Financer is probably not the correct word here. The common model around here is that an installer puts solar panels on your roof, and sells you the right to their electric output in exchange for a fixed fee (with a fixed annual increase). That is to say, the original homeowner never owned the solar panels, and so never had the right to sell it in the firstplace.

If the solar panels were financed with an unsecured loan, then the home buyer would unambigously own them. It is also possible for the lender to have a lien against the panels; which again would survive the home sale.