Abstract
Existing studies commonly examine flexibility-market regulation, renewable energy community participation and storage techno-economics separately. This separation makes it difficult to determine how market rules convert technically available flexibility into eligible and monetisable services in constrained systems. This paper addresses that gap through a harmonised assessment framework that maps product rules — including aggregation, baselines, activation, settlement and locational requirements — onto operational constraints and common technical and economic indicators. The novelty is integrative rather than algorithmic: the framework explicitly distinguishes physical, product-compliant and monetisable flexibility and applies the same assessment chain at transmission- and distribution-oriented scales. Two complementary cases are examined: El Hierro through hourly system indicators and transparent wind-to-pumping scenario screening, and the CEIS cooperative grid through techno-economic simulations of centralised and distributed battery energy storage systems (BESS). Under the original PROGRESS assumptions, the 3 MW centralised BESS achieves an NPV of approximately EUR 388,000, an IRR of 6.34%, a 7.49-year payback and an LCOS of 0.077 EUR/kWh. Including fixed O&M of 15 EUR/kW-year reduces its NPV to approximately -EUR 149,000; an additional annual value stream of about EUR 12,500 restores zero NPV. Distributed storage improves local self-consumption and reduces exported renewable surplus but requires larger additional value streams. For El Hierro, the screening indicates that improved wind-to-pumping utilisation could displace approximately 0.34–1.02 GWh/year of diesel generation. The results show that current arrangements favour centralised assets and that locational distribution services require explicit remuneration.