I actually wonder how solar panels reduce the rate at which a roof deteriorates. The panels themselves should bear the brunt of the light and rain that the shingles below them would otherwise endure, but on the other hand the panels don't cover the entire roof, so maybe at best you'd need to replace less of the roof but on the same schedule.
Yeah, that makes sense to me. I don't know the specifics of shingle deterioration, but just having them physically shielded from light and precipitation has got to drastically improve their lifespan. That's a good point about only part of the roof being protected though.
The president of the roofer's lobby has entered the chat!
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.