FOCUS
PV panels
always be treated as ‘on’. A metal roof may become energised even with all switches turned off, if there is damage to the cells or associated wiring.
Fire spread
From a firefighting standpoint, the cell installation simply prohibits the proverbial ‘chop a hole in the roof’ method for ventilation. However, as solar panels typically occupy only one side of a peaked roof – depending upon latitude and longitude – ventilation could be accomplished safely. It is a physical and economic problem,
and likewise – in many cases – the cell assemblies are mounted on ‘standoffs’ between the roof surface and the cells. This allows any fire breakthrough into a roof to spread laterally and is generally inaccessible, similarly to a metal roof assembly. In addition, the cell assemblies themselves may contain plastic and other combustible materials that will generate flame, heat, smoke, and toxic products of combustion. Furthermore, the fire spread (flame
spread) of assembly materials is an unknown. Whether fire exposure is from the underside, or is a roof or wildland fire, the solar cells will burn. Tests such as ASTM E108 and UL 790 have evaluated the fire spread properties of these assemblies, and the results of many such tests can be found on the internet for specific jurisdictions.
44 OCTOBER 2019
www.frmjournal.com
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