Until several years ago, most residential photovoltaic (PV) systems were purchased. Because of the upfront cost (and because solar systems were more expensive back then), there was a very limited pool of potential solar system owners.
Around 2008, solar leases or power purchase agreements started growing in popularity. This was a game changer in the solar world, because it helped remove financial obstacles. Suddenly people could have solar on their homes for as little as no money down, and often pay less each month for their electricity.
In the last couple years, solar loans became available with more appealing terms. Suddenly people could get a relatively low interest loan with a 20-year term. This again can be a game changer for the industry because the loan payments are in many cases less than the reduction in the electric bill.
So you may wonder, is it better to lease or own. Of course the answer is: it depends.