Mike Holt Enterprises Electrical News Source

Fire Mitigation Solutions for PV Systems Installed on Building Roofs

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This month we'd like to bring your attention to a Fire Protection Research Foundation report on the NFPA website, called Development of Fire Mitigation Solutions for Photovoltaic (PV) Systems Installed on Building Roofs - Phase 1, authored by Joel Sipe, Ph.D., Exponent.

The 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.

Visit the NFPA website here, or click on the image, to read the report.

Comments
  • Just heard this morning about a book called "The Death of Common Sense". This article made me think of that book. Below PV modules there is air. Maybe we need more real life data first; not sure an air fire is a concern. Also there have always been other systems on roofs, with higher voltages. I suggest a camera pointed at the array, good for security and fire and maintenance.

    larry nowers  April 18 2018, 12:22 pm EDT

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