against. On three days this month, unexpected flat price profiles resulted in negative revenues.

This article reviews grid-scale battery revenues for May 2026, including month-on-month comparisons, the contribution from energy and FCAS, state-level outcomes, and asset-level performance.

Last month's report benchmark can be found here (April 2026).

Executive summary

• NEM-wide battery revenues fell 45% to $29k/MW/year in May, the lowest monthly level since the index began in July 2022. South Australia saw the greatest decline, 65%, to $13k/MW/yr.
• 2-hour spreads narrowed across every mainland state. South Australia recorded the largest decline at 33% to $103/MWh. Victoria recorded the narrowest spread at $90/MWh.
• Capture rates ranged from 16% to 95%. The top performer was Limondale BESS, harnessing its 8-hour duration.
• The operating BESS fleet has grown 2.6 times year-on-year. Meanwhile, small-scale batteries have added 5.2 GW over the same period. Utility-scale storage is competing for the same evening demand, while home batteries minimise the demand itself.

All four mainland states saw battery revenues fall, with varying levels of suppression

NEM-wide energy revenue averaged $26k/MW/year in May. Every mainland state recorded lower revenues than in April. South Australia recorded the largest decline at 65% as the volatility conditions that sustained some early-2026 lift did not repeat. New South Wales limited per-MW revenue reductions to 35% month-on-month, supported by longer-duration assets. Queensland and Victoria moved down in line with the NEM-wide trend.