Real data from the field tells us that 25 years is a low-ball conservative number. The oldest in continuous operation PV plant still running on the panels installed over 40 years ago still operates at well over 80% of fresh efficiency.
And PV tech has only gotten better and more durable.
Modern PV panels are sold with warranties of 30 years or longer on maintaining over 80% of their fresh conversion efficiency.
So yes, it's been accounted for.