AND considering that replacing only the panels has to be far cheaper than the initial installation, if they do drop too much in 25 years. So long as your roof is still okay, I suppose.
What sort of roofing lasts 25 years?
Composition roofs need to be replaced when they are worn out and not before that. Good materials competently installed could last 50 years, more in mild climates. If you have the kind of weather that will wear down a roof in 10 years you probably cannot have solar panels.