CMP419: Generation Zoning Methodology Review
What is being proposed
To review the existing generation zoning methodology to incorporate offshore assets connected as part of the Holistic Network Design (HND) to enable the wider tariff to be applied to offshore generators. This modification seeks to also revisit the issue of zoning further to the expectations set out as part of the Authority decision on CMP324 and CMP325.
Current status
Proposal issued to the August 2023 CUSC Panel. The Panel unanimously agreed that CMP419 should follow the standard governance route and proceed to a Workgroup. The Panel agreed the Terms of Reference for the Workgroup. Workgroup Nominations opened on 30 August 2023 and closed 20 September 2023. Workgroup Nominations closed on 20 September 2023, the first Workgroup meeting held on 12 October 2023. The updated terms of reference was approved at the October 2023 CUSC Panel. The updated timeline submitted to the January 2024 CUSC Panel was approved. The updated timeline submitted to the April 2024 CUSC Panel was approved. Ahead of the CUSC Panel approving the reconvening of Workgroup meetings, the new Proposer will take on the feedback from the Workgroup and review the scope of the modification and will feedback to the Workgroup once this has been finished. Proposer is continuing to consider how to best progress the modification.The October 2024 CUSC Panel prioritised as High, therefore Workgroup activity will start before the end of January 2025. Upon receipt of the Authority Open Letter on 31 January: Outlining their approach to prioritisation of electricity transmission network charging modifications, Panel will review the modification status in the February Panel. On 14 February 2025 at the Special CUSC Panel the Panel discussed, at length and in detail, the prioritisation of CUSC Modifications. The CUSC Panel agreed Given the complexity of the defect, the potential for several alternative solutions and the advantage of an early decision on re-zoning for investors, this was placed as “Medium to High” in the prioritisation stack. (08/09/2025) In the postponed 03 September Panel, the Panel moved this modification prioity to low.
Details
Timeline
Analysis
CMP419 proposes to revise generation transmission charging zones to include offshore wind farms connected under the Holistic Network Design, allowing these generators to pay wider transmission tariffs rather than local rates. The modification has been deprioritised from Medium-High to Low as of September 2025, with workgroup activity stalled since 2024. This follows Authority expectations from previous zoning decisions CMP324 and CMP325.
Why it matters
Offshore generators currently face higher local transmission charges than onshore equivalents, creating an investment distortion that this modification seeks to remove. The deprioritisation to Low suggests either political resistance to socialising offshore costs across all transmission users, or recognition that the charging reform may be superseded by wider transmission access reforms.
Key facts
- •Modification first proposed August 2023
- •Deprioritised from Medium-High to Low in September 2025
- •Workgroup activity suspended since 2024
- •Affects offshore assets under Holistic Network Design
- •High impact on NESO and TNUoS-liable parties