Timing a commercial solar feasibility study well saves more money than choosing the cheapest provider. Order too soon, before basic eligibility is clear, and you pay for analysis on sites that fail on lease length or ownership alone. Order too late, after surveys and quotes are in flight, and feasibility becomes an expensive retrospective - too late to stop spend that should never have started.
This guide sets out practical trigger points for UK estates teams, asset managers, developers, and consultants.
Clear signals that feasibility is due now
You have a specific roof and a mandate to investigate. Someone with authority has asked whether solar is viable on a named building - not whether solar is “a good idea in general.” That shift from interest to address is the usual starting gun.
You are preparing a business case or board paper. Investment committees expect feasibility-grade yield, payback, capital cost, and risk flags in one place. A feasibility report is built for that audience - see solar investment board paper for what to include.
You are comparing multiple sites. When three warehouses are candidates but only one will be funded this year, feasibility gives you a consistent basis for ranking. Portfolio screening narrows the list first; full studies confirm the leaders.
An installer has expressed interest but you need independence. Installer preliminary assessments are useful but commercially aligned. Independent feasibility before quote comparison stops you negotiating on unequal assumptions.
Roof works or a lease event is approaching. Refurbishment, re-roofing, or lease renewal are natural moments to test PV integration. Feasibility should inform the capital programme, not follow it.
A net-zero or ESG target has a property-level delivery plan. Portfolio-level ambition needs site-level evidence. Feasibility translates group targets into pursuable projects.
When to use an early screen instead
Not every enquiry needs a full board-ready report on day one. Join the waiting list when you have a single site and need a clear first filter: roughly viable, marginal, or not viable.
Use an early screen when the question is “should we pursue a full assessment?” rather than “we are ready to put this in front of the board.” When that first pass is positive, advance to the full site assessment.
Early screening also suits portfolio triage - many addresses, limited certainty on roof area or consumption. Learn more in portfolio solar feasibility screening.
When feasibility is premature
Hold off on a full study if fundamental blockers are unresolved.
Lease length or landlord consent is shorter than payback without a clear path to extension. Feasibility can note the issue, but fixing the lease is often the real work.
Roof replacement is imminent but scope is undefined. Wait until you know whether the deck will be renewed, insulation upgraded, or plant moved - all of which change mounting approach and cost.
You lack any consumption data and cannot estimate load even roughly. Feasibility can use benchmarks, but wildly wrong load assumptions produce misleading self-consumption figures. A quick data request to facilities may be faster than a full report.
The building may be sold or vacated within two years. Strategic context should settle before technical spend.
In these cases, resolve the blocker or accept wider uncertainty explicitly before commissioning work.
When feasibility is overdue
Several patterns suggest teams have already passed the ideal ordering point.
Quotes from multiple installers are on your desk but no one document states common assumptions. Surveys are booked before anyone has tested payback. A DNO application is in progress on a roof with unknown structural capacity. The board asked for “options” and received marketing brochures.
If any of this sounds familiar, order feasibility before the next pound goes on professional fees. The commercial solar feasibility process is designed to precede - not follow - detailed design and procurement.
Feasibility in the wider project timeline
A sensible UK commercial rooftop sequence looks like this:
- Screen - light filter on eligibility and coarse economics.
- Feasibility - full report with financial model, flags, and verdict.
- Confirm - structural survey, roof condition report, detailed grid enquiry where flags warrant it.
- Design and procure - installer selection, detailed design, contract.
- Build and commission - construction, handover, performance monitoring.
Feasibility belongs at step two. It is explicitly not a substitute for step three - a distinction we cover in feasibility vs structural survey and feasibility vs design.
Seasonal and organisational timing
There is no wrong month to order feasibility, but organisational rhythms matter. Many estates teams align solar business cases with capital budget rounds in Q3 or Q4 for the following financial year. Ordering feasibility six to eight weeks before that deadline leaves time for board review and, if positive, survey quotes in the new year’s programme.
Year-end pressure can also produce rushed decisions without feasibility. Building the study into the annual property review cycle - one feasibility per major site per year where solar remains a strategic option - prevents reactive scrambling.
For current market and policy context that may affect timing, see commercial solar feasibility in 2026. Welsh public-sector bodies working to the 2030 net-zero ambition should also see UK energy compliance deadlines.
What to do next
If you have a named UK commercial rooftop, a decision to make, and no independent analysis yet, you are probably ready. Start with waiting list if you want a fast filter, or book a full assessment at join the waiting list when you need the complete report.
Review the example report and our methodology first if you need to brief colleagues on what they will receive. The right time to order is when feasibility can still change what happens next - not after the contracts are signed.