Energy storage: Navigating the UK LDES regime after Window 1

10 July 2026

The long duration energy storage (LDES) cap and floor regime is a significant development in the UK's energy storage strategy. It is modelled on the successful interconnector cap and floor regime, with important modifications, and provides a revenue support mechanism that is intended to facilitate private investment. Ofgem, the UK's energy regulator, has indicated that 16 projects, together representing 7,645 MW of storage, could receive regulated revenue support. For developers, sponsors, lenders and investors active in or considering UK grid-scale energy storage, the regime's mechanics – and its limits – merit close attention. In this briefing we discuss how the regime operates and what the implications are for market participants, whether currently engaged in the Window 1 process, assessing Window 2 prospects or evaluating secondary market positions.

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