Dozens of solar installation companies, such as SolarCity and SunRun, have sprung up in recent years, cashing in on the solar energy wave. “Save $$! Lock in your utility rate!” Technically they are known as solar service providers.
The EPA has a web site called Green Power Partnership where it has published a summary about Power Performance Agreements. In a nutshell, PPAs are arrangements where solar installation companies rent space on residential roofs to generate power. In exchange, the homeowner gets a reduction (usually 10-20%) of their utility bill. The solar service provider owns, maintains and operates the photovoltaic installation. The homeowner pays nothing up front, so there is no capital cost outlay. Sounds like a no-brainer, right? Wrong.
More on http://www.greenenergy.money/which-is-better-to-lease-or-own-solar-panels/