Solar Panel Warranty Guide: What’s Covered and How to Claim
A UK solar PV install carries four overlapping warranties: manufacturer product warranty on the panels (typically 12–20 years), manufacturer performance warranty on the panels (25–30 years, linear power output retention), manufacturer warranty on the inverter (5–12 years standard, extendable) and battery (10 years), and installer workmanship warranty (Spectrum: 5 years standard). On top, an Insurance-Backed Guarantee (QANW or similar) covers workmanship even if the installer ceases trading. Each warranty is claimed differently — manufacturer claims via the manufacturer’s UK distribution, workmanship via the installer or IBG insurer.
Solar warranties are the part of the purchase most customers skim over and the part that matters most over a 25-year asset life. Knowing what’s covered, by whom, and how to claim is the difference between a problem-free install and an expensive surprise in year 12.
The four warranty layers
| Layer | Typical term | What it covers | Who pays claims |
|---|---|---|---|
| Panel product warranty | 12–20 years | Manufacturing defects in the panel itself | Panel manufacturer (JA Solar, Aiko, Longi) |
| Panel performance warranty | 25–30 years | Power output retention to ~87–89% of original | Panel manufacturer |
| Inverter warranty | 5–12 years standard (Solis 5yr, SolarEdge 12yr; paid extensions available) | Manufacturing defects in the inverter | Inverter manufacturer (Solis, SolarEdge) |
| Battery warranty | 10 years to ~80% capacity | Cell failure, BMS failure, capacity loss | Battery manufacturer (Fogstar, Pylontech, Tesla) |
| Installer workmanship | 2–10 years (Spectrum: 5 years) | Errors in install — leaks, loose connections, wiring faults | Installer (or IBG insurer if installer ceased trading) |
| Insurance-Backed Guarantee (QANW) | 10 years typically | Installer workmanship if installer ceases trading | Independent IBG insurer |
Panel warranties in detail
Product warranty. Covers manufacturing defects: visible cracks, delamination, hot spots, electrical faults inside the panel. Triggered when a panel physically fails (not just produces less than expected). Replacement panels are usually a like-for-like swap.
Performance warranty. Linear degradation curve. A panel starts at 100% nameplate. Year 1 typically guaranteed 97–99%. Year 30 typically guaranteed 87–89% (Aiko 88.85%, JA Solar 87.4%). If the panel measurably outputs below the year-by-year curve, the manufacturer compensates — usually by replacement or financial credit.
The performance warranty isn’t a guarantee of generation — it’s a guarantee of the panel’s rated output under standard test conditions. Real-world generation depends on roof orientation, weather, shading. The warranty covers panel-side performance, not whole-system-side.
Inverter warranties
Standard inverter warranties are 5 years (Solis — Spectrum’s default, extendable to 10 or 20 years) or 12 years (SolarEdge, extendable to 20–25). Most manufacturers offer paid extensions. Worth taking the extension on commercial systems where inverter replacement is a major scheduled cost.
Inverter failures typically appear as error codes on the inverter display, dropouts in generation, or loud fan failure noise. The manufacturer’s UK service partner handles diagnosis remotely (via their monitoring portal) and replacement parts come from UK stock. Spectrum coordinates the warranty call on behalf of customers.
Battery warranties
LFP batteries (Fogstar — Spectrum’s default, Pylontech — commercial) typically warrant 10 years to ~80% capacity. Subject to cycle limits (the Fogstar Energy 16.1kWh is rated 8,000 cycles at 80% depth of discharge), depth of discharge limits (typically 80–90%) and ambient temperature ranges (typically -10°C to 45°C).
In practice, a properly installed UK domestic battery operating in a garage or utility room rarely hits any of the limits in 10 years. The most common warranty event isn’t capacity degradation — it’s BMS firmware failure or a connection issue, both of which the manufacturer covers via remote diagnosis and replacement.
Installer workmanship warranty
Covers errors specifically attributable to the installer’s work: roof leaks where penetrations were sealed, wiring faults, loose connections that develop over time, isolators that fail under normal use. Typically 5–10 years across the industry; Spectrum’s standard is 5 years on workmanship, backed by the QANW Insurance-Backed Guarantee (the IBG insures that term if we ceased trading — it doesn’t extend it).
This is the warranty that vanishes if the installer ceases trading — unless backed by an IBG.
