The Recognition of Fires Originating from Photovoltaic (PV) Solar Systems

There has been an observable increase in the fitting of photovoltaic (PV) solar panels on the roofs

of buildings in the UK over the last decade. The origin of some fires in domestic and commercial

properties has been attributed to PV systems. This thesis examines the ability of fire examiners to

recognise and record details of fires believed to have originated from PV systems, as well as

investigating the effect of internal heating in direct current (DC) isolators to the point at which they

fail.

National fire data was examined along with the methods for collecting and collating these data.

This clarified that national fire data cannot identify the specifics of electrical fires. Validity of these

data was then tested by identifying the confidence and competence in the recognition of the origin

of fire, (especially when associated with PV systems), of some fire staff responsible for collecting

fire data. This suggests that some fire scenes examiners are not confident in their own ability to

recognise fires originating from PV systems. Evidence for fires occurring in PV systems in Kent

between 2009 and 2014 was then examined, including a cold case forensic review of the

evidence. This provided an indication that a potential common point of failure, which may lead to

fire originating from a PV system, was to be found within the DC section of the PV circuits and

probably within the DC isolator switch itself. Experimentation revealed that internal heating of a

terminal connection can lead to changes of the phase of the insulating material, causing failure of

structural integrity and therefore allowing an arc to be established. Observable post fire indicators

associated with this mechanism of failure have been identified as well as hydrocarbons evolved

from pyrolysis of isolator insulating material.

Finally, areas for further experimental research and training of fire staff are suggested as well as

the modification of recording mechanisms and building regulations.