Five-Year View of TNUoS Tariffs for 2022/23 to 2026/27 National Grid Electricity System Operator April 2021 Five Year View of TNUoS for 2022/23 to 2026/27 | April 2021 Contents Executive Summary ......................................................................................................... 4 Charging Methodology Changes ..................................................................................... 6 Generation tariffs ........................................................................................................... 10 1. Generation tariffs summary .................................................................................................................... 11 2. Generation wider tariffs .......................................................................................................................... 11 3. Changes to wider tariffs over the five-year period ................................................................................. 15 Onshore local tariffs for generation ................................................................................ 19 4. Onshore local substation tariffs.............................................................................................................. 19 5. Onshore local circuit tariffs ..................................................................................................................... 19 Offshore local tariffs for generation ................................................................................ 23 6. Offshore local generation tariffs ............................................................................................................. 23 Demand tariffs ............................................................................................................... 24 7. Demand tariffs summary ........................................................................................................................ 25 8. Half-Hourly demand tariffs ..................................................................................................................... 26 9. Embedded Export Tariffs (EET) ............................................................................................................. 27 10. Non-Half-Hourly demand tariffs ............................................................................................................. 28 Overview of data input ................................................................................................... 30 11. Changes affecting the locational element of tariffs ................................................................................ 31 12. Adjustments for interconnectors ............................................................................................................ 31 13. Expansion Constant ............................................................................................................................... 32 14. Locational onshore security factor ......................................................................................................... 32 15. Onshore substation ................................................................................................................................ 32 16. Offshore local tariffs ............................................................................................................................... 33 17. Allowed revenues ................................................................................................................................... 33 18. Generation / Demand (G/D) Split ........................................................................................................... 34 19. Charging bases for 2022/23- 2026/27 ................................................................................................... 35 20. Annual Load Factors .............................................................................................................................. 36 21. Generation adjustment and demand residuals ...................................................................................... 36 Sensitivity Analysis ........................................................................................................ 39 22. Impact of new interconnectors ............................................................................................................... 40 23. TDR Sensitivities .................................................................................................................................... 47 Tools and supporting information Further information ................................................... 50 Appendix A: Background to TNUoS charging ................................................................ 52 Appendix B: Changes and proposed changes to the charging methodology................. 58 Appendix C: Breakdown of locational HH and EE tariffs................................................ 61 1 Five Year View of TNUoS for 2022/23 to 2026/27 | April 2021 Appendix D: Annual Load Factors ................................................................................. 65 Appendix E: Contracted generation ............................................................................... 67 Appendix F Transmission company revenues ............................................................... 69 Appendix G: Generation zones map .............................................................................. 74 Appendix H: Demand zones map .................................................................................. 76 Appendix I: Changes to TNUoS parameters .................................................................. 78 List of Tables and Figures Table 1 Summary of average generation tariffs .......................................................................................... 11 Table 2 Generation wider tariffs in 2022/23................................................................................................. 12 Table 3 Generation wider tariffs in 2023/24................................................................................................. 13 Table 4 Generation wider tariffs in 2024/25................................................................................................. 13 Table 5 Generation wider tariffs in 2025/26................................................................................................. 14 Table 6 Generation wider tariffs in 2026/27................................................................................................. 14 Table 7 Comparison of Conventional Carbon (80%) tariffs ......................................................................... 15 Table 8 Comparison of Conventional Low Carbon (80%) tariffs ................................................................. 16 Table 9 Comparison of Intermittent (40%) tariffs ......................................................................................... 17 Table 10 Local substation tariffs .................................................................................................................. 19 Table 11 Onshore local circuit tariffs ........................................................................................................... 19 Table 12 Circuits subject to one-off charges ............................................................................................... 22 Table 13 Offshore local tariffs 2022/23 ........................................................................................................ 23 Table 14 HH, NHH and EET Summary ....................................................................................................... 25 Table 15 Non-Locational demand residual banded charges ....................................................................... 26 Table 16 Gross Half-Hourly locational demand tariffs by demand zone* .................................................... 27 Table 17 Embedded Export Tariffs 2022/23 to 2026/27 .............................................................................. 28 Table 18 Non-half hourly demand tariffs from 2022/23 to 2026/27 ............................................................. 29 Table 19 Generation contracted, modelled and chargeable TEC ............................................................... 31 Table 20 Interconnectors ............................................................................................................................. 32 Table 21 Expansion Constant ..................................................................................................................... 32 Table 22 Allowed revenues ......................................................................................................................... 33 Table 23 Error Margin Calculation ............................................................................................................... 35 Table 24 Generation and demand revenue proportions .............................................................................. 35 Table 25 Demand charging bases ............................................................................................................... 36 Table 26 Residual components calculation ................................................................................................. 38 Table 27 Summary of in-flight CUSC modification proposals ................................................................... 59 Table