UK Planning Act 2008: Solar NSIP 100MW Threshold Guide
Updated 6 September 2026 · By SolarNevs Research Desk, Dealer surveys + verified sources · 1 source · Method ↗
Key Takeaways
- Codified under the Planning Act 2008 Sections 14 and 15, ground-mounted solar projects exceeding 100 megawatts in England are classified as Nationally Significant Infrastructure Projects.
- The solar NSIP threshold in England was raised from 50 MW to 100 MW with effect from 31 December 2025; projects at or below 100 MW now proceed through the standard planning route.
- Enforces a higher devolved capacity threshold of 3100 megawatts for generating stations located in Wales.
- Mandates that co-located battery energy storage systems (BESS) capacity is completely disregarded in determining if the solar project breaches the 100MW threshold.
- Requires developers of generating stations exceeding threshold limits to obtain a Development Consent Order under Section 31.
- Directs planning jurisdiction from local planning authorities to the Planning Inspectorate and the Secretary of State.
Statutory Purpose of Sections 14, 15, and 31
Enacted under the Planning Act 2008 (c. 29), Part 3 defines Nationally Significant Infrastructure Projects (NSIPs) across energy, transport, and water sectors.
Section 14(1)(a) explicitly includes the construction or extension of a generating station, while Section 15 sets the exact capacity thresholds triggering national planning examinations.
Solar NSIP Classification & Siting Matrix
The consenting route for ground-mounted solar in the UK is governed by precise statutory criteria:
Statutory Parameter | Legislative Provision | Regulatory Consequence for Solar Developers |
|---|---|---|
NSIP Classification | Section 14(1)(a) Construction or extension of a generating station | Categorizes utility-scale energy projects under the primary national planning regime |
England Solar Capacity | Section 15(2) In England, generating from sunlight, >100 megawatts | Replaces local Town and Country Planning applications with the DCO regime |
Wales Devolved Limit | Section 15(3A) In Wales, capacity is more than 3100 megawatts | Retains projects up to 3100MW under Planning and Environment Decisions Wales (PEDW) |
BESS Disregard Rule | Section 15(3C) Capacity provided by facility is to be disregarded | Prevents co-located 49MW solar + 100MW battery schemes from automatic NSIP capture |
Storage Exclusion | Section 15(3D) Not within 14(1)(a) to extent comprising exempt storage | Eliminates standalone BESS from the Nationally Significant Infrastructure regime |
DCO Requirement | Section 31 Development consent is required for NSIP projects | Grants single comprehensive development consent replacing multiple local permits |
Practical Compliance Steps for UK Solar Developers
To structure utility solar projects under Planning Act 2008 provisions:
- Evaluate AC Export Sizing: For sub-NSIP projects targeting local planning approval, ensure total solar generating capacity is engineered at or below 49.9MW AC.
- Separate Co-Located Storage Accounting: Document battery storage capacity independently under Section 15(3C) to demonstrate the battery does not contribute to the 100MW solar threshold.
- Prepare DCO Pre-Application Submissions: If sizing above 100MW in England, initiate formal environmental impact scoping and consultation under the Planning Inspectorate framework.
Frequently asked questions
What capacity threshold classifies an onshore solar farm as an NSIP in England under Section 15(2)?
Under Section 15(2)(aa), an onshore generating station in England generating electricity from wind or directly from sunlight is an NSIP if its capacity is more than 100 megawatts (August 2026).
What is the devolved generating station threshold in Wales under Section 15(3A)?
Under Section 15(3A), a generating station in Wales is within the statutory scope if its capacity is more than 3100 megawatts (August 2026).
How is co-located battery storage (BESS) capacity treated under Section 15(3C)?
Under Section 15(3C), capacity provided by an exempt electricity storage facility is disregarded when determining whether the generating station exceeds the threshold (August 2026).
When is a Development Consent Order required under Section 31?
Under Section 31, consent under this Act (development consent) is required for development to the extent it forms part of a nationally significant infrastructure project (August 2026).
References
- legislation.gov.uk: Planning Act 2008 Section 15 — accessed 31 August 2026
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