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 report 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.
Typical cost bands for UK commercial feasibility
Key numbers
Indicative UK market bands for commercial rooftop feasibility in 2026 - useful for budgeting, not a Stage1Energy quote.
- Independent feasibility report (per site)£825–£2.5k
- Consultant day rates£800–£1.5k+
- Installer-led “feasibility”Often £0, bundled
Independent market reports (£825–£2,500). Across the UK market, a standard commercial rooftop assessment with generation, financial modelling, engineering flags, and a written recommendation usually sits in this band. Single-site work often sits toward the top; higher order volumes can bring the per-site average below £1,000.
Consultant day rates (£800–£1,500+ per day). Engineering and sustainability consultancies often price as time and materials. Totals are less predictable unless scope is tightly defined.
Installer-led “feasibility” (often £0, bundled). Treat as sales support, not independent analysis - see feasibility study vs installer quote.
Stage1Energy path. Assessments open by waiting list - same report standard for one roof or a portfolio. Fees and timing are confirmed when capacity opens. Join the waiting list.
Free full assessment (£0). Stage1Energy offers the complete feasibility report free on one building - verdict, 25-year financials, engineering flags, and sourced workings - within three working days. Try the free assessment.
Stage1Energy paid sites. Additional single sites are a fixed fee at the top of the independent market band, with portfolio rates falling as volume grows. See pricing.
What you should get for the money
Whatever you pay in the independent market band, the report should deliver more than a generation figure on a letterhead.
- Defined scope
Written terms before work starts.
- Yield with assumptions
Feasibility-grade annual generation, method stated.
- Self-consumption split
On-site use versus export made explicit.
- Payback and NPV
Or equivalent metrics the board recognises.
- Engineering screen
Structure, wind, grid, and planning notes.
- Clear verdict
Human review before release - not an automated PDF alone.
Review our example report or what is in a solar feasibility report.
Cost drivers that push fees up or down
- Site complexityFlat single-pitch warehouses are faster than multi-level roofs with plant, skylights, and shading.
- Data qualityHalf-hourly consumption sharpens modelling; benchmarks widen uncertainty.
- Portfolio volumePer-site fees often improve when many assessments are ordered together.
- Site visitsRemote feasibility is standard at this stage; physical survey usually follows a positive verdict.
- Financial depthSimple payback costs less than a 25-year discounted cashflow with sensitivity.
- SpeedPriority turnaround commands a premium - same analytical standard, faster resourcing.
Hidden costs of skipping feasibility
The expensive shortcut
A structural survey on a roof that cannot economically host PV might cost £2,000–£5,000. A G99 application on an export-constrained site absorbs weeks of internal time. An installer quote on a marginal roof creates false momentum before anyone has tested the business case.
An early independent feasibility study is usually cheaper than the mistakes it prevents - surveys, grid applications, and installer tenders on roofs that were never going to clear the hurdle.
How to budget across a portfolio
Sequence spend rather than commissioning full studies on every roof at once. Start with your strongest candidate, then expand only where the first verdict supports it. Park marginal sites until tariff, load, or roof works change the economics. Register interest via the waiting list if you want Stage1Energy to assess one roof or a programme.
For portfolio approaches, see portfolio solar feasibility screening. Timing matters too - when to order a solar feasibility study.
Choosing on value, not price alone
Right question
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 report with transparent methodology is inexpensive insurance.
Compare providers on independence, stated limits, assumptions you can audit, and whether non-specialists can read the output. For the full commercial solar feasibility process, start there - then match scope to where you are in the journey.
Procurement and finance sign-off
A fixed-fee feasibility engagement is easier to route through delegated authority than an open-ended consultant day-rate. Attach the example report to internal requisitions so approvers understand deliverables. When Stage1Energy capacity opens, terms and fee are confirmed in writing before paid work starts - join the waiting list to register interest.
Where external funders require independent analysis, feasibility invoices and reports satisfy due-diligence without triggering full technical advisory mandates. Keep the scope letter and the PDF together in your data room.