Atlantic Cities reports:
A 300,000 square foot refrigerated warehouse in Delanco, New Jersey, burned down last week, and the local fire chief says solar panels are partly to blame. No, the 700 solar panels on top of the Dietz & Watson warehouse didn’t cause the fire, but their presence did dissuade Delanco Fire Chief Ron Holt from putting his team on the roof. “With all that power and energy up there, I can’t jeopardize a guy’s life for that,” Holt told NBC Philadelphia. The only thing firefighters fear more than fire is solar.
So long as a solar panel is getting sunlight, it’s impossible to turn off. “During daylight, there can be enough voltage and current to injure or even kill a firefighter who comes in contact with the energized conductors,” Matthew Paiss, a fire engineer with the San Jose Fire Department, wrote in a handy guide for firefighters. The Dietz & Watson warehouse fire started when the sun was out. By the time the sun went down, the fire was beyond control. The warehouse burned for 29 hours.
As Paiss explained in his essay on solar panels and firefighting, roof access is crucial for firefighters…
It’s kind of the opposite of a fuse. The emergency circuit shorts the outputs right at the panel. Even though the panel is still active, it cannot build potential. The charges will always take the lowest resistance path to return and the shorting circuit is that path. The big difference between a panel and a battery is that most batteries are capable of overproducing and therefor overheating when shorted, The panel’s output is limited by the sunlight hitting it and won’t overheat.
I’m not meaning the output. The cutoff would have to break or short-circuit the actual generation circuits, preventing any buildup of charge. It would be a true lockout fuse. If I recall my electrical class (sorry, I was a Chem-E, so that was a long time ago), it can be done fairly trivially.
No, the panel is generating electricty, think of playing with a big battery. Refiting/retrofiting existing systems, find something that works with existing systems. Also, there are different type of systems even now. Some panels produce DC power wires out, others have microinverters so the panel produces 110/220 volts AC wires out. The solar cells inside the panels produce electricty when enough sunlight falls on the cell, again think like battery cells with a charge. Systems installed today do have cutoffs, but those switched are not right at the electrical source which is the panel. Even if you installed a fuse at the panels output wires. The panel will have electrical potential in sunlight.
The best idea would be an automatic thermal cut-off, which acts like a fuse to cut off the power generation when the temperature rises above 150 or so. Probably a ground-based switch to cut off all at once would be best.
I’m not saying it can’t be done, I was just pointing out that your idea wouldn’t work due to the length of time involved in which no actual firefighting could be done.
Remember firefiters do walk on the roof of burning buildings to chop out the burning section.
Shoot/throw non-conductive line(s) across roof and pull cover across. The cover idea works better on smaller arrays like on a house.
Use foam like they use at airports etc. to cover all the roof and panels. Or spray a sticky form/paint that can cover the panel and block electric production.
Start people thinking of ideas and teach/share with the firemen the best practices.
OK John, You walk up onto the tar roof of the burning building and put covers on each and every individual solar panel. Remember, no water can be sprayed until all panels are covered and have discharged all of their power.
Still sound like a good idea?
I say mandatory safety measures that price them out of the market are in order.
Now that they are an “industry”, they are just as evil as other profit seeking concerns.
Solar panels make electricty when sunlight falls on the panel. Anyone with solar PV could keep traps to cover the panels and block the sunlight. Blocked sunlight means no electricty probuced.
This problem is easily overcome by way of a fail-to-safe shorting circuit at the output of each panel. Of course that’d increase the cost of the panels which would impact the already questionable efficiency of the system. Also, firefighters couldn’t be expected to know which systems are safe so older systems would probably have to be retrofitted or removed. Despite my complaings about all the wrong-headed federal regulations polluting our country, electrical safety standards are actually pretty sound.