Photovoltaic panels on the roof: what the P 118 fire safety standard requires

Installing photovoltaic panels on a house also comes with fire safety conditions, not just technical ones. The P 118 standard covers them in art. 2.4.18. In terms of permits, the Planning Code (Law 169/2026, art. 299 para. 2 letter a point 13) allows prosumers to install them, outside protected built-up areas and monument protection zones, without a building permit, after notifying the local authority in advance, on a structure that can carry the loads. This does not exempt you from the rules below; see also the article on works with no formalities.

A house with one or two storeys (art. 2.4.18.4)

• on roofs with more than two slopes, on each slope a clear space of at least 1 m is left from the external load-bearing walls, at least 1 m from the ridge and at least 50 cm on each side of a valley or dormer;
• on each slope with modules, two access paths at least 1 m wide and at least 1 m from the ridge are provided.

Buildings with three or more storeys and other uses (art. 2.4.18.5)

• a clear perimeter at least 1 m wide around the edges of the roof;
• at least 2.5 m around skylights, ventilation or smoke vent hatches and other roof penetrations;
• at least 4.00 m from fire walls separating fire compartments;
• the photovoltaic array is interrupted at settlement-expansion or seismic joints, in strips at least 1 m from the joint;
• groups of cells of at most 40 m x 40 m, at least 5 m apart.

What the roof and the façade must meet

• photovoltaic devices on the roof are considered roof components and must resist ignition or the spread of fire from an external source (art. 2.4.18.3);
• on façades with photovoltaic devices, the thermal insulation and composite insulation systems must be non-combustible, and the anchors and fixings non-combustible, with equipotential bonding and earthing (art. 2.4.18.8 para. 1 letters a-c);
• the layer on which the devices are fixed on the roof must meet the external fire performance in Tables 2 and 3, and the one on the façade at least EI 30 (art. 2.4.18.8 para. 1 letters d and e).

Recommendations for firefighter safety (art. 2.4.18.6)

• access to and escape from the roof, with easy routes to the roof areas;
• visible marking and labelling of the whole system (main switch, cables, inverters, distribution boards, batteries), with reflective, weather-resistant and recyclable materials;
• an easy-to-operate load-break switch;
• an arc fault detection device.

Firefighters treat fires in photovoltaic devices as fires in electrical equipment (art. 2.4.18.7). For solar water-heating collectors mounted on a building, measures are taken to limit the spread of fire through openings in the roof or walls (art. 2.4.18.1 para. 3).