The Offshore Coordination Project has been set up by the ESO with support from Ofgem and the Department for Energy Security and Net Zero.

Offshore wind has been identified as a critical technology in achieving net zero greenhouse gas emissions by 2050. In order to help realise this target, a step-change in both the speed and scale of deployment of offshore wind is required. One of the challenges to delivering the ambition for offshore wind deployment in the timescales required will be ensuring that the offshore and onshore transmission network enables this growth in a way that is efficient for consumers and takes account of the impacts on communities and the environment.

The ESO offshore coordination project, which contributes to the Offshore Transmission Network Review (OTNR), was set up in March 2020. Phase 1 of our project progressed at pace to assess the costs and benefits of a coordinated offshore network compared to the current radial approach, the technical considerations to achieve that, and how the offshore connections regime could change to drive greater coordination.

In July 2022 we published The Pathway to 2030 Holistic Network Design (HND) this has since been superseded by Beyond 2030 published in March 2024. We have now commenced work on the Holistic Network Design Follow up Exercise (HNDFUE) and the scope has been agreed through Terms of Reference (ToR), which can be found on the Department for Energy Security and Net Zero's OTNR website.  In November 2022 we published the Holistic Network Design Follow-Up Exercise Methodology, which provides an overview of our approach to developing the HNDFUE designs.

Our April 2024 Offshore Coordination update provides an overview of the ongoing work by the ESO on:

  • Beyond 2030 Report, HNDFUE ScotWind, Innovation and Targeted Oil & Gas (INTOG) and Celtic Sea progress
  • Progress of the HND
  • Offshore Hybrid Assets (OHAs) 
  • Other ESO work relating to connections reform and Centralised Strategic Network Plan (CSNP).

Read more about our zero carbon ambition.

Aerial view of car driving on country road between fields

Changes to the Holistic Network Design

Since the publication of the HND, Transmission Owners (TOs) and in-scope offshore wind developers with non-radial connections have started to produce the Detailed Network Design (DND).

As part of that process, TOs and developers have identified potential design changes. This required ESO, with input from stakeholders, to develop an impact assessment process to assess the impact of these changes, against the baseline of the HND, using the four HND design criteria. 

ESO have now completed the first impact assessment which identified a design that presents benefits across several Network Design objectives compared to the original HND design (the ‘baseline’). The outcome of this impact assessment is explained in the documents below.

ESO letter to Ofgem – South Cluster impact assessment outcome

South Cluster impact assessment outcome summary

Ofgem have published a response to the ESO South Cluster Impact Assessment and Asset Classification.

View Ofgem Response

Progressing delivery of the Holistic Network Design (HND)

Work is continuing within the Offshore Coordination Project to progress with facilitating the delivery of the transmission infrastructure recommended in the HND.

Our fortnightly technical/commercial forums are well established and are supporting both developers of non-radial offshore network in the HND and Transmissions Owners (TOs) to overcome barriers to delivery.

We have also developed and implemented an impact assessment process. As part of the Detailed Network Design (DND) phase, developers and TOs have identified design changes which has required us to develop a process to assess the impact of these changes against the four design criteria, compared to the baseline of the HND.

Progressing delivery of the Holistic Network Design (HND)

Technical/commercial forums

In order to support developers of non-radial offshore network in the HND and Transmission Owners (TOs) overcome barriers to delivery, we originally established two forums: an east coast technical forum, and a commercial forum. 

Due to the interlinking of barriers, it was decided to merge these two forums into one to create a fortnightly technical/commercial forum. This forum is coordinated by the ESO and attended by TOs, HND developers with non-radial connections, Ofgem, The Energy Department, and the Scottish government. The forum is well attended, and cross-cutting issues are being explored collaboratively, with members of the forums progressing actions where appropriate or escalating to other organisations or channels where the solution is not within the members’ remit. 

Currently, the focus of the forums is delivery of the HND and as such, membership of the groups covers those directly involved in this stage. As the HNDFUE has been finalised, we are now working to determine the appropriate approach to bringing additional stakeholders and/or issues into the scope of this work.

Impact assessment process

To support the delivery of network in our recommended network designs, we have developed and implemented an impact assessment process. As part of the Detailed Network Design (DND) phase, developers and TOs have identified changes to the original HND, which we want to ensure are assessed consistently and robustly to understand the impact of these changes against the four network design criteria, namely; cost to consumer, deliverability and operability, impact on environment, and impact on local communities. These changes may include a change in technology, a change in cable route or length, or a change of interface point.

While the HND is non-binding, deviations from the recommendations may have wider implications for the transmission network and other industry participants and processes. It is important that we understand the full impact of any design changes, as there may be consequences that are not immediately obvious, and the ESO is best placed to conduct this holistic assessment.

A structured approach is needed given there may be multiple impact assessments required, multiple parties may be involved in any one assessment, and the work involved needs to be planned alongside other deliverables for all parties involved. We have therefore, with stakeholder engagement and feedback, developed an impact assessment process. We will run impact assessments every two months which we will endeavour to complete within four to six weeks, although it should be noted that the timeframe for completing an impact assessment could be extended if there is a need to assess multiple options. We will keep the frequency and duration of impact assessments under review and look at adapting the approach if required. We are also engaging with Ofgem and the Energy Department to establish an appropriate governance process across network planning activities, changes to network plans, and wider impacts.

Further to the implementation of the assessment process, we have also shared a "you said, we did" document which provides context on the need for a process, communicates how stakeholder feedback has been taken into account and answers questions regarding various elements of the process. We value the feedback and input received during the development of the process.

Relevant documents 

Impact assessment process

Submission form 

"You said, we did" document

Useful information

A Holistic Network Design for Offshore Wind

On this page you will find Holistic Network Design for Offshore Wind suite of documents that together set out a coordinated approach for connecting 23GW of offshore wind.

Collaborating with stakeholders

We are working in collaboration with stakeholders on this important and fundamental piece of work for the energy industry, consumers, communities and the environment. We have made five commitments to improve our engagement approach.

Our role in connecting offshore wind farms to the grid

Offshore wind farms are a key part of the government’s plans for the UK to be net zero in 2050. We don’t own any of the turbines, or the substations and cables that link them, so what’s our role in connecting them to the grid?