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

摘要

There has been an observable increase in the fitting of photovoltaic (PV) solar panels on the roofsudof buildings in the UK over the last decade. The origin of some fires in domestic and commercialudproperties has been attributed to PV systems. This thesis examines the ability of fire examiners toudrecognise and record details of fires believed to have originated from PV systems, as well asudinvestigating the effect of internal heating in direct current (DC) isolators to the point at which theyudfail.ududNational fire data was examined along with the methods for collecting and collating these data.udThis clarified that national fire data cannot identify the specifics of electrical fires. Validity of theseuddata was then tested by identifying the confidence and competence in the recognition of the originudof fire, (especially when associated with PV systems), of some fire staff responsible for collectingudfire data. This suggests that some fire scenes examiners are not confident in their own ability toudrecognise fires originating from PV systems. Evidence for fires occurring in PV systems in Kentudbetween 2009 and 2014 was then examined, including a cold case forensic review of theudevidence. This provided an indication that a potential common point of failure, which may lead toudfire originating from a PV system, was to be found within the DC section of the PV circuits andudprobably within the DC isolator switch itself. Experimentation revealed that internal heating of audterminal connection can lead to changes of the phase of the insulating material, causing failure ofudstructural integrity and therefore allowing an arc to be established. Observable post fire indicatorsudassociated with this mechanism of failure have been identified as well as hydrocarbons evolvedudfrom pyrolysis of isolator insulating material.ududFinally, areas for further experimental research and training of fire staff are suggested as well asudthe modification of recording mechanisms and building regulations.