Every serious rooftop PV project in the UK passes through the same early question: is this roof worth pursuing at all? A rooftop solar feasibility study answers that question in writing - with generation modelling, a 25-year financial case, and engineering screening - before anyone climbs a ladder or prices a system.
This guide explains what a rooftop feasibility study covers on UK commercial buildings, how it differs from lighter screening, and how estates teams and landlords use it to control spend.
What a rooftop solar feasibility study tests
A feasibility study on a commercial rooftop answers four questions:
- Generation - how much electricity the roof could plausibly produce, zone by zone, once setbacks, plant, skylights, and shading are excluded.
- Financials - what the 25-year case looks like: capex, payback, NPV, and IRR, driven by how much generation the building consumes on site versus exports.
- Engineering flags - whether wind loading, structural capacity, DNO grid connection (G98/G99), or planning are likely to block or reshape the project.
- Verdict - pursue, pursue with conditions, or park, stated plainly enough for a board paper.
The study is desk-based. It uses aerial imagery, roof plans where available, and your consumption data - half-hourly if you have it. No site visit is needed to reach a screening-level verdict; the study tells you whether the site visit is worth paying for.
For the full scope definition, see what a solar feasibility study is.
Why roof area alone is a poor predictor
UK commercial roofs fail feasibility for reasons satellite imagery does not show. A large warehouse roof with weak daytime load can produce a longer payback than a smaller factory roof with process demand through the day. Export income is typically worth far less per kWh than avoided import, so self-consumption usually decides the case.
Engineering constraints cut the same way. Portal-frame structures near their load limit, asbestos cement decks, constrained DNO export capacity, or a roof due for replacement inside five years can all turn an apparently ideal footprint into a park verdict - or at least a “resolve this first” condition.
A rooftop feasibility study surfaces these constraints while the cost of changing course is still near zero.
Screening first, study second
Most estates teams do not start with the full study. The sensible sequence on UK commercial buildings is:
- Waiting-list assessment - register interest for a written verdict with indicative panel placement and monthly generation on one building.
- Full feasibility study - the complete report on buildings that clear the first pass: 25-year financials, zone-by-zone layout, four engineering flags, and sourced workings.
- Surveys and tenders - structural survey, DNO application, and installer quotes, commissioned only on roofs the study says are worth it.
This sequence protects budget in both directions: weak roofs are parked before survey spend, and strong roofs reach tender with an independent baseline that keeps installer proposals honest. Our guide on when to order a feasibility study covers the timing in more detail.
What the study costs
Stage1Energy’s full rooftop feasibility report is available via the waiting list, delivered in five working days from confirmed inputs once capacity opens - the same standard whether the verdict is pursue or park. See waiting list and our guide to feasibility study cost in the UK for what drives price across the market.
Because the fee does not depend on the outcome, the incentive sits with the decision, not the sale. That is the practical difference between an independent study and the free preliminary assessments offered by installers - explored further in feasibility study vs installer quote.
Who commissions rooftop feasibility studies
- Estates and facilities teams building an internal capex case for one building or a shortlist.
- Commercial landlords and asset managers ranking roofs across a portfolio before committing survey spend.
- Owner-occupiers testing whether their warehouse, factory, or depot clears the hurdle rate.
- Consultants and advisers who need a sourced, defensible number for a client recommendation.
Building-type specifics differ - see the use-case guides for warehouses, factories, and landlord portfolios.
Start with one roof
The fastest way to test the approach is to name a building. Join the waiting list to register interest for a written verdict with panel placement and monthly generation. When capacity opens, terms are confirmed in writing before work starts.