Solar Panel Warranties Explained: The 3 That Matter
“25-year warranty” sounds reassuring — until you learn it’s really three separate warranties, expiring at different times, and the year count hides what actually matters. The honest decoder.
The short answer
A “solar panel warranty” is really three warranties, and they expire independently. The product warranty covers manufacturing defects (10–12 years on budget panels — a red flag — 15–25 on quality tier-1, up to 40 on premium Maxeon). The performance warranty guarantees output over time (25 years near-universal, 30 on premium brands, 40 on Maxeon). The workmanship warranty is your installer’s, covering their fitting (5–10 years typically, 15–25 from the best). All three start at commissioning — and your weakest, usually workmanship, ends first.
The number that actually matters isn’t the term — it’s the guaranteed output at year 25, which ranges from ~80% (budget) to 92% (premium) on warranties that all say “25 years.” And the catch every glossy brochure omits: a warranty is only as good as the company behind it — with Panasonic exiting solar in 2025 and SunPower’s 2024 bankruptcy, backing matters as much as the number. Roof-warranty myths, transferability, and how to claim, below.
What this guide covers
Warranty is where solar quotes quietly differ most, and where the least honest selling happens — a big “25 YEARS” on the brochure that means far less than it implies. This guide is the decoder: what the three warranties actually cover, the one figure that separates good from average, and the small print that decides whether your cover is real.
The three warranties, decoded
Every quality solar installation carries three distinct warranties, and confusing them is how buyers get caught out.
1. The product warranty (or equipment warranty) covers manufacturing defects — delamination, frame corrosion, junction-box failure, glass breakage, faulty connectors. It’s the “will it physically break?” cover. In 2026: budget panels offer 10–12 years — treat that as a red flag — quality tier-1 N-type panels offer 15–25 years, and premium brands (Maxeon, REC) reach 25–40. A panel failing in year 14 is fully covered under a 25-year product warranty and entirely your problem under a 12-year one, so this gap is real money.
2. The performance warranty (or power warranty) covers the slow, normal fade instead: it guarantees the panel will still produce at least a stated percentage of its original output at set milestones. Nearly all panels carry 25 years; premium lines carry 30 (LONGi, Jinko, Trina, JA Solar, Canadian Solar) or 40 (Maxeon). This protects your long-term savings — but as the next section shows, the headline year count hides the figure that matters.
3. The workmanship warranty is different in kind: it’s your installer’s guarantee of their own work — mounting, wiring, weatherproofing, roof penetrations — not the manufacturer’s. It runs 5–10 years typically, 15–25 from the best installers, and in the UK the key question is whether it’s backed: a RECC-registered or insurance-backed guarantee still protects you if the installer goes out of business, whereas an unbacked promise is worthless the day they fold. All three warranties start at commissioning and expire independently — so your strongest cover (performance) can still be running two decades after your weakest (workmanship) has lapsed.
The number that actually matters: year-25 output
“25-year warranty” can mean 80% output or 92% — that gap is the whole game
Here’s what the brochures bury: two panels can both advertise a “25-year performance warranty” while guaranteeing completely different things at the end of it. A budget PERC panel typically guarantees ~80–84% of original output at year 25; a premium N-type or TOPCon panel guarantees 87–92% (REC and Maxeon reach 92%). On a system generating thousands of kWh a year, that 8–12 percentage-point difference compounds into real money over the term. So compare the guaranteed year-25 percentage, never just the year count. Two more distinctions worth knowing: favour a linear warranty (guarantees output every single year along a declining line) over a step warranty (only guarantees output stays above a level for blocks of years, leaving gaps); and check the annual degradation rate — around 0.3–0.5% a year is good (premium N-type), 0.8% is budget territory. A first-year drop of 2–3% is normal for all panels (it’s called light-induced degradation and it levels off), so don’t mistake it for a fault. The honest one-liner: the term tells you how long, the year-25 percentage tells you how much — and the second number is the one that pays you.
What the brands actually offer in 2026
| Tier | Product | Performance (year-25 output) |
|---|---|---|
| Premium (Maxeon) | Up to 40 yr | 40 yr · ~92% at yr 25 |
| Premium (REC Alpha) | 25 yr | 25 yr · ~92% |
| Tier-1 N-type (LONGi, Jinko, Trina, JA, Canadian) | 15–25 yr | 30 yr · ~87–88% |
| Mainstream (Qcells, Silfab) | 25 yr | 25–30 yr · ~86–90% |
| Budget PERC | 10–12 yr | 25 yr · ~80–84% |
The pattern the table makes plain: the performance term has converged (25–30 years almost everywhere), so the real differentiators are the product term and the year-25 output floor. Maxeon’s 40-year cover is the market’s strongest (and its back-contact cells genuinely degrade slowest), but it commands a price premium and — crucially — only delivers its full 40 years when an accredited installer registers the system. For most UK homes, a quality tier-1 N-type panel with 25-year product cover and an 87%+ year-25 guarantee is the sweet spot of warranty strength and sensible price. Verify the exact figures against the datasheet for the specific panel model in your quote, because terms differ between series within a single brand.
The catch reviewers skip: who’s actually backing it?
A 40-year warranty from a company that won’t exist in year five is worth nothing — and this isn’t hypothetical. Panasonic exited the solar panel business in 2025; SunPower Corporation filed for bankruptcy in 2024. The solar manufacturing world has seen real consolidation, and a warranty is a promise only as durable as the promiser. Two protections follow. First, on panels: favour large, financially stable tier-1 manufacturers (LONGi, Jinko, Trina, JA Solar, Canadian Solar, Qcells, Maxeon) and ask whether the manufacturer carries third-party warranty-backstop insurance. Second, on the installation: the UK equivalent of this risk is your installer folding mid-workmanship-term, which is exactly why an insurance-backed guarantee (IBG) — standard with reputable RECC-registered installers — matters so much. It keeps your workmanship cover alive even if the company doesn’t. When you compare warranties, you’re not just comparing years and percentages; you’re betting on two businesses staying solvent for decades, so weigh their stability alongside their numbers.
