​NEM grid-scale battery revenues averaged $29k/MW/year in May 2026. That is down 45% on April, and the lowest monthly figure since Modo Energy's index began in July 2022.

Three days returned net-negative revenue across the fleet: 17, 25 and 27 May. On each, the intraday price profile was flatter than normal, or even inverted the usual duck curve. Pre-dispatch forecasts also drifted from actual prices. Batteries that relied on those signals or expectations of the typical shape optimised poorly.

May saw multiple days with flat intraday price profiles, driven by low solar and high wind. This was clearest in Victoria's 1-4 May, where 2-hour spreads were between $5-32/MWh.

These factors sit on top of larger structural shifts compressing spreads across the NEM. Home batteries are reducing evening peak demand, and a fleet 2.6 times its year-ago size is now competing for the same arbitrage pool.

This article is a companion to the May 2026 monthly revenues report.

Executive Summary

• NEM grid-scale battery revenues averaged $29k/MW/year in May 2026. That is down 45% on April, and the lowest since the index began in July 2022.
• 2-hour spreads hit record lows. Low midday solar, higher evening wind, and home batteries all flattened intraday price shapes.
• Spreads did not explain all revenue losses. Several of the worst revenue days had average-to-high spreads but poor capture.
• Three days returned negative revenues (17, 25 and 27 May). Pre-dispatch predicted cheaper midday charging and higher evening peaks than the day actually delivered.
• The flattest days came in Victoria (1-4 May) and South Australia (1-3 May). They traded at 2-hour spreads of $5-36/MWh and earned just $2-11k/MW/year.

May two-hour spreads fell 65% year-on-year

NEM-wide 2-hour spreads fell 65% year-on-year, from $280/MWh in May 2025 to $99/MWh this May. New South Wales led the compression at 82%. The other states roughly halved. Battery revenues followed, down 69% over the same period.