According to Chief Jeffrey Winward of the fire department in Lowell, Massachusetts, crews may take longer to assess a scene before going in because he'd rather see a structure burn to the ground than put firefighters at risk of electrocution.
In New Jersey, firefighters let a Dietz & Watson warehouse burn for 29 hours in 2013 rather than tangle with the rooftop array. If they had inadvertently cut through the system's conductors, solar experts say it would have been like cutting into a live wire.
These panels run DC current through an inverter, which converts it to AC power, and if your home isn't using that power, it's sent to the grid. It's rather more complex than just having the power company run a connection to your circuit breaker panel, and there's no telling where the lines are running in a rooftop solar panel system. That gives firefighters understandable pause. Depending on which lines are cut during the course of fighting a fire, "It'll melt tools, it'll kill people."
What this means is that if your house catches fire and you have a rooftop solar array, firefighters may not come rushing in to limit the damage; instead, they may simply deploy to keep the blaze from spreading and allow the house to burn. The larger the system, the higher the voltage - and the greater the danger presented to first responders.