Insurance-Backed Guarantee (IBG)
An IBG is independent insurance that pays out on the installer’s workmanship warranty if the installer is no longer trading. QANW is the most-used IBG provider for UK solar. Spectrum’s installs carry a QANW IBG as standard at no extra cost — it’s a built-in protection, not an upsell.
An IBG matters because the UK solar industry has seen meaningful installer failures since 2023. Buying solar from an installer without an IBG means your workmanship cover is only as durable as the installer’s balance sheet. With an IBG, it’s independent of that.
Spectrum installs include QANW IBG as standard
MCS NIC200223. Workmanship covered by Spectrum’s 5-year installation guarantee and the QANW IBG — layered protection from day one.
Request a QuoteHow to actually make a warranty claim
Panel claim:
- Notice the issue — visible damage, generation drop, monitoring flag.
- Contact your installer (or a new MCS installer if original has ceased trading).
- Installer inspects, photographs, takes I-V curve measurement to confirm the fault.
- Installer files claim with panel manufacturer’s UK distribution.
- Manufacturer approves and ships replacement.
- Installer swaps out the faulty panel.
Inverter claim: Similar process. Inverter manufacturer’s UK service partner can usually run remote diagnosis through their monitoring portal, accelerating the claim.
Battery claim: Manufacturer pulls BMS logs remotely if the battery is online, diagnoses cell or BMS fault, and ships replacement.
Workmanship claim: Contact installer directly. If installer has ceased trading, file with IBG insurer (claim form, photographs, original install paperwork).
What invalidates warranties
- Unauthorised modifications. Cutting cables, changing isolators, fitting non-approved kit.
- DIY work. Any electrical work on the system not done by an MCS installer typically voids workmanship cover.
- Pressure-washing panels. Forces water past seals; manufacturer rejects warranty claims on cleaning damage.
- Failure to service. Manufacturer extended warranties often require evidence of annual maintenance.
- Climate damage outside the warranty terms. Hurricane winds, extreme hail, fire from external causes — usually excluded; check your home insurance instead.
FAQs
How long is a solar panel warranty?
Typically 12–20 years product warranty (manufacturing defects) and 25–30 years performance warranty (power output retention). JA Solar warrants 30 years to 87.4%, Aiko 30 years to 88.85%, Longi 30 years to ~87%. The performance warranty is what protects the long-tail value of the panel.
What is an Insurance-Backed Guarantee?
An IBG (typically QANW for UK solar) is independent third-party insurance that honours the installer’s workmanship guarantee even if the installer ceases trading. Spectrum installs include QANW IBG as standard at no extra cost. It’s a meaningful protection layer separate to manufacturer warranties.
Do solar warranties transfer to new homeowners?
Manufacturer warranties usually transfer with the property automatically — they’re tied to the installation address, not the original buyer. Workmanship warranties from the installer sometimes require formal transfer; check the original install paperwork. QANW IBG is typically transferable to subsequent property owners.
Are solar warranties worth paying extra for?
Inverter extended warranties (10 years to 15 or 20 years) are usually worth the modest cost — inverter replacement is the biggest scheduled mid-life expense. Panel warranties don’t typically have paid extensions. Battery warranties are usually fixed at 10 years — manufacturer doesn’t offer extensions.
What does a solar panel performance warranty actually pay?
If a panel measurably outputs below its year-by-year warrantied power curve at standard test conditions, the manufacturer compensates — typically replacement panels or pro-rated financial credit. The warranty isn’t a guarantee of system generation, just of panel-side rated output. Real-world generation also depends on weather and orientation.
Who fixes the panels if my installer is closed?
Any MCS-certified installer can handle warranty claims for systems they didn’t originally install. The manufacturer pays the claim regardless of which installer files it. Spectrum routinely picks up orphaned systems and processes warranty claims through the panel/inverter/battery manufacturers. See our takeover servicing article.
Does home insurance cover solar panels?
Most UK building insurance policies cover solar PV systems as part of the building structure, including damage from storms, fire, theft and vandalism. Warranties cover manufacturing defects and performance loss; insurance covers external damage. Notify your insurer when you install solar — some policies require it.
Related reading
- Solar panel maintenance schedule UK
- Solar repair: what to do when your installer goes bust
- Fogstar vs Pylontech: which solar battery is right for you?
For the full Spectrum service overview see domestic servicing.
Speak to Spectrum Energy Systems
MCS NIC200223. QANW Insurance-Backed Guarantee included on every install. Layered warranty protection from manufacturer + installer + IBG insurer.
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