Keep in mind the reason an asphalt shingle roof ages is rain, hail, and show over time remove the small aggregate from on top of the asphalt and then the damaging UV rays degrade the asphalt product over time. Thus the shingles under the PV system will not age since the photovoltaic panels placed on top of the shingles protect the surface from erosion and from UV rays. So in actuality those shingle under the solar panels truly do not require replacement.
However, the rest of the roof does continue to degrade over time and may require replacement after the install of solar on part of the roof. There are two common ways to deal with this scenario. The least costly way is to have roofers weave the new shingles in with the old ones at the perimeter of a solar photovoltaic system. Or the more common way, especially when insurance companies are paying for the roof change, is to have a solar integrator removed the entire solar system and then re-install the solar after the new shingles are installed.
