Budget holders often ask for a single number when scoping commercial solar work. In practice, “feasibility” covers everything from a one-page email opinion to a 40-page dossier with a 25-year financial model. The cost depends on which end of that spectrum you need — and whether the provider has an incentive to tell you what you want to hear.
This guide sets out typical UK pricing bands, what drives cost, and how to avoid paying for the wrong depth of work at the wrong time.
Typical cost bands for UK commercial feasibility
Free or nominal screening (£0–£250). Some providers offer a rapid verdict: viable, marginal, or not viable, based on limited inputs. This is useful for filtering a long list of roofs before deeper spend. Stage1Energy’s free screening sits here — a written verdict in three working days, not a substitute for a full dossier.
Fixed-fee feasibility dossier (£1,000–£2,500 per site). A standard commercial rooftop assessment with feasibility-grade generation, financial modelling, engineering flags, and a written recommendation. Stage1Energy charges £1,250 per site for delivery in five working days, with priority delivery at £1,750. Fixed fees suit estates teams who need predictable costs across multiple addresses.
Consultant day rates (£800–£1,500+ per day). Engineering and sustainability consultancies often price feasibility as time and materials. A straightforward warehouse might take two days; a complex multi-roof campus can run longer. Totals are less predictable unless scope is tightly defined.
Installer-led “feasibility” (often £0, bundled). Many installers provide free preliminary assessments ahead of a quote. The work can be thorough, but the commercial model ties it to winning the installation contract. Treat it as sales support, not independent analysis — see feasibility study vs installer quote.
Bespoke portfolio or advisory work (£5,000+). Strategy reviews, tariff optimisation across a fleet, or investment-grade modelling for fund managers sit outside standard per-site feasibility and are priced accordingly.
What you should get for the money
A paid feasibility study at the £1,000–£2,500 level should deliver more than a generation figure on a letterhead.
Expect a defined scope in writing, feasibility-grade annual yield with stated assumptions, self-consumption and export split, payback and NPV or equivalent metrics, screening notes on structure, wind, grid, and planning, and a clear verdict. Human review before release is a reasonable minimum — automated PDFs without oversight are difficult to defend in a board paper.
Review our example report to see how a complete dossier is structured, or read what is in a solar feasibility report for a section-by-section checklist.
Cost drivers that push fees up or down
Site complexity. Flat single-pitch warehouses are faster to assess than multi-level roofs with plant, skylights, and shading from adjacent buildings.
Data quality. Half-hourly consumption data sharpens self-consumption modelling. Estimated load from benchmarks is acceptable at feasibility stage but may widen financial uncertainty.
Portfolio volume. Per-site fees often improve when many assessments are ordered together, though delivery may be scheduled in batches.
Site visits. Remote feasibility using aerial imagery and plans is standard for rooftop PV at this stage. Adding a physical survey increases cost and is usually deferred until after a positive feasibility verdict.
Depth of financial modelling. A simple payback calculation costs less than a 25-year discounted cashflow with sensitivity analysis. Full dossiers typically include the latter.
Speed. Priority turnaround commands a premium. Stage1Energy’s two-working-day option reflects resourcing, not a different analytical standard.
Hidden costs of skipping feasibility
The cheapest feasibility is not always the one with the lowest invoice. Skipping independent assessment and moving straight to structural surveys, DNO applications, or installer quotes can waste far more.
A structural survey on a roof that cannot economically host PV might cost £2,000–£5,000. A G99 application pursued on a site where export is constrained can absorb weeks of internal time. An installer quote on a marginal roof creates false momentum — teams invest in negotiations before anyone has tested the business case.
Feasibility at £1,250 per site is deliberately priced to be cheaper than the mistakes it prevents.
How to budget across a portfolio
If you manage multiple commercial properties, sequence spend rather than commissioning full studies on every roof at once.
Start with free screening or a light filter on basic criteria: roof area, ownership, lease length, and coarse consumption fit. Advance the strongest candidates to full feasibility. Park marginal sites until tariff, load, or roof works change the economics.
For portfolio approaches, see portfolio solar feasibility screening. Timing matters too — when to order a solar feasibility study covers common trigger points in the year.
Choosing on value, not price alone
The right question is not “what is the cheapest feasibility?” but “what decision does this fee unlock?” If the answer is authorising £50,000 of surveys across five sites, a fixed-fee dossier with transparent methodology is inexpensive insurance.
Compare providers on independence, stated limits of the work, assumptions you can audit, and whether the output is readable by a non-specialist audience. A well-written £1,250 dossier often outperforms a fragmented consultant pack at twice the price.
For an overview of the full commercial solar feasibility process and how Stage1Energy delivers it, start there — then match the fee tier to where you are in the journey.
Procurement and finance sign-off
Facilities and estates teams often need finance approval for feasibility spend before board approval for install spend. A fixed-fee quote at £1,250 per site is easier to route through delegated authority than an open-ended consultant engagement. Attach the example report to internal requisitions so approvers understand deliverables.
Where external funders or joint-venture partners require independent analysis, feasibility invoices and dossiers also satisfy due-diligence requests without triggering full technical advisory mandates. Keep the scope letter and the PDF together in your data room — auditors and asset managers will ask for both.