CMP423: Generation Weighted Reference Node
What is being proposed
This modification proposes to switch from a demand weighted Reference Node to a generation weighted Reference Node instead.
Current status
Proposal issued to the October 2023 CUSC Panel. The October 2023 CUSC Panel unanimously agreed that CMP423 should follow the Standard governance route and proceed to a Workgroup. The Panel did not approve the Terms of Reference for the Workgroup. Workgroup nominations closed on 21 November 2023 and Workgroup meetings commenced from 22 January 2024. Ahead of the CUSC Panel approving the reconvening of Workgroup meetings,the ESO will continue with the required further analysis, develop the legal text and share the transport model with the Workgroup members that have signed the software license agreement. The October 2024 CUSC Panel prioritised as Medium, therefore Workgroup activity will start from Spring 2025. On 17 December 2024 the Proposer requested the status for this modification be changed to urgent. A Special CUSC Panel was held on the 10 January 2025 to review and approve. The Panel by majority agreed that CMP423 did not meet the Authority’s Urgency criteria, and therefore did not recommend urgent treatment. Panel’s recommendation was sent to the Authority on 10 January 2025. On the 20 January 2025 the Authority rejected the requested change of governance route from Standard to Urgent. Standard timeline was presented at the CUSC January Panel. Upon receipt of the Authority Open Letter on 31 January: Outlining their approach to prioritisation of electricity transmission network charging modifications. 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 due to the complexity and technical aspects of the defect, alongside the amount of time the TNUoS Task Force had already contributed to the development of the solution, the Panel considered modification should be prioritised as ‘Medium to High’. (09/06/2025) The Workgroup Consultation was issued on 28 May and will close on 19 June. On 26 September 2025 the CUSC Panel , the Panel agreed that the Terms of Reference have been met and agreed for CMP423 to proceed to Code Administrator Consultation. The Code Administrator Consultation will be published on 09 October, and this will close on 31 October 2025. The Draft Final Modification Report will be presented to Panel on 28 November 2025. (02/12/2025) The Panel recommended by majority that the Proposer’s solution better facilitates the CUSC Applicable Objectives. The Final Modification Report will be sent to Ofgem on 09 December 2025
Details
Timeline
Analysis
CMP423 proposes switching from a demand-weighted to generation-weighted Reference Node for TNUoS charging calculations. The CUSC Panel has recommended approval by majority, with the Final Modification Report sent to Ofgem on 9 December 2025. This changes how transmission charges are calculated and allocated across the network.
Why it matters
This shifts cost allocation from load centres to generation centres, likely redistributing TNUoS charges from demand-heavy regions (South) to generation-heavy regions (Scotland, North). As such, it represents a fundamental rebalancing of who pays for transmission infrastructure rather than changing total costs.
Key facts
- •CUSC Panel recommended approval by majority on 2 December 2025
- •Final Modification Report sent to Ofgem on 9 December 2025
- •High impact on both generation and demand users
- •Authority rejected urgency request on 20 January 2025