When you commission a commercial solar feasibility report, you are buying a structured answer to whether a UK rooftop is worth pursuing — not a folder of disconnected calculations. Providers vary in format, but strong reports share a common architecture: site context, technical screening, financial outcomes, risk flags, and a verdict.
This guide walks through each section so you know what to expect, what to challenge, and what should explicitly be out of scope. For the finished product, review our example report.
Executive summary and verdict
The opening should stand alone. A busy director should read two pages and understand the recommendation: pursue, pursue with conditions, or do not pursue — with the headline numbers that support it.
Expect estimated capacity (kWp), annual generation (kWh), simple payback or IRR, major flags in plain language, and the conditions attached to a “pursue with caution” outcome. If the summary buries the verdict on page thirty, the document is not doing its job.
Stage1Energy dossiers end with a written verdict reviewed before release. That human checkpoint matters when the output feeds a solar investment board paper.
Site overview and roof resource
This section anchors everything to a specific building: address, roof type, approximate area, orientation, pitch, and known obstructions — plant, skylights, edge setbacks, shading from adjacent structures.
Aerial imagery or survey-derived plans should show usable roof zones. The report should state how much area was excluded and why. Vague statements like “large flat roof” without quantified area undermine trust in the generation model.
For portfolio work, consistent site overview formatting across dossiers makes comparison easier — a topic covered in portfolio solar feasibility screening.
Indicative layout and system sizing
Feasibility includes a concept array layout: where panels would sit, approximate module count, and nameplate capacity. This is not detailed design — cable routes, inverter placement, and string configuration come later — but it must be physically plausible.
Good reports explain sizing logic. A roof might accommodate 500 kWp geometrically but only 350 kWp economically because export limits or load profile favour a smaller system. That nuance separates feasibility from maximised sales layouts.
See feasibility vs design for where this section stops and detailed engineering begins.
Generation estimate
Annual kWh yield should be presented with the modelling approach stated — PVGIS, industry-standard simulation tools, or equivalent — plus assumptions on losses, degradation, and shading.
Feasibility-grade generation is a screened estimate. Generation figures have been checked against twelve months of metered output from an operating commercial installation. Read how accurate solar generation estimates are for the right expectations.
Monthly or seasonal profiles are useful when consumption is variable. A warehouse with heavy winter heating may care as much about when energy is produced as how much.
Consumption, self-consumption, and export
Financial viability on commercial rooftops usually hinges on self-consumption. The report should document load data sources: half-hourly meter data, tenant bills, or benchmark estimates — and the split between on-site use and export.
Export revenue is often discounted relative to imported electricity. Reports that assume 100% self-consumption without evidence should be questioned. Sensitivity on export price and load uncertainty strengthens the dossier.
Financial analysis
At minimum, expect capital cost indication (often benchmark £/kWp at feasibility stage unless quotes exist), annual savings, payback period, and preferably NPV or discounted cashflow over 20–25 years.
Assumptions must be visible: electricity tariff, export rate, inflation, degradation, and any available incentives. Hidden assumptions produce board papers that collapse on first scrutiny.
Full dossiers align with the depth shown in our pricing and methodology pages — fixed fee, written scope, no open-ended advisory hours.
Engineering flags
Feasibility does not replace structural calculations, but it should screen for issues that could kill or complicate the project.
Typical flags include roof construction type and age, apparent loading concerns, ballast versus penetration mounting, wind exposure, access for installation and maintenance, and roof condition indicators visible from imagery or records.
These are screening notes — “commission structural survey” rather than “structure approved.” The distinction from a full survey is covered in feasibility vs structural survey.
Grid connection screening
UK commercial systems often hinge on DNO constraints. The report should indicate whether the connection likely falls under G98 or G99, whether export limiting may be needed, and any obvious red flags from available capacity data.
This is not a formal connection offer. It is enough to know whether grid cost and timeline belong in the risk register before you spend on applications.
Planning and permitted development
Most commercial rooftop PV proceeds under permitted development rights, but exceptions exist — listed buildings, conservation areas, Article 4 directions, and some lease structures. Feasibility should flag which route looks probable and what further checks are needed.
Risks, limitations, and next steps
Every credible report states what it is not: not design, not structural certification, not a grid connection agreement. Limitations on data quality — estimated load, ageing roof imagery — should be explicit.
Next steps should be actionable: order structural survey, obtain half-hourly data, initiate G99 enquiry, or do not proceed. Vague “further investigation recommended” without priority wastes the verdict.
What a Stage1Energy dossier delivers
Stage1Energy’s site assessment packages these sections into a board-ready dossier for UK commercial rooftops. Free screening covers a lighter subset when you need a fast filter before committing to the full report.
If you are commissioning elsewhere, use this checklist. If you are preparing to read what you receive, continue to how to read a solar feasibility report.
For the wider process, see what is a commercial solar feasibility study and the commercial solar feasibility hub.