"25-year warranty" usually refers to one of three different guarantees, each covering something different — worth knowing which is which before you need one.
Equipment warranty: covers defects, not performance
An equipment (or product) warranty covers manufacturing defects in the panel, inverter, or battery itself — if a component fails due to a manufacturing flaw, this is what gets it replaced. Equipment warranties are often shorter than performance warranties, commonly 10-25 years depending on the manufacturer and component.
Performance warranty: covers output over time
A performance warranty guarantees a minimum output level at specific points in the panel's life — commonly around 85-88% of original output at year 25. This is the warranty relevant to the degradation calculator's numbers; if a panel underperforms this guaranteed curve, the manufacturer is on the hook, though claims processes and remedies vary.
Workmanship warranty: covers the installer's work, not the equipment
This covers installation-related issues — a roof leak from mounting hardware, wiring errors, or racking problems — and is provided by the installer, not the equipment manufacturer. Workmanship warranties are typically shorter (often 5-10 years) and are only as good as the installer's continued existence, which matters if a company goes out of business.
Inverters and batteries have their own separate clocks
Panel warranties often outlast inverter and battery warranties significantly — see our equipment lifespan guide for how these different timelines typically play out over a system's life, and budget for likely mid-life inverter replacement even under a strong panel warranty.
Frequently asked questions
Which warranty matters most if a panel just stops working entirely?
The equipment warranty covers outright failure from a manufacturing defect — the performance warranty is more relevant to gradual output decline over time, not sudden complete failure.
What happens to my warranty if the installer goes out of business?
Workmanship warranties tied to the installer typically become unenforceable if the company closes, though equipment warranties from the manufacturer usually remain valid regardless of installer status — this is one reason installer stability matters when choosing a company.