Does solar void your roof warranty? (and other component cover)
The ~80-a-month question deserves a clear answer: a properly done installation shouldn’t void your roof warranty — a badly done one can. Mounting panels means fixing rails to the roof structure; done right by an MCS-certified installer with correct fixings and weatherproofing, it doesn’t compromise the roof, and their workmanship warranty then covers the penetrations they made. Done wrong, it causes leaks and hands a warranty provider grounds to decline. Protections: use MCS certification, keep the sign-off, and if your home is a new-build under an NHBC or similar structural warranty, notify the provider before installing — some require it. Meanwhile the other components carry their own separate warranties: string inverters run 10–12 years (microinverters up to 25), and batteries around 10 years with their own throughput caps — the Fronius 5+5 structure we reviewed is a good example of how inverter cover can have small print of its own. Don’t assume “the warranty” is one thing covering everything; it’s a stack of separate promises with separate clocks.
Transfers, exclusions & how to claim
Transfers (a resale asset): most panel warranties transfer to a new owner, sometimes with a registration step or small fee — a genuine selling point, since a documented system with 18 years of cover left is an asset a buyer values (our moving-house guide covers the full handover). Exclusions (what insurance, not warranty, handles): storm and hail beyond the tested rating, falling branches, flood, fire, theft, rodent damage — external accidents are a home insurance matter, so confirm your buildings cover includes the panels. Warranties are also voided by DIY or unaccredited installation, unauthorised modifications, and (a real trap) failure to register where registration is required — the reason Maxeon’s 40 years can quietly become 25. Claiming: contact your installer first (they diagnose, often remotely, and handle workmanship issues directly); for a manufacturer claim you’ll need the certificate, and performance claims specifically require I-V curve testing and monitoring data against the guaranteed curve, settled pro-rata. And a final vigilance note: “your solar warranty has expired” texts are a known scam impersonating MCS or your installer — real warranty matters never arrive as an urgent text pushing a paid package.
Frequently asked questions
How long is a solar panel warranty?
There’s no single number: product cover runs 10–40 years (budget 10–12 is a red flag), performance 25–40 years, and the installer’s workmanship 5–25. All start at commissioning and expire independently, so the weakest (usually workmanship) ends first. Always ask which of the three a “25-year” claim refers to.
Product vs performance warranty — what’s the difference?
Product covers manufacturing defects (delamination, corrosion, breakage — “will it break?”); performance guarantees minimum output over time (“will it quietly underperform?”). The figure that matters on performance is the guaranteed year-25 output %, which ranges 80–92% on warranties all labelled “25 years.”
Does solar void my roof warranty?
A proper MCS-certified install shouldn’t; a bad one can, by causing leaks. Use a certified installer (their workmanship warranty then covers the penetrations), keep the paperwork, and notify your NHBC/structural warranty provider first if it’s a new-build — some require it.
Are warranties transferable when I sell?
Usually yes — most panel warranties transfer to the buyer, sometimes with registration or a small fee, making a documented system a resale asset. Keep the full warranty pack together to pass on. Workmanship transfer varies by installer — check.
What isn’t covered?
External damage — storm, hail beyond rating, branches, flood, fire, theft, rodents — is home insurance, not warranty. Warranties also void on DIY/unaccredited installation, unauthorised mods, and missed registration (which can shorten premium terms like Maxeon’s 40 years).
How do I claim?
Installer first — they diagnose (often remotely) and handle workmanship issues; for manufacturer claims you need the certificate, and performance claims need I-V testing plus monitoring data vs the guaranteed curve, settled pro-rata. Keep every document from day one, and beware “warranty expired” scam texts.
Compare the year-25 output and the company — not the headline number
The bottom line: A solar warranty is three warranties — product (defects), performance (output), workmanship (the install) — each on its own clock. Ignore the big “25 years” and check the details that pay: the guaranteed year-25 output % (80% budget vs 92% premium), a linear rather than step curve, a 15–25-year product term (not 10–12), an insurance-backed workmanship guarantee, and — the one most people miss — a manufacturer and installer financially stable enough to honour the promise. Register the product, keep every document, and insure for what warranties exclude.
Get my free quotes →The verdict
Solar warranties are designed to reassure, and mostly they should: modern panels fail rarely and degrade slowly, and a quality system will very likely outlive its warranty quietly. But the reassurance is sold dishonestly often enough that the number on the brochure has stopped meaning much — which is why the real skill is reading past “25 years” to the three separate promises underneath, and to the two businesses that have to survive to keep them. The guaranteed output at year 25, a linear curve, a long product term, a backed workmanship guarantee, and a solvent manufacturer — that’s the whole checklist, and it’s a better guide to quality than almost any spec on the datasheet.
The practical way to use it is at quote stage, comparing like for like — which is exactly where a good installer earns trust by showing you the real terms rather than the marketing ones. A couple of free, no-obligation quotes from MCS-certified installers, each with its warranty stack laid out, turns this guide from theory into the two or three numbers that actually decide which system is the sound buy.
Important
Going Solar UK is an introduction service, not an installer, manufacturer or financial adviser. This guide is general 2026 information, not a substitute for reading the specific warranty documents for the panels, inverter, battery and installation in your own quote: terms vary by manufacturer, model, series and installer, and change over time – always confirm current warranty details and registration requirements in writing before purchase. Figures are typical estimates, not guarantees.
We may receive a commission when we introduce you to an installer, at no cost to you. Any contract for work is directly between you and the installer.