Wrong Solar Panels Installed? MCS Certificate Mismatch

A homeowner on r/SolarUK has reported that the wrong solar panels were installed on their roof: the MCS certificate lists one brand and the serial numbers on the roof point to another. The story, picked up by The Cool Down on 28 September 2026, is a useful reminder to check your own paperwork against what is actually on the roof. Here is what was reported, what the rules say, and what to do if it happens to you.

What was reported

According to the report, the contract and MCS certificate specified 31 Aiko 3s Neostar 475W modules, but the serial numbers on the installed panels identified 470W Jinko modules. The homeowner had wanted the Aikos for their all-black look and shading performance, and said they were charged the Aiko price. Commenters suggested the price gap could be over £1,000, though that is a commenter estimate, not a confirmed figure.

The installer reportedly blamed an unnoticed supplier "like-for-like" substitution: the Aiko panels were said to be backordered until November, and a different model arrived instead. The installer acknowledged the error and agreed the MCS certificate could be updated. As of the report, the homeowner was still deciding whether to push for the correct panels or compensation. We have not independently verified the original Reddit post, so treat the details as the homeowner's account.

What the MCS certificate is meant to show

MCS says its certificate records "the type and model of the installed technology", the installation company and confirmation that the system complies with MCS Standards (MCS certificate queries). That makes the certificate more than a formality: it is the record of what was supposedly fitted. Our guide to the MCS certificate for solar explains what it unlocks, including Smart Export Guarantee eligibility.

If the certificate is wrong, MCS says to contact your original installer first. If they are no longer certified or trading, MCS can help, but you would need proof of address, supporting evidence and a fee of £30 plus VAT for an amendment.

Do you have a legal case if panels are swapped?

This is general information, not legal advice. Under section 11 of the Consumer Rights Act 2015, every contract to supply goods by description is treated as including a term that the goods will match that description. A contract naming a specific panel brand and model is a strong description. Whether a swap to a cheaper model is a breach, and what remedy fits, depends on your contract, how the substitution was disclosed and whether the replacement performs equivalently. A like-for-like swap you agreed to in writing is a different position from one you discover afterwards.

The reported case also shows why substitutions matter for more than price. Panel brands differ on warranty terms, shading behaviour and appearance, as our Aiko vs LONGi comparison shows, so a swap can change what you bought even if the headline wattage is close.

How to check your own installation

• Compare three documents: your signed quote or contract, the installer's commissioning paperwork and the MCS certificate. Brand, model and panel count should match.
• Check the roof: panel labels carry the manufacturer and model, and a serial number. Photograph them on handover day, ideally with the installer present.
• Ask about delays in advance: if a product is backordered, get any substitute offered in writing and agree it before install day, not after.
• Chase the certificate: MCS installers are expected to issue the certificate within 10 working days of commissioning, according to MCS guidance, so check it promptly while the installer is still engaged.
• Keep the paper trail: if you spot a mismatch, raise it with the installer in writing and ask for a corrected certificate and a proposed remedy.

For more on what to ask before signing, see our questions to ask a solar installer and the guide to comparing solar quotes, and check the roof and panel warranty position before work starts.

The bottom line

One reported case is not evidence of a widespread problem, but it is cheap to guard against. Match the contract, the certificate and the panels on your roof, and settle any substitution in writing before the scaffolding comes down.