Revenues in Great Britain fell 37% month-on-month to £44k/MW/year in May 2026, down from £69k/MW/year in April, and 33% below May 2025's £65k/MW/year. It was the second-lowest revenue month of the past year, behind only February. Every market earned less than in April, but a collapse in Balancing Mechanism revenues drove most of the decline.

Wind generation fell 24%, which lifted outright wholesale prices but flattened them. With fewer price extremes to trade against, both wholesale spreads and balancing opportunities shrank. These are not the conditions in which batteries thrive. Balancing Mechanism revenues turned negative for the first time in over a year, subtracting £0.7k/MW/year after contributing £12k/MW/year in April.

For subscribers to Modo Energy's Research, this article will also cover:

• A breakdown of revenue changes across each service
• Why wholesale spreads compressed even as prices rose
• Why Balancing Mechanism revenues turned negative
• How rising wholesale prices reshaped the Frequency Response stack
• A data download of all charts

Revenues fall in every service

May's revenue stack inverted the pattern of recent months. Wholesale was the largest contributor at £18.5k/MW/year, ahead of Frequency Response and the Capacity Market. The Balancing Mechanism, which contributed £46.5k/MW/year as recently as March, subtracted £0.7k/MW/year.

Every market earned less than in April 2026. The Balancing Mechanism fell the furthest, down £13k/MW/year, with Frequency Response the next largest reduction. No services saw revenues increase.

Wholesale Market revenues

Day-ahead spreads fell to £48/MWh in May 2026

Wholesale spreads narrowed in May. Day-ahead spreads fell to £48/MWh, down 39% from April, and intraday spreads compressed too. The squeeze came from the bottom of the price range. Gas kept daytime and peak prices elevated, but with less wind on the system the cheap hours during which batteries charge largely disappeared. The gap between the day's highs and lows shrank even as the average price rose.