The solar panels we sell are always warranted by the manufacturer for 25 years — with a production guarantee that ensures the panel will be replaced should its efficiency degrade beyond the limits defined in the warranty. That means if the panel doesn't produce properly, it would be replaced if the warranty is still in effect.
If a solar panel is damaged by an external blow, such as a tree branch in a severe storm, the damage would be covered by the owner's insurance policy that covers the property.