The short answer
The UK has hundreds of commercial solar installers; the shortlist that matters is MCS-certified, properly insured, has installed systems of your size in your sector, and puts O&M terms in writing. These are the checks we run on any installer before we introduce them to a business.
Choosing the installer is where businesses most often lose money on solar — not on the panels themselves. The kit is largely commoditised; the difference between a four-year payback and a project that disappoints comes down to design quality, honest yield estimates, and whether anyone is still answering the phone in year three. This page sets out what to look for, explains the certifications that get thrown around, and is upfront about how we make money — because that transparency is the point.
What separates good commercial installers
These are the six checks we run on any installer before we introduce them. None of them is exotic; together they filter out most of the firms that cause problems. Use the same list yourself even if you never use our service.
| # | Criterion | What we check |
|---|---|---|
| 1 | MCS certification | A current MCS certificate covering solar PV. This underpins consumer protection and is often required for grid and incentive paperwork. |
| 2 | Consumer-code membership | Membership of a recognised consumer code such as RECC, which backs the workmanship and deposit-protection promises with a route to redress. |
| 3 | Adequate insurance | Public liability and professional indemnity cover appropriate to working at height on commercial roofs, plus a workmanship warranty. Ask to see current certificates rather than taking it on trust. |
| 4 | Size and sector track record | Completed installations at roughly your system size and in your sector — a firm that fits domestic roofs is not the right team for a 250 kWp warehouse array. |
| 5 | Written O&M terms | Operations-and-maintenance terms set out in writing: response times, what is covered, and what monitoring is included after commissioning. |
| 6 | Transparent quoting | Quotes that state kWp, a P50 yield figure, degradation, inverter warranty and who handles the DNO application — not just a headline price. |
Criteria 5 and 6 are the ones cheaper operators skip, because they are where corners get cut. A quote with no P50 yield and no O&M terms is not a bargain; it is an unanswered question. Our guide to comparing commercial solar quotes turns criterion 6 into a line-by-line checklist.
MCS, RECC, and what certifications actually cover
The two names you will see most are MCS and RECC, and they do different jobs:
- MCS (Microgeneration Certification Scheme) certifies that the installer and the products meet a defined technical standard. It is the baseline competence signal and is frequently a precondition for grid and incentive paperwork.
- RECC (Renewable Energy Consumer Code) is a consumer-protection code. It governs how the installer sells and contracts — deposit protection, clear cancellation rights, and an independent route if something goes wrong.
Neither is a guarantee on its own, and neither tells you whether the firm has done a job your size before. Treat them as the floor, not the ceiling: a good installer clears both and then proves the size, sector and O&M criteria on top.
Questions to ask before signing
Before you commit, put these to any installer and listen for straight answers:
- What is the predicted first-year yield in kWh, and is it a P50 figure?
- Which panels and inverters, and what are the product and performance warranties?
- Who applies to the DNO for the G99 connection, and who carries the risk if it is refused or limited?
- What does your operations-and-maintenance contract include, and for how long?
- Can I see two reference installations of similar size in my sector?
The quote-comparison checklist expands every one of these into something you can score like-for-like across three quotes.
How introductions work
How we make money — plainly
If we introduce you to an installer, the installer pays us when that introduction becomes a booked survey. You pay nothing, and our checks are published. We do not run pay-to-play listings: an installer cannot pay to be recommended, and paying more buys no preference. We would rather tell a business we have no match than send it to an installer that does not fit — a mismatch helps nobody.
The funnel is simple. You run the free roof assessment and get your indicative numbers. If the figures stack up and your site qualifies, we tell you whether we can introduce you to an installer in your area for a free site survey — not a sales call. You are under no obligation at any point, and because the assessment is independent of the installer, the numbers you start from are a neutral baseline rather than a pitch.
Find installers by region
Each regional guide covers the local context — grid operator, typical yield and any live local support. Pick your area:
Find installers by region
Red flags to walk away from
A few behaviours reliably signal an installer to avoid. Treat any of these as a reason to stop and get other quotes:
- Door-knock and high-pressure tactics — a genuine commercial installer does not cold-call you into signing on the day.
- "Free" with no contract to read — "free solar" usually means a funded Power Purchase Agreement, which is a 15–20-year commitment. If there is no contract setting out the rate and term, walk away. We explain how these deals really work on our commercial solar financing guide.
- No P50 yield in the quote — a headline kWh figure with no P50 basis is an optimistic guess you cannot hold them to.
- No O&M terms and no references — if they will not put maintenance in writing or show you a comparable job, assume the worst.
Frequently asked questions
How do I check an installer is MCS certified?+
Ask for the company's MCS certificate number, then look it up free on the MCS certified installer database at mcscertified.com. Confirm the certification covers solar PV specifically and is current, not lapsed. A genuine installer will give you the number without hesitation; reluctance to share it is itself a warning sign worth acting on.
Should I get multiple quotes for commercial solar?+
Yes — get at least three. Quotes for the same roof routinely differ by 30–40% on price and far more on quality, so a single quote gives you nothing to judge it against. Compare them on cost per kWp and projected payback, not headline price. Our quote-comparison checklist sets out exactly what each quote should contain.
Do you charge businesses to use Business Solar Check?+
No. The assessment is free to your business, with no obligation. If we introduce you to an installer, the installer pays us when that introduction becomes a booked site survey, not you. That keeps our advice on your side of the table: we have no reason to push you toward a sale, only toward a roof that genuinely stacks up.
How would you check an installer before introducing them?+
Against six published criteria: MCS certification for solar PV, a consumer-code membership such as RECC, adequate insurance, a track record at your system size and in your sector, written operations-and-maintenance terms, and transparent quoting including a P50 yield figure. We do not run pay-to-play listings, so no installer can pay to be recommended.
Can you introduce me to an installer in my area?+
We can't promise it yet: we are still signing up installers. You can still run the free roof assessment to get your numbers, and we will tell you honestly whether we can introduce you to an installer rather than passing you to whoever is nearest.
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Updated June 2026 · By Taro Schenker, founder of Business Solar Check. We're independent — we don't install solar. Figures are indicative UK averages; your site survey confirms the numbers for your roof.