You may have seen coverage of the ECO-funded insulation failures — around 22,000 homes affected, with 98% of audited external wall insulation needing corrective work. It happened because work was subcontracted to uncertified operatives at volume, with inadequate quality control.
Solar installation has a different risk profile (it sits on top of the building, not inside the walls), but the lesson is the same: certification matters, and who actually does the work matters more than who sells it.
What protects you specifically: MCS certification means the installer is audited annually. TrustMark registration provides access to the insurance-backed guarantee through the Independent Warranty Association — so if the installing company ceased trading, your warranty would still be honoured. TrustMark registration provides access to a dispute resolution service if you need to escalate a complaint.
The UK government consulted in June 2026 on establishing an Installation Assurance Authority and a public register of approved installers. Until that exists, MCS + TrustMark + Gas Safe is the strongest consumer protection stack available.