Since a solar PV system is made up of panels that have a sturdy tempered glass surface (naturally sheds water and dust) mounted 4" to 8" above the roof to prevent debris from building up underneath, they’re generally maintenance free. However, for maximum efficiency, it is recommended to wash the face of the PV panels at least once a year.
A solar PV system that tilts the panels to track the sun in order to optimize energy production has motors that will require regular maintenance.