In fires that BRE has been informed of where the PV systems have been
the cause of the fire, these fires have generally resulted from poor
installation or the use of wrongly specified, incorrect or faulty
equipment. Specifically, there have been reports of installations of AC
isolator switches being used mistakenly in DC circuits resulting in a
build-up of heat within the switch enclosure and leading to a fire.
Other incidents have resulted from the use of faulty inverters or faulty
DC switches or the absence of isolator switches. Any switching or
connection faults on the DC side of a system can result in the
generation of a high temperature arc or high resistance fault which
could start a fire. DC arcs can be difficult to extinguish and pose a
risk to fire-fighters attempting to suppress the fire.
Current MCS guidance [ref. 5] for the installation of PV systems
recognises the potential risks from fire and includes some
recommendations for prevention/mitigation of these risks, although
further guidance is a topic still under discussion within MCS. Clearly
good design and proper routine testing, servicing and maintenance are
essential for risk management.
In the event of a failure of the AC supply to a building, (for example
due to a local power cut, or a fire) the inverters are designed to shut
down automatically. However, the solar DC supply (from panels to the DC
isolator) will still be live during daylight. It may therefore still be
necessary to manually isolate the DC cables and components from the PV
panels which will otherwise remain live.
If a fire damages the DC cables from the PV array, for example by
burning off insulation, then there will be risk of electric shock from
the exposed DC conductors, in particular to fire-fighters.
Poorly installed panels may obstruct or restrict use of roof windows as
means of escape.
Concernshave been raised regarding the presence of heavy metals within
some specific types of PV cells, and whether such metals can be or are
released during a fire [e.g. ref. 15]. Therefore, while such risks are
considered to be low, caution is needed, as with any fire involving
electronic elements, in dealing with fire damaged components and
residues since a variety of heavy metals and other toxins may be
Many PV systems feed energy into the electricity grid at times when it
is not required by the building. Reports are now indicating that, where
such a feed in is occurring from a number of distributed sources, this
can cause voltage fluctuations in the grid. Fluctuations are known to
have the potential to cause fires in sensitive equipment, such as
More information available here at the BRE website