Commercial solar insurance in the UK
A well-specified solar array rarely changes your building insurance premium and often reduces it via a green-buildings discount. Here's what to declare, what to expect and how to make sure your workmanship warranty is genuinely insurance-backed.
Typical system sizes
Small commercial (<100 kWp)
Usually a policy endorsement only — no premium change on most Aviva, AXA, Zurich and RSA schemes. Notify sum-insured uplift of £45–£110/kWp.
Mid-size (100 kWp – 1 MWp)
Broker-arranged endorsement; some insurers now require an annual thermographic scan (a £600–£1,500 O&M line item). Green-building discount often 3–8% off buildings premium.
Large (1 MWp+)
Bespoke placement covering material damage + business interruption + revenue loss + G99 loss-of-export. Priced £0.6–£1.20/£1,000 sum insured.
Group / portfolio
Fleet MDBI policy at the group level; single certificate, single renewal, aggregated deductible.
Green-building discounts are becoming material
Aviva, Zurich, Allianz and RSA have all launched green-building endorsements in 2024–25, typically discounting 3–8% off the buildings-cover element for EPC A/B assets with on-site renewables. Over a 10-year hold that's often worth £3k–£25k per commercial site — enough to move the solar business case on its own.
FAQ
Do we have to tell our insurer we've installed solar?
Yes — always. Non-disclosure is grounds for a claim being repudiated. Notify at commissioning with the MCS certificate, single-line diagram and a photo of the finished install; most insurers respond with a written endorsement inside two weeks.
Will our premium go up?
Rarely on well-specified systems under 100 kWp — typically a nil endorsement. Larger systems may see a small proportional uplift matching the sum-insured increase, often offset by a 3–8% green-building discount now offered by several major insurers.
What is an insurance-backed workmanship guarantee?
A third-party insurance policy that pays out if the installer becomes insolvent within the workmanship warranty period (typically 10–12 years). QANW, IWA and HomePro are the main UK IBGs. Insist on one — it protects you against the biggest risk in the sector.
What about business interruption from an inverter or panel failure?
Standard MDBI policies cover business interruption from insured perils (fire, weather). Loss of export income from an inverter failure is usually covered under the O&M-provider's response-time SLA, not the buildings policy. Larger systems buy a separate revenue-loss policy.
What documentation does our insurer need at renewal?
Typically: MCS certificate, DNO G99 acceptance letter, most-recent annual O&M report, thermographic scan (systems >250 kWp), and inverter warranty status. A good installer prepares this pack automatically.
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