Supporting the call for Transmission Network Use of System (TNUoS) charging reform

As part of our stakeholder led advocacy priorities, we’re backing calls from our customers and broader stakeholders that a review and reform is required to the current transmission charging methodology to support decarbonisation at the scale and pace required for net zero.

Our generation customers and wider stakeholders in the north of Scotland consistently tell us that charges for transmission access, as well as uncertainty about future charges, are acting as a blocker to the commercial viability of renewable energy projects. This in turn creates uncertainty for us in terms of efficient system planning for the network, whilst also impacting on the energy markets where generators seek to earn revenue.

This webpage pulls together all of our research to date in one location. Here you will find any papers, videos, FAQ's, news and views, relevant consultation papers and our latest position.

TNUoS: The biggest barrier to net zero targets? from SSEN on Vimeo.

What is TNUoS? 

Managed by National Grid as the Electricity System Operator (ESO), and regulated by Ofgem, TNUoS is a charge to recover the cost of the installation and maintenance of the GB transmission network. The ESO recovers theTransmission lines with wind turbines in the background revenue on behalf of all onshore and offshore transmission owners and other network schemes. TNUoS is currently paid by all users of the transmission network; commercial and residential electricity bill payers pay to use the networks to consume electricity and both transmission connected and embedded generators over 100MW capacity pay to use the transmission network to export their electricity. Generation TNUoS is calculated through various factors, mostly location. In general terms, generators located closer to areas of demand pay less, with those in more remote areas paying more to transmit power onto the system. This results in higher costs for the delivery of renewable projects in Scotland compared to other parts of GB, with particular disparity in the north of Scotland which are furthest away from the biggest areas of demand in the south of England. You can find out more about TNUoS on the National Grid ESO's Website. 


Why is TNUoS a problem? 

Evidence shows us that TNUoS charges are indeed many times higher in the north of Scotland than elsewhere in GB. The charges for a single generator can Wind turbines with a rainbow in the skyalso swing dramatically from year to year and this is near impossible to predict or plan for commercially. The issue of volatility and unpredictability is notunique to the north of Scotland but experienced by all generators regardless of technology or location. This uncertainty increases the risk for generation developments which comes at a cost and we expect this cost ends up on the end consumers electricity bill. Such timing and sizing uncertainty for generation developments in turn creates huge uncertainty for us, as a Transmission Owner (TO), in terms of efficient system planning, as we work to connect the renewable energy needed to support greater electrification in society and deliver a network for net zero. 


Our stakeholder-led case for reform 

To respond to our stakeholders' TNUoS concerns, we published our TNUoS Discussion Paper in February 2021 to explore the case for TNUoS reform in greater detail, advocate for the interests of our customers and stakeholders along with providing evidence of the impact. Using the paper as a tool to encourage further debate, we continued to listen and respond to our stakeholders via a range of methods including written responses, calls, feedback forms and through an interactive stakeholder webinar session, which was joined by over 100 participants from developers to local authorities. A full recording of the webinar can be viewed opposite. 

Following this engagement, we published a summary report of all feedback received which overwhelmingly supports the need for TNUoS reform. In summary: 

  • 93% of all stakeholders agreed that some form of TNUoS reform is required.
  • 70% agreed with the findings outlined in our TNUoS paper.
  • 84% told us that TNUoS acts as a barrier to the delivery of their renewable projects in Scotland.

It is clear that urgent action is required to find solutions in the context of the climate emergency. 

Our TNUoS discussion paper, TNUoS offshore wind addendum paper, stakeholder feedback summary and response to Ofgem's Access SCR consultation can be downloaded from the 'document downloads' section further down this page. 

SSEN Transmission - Transmission Charges Webinar Recording from SSEN on Vimeo.

TNUoS - The Road to Reform  

In response to Ofgem’s recent much welcomed Call for Evidence (CfE), which closed on 12th November 2021, we held an interactive webinar, supported by RenewableUK, to provide our stakeholders with an overview of the CfE and encourage our stakeholders to respond. The webinar attracted a wide demographic of stakeholders, with 106 people attending. A full recording of the webinar can be viewed opposite. 

Of those attending: 

  • 51% had not read the Call for Evidence and;
  • 40% had not yet decided if they were going to respond. 

This was an opportunity to capture stakeholders views and opinions on what factors need to be considered when reforming TNUoS. Feedback received overwhelmingly supported the need for fast, simple and fundamental TNUoS reform with a just and affordable transition to Net Zero being at the forefront.  

We hope that the views from our stakeholders captured at the event will help to support Ofgems thinking and decision making in this area. 

You can see a full summary report of all feedback received below. Our final response to Ofgem's call for evidence can also be read below. 

