"Deals" with solar panel companies often tie the householder to a 25 year lease. In effect, someone else "owns" a bit of your roof.
Many mortgage companies won't go near this arrangement, especially when it comes to resale or re-mortgaging.
The alternative is a sort of government subsidy (feed-in tariff.)
But... this has been cut over the years, until it's barely worth the bother.
So much for encouraging efficiency and renewables :o(((