Third-party financing has become the mechanism for funding solar at the residential level in many markets. For example, third-party financed systems — which can include solar power purchase agreements (PPAs) and solar leases — are reported to have made up two-thirds of installations in the California market during the first half of 2012. The reason for their popularity? PPAs and solar leases significantly reduce or even eliminate the high upfront costs associated with solar photovoltaic (PV) systems.