NESO outlines new timelines for Strategic Energy Plans

Strategic planning 5 Dec 2025 - 3 minute read
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Delivering the joined up, strategic energy planning Great Britain needs to enable economic growth and pave the way to a sustainable energy future.

The National Energy System Operator (NESO) is reaffirming its commitment to delivering the joined up, strategic energy planning needed for Great Britain to support economic growth, deliver a secure energy system and pave the way to a sustainable energy future. 

Robust, credible, and transparent data underpins every aspect of our work. This approach gives stakeholders, investors, and government the confidence that our plans are built on the most up to date and reliable information. 

The Strategic Spatial Energy Plan (SSEP) will chart the course of investment in Great Britain’s energy transition for the next 25 years and represents a fundamental shift in how we plan our energy systems.

Following the publication of our open letter to industry on 20 November 2025, NESO has worked closely with partners, including the Department for Energy Security and Net Zero (DESNZ) and Ofgem, to assess the impact of refreshed energy generation cost data on our delivery timelines. This new data, released by DESNZ, is a significant step forward in transparency, enabling all stakeholders to see and understand the key inputs shaping national energy planning.

To ensure the SSEP is as robust and resilient as possible, NESO and DESNZ have decided to re-run the SSEP modelling using the latest data (DESNZ letter to NESO on extending the SSEP timeline to integrate updated data).  As a result, the final SSEP will now be delivered in Autumn 2027, with pathway options submitted for decision by the Secretary of State for Energy Security and Net Zero in summer 2026.

The Centralised Strategic Network Plan (CSNP) and Regional Energy Strategic Plans (RESPs) will draw on the most robust and up to date SSEP outputs, ensuring that NESO’s analysis and recommendations are based on the most credible and current information. Delivery of the CSNP and RESPs is now planned by the end of 2028, dependent on the Secretary of State’s decision on the SSEP pathway.

In addition, following agreement with Ofgem (Ofgem direction to NESO on network options assessment), NESO can confirm that the refresh of the second Transitional Centralised Strategic Network Plan will be delivered by 30 June 2026. Publishing in the summer allows us to incorporate the new connections delivery pipeline, ensuring that we design the future network based on projects that will be progressing rather than those that will be deprioritised. It will also provide insight to Ofgem’s funding decisions for network requirements ahead of the first SSEP and CSNP. 

Julian Leslie, Director of Strategic Energy Planning said:

“NESO remains committed to ongoing engagement and openness throughout this process. By working collaboratively with partners and stakeholders, NESO is setting a global standard for strategic energy planning ensuring Great Britain’s future energy system is clean, reliable, and delivers value for all."

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