Managing archaeological risk on larger-scale solar projects

Archaeology and solar arrays

Solar arrays are now a familiar part of the UK’s renewable energy landscape, helping to support the transition to low-carbon power. While they are often less archaeologically intrusive than many other forms of development, they can still affect archaeological remains, particularly where works involve ground disturbance across large areas of land.

Why does archaeology matter for these projects?

These types of projects differ from many traditional developments, as much of a solar scheme consists of solar panels mounted on frames, usually supported by narrow steel posts driven into the ground. These supports typically affect only a small proportion of the overall site area, meaning that the archaeological impact across panel areas may be relatively limited in many cases.

However, not all parts of a designated area for solar arrays have the same level of impact. Cable trenches, access tracks, substations, transformers, battery storage, drainage features, landscaping and construction compounds can involve more substantial groundworks. These elements have a greater potential to remove or truncate buried archaeological remains and therefore often require closer assessment.

This means that archaeological risk on solar projects is rarely uniform. Some areas may involve very limited ground disturbance, while others may be more sensitive because of either the nature of the proposed works or the archaeology present.

How is archaeological potential assessed?

Archaeological work should be considered from the outset of a solar project. In most cases, this begins with a desk-based assessment, bringing together existing information about the site and its surrounding landscape to understand whether archaeological remains may be present and how significant they could be. This is often supported by a site walkover, which can help identify visible features, historic landscape elements or signs of previous disturbance that may influence the approach to further assessment.

For solar projects, non-intrusive survey is often particularly useful because of the size of the sites involved. Geophysical survey can cover large areas efficiently and may identify buried features such as ditches, enclosures, settlement remains or former field systems.

Where more certainty is required, trial trenching may be needed to confirm the presence, character, depth, date and preservation of archaeological remains. This is especially important where proposed infrastructure is fixed, where ground disturbance will be more substantial, or where non-intrusive survey results are unclear.

When is archaeological work undertaken?

Solar projects often retain a degree of design flexibility, particularly in relation to the layout of panels, cable routes, access tracks and ancillary infrastructure. Where enough information has been provided to support the planning decision, some archaeological evaluation or mitigation may be secured by planning condition and undertaken after consent.  

However, this will depend on the circumstances of the site. Where there is a high likelihood of significant archaeology, where key infrastructure cannot be moved, or where the available information is not sufficient to understand the likely impact, further archaeological evaluation may be required before determination.

Early engagement with the local planning authority’s archaeological adviser is therefore important. It helps establish what information is needed, when fieldwork should take place, and whether any post-consent approach is likely to be acceptable.

How can impacts be managed?

The preferred approach is to avoid harm where possible. On solar projects this can often be achieved through design changes, such as moving higher-impact infrastructure away from archaeologically sensitive areas or preserving remains within open grassland.

The impact of solar arrays depends on both the nature of the archaeology and the level of ground disturbance proposed. While panel supports may have a limited effect on many below-ground remains, more sensitive archaeology – such as burials, structural remains, waterlogged deposits or fragile layers – may need to be avoided through careful layout design or protected through alternative construction methods.

Where avoidance is not possible, archaeological excavation, recording, reporting and archiving may be required before construction works take place.

What does this mean for developers?

The presence of archaeology does not necessarily prevent a solar array project. With early advice, proportionate assessment and a flexible approach to design, archaeological risk can usually be managed effectively.

The key is to build archaeology into the project from the outset. Understanding where ground disturbance will occur, identifying areas of archaeological sensitivity, and agreeing an appropriate strategy with the relevant archaeological adviser can help avoid unnecessary delay later in the programme.

Handled well, archaeology can support the delivery of renewable energy schemes while protecting sensitive archaeological remains.

Further information

Contact Philip Evans

For more information about the role of archaeology within planning and development, visit our earlier blogs:

• Archaeology and the planning process
• What is predetermination archaeology?
• Archaeological planning conditions explained
• Archaeological Written Schemes of Investigation: an explanation
• Demystifying the Treasure Act
• Types of archaeological fieldwork investigations
• Archaeological burials and their potential impact on new development
• Archaeology and the planning process: the role of desk-based assessments during a development