The best solar inverters should last between 10 and 20 years, but it can be less or more than these numbers as well. The lifespan of your solar inverter will depend on the conditions and humidity it is exposed to and how often it is in use. If you need more power from it, it might mean that it will be replaced sooner. A good way to ensure a longer lifespan for your solar inverter is by purchasing a high-quality one with a good reputation and warranty.