A solar panel system should last 25–30 years. Most of the warranties that protect it will run out long before that — unless you know what to look for and ask the right questions before you sign. This guide covers every layer of cover, what each one actually does, and the one document that could save you thousands if your installer disappears.
Why solar warranties are more complicated than they look
When a salesperson says "it comes with a 25-year warranty", they're not lying — but they're almost certainly not telling you the whole story either. A typical solar installation comes with several separate warranties, issued by different parties, covering different things, with different claim processes. Knowing which is which matters, because the one most likely to fail you — the installer's workmanship warranty — is also the one most homeowners never even think to ask about.
Let's go through each layer in plain English.
Layer 1: The product warranty (what the manufacturer promises about the hardware)
A solar panel's product warranty is the manufacturer's assurance that the panel is free from flaws or defects that could impact its power output, protecting customers from problems caused by the panel's production process. Think cracked glass caused by an internal fault, a junction box that fails, or cells that simply stop working out of the box.
Product warranties typically run for 12–20 years, covering manufacturing defects. That sounds solid, but there are important caveats.
Product warranties exclude damage caused by external factors like accident, vandalism, fire, or extreme weather — hailstones or strong winds, for example. Storm damage, bird pecking, and anything your home insurer would normally handle are not covered here. Check your buildings insurance policy covers the panels, and tell your insurer they've been installed.
Product warranties typically cover the replacement part but may not cover labour. Some premium brands include labour for the first few years, so it's worth checking the exact terms before choosing a panel brand, not just the headline number.
Layer 2: The performance warranty (the one that actually matters for your bills)
Also called a power output warranty, this ensures that the panels will produce a minimum level of electricity over time. As panels naturally lose efficiency, a performance warranty guarantees they do not degrade faster than a set rate.
Most standard panels guarantee around 80–85% output after 25 years. Better-tier panels from established manufacturers now go further: JA Solar warrants 30 years to 87.4%, Aiko 30 years to 88.85%, and Longi 30 years to around 87%. The difference matters over a long ownership period.
There is one thing the performance warranty does not cover that homeowners often misunderstand. 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, and shading. The warranty covers panel-side performance, not whole-system-side. In other words, if your output is lower than expected because your roof faces north-east and gets afternoon shade, that's not a performance warranty claim.
If you want to understand how roof orientation affects your actual output, our guide to solar panels on an east-west roof explains what to realistically expect.
Layer 3: The workmanship warranty (the one most likely to let you down)
This is the warranty that covers how the system was installed — the physical mounting on your roof, the wiring, the waterproofing around every roof penetration, the connections between panels and inverter. Some installers provide a separate warranty for installation work. This protects against faults caused by poor workmanship, such as water ingress or faulty wiring.
The Microgeneration Certification Scheme (MCS) requires a minimum two-year workmanship warranty from certified installers, and quality installers typically offer five to ten years. Two years is the legal minimum — not a sign of a good deal. Given that solar panels tend to last around 30–40 years, a two-year workmanship warranty might cover just 5% of your system's lifespan. Always push for the longest workmanship warranty you can get in writing.
The deeper problem with workmanship warranties is that they are only as good as the company that issued them. If your installer folds in year three of a ten-year guarantee, that document is worthless — unless it's backed by insurance.
Layer 4: The insurance-backed guarantee (IBG) — the safety net that most people overlook
An Insurance-Backed Guarantee (IBG) is an insurance policy designed to cover the warranty on a system provided by the original installer. The idea is to provide extra peace of mind that the warranty on your solar panels will still be valid if the original installer ceases trading.
This matters because smaller businesses, and occasionally even some larger solar panel companies, can unfortunately cease trading within the timeframe of a typical workmanship warranty. If your installation company were to cease trading, you would have nowhere to go to claim on your warranty if there were an issue with the system, often leaving you with a bill to rectify the problem.
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, though Qualitymark Protection and HIES also offer recognised schemes. Solar insurance-backed guarantees provide financial protection to homeowners in the event their installer ceases to trade and is unable to honour their written guarantee.
Ask every installer, before you sign: "Is the workmanship warranty backed by an insurance-backed guarantee, and which provider?" If they can't name one, treat that as a red flag. Our guide to solar quote red flags covers the other warning signs to watch for when comparing installers.
