MCS certification is the non-negotiable baseline
The Microgeneration Certification Scheme (MCS) is the UK's quality standard for small-scale renewable energy installations. An MCS-certified installer has been assessed against defined standards for competence, equipment quality, and installation practice.
MCS certification is required to qualify for the Smart Export Guarantee (SEG), which pays you for surplus electricity exported to the grid. Without MCS certification, your installation will not qualify for SEG payments — a potentially significant income stream over the life of the system.
Check an installer's MCS certificate number at mcscertified.com. The certificate lists the specific technologies they are certified for — confirm solar PV is included.
Check whether the installer uses their own teams
Some solar companies sell installations and then subcontract the physical work to third-party teams. This is not inherently problematic, but it matters for accountability: if the subcontractor does poor work, who is responsible for remediation? Ask directly whether the installation will be carried out by employed staff or subcontractors.
A company with a stable, employed installation team has more accountability than one relying on a variable pool of subcontractors. The MCS certificate should reflect the company actually carrying out the work, not just the company selling the system.
Get three quotes and compare on substance
Obtain at least three quotes from MCS-certified installers who have carried out a site survey. A quote without a site survey cannot accurately assess roof structure, shading, electrical load, or the correct system size for your household.
Compare quotes on: panel brand and model and their rated efficiency and warranty terms; inverter brand (Fronius, SMA, Solaredge, Enphase, and Growatt are established brands with UK support); number and wattage of panels; the estimated annual kWh generation figure and the assumptions behind it; battery storage if included; and the total installed cost including scaffolding and grid connection fees.
Be sceptical of quotes that are significantly lower than others — the main cost driver is equipment and labour, and both are relatively fixed. A very low quote often means lower-grade panels, an inexperienced team, or costs omitted from the quote.
Check reviews and ask for references
Look for verified reviews on Trustpilot, Google, or Checkatrade — not just testimonials on the installer's own website. Pay attention to reviews that mention post-installation support: how the company responded to a problem is often more revealing than the installation experience itself.
Ask for references from two or three local customers with installations at least 18 months old. A company confident in its work will provide these without hesitation. Ask those customers specifically about the commissioning process, inverter setup, and any follow-up support they needed.
Understand your warranty and handover documentation
A proper installation should come with product warranties (panel manufacturer warranty typically 10–12 years; performance warranty 25 years; inverter warranty typically 5–12 years depending on manufacturer) and a workmanship warranty from the installer (minimum 2 years, better installers offer 5–10 years).
At handover, you should receive MCS installation certificate, electrical installation certificate, commissioning report showing system is generating correctly, product warranty documentation for panels and inverter, and Smart Export Guarantee registration instructions.
Keep copies of everything. Future warranty claims — and future sale of the property — depend on this documentation. Many homeowners struggle with warranty claims years later because they cannot locate their original installation paperwork.
Once your installation is live and commissioned, the ongoing maintenance costs are low: a professional clean annually, an electrical inspection every three to five years, and eventual inverter replacement. FindSolarCleaner.co.uk helps with the first of those.