Solar is sold on a 25-year warranty. That number appears on almost every quote, and it is doing a lot of work that it should not be trusted with.
An installed solar system is several products from several manufacturers, assembled by a contractor. Each part carries its own terms. They are issued by different parties, they run for different lengths of time, and a failure is covered by exactly one of them.
The four warranties, and who issues each
| Warranty | Covers | Issued by | Typical term |
|---|---|---|---|
| Performance | Output staying above a declining guaranteed percentage | Panel manufacturer | 25 to 30 years |
| Product | The panel itself failing, delaminating, or a junction box fault | Panel manufacturer | 12 to 25 years |
| Inverter | The inverter failing | Inverter manufacturer | 10 to 12 years string, commonly 25 for microinverters |
| Workmanship | The installation: mounting, roof penetrations, cabling, leaks | The installer | 2 to 10 years |
| Mounting and roof | Rails, clamps, flashings, and the roof structure itself | Mounting manufacturer and installer | Varies widely |
Terms differ by product and market. This is the shape of the arrangement rather than a quote of any particular manufacturer.
The headline number is the first row. It is also the row least likely to result in a payment, because breaching a performance warranty requires a panel to be measurably below a line that most panels stay above.
What people actually claim on is the second and third rows, and those are shorter.
Performance and product are different promises
The performance warranty says: this panel will still produce at least X% of its rated output in year N. It is a promise about gradual decline.
The product warranty says: this panel will not be defective. It is a promise about the thing breaking. A panel with a cracked laminate, a failed junction box or water ingress is a product claim, and if the product warranty has expired then the fact that the performance warranty runs for another decade is irrelevant.
Historically the gap between the two was wide, with 10-year product cover against 25-year performance cover. It has narrowed, and premium manufacturers now offer product terms matching the performance term. When comparing two quotes, the product warranty is the more informative number.
How the performance line relates to what panels actually do is in how much output solar panels lose. In short, the guaranteed floor sits close to the measured median rather than well below it.
What is usually excluded
Exclusions are where a warranty is really defined, and they are consistent enough across manufacturers to list.
- Labour and access. This is the big one. A warranty that replaces a failed panel free of charge may not pay for the scaffolding, the electrician, or the day of work needed to fit it. On a roof, access frequently costs more than the part.
- Shipping of the replacement, in some terms.
- Cosmetic changes that do not affect output, such as discolouration.
- Damage from installation, meaning a manufacturer can decline a claim that is really a workmanship issue, which then falls to the installer.
- Consequential loss. The lost generation while the system was down is not usually recoverable.
- Anything after the installer has ceased trading, for the workmanship portion, unless the warranty is insurance-backed.
Conditions that can void it
Warranties carry obligations on the owner, and some are easy to breach without noticing.
One worth knowing about, because it is unusual and explicit: the Tesla Powerwall warranty for the European region, which covers the UK, states that Tesla requires the ability to update the unit through remote firmware upgrades in order to provide the warranty for its full ten-year period, and that if the unit is not connected to the internet for an extended period or has not been registered, the full term may not be honoured.
That is a connectivity requirement attached to a hardware warranty. It is disclosed, it is in the document, and almost nobody reads it. Other manufacturers attach their own conditions: annual inspections, approved cleaning methods, registration within a set window after commissioning.
- Register the products after commissioning, within whatever window the manufacturer sets. This is the most commonly missed step.
- Keep the MCS certificate, the commissioning documents and the invoice. A claim usually needs proof of installation date.
- Check whether any inspection or maintenance schedule is a condition rather than a recommendation.
- Check whether pressure washing or particular cleaning agents void anything before anyone touches the glass. See when cleaning actually pays.
The question to ask about any warranty
Not how long it runs. Who honours it, and what it costs you to use it.
- 1Is the manufacturer likely to exist in fifteen years, and does it have a presence in this country to claim against? Solar manufacturing has a history of insolvencies, and a warranty from a company that has gone is a piece of paper.
- 2Does the warranty pay for labour and access, or only supply a part?
- 3Is the installer's workmanship warranty insurance-backed, and by which insurer?
- 4What is the shortest term among the four, and what happens on the day after it expires?
That last question is the useful frame. A system is protected for as long as its shortest relevant warranty, not for as long as the number on the brochure. Where each of these sits in a quote, and what else is commonly missing from one, is in how to read a solar quote.
The Powerwall connectivity condition is stated in the Tesla Powerwall Limited Warranty for the European Warranty Region, revision 1.16, which lists the UK among the countries covered. Other terms in this guide describe common industry practice and vary by manufacturer; read the specific warranty document for the products being quoted. Checked 2026. Source