Don't forget: the inverter has its own warranty
The warranty on your inverter is typically 5–10 years, but can often be extended to 15 years or more. As inverters work continuously and contain sensitive electronics, they are more likely to need replacement than panels over a system's lifetime. Standard string inverters typically last 10 to 15 years, so an inverter replacement is a likely mid-life cost for anyone with a longer-running system — factor this in when you're comparing quotes.
If you're adding battery storage, battery warranties are usually between 5 and 15 years, depending on usage and manufacturer. Check the battery warranty separately — it is not covered by the panel warranties.
What voids a solar warranty — the things installers don't always mention
- DIY electrical work on the system. Any electrical work on the system not done by an MCS installer typically voids workmanship cover.
- Pressure-washing the panels. Forces water past seals; manufacturers reject warranty claims on cleaning damage.
- Skipping maintenance. Many warranties require routine maintenance to remain valid. UK homeowners should retain maintenance logs and follow care instructions. Failing to meet these requirements can void the warranty.
- Storm and external damage. Climate damage outside the warranty terms — hurricane winds, extreme hail, fire from external causes — is usually excluded. Check your home insurance instead.
What happens to the warranties if you sell your home?
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.
Some manufacturers require online registration within a certain period — often 30–60 days. Your installer should help with this, but check and confirm it's been done. Keep confirmation emails as proof. If you're buying a property that already has panels fitted, our guide on buying a house with solar panels explains exactly what documents to ask the seller for.
A quick checklist: what to ask before you sign
Good warranty cover isn't just about the headline numbers — it's about having everything in writing and understanding who honours each promise. Before agreeing to any installation, confirm:
- Product warranty length and whether it includes labour as well as parts
- Performance warranty length and the guaranteed output percentage at 25 years
- Workmanship warranty length (push for at least five years)
- Whether the workmanship warranty is backed by a named IBG provider
- Inverter warranty length and whether an extension is available
- Whether manufacturer warranties need to be registered, and who does it
Getting quotes from multiple vetted, MCS-certified installers makes it much easier to compare these terms side by side — not just the price. FairSolar connects you with local installers who have been checked against exactly these standards. You can use the free quote form to get quotes from vetted local installers and compare the full package, including warranty terms, with no obligation and no pushy follow-up calls. FairSolar is free to homeowners — find out how FairSolar is paid if you'd like to know more about how the service works.
Frequently asked questions
What does a solar panel warranty cover in the UK?
There are typically four separate layers: a product warranty from the manufacturer covering physical defects (usually 12–20 years), a performance warranty guaranteeing minimum power output over time (usually 25–30 years), a workmanship warranty from the installer covering the quality of the installation (a minimum of two years under MCS rules, but five to ten years from quality installers), and ideally an insurance-backed guarantee (IBG) that protects the workmanship warranty if the installer ceases trading.
What happens if my solar installer goes bust?
If your installer ceases trading, your manufacturer warranties for the panels and inverter remain valid — you can claim through those directly or via another installer. However, the installer's workmanship warranty disappears with the company unless it was backed by an Insurance-Backed Guarantee (IBG) from a third-party insurer such as QANW or Qualitymark. Always ask any installer which IBG provider backs their workmanship guarantee before you sign.
How long is a solar panel warranty in the UK?
It depends on the type of warranty. Product warranties (covering manufacturing defects) typically run 12–20 years. Performance warranties (covering minimum power output) typically run 25–30 years. Workmanship warranties from the installer must be at least two years under MCS rules, but reputable installers commonly offer five to ten years. Inverter warranties are usually 5–10 years, often extendable.
Does my solar panel warranty transfer if I sell my house?
Manufacturer warranties on the panels are generally tied to the installation address, not the original owner, so they typically transfer automatically. Workmanship warranties from the installer may require formal transfer — check the original paperwork. Some manufacturers also require the warranty to have been registered within a set period after installation, so confirm this was done and keep the paperwork.
Can I void my solar panel warranty accidentally?
Yes. Common ways to invalidate cover include carrying out DIY electrical work on the system without an MCS-certified installer, pressure-washing the panels (which forces water past seals), failing to keep maintenance records if the warranty requires them, and damage from extreme weather events — which is usually excluded from manufacturer warranties and should instead be claimed on your home insurance.