As more rooftop solar arrays are installed on residential and commercial buildings, firefighters are faced with new challenges when a blaze erupts. But with the proper training and preparation, these new hazards can be safely mitigated.
A massive fire erupted in early September at the Dietz & Watson distribution center in South Jersey, a 300,000 square-foot storage facility for meats and cheeses. The roof of the warehouse was covered with 7,000 photovoltaic panels which, according to state fire marshal William Kramer, prevented firefighters from opening up the roof to ventilate the structure while posing the threat of electrocution. The result? The solar panels were blamed for the “complete destruction of the warehouse,” reported NBC Philadelphia.
Ken Willette, division manager of the National Fire Protection Association, explained that solar panels are made up of photoelectric cells and any type of light—streetlights, floodlights and even firefighter’s flashlights—can activate the panels. Therefore, electric shock is always a possibility since the panels “can’t be shut off,” Willette said.
The other main hindrance is the inability to ventilate the roof to release trapped flames and help prevent the fire from spreading. "With PV arrays now covering large areas of roofs, firefighters are limited in where they can cut and where they can exit the roof," writes San Jose fire engineer Matthew Paiss in Home Power. He cites another danger of solar panels: "Since the PV modules cannot be cut through, and moving them is time-consuming and potentially dangerous, rooftop PV systems pose some risks—mainly shock and trip hazards," Paiss said.
Despite this highly-publicized incident where solar panels complicated firefighting efforts, this occurrence is actually rare. "There are hundreds of thousands of solar systems nationwide and only a handful have been linked to fires since 1996,” SEIA Vice President of Communications Ken Johnson told The Star-Ledger. “By contrast, there have been tens of thousands of fires related to toasters, microwaves, TVs, washers and dryers, computers and entertainment equipment.”
To address the increased risks associated with fighting structure fires on buildings with solar panels, the Fire Protection Research Foundation released a 2010 study that highlights appropriate training techniques to prepare for firefighting in the alternative energy era. As soon as firefighters arrive on scene, they are advised to make the determination between solar thermal panels and solar photovoltaics as each presents a different hazard (thermal panels pose the risk of scalding from hot fluid while PV panels carry the risk of electric shock).
“During roof operations, firefighters will need to consider the additional weight of the PV array on a roof structure that may be weakened by the fire,” writes study author Casey C. Grant. “Care should be taken throughout fireground operations never to cut or damage any conduit or any electrical equipment, and they should be treated as energized at all times. One tactic for minimizing or eliminating the electrical output from a solar module is to cover it with a 100 percent light-blocking material such as certain types of tarpaulin.”
Since the National Fire Protection Association began recommending three years ago that all firefighters begin practicing new safety techniques, various trainings have been held to teach new ventilation tactics and how use water safely to combat a burning rooftop solar array.
“From a firefighting standpoint, we'll adapt," Kramer said. "We're in support of alternative energy, but people have to realize what they’re installing. Nobody thinks a fire’s going to happen in their house."