Should the roof be replaced prior to installing a solar PV system on it…sometimes? It would not be wise to install a PV system on a roof that has only 5 years or less of life remaining. The shingles under the PV system will be protected, and age slower than others as they’re shaded from UV damaging rays. However, the rest of the roof will continue to degrade and will still need replacing. Roofers can weave around a solar roof mounted system but they will not like to and or the system can be removed and re-installed. Better to replace a worn out roof simultaneous with the installation of a solar system.