Tactical Agility for Solar Panel Fire Suppression
By JERRY KNAPP
You are dispatched to a working house fire. As you approach the scene you see the column of black smoke. Life safety is our job so you are thinking about search and rescue as a priority. Getting that first line in operation quickly is always, always a priority to protect searchers and give trapped occupants the best chance of survival. You think back to all the drills you did stretching then repacking making sure you and your crew can do this efficiently with a simple hose load that will deliver decisive amounts of water to the seat of the fire.
As you arrive on scene what surprises you is that the house and contents is not burning but the solar panels on the roof are burning furiously. You stretch your attack line and realize, ummm….a solid bore nozzle and 600 volts of direct current are something you don’t want to mix. But….If you don’t do something soon the attic will be on fire. If it gets in the attic, what the attic fire does not damage the water damage you will do will be very expensive for the homeowner.
We know solar panels aka photo voltaic systems are in wide-spread use. Residential systems can be up to 600volts DC, clearly enough to kill us. We also know DC current causes our muscles to contract so if we contact the high voltage causing the current to continue to flow thru us. Wires running from the roof panels to the storage system or cut over panels are energized as long as there is light on the panels.
Many solar systems have battery storage systems in the garage or basement which if they get damaged can go into thermal runaway. But right now your priority is the fire on the roof. I was faced with this situation and for a few moments, well many moments really, I was without a good tactic. Standing in the driveway with a solid charged 1 ¾” line with a 15/16th smooth bore, looking up at the roof I saw the burning panels looked much worse than it really was. The panels were raised off the roof by a few inches and despite the heavy black smoke and widespread flames, there is not much mass to burn on a solar panel. The roof shingles were not showing signs of being pyrolized by the heat, not melting and seemed to be a decent fire barrier and the fire was all above it.
Reports from inside indicated no extension into the attic and the chief had ordered the system isolated using the breaker and cut over panels. What to do….Think Tactical agility.
It seemed on this bright sunny day if it rained it would extinguish the fire for us. I considered a rain dance but did not know the steps and needed to extinguish the fire sooner rather than later. So I made it rain. Pointing the nozzle up and toward the roof and burning panels I discharged water in short bursts so it rained down. Short bursts broke up the solid stream to insure I did not make a continuous path for electricity to follow back to me and ruin my day. After a couple of bursts the limited amount of fuel in the panels was extinguished. The large drops of water that came down on the flat panels spread out quickly extinguishing the fire. 180 gpm nozzle flows 3 gallons a second so a few 3 second bursts (9 gallons/ burst) knocked the fire down quickly and permanently.
New technology provides new challenges. We must use our tactical agility to overcome today and tomorrows fire suppression
needs.