Solar Panel Warranties Explained: Product, Power & Inverter

Solar panel warranties, explained

A solar warranty is not one promise but three, and they protect very different things. Buyers who skim the brochure often discover too late that "25-year warranty" referred to performance, not the hardware — or that the inverter, the part most likely to fail, had its own much shorter clock. Knowing the three apart is one of the easiest ways to judge quality and avoid an unpleasant surprise years later.

This guide breaks down what each warranty covers, how to read one, and the fine print that decides whether a claim actually gets paid.

The three warranties

1. Product (workmanship) warranty — covers defects in the panel itself: manufacturing faults, frame or junction-box failures, delamination. This is the truest measure of how much the manufacturer trusts its own build. It typically runs 12 to 25 years; premium brands offer 25, budget panels often just 10–12.

2. Performance (power) warranty — guarantees the panel still produces a minimum share of its rated output over time, despite normal degradation. A common promise is around 85–90% at year 25, with a small first-year allowance and a fixed annual decline after that.

3. Inverter warranty — separate, and usually the shortest: 10–15 years for string inverters, longer for many microinverters. Since the inverter is the component most likely to need replacing, this clock matters more than buyers expect.

How to read a performance warranty

Performance warranties are quoted as two numbers: a year-one floor (e.g. 98%) and an annual degradation rate (e.g. 0.5%/year). Together they define a sloping line the panel must stay above. A tighter degradation rate is a real quality difference: 0.25%/year leaves far more output at year 25 than 0.7%/year, even if both "end" near 88%.

What is — and isn't — covered

This is where claims live or die:

• Usually covered: manufacturing defects, output falling below the guaranteed curve, premature material failure.
• Often excluded: damage from improper installation, extreme weather beyond rated limits, unauthorised repairs, and — crucially — the labour and shipping to swap a failed panel. A "free replacement panel" can still cost you a call-out.
• Conditions: many warranties require professional installation and proof of normal maintenance to stay valid.

The hidden details that matter

• Labour coverage: does the warranty pay only for the part, or also for removing and refitting it? The latter is far more valuable.
• Transferability: can the warranty pass to a new homeowner? This protects resale value.
• Company longevity: a 25-year warranty is only as good as the company behind it. A long warranty from a manufacturer that may not exist in 15 years is worth less than a solid one from a stable brand.
• Who you claim from: the panel maker, the installer, or both? Know before you need it.

Using warranties to compare quotes

Two quotes at the same price are rarely equal once you read the warranties. Favour the system with a longer product warranty, a lower degradation rate, labour included, and a manufacturer likely to be around to honour it. A strong warranty is the manufacturer betting on its own panels — a signal worth more than most marketing claims.

FAQ

What does a solar panel warranty actually cover? Three things, separately: panel defects (product), guaranteed output over time (performance), and the inverter — each with its own length.

Is a 25-year warranty on the panels or the power? Usually the performance (power) warranty. Check the product warranty separately; it is often shorter.

Does the warranty pay for labour to replace a panel? Not always. Many cover only the part, leaving you the removal and refitting cost. Confirm before buying.

What voids a solar warranty? Commonly improper installation, unauthorised repairs, abrasive cleaning, or damage beyond the panel's rated limits.

Red flags, and keeping cover valid

A few warning signs are worth spotting before you sign. Be wary of an impressively long performance warranty paired with a short product warranty — it often means cheap hardware dressed up. Watch for vague language about who pays for labour, high degradation allowances that let output sag faster, and clauses that void everything if anyone but the original installer touches the system.

Keeping a warranty valid is mostly common sense: use a qualified installer, keep your purchase and installation paperwork, follow the manufacturer's cleaning and maintenance guidance, and never use abrasive tools or pressure washers that can be cited as misuse. Register the product if the maker requires it, and note who to contact for a claim — the panel maker, the inverter maker and the installer may each handle different parts. A little record-keeping now is what makes a claim painless years later.

Bottom line

Treat the warranty as a spec, not a footnote. Read all three — product, performance and inverter — check for labour coverage and transferability, and weigh them against the maker's stability. The cheapest quote with a thin 10-year product warranty is often the expensive one in disguise.

Last updated June 2026. Informational only — always read the specific warranty documents for any panel and inverter you are quoted.