Powering a site the grid cannot reach

The client was progressing a development on a remote upland UK site through a national planning route, rather than through the local planning authority. The accommodation, office and welfare buildings on the site needed to be powered independently of the main supply, and the client required a feasibility note to support the renewables and sustainability section of its pre-application submission.

The brief was specific. Arc was asked for an attachment-ready note that established a credible renewable solution existed and could be sized within the site, not a detailed engineering report or a multi-scenario cost analysis. Matching the depth of the output to its stated purpose was the central discipline of the engagement.

The site is upland, exposed and remote, on terrain where the access road is single-track and liable to closure in heavy snowfall. The buildings in scope are separated from the main supply for operational reasons, so the renewable system carries a resilience requirement as well as an energy one: it has to hold power through a multi-day interruption.

A binding spatial constraint shaped the whole assessment. All renewable capacity had to sit within the operator-controlled footprint, with no use of the surrounding common land and no land swaps. That ruled the available siting down to level platforms and suitable south-facing aspects within the site boundary.

Arc reviewed the technologies relevant to an exposed upland site of this character. Rooftop solar was excluded on confirmed operational safety grounds. Wind was excluded for operational security reasons. Geothermal was excluded by the site geology, where underlying limestone caverns and aquifers preclude ground loops and deep wells without unacceptable hydrogeological risk.

That left a single credible route: ground-mount solar PV, paired with battery storage sized against a 48-hour winter autonomy target, and supported by an appropriately sized backup generator. The 48-hour autonomy target, not the energy yield, is the binding design constraint for this site.

Arc set out three system architectures so the client could see the trade-off between solar, storage and generator runtime, rather than committing to a single design before the load was confirmed. Each was presented as a capacity range, not a point estimate, and without capital, operating or payback figures, which would have overstated the certainty available at this stage.

The result is a concise, branded feasibility note that does exactly what the client needed: it establishes, on the evidence available, that a credible off-grid renewable solution exists for the site and can be accommodated within the controlled footprint. It is sufficient to support the renewables and sustainability section of the pre-application submission, and it is explicit that it is not a basis for procurement or detailed design.

Every figure is framed as an order-of-magnitude estimate, with the open variables, the heating strategy and the confirmed operational load, identified plainly. From there, Arc set out a defined next stage: a confirmed load assessment, a modelled yield study, an annotated siting overlay, and indicative cost for the selected architecture. Matching output depth to the client's stated purpose, and giving a clear path to the next commercial stage, was what made the note useful rather than merely thorough.

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