When it comes to large solar energy installations in the commercial, institutional and industrial sectors, rarely are the solar panels and the host building owned by the same entity.
In other words, say Walmart installs solar power atop one of its stores. Instead of going it alone and owning the system itself, the retailer instead contracts with one or more other companies to get the project done. A solar company may design, install and maintain the system, which may actually be owned by, say, a third-party financing firm. Walmart, for its part, simply agrees to purchase the system's electricity output at a fixed rate for a specified term.
This arrangement -- and variations thereof -- is commonly called a power purchase agreement (PPA).