CMP463 Stabilising the Specific Onshore Expansion Factors from 1 April 2026
- Publication type:
- Code modification
- Publication date:
- Topic:
- Electricity transmission,
- Energy network price controls
- Subtopic:
- RIIO-3
Our decision to accept CUSC Modification CMP463: Stabilising the Specific Onshore Expansion Factors from 1st April 2026. This modification will change CUSC section 14 to freeze the cost of Specific Expansion Factors (SEFs) at the 2025/26 value.
Details of outcome
We made a previous decision to fix the Expansion Constant (EC) and the non specific Expansion Factors (EFs). It was assumed the SEFs would not be updated by NESO, but they have decided to update them and increase the value. This would cause a last minute unexpected change in charge to certain generators, constituting a harm to competition (due to the unfair nature of it). As such, we have approved this modification.
Start date
1st April 2026.
Code modification description
- SSE raised the modification and requested urgency
- The modification is resulting from an unforeseeable change to charges resulting from NESO updating SEF values.
- This change would only effect certain generators, but for them would constitute a significant change.
- The proposal freezes SEFs in line with our previous decision on the EC and EFs.