Where a photovoltaic system is mounted on a roof, reference must be made to local code. In Italy, this is the "Guide to installing photovoltaic systems"
and relevant explanatory notes to the guide issued by the Italian fire service, which state that a qualified technician tasked with fire prevention is required to compile a risk assessment on the potential spread of fire resulting from the presence of the PV system.
According to the Italian fire service, there are no particular requirements for roofs when installing photovoltaic panels rated class 1 (top panel safety rating). For panels rated class 2 or higher, there is a distinction to be made: where they are installed on a non-combustible element or one with an EI 30 fire rating (such as a composite slab, screed, etc.), the roof does not require any further measures, otherwise the build-up must be rated Broof(t2) Broof(t3) or Broof(t4), according to standard EN 13505-5