Some people prefer to buy their power outright. It's not very common but sometimes people will pay cash to buy all of the equipment and labor necessary to power their home with solar..
There are numerous solar financiers. Each and everyone offers something a little bit different. Terms can range from 5-30 years. These options let you tailor the payments to fit your budget and ultimately save on your monthly power bill by owning it. Think of buying a house over renting.
This option is extrememly popular. It allows homeowners to enjoy all the benefits of solar without a financial obligation because there is no loan requirement. Very simply it provides power at a lower, consistent rate versus buying it from the electric company and their higher, inconsistent rates.