Fire Protection Research Foundation report: "Development of Fire Mitigation Solutions for Photovoltaic (PV) Systems Installed on Building Roofs - Ph. 1" (PDF)
Author: Joel Sipe, Ph.D., Exponent
Date of issue: July 2016
Introduction
The installation of large PV systems on commercial building roofs is an emerging risk due to a favorable value proposition attracting building owners to install the technology. With these systems, the likelihood of a rooftop fire significantly increases since electrical breakdown – leading to arc faults, ground faults, and short circuits - can occur anywhere across the system. Any electrical fault can be accompanied by ensuing fire.
The rooftop placement is beyond the building fixed fire protection and detection features. This can mean delayed fire detection and no fixed fire protection. In addition, combustible features of the module and other components add fuel to support a fire. Where a fire develops below PV modules, the modules will reflect heat from a fire back down towards the roof enhancing the combustion rate of conventional roof materials. Roof assemblies traditionally considered “noncombustible” become combustible or fast-burning.
With these types of systems, the fire service takes a cautious approach as power generated by the panels cannot be turned off. Even at night, fire service scene lighting has been identified as sufficient to generate an electrical shock hazard. Defensive fire service actions – spraying water from a distance - have been found to have reduced impact as the PV panels conceal and shield the fire below.