Until 2008, if you wanted to power your house with solar electricity, you had to purchase the equipment yourself. This could cost between $20,000 and $30,000. In 2008 companies like Sunrun (a Clarus Power partner) invented solar-as-a-service- they purchase the system for you, have it installed on your roof and you simply purchase power under a long-term (twenty-year) agreement.
In some markets (depending on regulatory requirements) that long-term agreement is a Lease and in some markets it is a Power Purchase Agreement (PPA). Under a Lease you “rent” the equipment from the solar company and under a PPA you purchase all of the electricity generated by the solar panels.
In both instances, it often requires no upfront investment (that’s right, it’s $0 down!), generates 20% savings on your electricity bills, and comes with free maintenance and monitoring for the term of the contract.