What happens to the warranty if the Solar installer goes out of business?

There are typically two types of warranties that come with a solar panel installation:

Equipment warranties - the inverters, modules, and the racking system will have a manufacturer warranty. Panels are typically 25 years - inverters 10–25 years. If your installer goes out of business, the equipment manufacturer should/will still honor their warranty. Make sure you get your equipment warranty info from your installer when you purchase your system. It can be hard to figure out what brand of solar panel you have once they are up on the roof - they all look the same.

Installation warranties - the installer will warranty their workmanship, typically for 10 years. This should cover things like roof leaks and other damage or problems from improper installation. If you are installer goes out of business - you are pretty much out of luck on that. That is not unique to solar - applies to any trade - roofers, HVAC installers, plumbers, electricians.