Purpose of this guidance note
This guidance sets out the stance taken by our ecology team, acknowledging recent discussions and research findings in the industry, and anticipating the publication of further guidance by Natural England and UKHab, on the treatment of land occupied by solar arrays within the Statutory Biodiversity Metric.
Latest industry discussions and published guidance
A paper was presented at the CIEEM conference in November 2025, based on research into habitats directly beneath solar panel arrays (Clarkson Woods, unpublished). This note will be updated with links to further guidance when it is published.
View from the planning ecology team
Our position on post-development habitats in the Biodiversity Metric under and around solar arrays is set out below.
The UKHab system was designed for baseline mapping and its use in the BNG Metric should be used advisedly. Land beneath ground-mounted solar arrays can in some situations sustain a habitat that contributes to the post development biodiversity value but will face physical limits on the type and condition it can reliably achieve.
We will accept the following for quantifying post-development habitat mapping of solar schemes:
- for areas occupied by blocks of solar arrays, we will accept Modified Grassland (poor) in a ratio of 90% grassland to 10% built structure, applied to the whole block. This consists of the panels themselves over grass and the intervening grass access strips treated as a block. The 10% reduction allows for the built footprint occupied by supporting structures and footings.
- we encourage proposals to make full use of the peripheral areas of the solar development that are not occupied by the arrays. These areas may achieve a higher distinctiveness habitat, a higher condition or both, dependent on the proposed habitat creation or enhancement. These must be justified appropriately in the proposals.
We also note that the CIEEM/CIRIA/IEMA Good Practice Principles for BNG encourage solar developers to enhance biodiversity through off-panel areas, buffer zones, and targeted habitat creation, rather than relying on under-panel areas to deliver net gain. You can read the guidance here.
Rationale
While we recognise that vegetation may persist beneath ground-mounted solar panels, if installed at a suitable height above the ground, various physical factors place limitations on the target habitat that may be achieved and a realistic target condition. This includes shading cast by the panels, the height of the panels above ground level, rain shadow and altered microclimates, ground area lost to footings or supporting structures for the arrays, compaction during construction and maintenance affecting habitat condition, and restricted access for favourable conservation management or grazing.
The Statutory Biodiversity Metric User Guide confirms that habitat classification must reflect the realistic potential to achieve and maintain condition targets, not just the presence of vegetation. The classification should not be based solely on vegetation cover but on the functional ecological value and management constraints imposed on that habitat by the infrastructure.
In line with the national guidance, informed by scientific research on existing solar installations, we conclude that G4 (poor) is a realistic and achievable target. If the ground under the panels is to be managed with the use of herbicides, a bare ground category may be more appropriate. The proposed management of the habitat will be taken into consideration.
The performance of habitats under and around ground-mounted solar arrays is an area where future research and survey evidence will inform the industry. We will review our guidance periodically if there are important findings on the classification of land and mitigation for species such as ground-nesting birds.
Additional information
UK Habitat classification documents
Statutory biodiversity metric tools and guides
Clarkson Woods, unpublished
Solar Energy UK (SEUK) Natural Capital best practice guidance