Fires in PV are estimated to occur at c. 3 fires per year per 100 MW capacity installed, with connectors a significant cause. Other fire causes are the PV module itself, DC isolator switches and fuses, cables and inverters. Because PVs generate continuous current, high voltage arcs can occur and be sustained. These can be extremely hot and cause ignition of adjacent materials. Most fires are not caused by the equipment, for example inverters are generally equipped with sensors and safety features to avoid failures. Fires are however significantly caused by damage during and faulty installation, in particular loose or badly installed electrical connections, moisture ingress or by damage to cables for example by rodents. These problems are accentuated by weathering and absence of maintenance or inspections of rooftop installations. One third of fires were of unidentified cause, or cause outside the PV installation. The authors conclude it is important to mitigate consequences in case of ignition.
“Fault tree analysis of fires on rooftops with photovoltaic systems”, N. Nizam Ong et al., Journal of Building Engineering 46 (2022) 103752 https://doi.org/10.1016/j.jobe.2021.103752