Solar, Archaeology and Proportionality: Finding the Right Balance Comments on the new CIfA guidance

There’s been a noticeable shift in how archaeological evaluation is being approached on large-scale solar schemes, and, from both a delivery and technical perspective, it feels like a step in the right direction. From our perspective, this is a much-needed and somewhat overdue corrective and, crucially, has the potential to be relevant in more than just solar schemes.

In a welcome turn of events for practitioners and clients, the recently published CIfA guidance, ‘Archaeology and Solar Farms: Good Practice Guide’, clearly and unambiguously advocates for a more iterative, evidence-based approach to trial trenching. We have experienced a marked increase in county archaeologists requiring pre-determination evaluation over the last few years, and so much of this reflects the challenges we regularly see, particularly around proportionality, programme pressure, and cost.

At its core, the guidance acknowledges something that is often overlooked: the below-ground impact of solar development is not uniform. While elements such as substations, cable routes, and drainage works can have a significant footprint, panel arrays are typically low-impact and relatively dispersed.

So, it raises a simple but important question:
Should we be applying the same level of archaeological investigation across an entire site?

The answer, increasingly, appears to be no.

Instead, this new professional guidance demonstrates a clear push toward targeted, evidence-led evaluation, using non-intrusive techniques like geophysics to guide where (and whether) intrusive works are actually needed. Trial trenching, in this context, becomes a tool to answer specific questions, rather than a blanket requirement.

From a commercial perspective, this is significant. Large-scale, untargeted trenching:

  • can introduce unnecessary cost
  • create programme risk at a critical stage
  • and, in some cases, provide limited additional value

Which leads to a practical consideration:
Are we designing evaluation strategies that genuinely inform decision-making, or simply following a standard process?

There is also increasing recognition that trial trenching itself is not without impact. In some cases, it can result in greater ground disturbance than the development it is assessing.

That brings in a wider point:
How do we balance archaeological investigation with the sustainability objectives that underpin many solar schemes?


If developments are being promoted on environmental grounds, it seems reasonable that the approach to enabling works should reflect that.

One of the more pragmatic aspects of the guidance is its support for post-determination approaches, where appropriate. Securing archaeological work by condition allows for:

  • earlier planning decisions
  • reduced upfront cost exposure
  • and more flexibility to target mitigation once impacts are clearly defined

From our experience, this can be a more efficient route, provided there is early and constructive engagement with the county archaeologist.

That said, it does raise an important question:
How comfortable and confident will stakeholders be in moving away from pre-determination trenching as a default position?

Another area likely to prompt discussion is the suggestion that, in some circumstances, solar arrays could be installed over archaeological remains, particularly where their significance is low and future understanding wouldn’t be compromised.

This challenges a long-standing assumption around preservation in situ and opens up a more nuanced conversation:
Is there scope for a more flexible approach, particularly for lower significance assets?

A practical shift

From our perspective, this guidance does not introduce a radical new methodology – indeed, perhaps it reflects the approach that was always intended by policy – but it does help articulate a more balanced approach that many in the sector are already working towards.

It reinforces the idea that archaeological mitigation should be:

  • proportionate
  • evidence-led
  • and aligned with actual development impact

For clients, this presents an opportunity to:

  • reduce unnecessary upfront costs
  • improve programme certainty
  • and ensure that archaeological work is targeted where it adds genuine value

It will be interesting to see how this guidance is applied in practice by county and local authority archaeologists, now that it has been formally published. It provides a strong framework for a more balanced and commercially realistic approach, and should help support more consistent and effective discussions between developers, consultants and local authority archaeologists. 

As a final thought, as archaeological consultants, we can see the potential value in extending this pragmatic approach to other development sectors where archaeology is affected, and we shall certainly be continuing to advocate for this pragmatism across sectors for our clients.

For further advice on the new CIfA guidance, please contact tor&co.
enquiries@torandco.com

Dervla Rooney BA MCIfA
Associate Director
Heritage

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