Solar installations come with three warranties: product warranties, power production warranties, and installation warranties.
Product warranties guarantee the physical integrity of your solar panels and inverters. For example, should a soldered connection on one of your panels fail (adversely affecting its electricity production), that panel would be replaced under the product warranty. Product warranties are offered through the manufacturer, not your installer.
For solar panels, most manufacturers offer a 10-year product warranty. Some high-end panel manufacturers offer longer product warranties, up to 25 years. Inverters come with product warranties that range from 10 to 25 years. Central (or string) inverter manufacturers offer 10- to 15-year product warranties, while microinverter manufacturers offer 25-year product warranties.
Next, the power production warranty guarantees that the solar panel will produce at least 80 percent of its nameplate capacity for a minimum of 25 years. Just like the product warranty, the power production warranty is offered by the panel manufacturer. While details vary from manufacturer to manufacturer, the power production warranty assures that your system will continue to produce power over its lifetime. In practice, identifying whether your system is experiencing a drop in performance that violates this warranty is difficult without the assistance of an installer. Despite that, production warranties serve as a proxy for the expected performance degradation of your solar panels over time.
Finally, the labor warranty covers the installer’s workmanship, including their electrical wiring work and any roof penetrations they make to attach your solar array to the roof. Unlike the product or power production warranties, the labor warranty is offered by your installer. Labor warranties vary among installers and regional markets. That said, they typically range from three to 10 years. Some installers will offer an option to upgrade to a longer labor warranty.