Expected savings. This largely depends on the size of your system, how much power you use, where you live and other factors. In general, you can expect to save a low of $12,500 to a high of $49,500 after 20 years. Most solar panels last between 20 to 30 years, so you should be able to maximize your savings. The majority of homeowners will break even after seven or eight years and then the system starts paying for itself. While some factors cannot be changed, you can increase your savings by reducing overall power usage and installing a larger system that produces more power.