Most commercial solar projects stall because someone skipped the boring desk work. An installer visit, a structural engineer’s day rate, or a DNO application fee gets committed before anyone has tested whether the roof, load profile, and lease structure can actually support a viable system.
This checklist is designed for estates teams, asset managers, and advisers who need a repeatable process — one building or thirty. It is not a substitute for a formal commercial solar feasibility study, but it tells you when that study is worth ordering and what to have ready when you do.
1. Pre-commission checks
Before you spend on feasibility, surveys, or quotes, confirm the basics:
- Ownership or consent — Do you own the roof, or does the lease allow alterations and who benefits from export revenue?
- Roof access — Can you obtain plans, as-built drawings, or at least a measured aerial view?
- Consumption data — Do you have annual kWh, half-hourly data, or a credible estimate of daytime load?
- Strategic fit — Is solar aligned with capex policy, ESG reporting, or a net-zero pathway you must defend?
- Budget realism — Have you separated feasibility cost (£1,250 per site at Stage1Energy) from later survey, design, and install spend?
If you cannot answer items 1–3, start with free screening on one building. It needs only an address and replies within three working days with a verdict, panel placement, and monthly generation profile.
2. Data to gather
A strong feasibility study runs on good inputs. Collect what you can before commissioning:
| Input | Why it matters | Minimum acceptable |
|---|---|---|
| Site address and building type | Roof geometry, planning context | Full postal address |
| Roof area and type | Usable PV area, loading assumptions | Coarse m² and flat/pitched/mixed |
| Electricity consumption | Self-consumption economics | Annual kWh or half-hourly CSV |
| Grid connection | DNO route (G98/G99) | MPAN, fuse rating if known |
| Lease terms | Revenue sharing, reinstatement | Summary of roof rights |
| Existing roof condition | Structural follow-up risk | Age, known defects, recent reports |
You do not need a site visit to start. Remote feasibility using aerial imagery and consumption data is standard at this stage. See what is in a feasibility report for how inputs become outputs.
3. Questions to ask installers (before you trust a quote)
Installer quotes are sales documents. Before treating a payback figure as independent, ask:
- What roof area did you assume? Net usable area after setbacks should be stated, not gross footprint.
- What self-consumption ratio did you use? Export-heavy sites look worse than load-matched ones.
- What tariff assumptions? Import rate, export rate, and escalation should be explicit.
- What is excluded? Structural certification, DNO fees, scaffolding, and monitoring are often absent.
- Who owns the performance risk? Indicative generation is not a guarantee unless contractually backed.
A feasibility study versus installer quote explains why independent analysis sits upstream of procurement. If the installer cannot answer these questions in writing, order feasibility first.
4. Red flags — pause before spending more
Stop and get independent screening if any of the following appear without evidence:
- Payback under five years with no consumption data cited
- “No planning needed” on a tall building in a conservation area
- Structural clearance assumed without roof type or age
- G99 grid connection treated as automatic on a constrained estate
- Portfolio ranking based on roof size alone, ignoring load and lease
Stage1Energy flags four engineering categories in every dossier: wind, structure, DNO, and planning. Free screening does not include full flags, but a pursue-or-park verdict tells you whether deeper work is justified.
5. When to escalate to a full feasibility study
Move from checklist (or free screening) to a full 29-page dossier when:
- A board or investment committee needs a sourced business case
- Capex approval requires payback, NPV, and IRR on documented assumptions
- Multiple stakeholders need a single independent document, not installer slides
- You are comparing more than one site and need consistent methodology
- Engineering or planning risk could change the pursue-or-park answer
The full study costs £1,250 per site and delivers in five working days, with every material figure traced to its source. See example report and pricing before you book.
6. Portfolio owners — adapt the checklist
For landlords and REITs with many assets, run the checklist as a filter, not a per-building marathon:
- Apply ownership, lease, and coarse roof filters across the register
- Screen the shortlist for generation potential
- Commission full feasibility on the top five to ten sites, not every address at once
This sequencing keeps feasibility spend on roofs that can actually deliver.
Bringing it together
A commercial solar feasibility checklist does not need to be a formal document. It needs to be a habit: verify rights and data, challenge installer assumptions, spot red flags early, and escalate to independent feasibility when the financial or governance stakes justify it.
Next step: Screen one building free — verdict, placement, and monthly generation within three working days. No card required.