Warranty terms across manufacturers

In short: Of the 121 manufacturers with at least five datasheets in our catalogue, 28 state a median product warranty of 25 years or more, and 88 a median performance warranty of 30 years. The table further down names the companies with the longest terms, and the names can change with every catalogue sync. Terms also vary inside one brand, so the warranty that counts is the one printed for the model you buy.

A warranty is the one line on a datasheet that is a promise, not a measurement. Manufacturers set it company by company, so this page compares companies: which ones state the longest terms, and how far one company's terms move between its own products. It ranks what manufacturers print. It doesn't rank how long modules last, or how good the companies are.

The two warranties do different jobs. The product warranty covers defects in the module itself. The performance warranty promises a share of rated power for a number of years. How each is built is in product warranty versus performance warranty.

How manufacturers are counted

Of the 14,005 modules in the catalogue, 13,615 state a product warranty and 13,877 a performance warranty. Only the 121 manufacturers with at least five distinct datasheets stating a product warranty are compared below.

Two choices shape every figure. A manufacturer counts once, with the median over its own modules; counting modules would let a company with long ladders of power ratings (one datasheet listing many wattages of the same module) outweigh one with short ladders. And the minimum sample is counted in datasheets, not modules. A datasheet with ten power ratings is still one product and one warranty decision. The exact counting rules are under "Figures and denominators" below the article.

Does the threshold change the answer?

Five datasheets is a judgement call, so the same count is shown at four thresholds. Divide the right-hand column by the middle one at each row. If that share holds roughly steady as the threshold rises, the choice of five isn't deciding the result.

Product warranty length by manufacturer

Company medians land on a handful of round numbers. Look at which rows hold the bulk of the manufacturers, and how many reach 25 years or more.

Hold that against the performance warranty. 88 of the same manufacturers have a median performance warranty of 30 years and 31 of 25 years. Whatever those two leave of the 121 sits at some other length, so you can see at a glance which of the two terms is spread wider.

The manufacturers with the longest stated terms

The table is sorted by the terms alone: median product warranty first, then median performance warranty, then the power promised at its end.

The 15 manufacturers with the longest stated warranties among 121 with at least 5 datasheets stating a product warranty, as of the last catalogue sync. Sorted by median product warranty, then median performance warranty, then the power promised at its end.

"Shortest" is the shortest product warranty the company states anywhere in our catalogue; "End power" is the median share of rated power promised when the performance warranty runs out.

Read the Datasheets column first. A row resting on five datasheets says less about a company than a row resting on fifty, and both pass the same threshold.

Then read the Shortest column. Of the 28 manufacturers with a median of 25 years or more, 23 also state a shorter product warranty on some of their modules. The median describes the company's catalogue. The module you're about to buy has its own datasheet.

Where the ten largest manufacturers sit

"Largest" means the ten manufacturers with the most datasheets in our catalogue, not the most modules shipped. Set the first row against the threshold table above, and the last row against the performance figure in the summary at the top. That shows whether the biggest catalogues sit with the rest or apart from them.

Whatever the rows show, they explain nothing. Warranty length is a commercial decision, and our catalogue holds no data on claims, on how often they are paid, or on the reserves behind them.

How the product and performance terms pair up

The two are separate clauses, so a long one doesn't imply a long other. Of the 28 manufacturers with a median product warranty of 25 years or more, 22 have a median performance warranty of 30 years and 6 of 25 years.

The end figure differs too. Of the 120 compared manufacturers that state it, 12 promise a median of 89 % or more of rated power at the end of the performance warranty, and 38 promise under 85 %.

That end figure is the warranty's bound on power loss. A module loses power slowly over decades, and some old modules in the field also show visible wear, such as the browned patches and cracks below. The photo shows condition, not how much power that module lost. The performance warranty says how far the loss may go before the manufacturer owes you something.

The end figure follows from two numbers in the schedule: the loss allowed in the first year and the annual degradation rate after it. So two 30-year warranties can end several points apart. Take two made-up schedules:

• 1 % in the first year, then 0.4 % a year: 29 × 0.4 = 11.6, and 100 - 1 - 11.6 = 87.4 % at year 30;
• 2 % in the first year, then 0.55 % a year: 29 × 0.55 = 15.95, and 100 - 2 - 15.95 = 82.05 % at year 30.

Same headline length, more than five points apart at the end.

In the figure below, module A starts at the catalogue's median schedule and module B on the first schedule above. The "2 % then 0.55 %/yr" button loads the second.

One manufacturer, several terms

95 of the 121 manufacturers state more than one product warranty length across their own modules.

LONGi's limited warranty for Hi-MO X6 modules in the distributed generation market, dated 25 March 2024, shows how that is written down. The same document gives some model numbers (the Scientist and Artist variants of the 54-cell module) 25 years of product warranty, and others, including other variants of the same 54-cell module, 15 years. The term is attached to the model number. The brand doesn't settle it.

Two examples, chosen by rule

I picked both modules by a rule, not by brand. The first, Hyundai's HiT-H455CE-BF, is the module with the most shop offers in our live offers list among manufacturers with at least five datasheets and a median product warranty of 25 years or more. The second, JA Solar's JAM54D40-470/LR, is the one with the most shop offers from the ten largest manufacturers, ties broken alphabetically by page name. Nobody paid for a place. Each card shows only the headline figures the module's datasheet states.

Cheapest current offers for Hyundai HiT-H455CE-BF, prices read 9 Oct 2026.

Each price is the figure the shop printed, on its own side of VAT.

Cheapest current offers for JA Solar JAM54D40-470/LR, prices read 9 Oct 2026.

Each price is the figure the shop printed, on its own side of VAT.

The comparison of the two puts their product and performance terms side by side.

What this means when you buy

Use the brand to shortlist and the model number to decide. A company's median tells you where its catalogue sits; whether your module gets that term is on its datasheet and, in the end, in the warranty document for that model.

Compare the terms one at a time. If the offers you're weighing all print the same performance warranty length, that headline won't separate them, and the end figure and the product term will.

Know what a defect is not. The product warranty is about how the module was made, not what happens to it afterwards. A module dropped in handling, or hit hard enough to shatter the glass, is usually outside the terms.

Read the claim terms as well as the length. In the LONGi document, the warranty starts at delivery to the first buyer or six months after the modules leave the plant, whichever comes first. A defect has to be reported in writing within 30 days of being found, with the serial number and proof of purchase. Compensation is capped at the invoice price of the defective modules. Passing the warranty to a later owner needs written notice to the supplier, and the modules have to stay at their first site. Other manufacturers write other terms.

A claim is checked against paperwork, and the paperwork is easiest to collect on the day the modules arrive:

• the serial number of every module, before the labels end up facing the roof;
• the invoice;
• the installation date;
• the warranty document for your model number, as it stood when you bought.

The payback calculator shows how many years a system needs to pay for itself. That's the stretch to hold a 12-year and a 25-year product warranty against.

Limits of this comparison

Every figure here is our reading of manufacturers' datasheets. A datasheet can state a term that differs from the current warranty document, and the document is what binds. Terms can also vary by market, as the LONGi document's market-specific title suggests, while our catalogue holds one datasheet per product.

A company's catalogue in our data is the set of datasheets we hold, not its full product list. A company with fewer datasheets than the threshold is simply absent from the table.

And a warranty is only as good as the company that has to honour it. No datasheet field measures that.