Great Britain's battery storage fleet reached 8.5 GW and 14.4 GWh after a record third quarter in 2026, when nine batteries added 917 MW and 1,844 MWh. Modo Energy reports that its GB BESS revenue index rose 23 per cent between the second and third quarters while capacity grew 12 per cent, even as connections reform pushed parts of the pipeline back.
Record quarter takes the GB fleet to 8.5 GW
Nine batteries entered commercial operation in Great Britain during the third quarter of 2026, adding 917 MW and 1,844 MWh to the fleet and setting a new quarterly record. That exceeded the previous record of 674 MW set in the third quarter of 2025. Total installed capacity reached 8.5 GW and 14.4 GWh, according to Modo Energy's buildout analysis.
Projects are also getting larger. Since the first quarter of 2025, five of seven quarters have each added a site of at least 100 MW, including Thurrock and Kilmarnock South at 300 MW apiece. Coalburn 1 joined in the third quarter of 2026 at 500 MW, making it the largest battery in Great Britain.
Revenues hold up as capacity grows
Modo Energy reports that revenues stayed stable despite the accelerated buildout. Its ME BESS GB Index rose 23 per cent from the second quarter to the third quarter of 2026, while capacity increased by 12 per cent. The index is the source's own measure of revenue performance for batteries in the GB market.
Quarterly figures can be revised as more assets are captured. Modo Energy notes that some batteries appear in its asset database only after the quarter ends, so the most recent quarter may still increase. First quarter 2026 volumes were revised upward from 397 MW to 590 MW, while second quarter 2026 remained unchanged at 209 MW.
Connections reform reshapes the pipeline
Connection reform is changing the queue while large pipeline projects continue to reach commercial operation. Modo Energy's October 2026 pipeline update states that 6.5 GW of its second quarter 2026 pipeline now expects a connection date at least six months later than previously assumed, and that only 37 per cent of the pipeline holds a Gate 2 date.
The buildout record and the pipeline delays therefore sit alongside each other in the same market. Larger sites continue to complete, but the timing of later projects depends heavily on reformed connection arrangements and the visibility that Gate 2 dates provide to developers and investors.
Wider market signals for storage investment
Global figures published in 2026 point to continued expansion. One estimate puts the worldwide battery energy storage system market at USD 31.784 billion in 2026, up from USD 29.858 billion in 2025, a rise of about 6.45 per cent, with a compound annual growth rate of roughly 6.03 per cent between 2026 and 2032.
Another forecast values the global on-grid battery energy storage systems market at USD 33.12 billion in 2025, rising to USD 141.99 billion by 2035 at a 15.6 per cent compound annual growth rate. Europe is described as emphasising decarbonisation, flexibility and cross-border electricity coordination, with the United Kingdom addressing renewable integration, flexibility and evolving market and network rules.
Key Takeaways
Great Britain's battery fleet reached 8.5 GW and 14.4 GWh after nine batteries added 917 MW and 1,844 MWh in the third quarter of 2026.
The ME BESS GB Index rose 23 per cent quarter on quarter while capacity grew 12 per cent, indicating revenues held up during rapid buildout.
Coalburn 1, at 500 MW, became the largest battery in Great Britain.
Connection reform has pushed 6.5 GW of Modo Energy's second quarter 2026 pipeline to at least six months later, with only 37 per cent holding a Gate 2 date.
Sources