Most firms that fit domestic solar are not set up for a commercial roof, and the difference is not the panels. It is the structural work, the network application, the health and safety regime on an occupied building and the ability to carry a warranty for twenty five years. Checking those four things takes an afternoon and is the single highest value hour of the whole project.
Certification proves competence for a scale, not for every scale
MCS certification is the scheme most UK installers hold, and it matters because export payments and many funding routes depend on the installation being certified. But certification is held against defined scopes, and a firm certified for domestic scale work is not thereby competent on a forty metre commercial roof with a three phase supply. Ask which scope the certificate covers and ask to see it, rather than accepting a logo on a brochure.
Vetting solar panel contractors: ask for buildings, not testimonials
A commercial reference is a building you can look at and an occupier you can ring. Ask for three of them with the same roof type, the same rough size and the same kind of occupation as yours, and then actually ring one. The questions worth asking are about the things that go wrong: did the programme hold, was the shutdown when they said, what did the first year of monitoring show against the modelled figure, and how quickly did somebody come out when something failed.
Commercial solar companies: check who is behind the warranty
A workmanship warranty is only as good as the company offering it. Look the company up at Companies House: how long has it existed, are accounts filed on time, has it been renamed or reincorporated recently. A twenty five year promise from a two year old company with a single director is not a warranty, it is an intention. For the same reason, ask whether the panel and inverter manufacturer warranties are registered to you rather than to the installer, because that is what survives the installer disappearing.
Consumer codes and what they actually cover
Codes such as RECC and quality schemes such as TrustMark set standards for sales conduct, contracts, deposit protection and complaints, and membership is worth having. Read what the protection actually covers before treating it as insurance. For a business buyer, many consumer protections do not apply at all, which is precisely why the contract, the warranty terms and the accounts of the company behind them matter more on a commercial job than on a house.
Questions people ask about commercial solar installers
Does a commercial installer have to be MCS certified?
Not for every project, but certification is required for the installation to qualify for export payments under the Smart Export Guarantee and for several funding routes. If the business case depends on export income, certification is not optional, and you should see the certificate and its scope.
How many quotes should a business get?
Three, and they should be compared on modelled generation, assumed self consumption, export position and warranty terms rather than on headline price. Quotes that differ by a large margin usually differ on assumptions, and the cheapest assumption is the one that fails.
What should never appear in a commercial solar quote?
A guaranteed saving figure with no stated assumptions, a system size fixed before the network operator has answered, a structural opinion given verbally, and a deposit demand out of proportion to the work done. Any of those is a reason to ask more questions rather than to sign.
Are commercial solar panel installers near me better than a national firm?
Neither is better by default. What matters is who will actually be on your roof, who holds the warranty and how long it takes somebody to attend when an inverter fails. Ask both firms those three questions and the answer usually becomes obvious.