Fire hazards on rooftops
One of the potential risks in placing solar panels on a rooftop is the possible fire hazard it creates. A commercial solar panel installation is a high-voltage system with electrical conduit typically running right on the roof deck. Ignition from short circuits or overheating in the system can be a major concern. Not only does the equipment present new ignition sources, but the solar panels can also affect the way a roof burns. On a typical industrial roof with a UL Class A rating for the roof assembly, a fire won’t spread quickly across the flat surface. Although this rating does not guarantee non-combustibility, it does provide a minimum resistance to horizontal fire spread. By adding solar panels, the roof may become more susceptible to fire and its spreading.
The spread of solar panel fires
Solar panels installed on an existing roof covering can change the way the roof burns. Solar panels typically have a flat metal bottom and are elevated on metal racks above the surface of the roof. The metal bottom of the panel reflects heat extremely well. If there is an ignition source and the roof covering starts to burn, the heat reflects off the bottom of the panel, creating a heat feedback mechanism. This allows the fire to quickly spread under the panels and across the surface of the roof.
Challenge for firefighters
Another fire safety challenge for buildings with solar panels comes after a fire starts. Many municipal fire departments will not send their firefighters onto a burning roof with a solar panel installation due to the possibility of electrical shock. As a result, firefighting is typically accomplished from a distance with hose streams from aerial ladders. Since they are fighting a fire from a distance and shielded by the panels, it can be very difficult to control the fire, let alone extinguish it.
Although there are potential fire safety dangers, this doesn’t mean that solar panels, or other alternative energy sources, are a bad idea. It is important to consider the installation process carefully, particularly for retrofit installations. In addition, the design and materials used, specifically on the roof covering, should be chosen to help keep the risk at an acceptable level.