Solar Panel Warranties Explained: Product vs. Performance Guarantees

"25-year warranty" appears on nearly every solar quote, but that single phrase usually describes two separate guarantees with different terms, different things that trigger a claim, and — critically — different companies that stand behind them.

The two warranties, and why they're not the same thing

Product (equipment) warranty covers manufacturing defects in the physical panel — things like frame failure, delamination, or junction box issues. This is typically backed by the panel manufacturer and commonly runs 10–25 years depending on the brand and product tier.

Performance warranty guarantees the panel will still produce at least a specified percentage of its original rated output after a set number of years — addressing gradual, expected power output decline (degradation) rather than defects. This is where the "25-year" figure most often comes from, and it's a production guarantee, not a defect guarantee.

| | Product warranty | Performance warranty | |---|---|---| | Covers | Manufacturing defects | Guaranteed minimum output over time | | Typical length | 10–25 years, varies by brand | Typically 25 years | | What triggers a claim | Physical failure or defect | Measured output below the guaranteed curve | | Backed by | Panel manufacturer | Panel manufacturer |

A third warranty that's separate from both: installation/workmanship

Installation or workmanship warranties — covering leaks, mounting issues, or wiring problems caused by installation error rather than the panel itself — are typically provided by the installer, not the manufacturer, and are often shorter (commonly 2–10 years). This is the warranty most likely to be affected if your installer goes out of business, which is worth asking about directly.

Questions worth asking before signing

• What is the product warranty length and manufacturer, specifically — not just "industry-leading"?
• What is the guaranteed performance curve, and does it match industry-typical degradation (commonly modeled around 0.3–0.5% per year for modern panels)?
• What is the installer's separate workmanship warranty, and what happens to it if the installer closes?
• Is the inverter's warranty the same length as the panels' — inverters commonly have shorter warranties (often 10–12 years) and may need replacement before the panels do.

FAQ

If a panel manufacturer goes out of business, is my warranty void? Often functionally yes, unless the warranty was backed by a separate insurance product designed for this scenario — this is a real risk worth asking about, particularly with newer or smaller manufacturers.

Does a longer warranty always mean a better panel? Not necessarily on its own — compare the guaranteed performance curve and the manufacturer's track record, not just the headline year count.

Do warranties transfer if I sell my house? Most manufacturer warranties are transferable to a new homeowner, but confirm this specifically in the warranty documentation rather than assuming it, since terms vary by manufacturer.

Fact-checked by Priya Nadar, P.E. Found an error? See our Corrections Policy.