TNUoS Industry News and Analysis

  • Scottish Renewables logo

    'Postcode Pricing' Threatens GB Renewable Energy Growth 

  • The Herald logo

    SNP calls for cuts to electricity transmission costs to help Scottish renewable sector flourish

  • The National logo

    Transmission charges: Tories accused of 'Great Scottish Renewables Robbery'

  • UK Gov accused of ‘great Scottish renewables robbery’ over grid charging

  • Offshore Wind Scotland logo

    Scottish offshore wind growth at a risk from rising offshore transmission charges

  • Scottish Renewables: Transmission Charging and it's Impact on Renewable Energy Development

    Scottish Renewables: Transmission Charging and it's Impact on Renewable Energy Development

  • RE NEWS BIZ logo

    Sturgeon calls for network charging reform

  • HIE Logo

    HIE: Charging system for energy technologies needs to be fit for the future

  • Energy Voice Logo

    Aberdeen MP calls on Scotland Office to join efforts to remove ‘barrier’ to renewables

  • Westminster Committee Hears Scots Offshore Wind Ambition in Peril from Electricity Network Charging Issue

  • Scottish Renewables: Electricity Network Charging Report

  • renewable UI logo

    Billions of pounds of green investment jeopardised by GB regulations which favour EU energy imports

  • UK Parliament logo

    UK Parliament: Renewable energy in Scotland

SSEN Transmission TNUoS Press Coverage

  •  David Boyland, SSEN Transmission’s Senior Commercial Policy Manager

    Locational Marginal Pricing: will it help or hinder net zero?

  • Utility Week: TNUoS: The biggest barrier to net zero targets?

  • The Energyst: SSEN Transmission calls for reform of “unfair and volatile” charging regime

  • reNEWS.BIZ: SSEN seeks views on grid charging reform

  • The Scotsman: Scottish energy group urges reform of 'unfair' charges

  • Current News: SSEN brands TNUoS costs 'unfair and volatile' as it calls for reforms to boost renewables

  • Utility Week: ‘Volatility and unpredictability’ of transmission charges inflating renewable costs

  • The Herald: Scotland's green future at risk from discriminatory grid charges to power firms

  • Utility Week: Taking a stakeholder-led approach on the case for TNUoS reform

  • John O'Groat Journal: North of Scotland transmission charges 'act as barrier to renewable energy viability'


Contact Us

If you’d like to talk to us or share your views please get in touch using the contact details below:

Andrew Urquhart

Head of Whole System

News and Views

  • Transmission system charges per country

    SSEN Transmission welcomes RIDG / RUK “Charging the Wrong Way” report

    We welcome the publication of RIDG and Renewable UK’s “Charging the Wrong Way” report today, highlighting the stark anomalies in how electricity generators access the GB market compared to those in Europe... 
  • Andrew Urquhart, Head of Whole System

    Powering change: taking a stakeholder-led approach on the case for TNUoS reform

    A blog by Andrew Urquhart, Head of Whole System at SSEN Transmission
  • windmills

    Stakeholder feedback suggests 93% support TNUoS reform to deliver net zero

    Based on analysis carried out by SSEN Transmission, 93% of its engaged stakeholders support reform of the current Transmission charging regime to support the UK’s legally binding net zero emissions target; which currently results in Scottish generators paying a higher cost for use of the transmission network compared to other areas in GB... 
  • powerlines

    SSEN Transmission calls for reform of “unfair and volatile” charging regime

    SSEN Transmission has published a discussion paper calling for views on the current Transmission Network Use of System (TNUoS) charging regime, which results in Scottish renewable generators paying significantly higher costs to connect their electricity... 
  • Andrew Urquhart ,Head of Whole System

    TNUoS: The biggest barrier to net zero targets?

    A blog by Andrew Urquhart, Head of Whole System, SSEN Transmission 
  • windmills with a rainbow in the sky

    Title - Tackling TNUoS: recognition of a review is welcome, but what we need now is action

    We submitted a response to Ofgem’s Access and Forward Looking Charges Significant Code Review (SCR) consultation, sharing our views on its proposals for transmission charging for small distributed generation (SDG). 

  • Transmission charging volatility results in net zero risk to offshore wind and higher costs for consumers

    SSEN Transmission has this week published some further analysis exploring the impact of the current Transmission charging regime on meeting the UK’s legally binding net zero emissions target; this time focusing specifically on impact for offshore wind developers. 
  • Andrew Urquhart, Head of Whole System

    TNUoS charging: counting the hidden cost to consumers

    Following the publication of SSEN Transmission's TNUoS Offshore Wind Addendum paper, Andrew Urquhart, Head of Whole System blogs about our stakeholder led analysis. 
  • Andrew Urquhart ,Head of Whole System

    Taking the first step on the road to TNUoS reform

    Andrew Urquhart, Head of Whole System at SSEN Transmission shares our support for Ofgem’s TNUoS Call for Evidence Next Steps publication.