Fire risk assessment of rooftop grid-connected photovoltaic system

The increasing global focus on environmentally sustainable energy has led to a rapid surge in rooftop photovoltaic (PV) system installations. Despite their environmental benefits, these systems pose significant fire risks. This research aims to provide critical insights into the fire risks associated with rooftop PV systems, offering valuable guidelines to enhance safety measures in the PV industry from design and installation perspectives. A comprehensive fire risk assessment of rooftop grid-connected PV systems was conducted to investigate the direct and root causes of fires in PV systems, the failure rates of various PV components, and the fire performance in terms of thermal stability of ageing materials. The work encompasses three distinct investigations. The first involves two fault tree analyses to investigate annual PV fires (failures/year) and PV-related fires (fires/MW/year), using ‘OR’ logical gates to illustrate interconnected risk factors. This analysis indicates a high likelihood of PV fire incidents, with a concerning failure rate of 0.9741 failures/year. Arc faults emerge as the primary direct cause of fires, often due to poor installation and material ageing from weathering. The analysis further establishes an annual fire incident frequency of 0.0289 fires/MW, with connectors identified as the prime components responsible for PV-related fires. Notably, 33% of PV fire incidents had unknown or unrelated ignition sources, emphasizing the importance of focusing on mitigating the consequences of PV-related fires. This quantitative analysis allows for estimating fire incidents relative to installed PV capacity, providing a more representative perspective. The second investigation involves a BowTie analysis of rooftop grid-connected PV systems. This analysis identifies the initiation of PV ignition as the top event, with four major electrical threats being identified as the key factors leading to it. A meticulous examination through event tree analysis projects 16 potential outcome scenarios. This analysis reveals a robust system design under normal operating conditions, with a high probability of all four barrier components functioning as intended. The risk evaluation reveals that electrical shock presents a very high risk to individuals in the vicinity, including firefighters. The study proposes supplementary measures, particularly for firefighters, to reduce the impact of electric shock in such situations. The third research focus is on investigating the fire susceptibility of aged polymers used in PV systems, specifically polycarbonate (PC), acrylonitrile butadiene styrene (ABS), and polyvinyl chloride (PVC). Preliminary ageing experiments revealed that ultraviolet (UV) exposure is the primary ageing factor in comparison to thermal and moisture ageing. In subsequent studies, PC, ABS, and PVC were subjected to prolonged UV exposure for periods of 4, 8 and 12 weeks to further evaluate their thermal stability as they aged. The outcomes indicate that the thermal stability of aged polymers decreases, thereby affecting their fire properties. Notably, among the materials studied, PC exhibited the highest activation energy after 12 weeks of prolonged accelerated UV exposure measuring 150 kJ/mol, followed by ABS at 124 kJ/mol and PVC at 117 kJ/mol. These significant findings establish a compelling correlation between the ageing of materials, their thermal stability, and fire properties, emphasizing the need for improved material design for enhanced fire resistance in PV systems. These findings can assist in developing mitigation strategies and enhanced fire-resistant materials for PV components, potentially enabling the design of more effective fire safety systems through accurate predictions of PV-related fires. The comprehensive risk assessment and analysis conducted in this study contribute significantly to understanding and mitigating fire hazards in PV systems, thus ensuring a safer and more reliable adoption of this renewable energy source.

Text FK 2023 35 - Declaration Form.pdf Restricted to Repository staff only Available under License Creative Commons Attribution Non-commercial No Derivatives. Download (1MB) Text FK 2023 35 - Full Text.pdf Available under License Creative Commons Attribution Non-commercial No Derivatives. Download (11MB) Text FK 2023 35.pdf Restricted to Repository staff only Available under License Creative Commons Attribution Non-commercial No Derivatives. Download (11MB) Official URL or Download Paper: http://ethesis.upm.edu.my/id/eprint/18955

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