Amendments to the Terms and Conditions related to Balancing for Static Firm Frequency Response Service (SFFR)
- Publication type:
- Decision
- Publication date:
- Topic:
- National Energy System Operator (NESO)
- Subtopic:
- Balancing supply and demand
Our decision on the 23 March 2026 submission from National Energy System Operator (NESO) proposing amendments to the Terms and Conditions related to Balancing by updating the service documentation for SFFR.
Details
The Authority has decided to approve NESO’s proposal to amend the service documentation for the SFFR Service (consisting of SFFR Service Terms and SFFR Procurement Rules) within the Terms and Conditions related to Balancing.
The proposed amendments covered:
- reducing the minimum unit size from 1 MW to 0.1 MW
- reducing the minimum bid size from 1 MW to 0.1 MW, introducing a new maximum bid size of 100 MW and allowing non-integer bids
- tightening the Percentage Performance Measure
- clarifying when and what data NESO can require from providers
- formalising the requirement to submit the frequency measurement used to trigger response
- introducing powers to suspend or de‑register units
- lowering the 'Frequency Trigger' from 49.70 Hz to 49.65 Hz
- updating references to consolidated Stacking Guidance
- clarifying that if SFFR is triggered near the end of an EFA block, full delivery is still required
This decision letter sets out our rationale for approving the proposed amendments and the next steps we expect NESO to take.