Most feasibility analysis on UK commercial rooftops is free — and produced by companies that only earn money if you install. That is not a scandal; it is a business model. But it means the market’s default decision document is written by a party with a direct interest in the decision.
An independent solar feasibility study removes that interest. This article explains what independence actually changes, when it matters most, and how to tell genuinely independent work from installer marketing with a consultancy tone.
What independence changes in practice
The difference is not the template — installer assessments and independent studies can look superficially similar. The difference is in the assumptions and the willingness to conclude no.
- Self-consumption assumptions. The single biggest lever in UK commercial solar economics. Sales-led documents tend toward generous figures; an independent study models against your actual or realistically forecast load, and says so when the data is weak.
- Capex scope. Quotes routinely exclude grid connection costs, structural remediation, or access equipment. An independent study flags these as unknowns with named next steps rather than leaving them off the page.
- Export pricing. Export earns far less per kWh than avoided import. Independent modelling discounts export properly instead of letting it prop up a marginal payback.
- The park verdict. An independent assessor can conclude “do not pursue” without losing anything. On weak roofs, that conclusion is the product.
The structural comparison is covered in feasibility study vs installer quote; if you already hold a proposal, work through how to validate an installer quote.
When independence matters most
Independence carries the most weight at the moments where money is about to be committed on someone else’s numbers:
- Before board or investment committee approval. Governance processes increasingly ask who produced the analysis and what they stood to gain. An independent dossier with sourced workings survives that question.
- Before survey and application spend. Structural surveys, drone flights, and G99 applications cost real money per site. An independent screen stops that spend landing on roofs that were never viable.
- Across a portfolio. Three installer PDFs on the same roof routinely disagree because each optimises its own bill of materials. Portfolio ranking needs one consistent, disinterested baseline — see portfolio solar feasibility screening.
- In landlord–tenant negotiations. When benefit-sharing is on the table, both sides move faster from a number neither side’s contractor produced.
How to test whether a study is genuinely independent
Ask four questions of any feasibility provider:
- Do you sell, design, or install PV systems — or earn referral fees from anyone who does? Any yes compromises the verdict.
- Is your fee the same for a pursue and a park verdict? If income depends on the project proceeding, the incentive is visible in the assumptions.
- Are the workings shown? Every material figure should trace to a formula, an input, and a source — not a black-box model.
- What proportion of your assessments recommend against proceeding? A provider who never says no is not testing anything.
Stage1Energy answers these directly: no installation sales, no referral relationships, a fixed fee either way, sourced workings on every material figure, and a commitment to publish our park rate once we reach ten completed assessments. The methodology page documents the standard each dossier is prepared to.
What an independent study costs — and saves
The full Stage1Energy dossier is £1,250 fixed per site, delivered in five working days. Set that against what it protects: a structural survey, a G99 application, and installer tender time on a roof that fails feasibility can easily exceed the study fee several times over — before counting management attention. Market context is in what a feasibility study costs in the UK.
Start with a free, independent screen
If you want to test the approach before committing to the full solar feasibility study, free screening returns an independent written verdict on one named UK building within three working days — panel placement, monthly generation profile, and a pursue-or-park recommendation. No card, and no one paid to say yes.