Decision to accept CUSC modification proposal CMP379
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Connection and Use of System Code (CUSC) CMP379: Determining TNUoS demand zones for transmission connected demand at sites with multiple Distribution Network Operators (DNOs) was raised by National Grid ESO at the Modifications Panel meeting on 24 September 2021. A second Final Modification Report (FMR) was submitted to the authority on 7 September 2023. The latest Transmission Entry Capacity (TEC) register shows that during the 2022/23 charging year several transmission-connected users (primarily energy storage systems) are expected to connect to the National Electricity Transmission System (NETS) located at a boundary point between multiple DNO areas. At present the CUSC charging methodologies do not clearly set out how the TNUoS demand zone and therefore the TNUoS demand tariffs should be determined for such a connection.
In the baseline CUSC, the treatment of demand users connecting at a boundary point between GSP Groups is not specified, and as such we believe some clarity on how TNUoS tariffs for such users are calculated is necessary. Implementation of this proposal means that a transmission site connecting at a GSP that feeds more than one GSP Group, demand tariffs will be derived from the average zonal tariffs from the relevant zones which we consider to be a pragmatic solution which will better facilitate ACOs b) and e) and has a neutral impact on the other applicable objectives.
Main document
[CMP379 Decision Letter [PDF, 151.61KB]
](https://www.ofgem.gov.uk/sites/default/files/2023-10/CMP379%20Decision%20Letter.pdf)