How do I choose a solar installer in Scotland?

Why does MCS certification matter?

MCS (Microgeneration Certification Scheme) certification is the quality standard for small-scale renewable installations in the UK. It matters for three practical reasons. First, you need an MCS certificate for your installation to register for Smart Export Guarantee payments. Second, the 0% VAT relief on qualifying solar installations requires the work to be carried out by an MCS-certified installation company. Third, it is a baseline assurance that the installer meets a recognised standard for products and workmanship.

Do not take an MCS certificate shown to you on paper at face value. Verify it independently on the official database at mcscertified.com by searching the installer name. If you cannot find them, or the certification has lapsed, that is a warning sign regardless of what you have been told. See our guide to MCS certification in Scotland for more on why it matters.

What is TrustMark and should my installer be registered?

TrustMark is the UK government-endorsed quality scheme for tradespeople, covering workmanship, customer service and complaint handling. An installer registered with TrustMark has met additional standards beyond the basic legal requirements, and you have access to a structured complaints process if something goes wrong.

Checking TrustMark registration is a useful secondary check alongside MCS. You can search for an installer on the TrustMark website. Registration is not a substitute for MCS certification, but together they give you a stronger picture of the installer's standards. Neither check takes long and both are worth doing before you commit.

Why should I get at least three quotes?

Getting at least three written, itemised quotes lets you compare offers on a like-for-like basis. A proper quote sets out the panel brand and model, inverter type, system size in kWp, estimated annual generation, total installed cost, warranty terms and a proposed installation date. When you have three of these in front of you, it is much easier to spot the quote that is vague, the one that is unusually cheap, and the one that is unusually expensive.

Be wary of any quote that is not itemised or that will only be provided after you commit. A reluctance to put details in writing is one of the clearest warning signs. Use our Solar Buyer's Guide as a checklist for what each quote should contain.

What are the 10 key questions to ask an installer?

When you have your quotes, ask each installer the same set of questions so you can compare the answers. The 10 key questions cover: Are you MCS-certified and what is your MCS number? Are you registered with TrustMark? What panel brand and model are you proposing, and why? What inverter is included? What is the system size in kWp and estimated annual generation? What warranties apply to panels, inverter and workmanship? Will you handle G98/G99 DNO notification? Will you help with SEG registration? What is the total installed cost and payment schedule? And what is the proposed installation date?

A competent installer answers all ten clearly and in writing. If an installer is evasive on any of them, or will only answer verbally, treat that as a red flag. The full set of questions and the red flags to watch for are set out in our guide to choosing a solar installer and our installer red flags guide.

What are the red flags when choosing a solar installer?

The clearest red flags are pressure to sign on the day, a quote that is vague or missing key details, an MCS number that cannot be verified on mcscertified.com, no written warranty, and reluctance to handle DNO notification or SEG registration. Other warning signs include a salesperson rather than a technical person doing the survey, a price that is far below every other quote, and any promise of specific savings that sounds too good to be true.

If you feel pressured at any point, walk away. A reputable installer gives you time to compare quotes and does not require a decision on the spot. See our installer red flags guide for the full list.

Should my installer handle DNO notification and SEG registration?

Yes. A reputable installer handles G98/G99 DNO notification with your electricity network operator and helps you register for Smart Export Guarantee payments as part of the installation. These are not optional extras to be left to you afterwards. DNO notification is a legal requirement for connecting generation to the grid, and SEG registration is what allows you to be paid for exported surplus.

Confirm in writing, before you sign, that both are included. If an installer expects you to sort out DNO notification or SEG registration yourself, that is a red flag. See our guides to G98/G99 DNO notification and SEG registration for what these involve.

What warranties should a solar installer provide?

You should receive written warranties covering four things: the panels (typically a 25-year performance warranty guaranteeing output above a set percentage), the inverter (typically 10-15 years), the workmanship or installation itself, and any battery included in the system. Get the warranty terms in writing as part of the quote, not as a verbal promise, and check what the process is if you need to make a claim.

Warranty terms differ between manufacturers and installers, so read them rather than assuming they are all the same. See our warranty guide for what to check before signing.

Does my solar installer need insurance?

Yes. A reputable installer holds public liability insurance and, where they have employees, employer liability insurance. Ask for proof of current insurance as part of your checks. Insurance cover protects you if the installation causes damage to your property or if someone is injured during the work. An installer who cannot show proof of insurance is one to avoid, regardless of how competitive the quote looks.

What should be in the contract before I sign?

A solar contract should set out the panel brand and model, inverter type, system size in kWp, estimated annual generation, total installed cost, payment schedule, warranty terms, confirmation that DNO notification and SEG registration are included, and a proposed installation date. Everything you have discussed should be in the written contract — if it is not, ask for it to be added before you sign.

Do not sign a contract with blank sections, verbal-only promises, or a payment schedule that asks for most of the money before installation begins. A typical schedule involves a deposit with the balance due on satisfactory completion. If anything in the contract is unclear, ask. If you want an installer partner who follows all of this, submit your postcode through the form on this page or call 0141 230 0198 and we will connect you with an MCS-certified installer partner.

For more answers to common renewable energy questions, visit More answers from Scottish Energy Efficiency.