What is the "Solar Services Model" often reffered to as a Power Purchase Agreement(PPA)?

The Solar Services model is when a building owner allows their roof to be used for the installation of a solar system. An outside party owns the system, receives the rebates and incentives, and sells the power to the host site at a pre-determined rate which is typically less than the utility price. These deals are structured to be long term agreements and are a great hedge against rising energy prices for companies that cannot afford a larger initial investment.