Electrical wires that run into traditional solar-energy systems may present a danger to firefighters during building fire, said Patrick Chapman, chief technology officer of SolarBridge Technologies, who said they can continue to generate electricity even as a fire engulfs a building.

“When a building is on fire, one of the first things that is done is to cut power,” Chapman said. “The problem with a traditional photovoltaic or solar cells system is that you can’t turn off a solar panel. If the sun is shining on it, it’s producing power. At some point, there is power coming from the roof, down a wire and into an inverter that you can’t turn off.”

In-building electrical systems can be turned off from a single point. However, a typical solar-power system today has an inverter unit, which is a DC to AC power converter that sits near a breaker box or a service panel. It takes the power and connects it to the grid. A dangling wire can stay active even after power is cut to the building, Chapman said.

“With the conventional inverter, if you shut off power to the building you still have this live DC wiring that’s typically between 600 and 1,000 volts,” he said.

Fire chiefs leading incidents need to be aware of the risk of traditional solar systems, where there is one or more conduit of DC wiring that comes down to the service panel from the roof.

“You have to be careful when cutting lines and spraying water,” Chapman said.