Through 2033, those who install solar on their homes will get a 30% credit on their Federal taxes. This is a nice incentive that makes solar affordable. Homeowners are in no way obligated to spend the money on their solar system, but the credit is structured to help them do just that.
For more information on this credit, how it works and who qualifies, see the following link to the Dept. of Energy web site: Homeowner’s Guide to the Federal Tax Credit for Solar Photovoltaics