In "How Furniture Design Affects Firefighting, we looked at how the spec'ing out of particular materials can cause headaches for firefighters. Now comes news of another unforeseen troublemaker in the battle to extinguish blazes: Solar panels.
Solar panels of course generate electricity, and are located on roofs. The problem is that roofs are where firefighters will typically "vent" a burning building, to release some air pressure on the fire. But smashing or cutting the holes required for venting presents an issue as firefighters can suddenly be exposed to live electricity, even at nighttime or in the absence of sunlight, from a cut solar panel. If the roof in question is metal, you've now got a live roof covered in human beings now exposed to double jeopardy.
Last week, firefighters in New Jersey arrived at the scene of a burning warehouse. Stymied by the solar panels on the roof, the building continued to burn for 29 hours while firefighters were forced to improvise. According to an article on that blaze in Reuters,
Even when systems are equipped with shutoffs, any light can keep panels and their wires energized, [Consumer Safety Director for Underwriters Laboratories, John] Drengenberg said.
...Experiments, funded by the Department of Homeland Security, have shown that the light emitted by fire equipment can generate enough electricity in the panels that a firefighter who inadvertently touches an energized wire might not be able to let go, a phenomenon known as "lock on."
What is the solution? Solar panels are only increasing in popularity and are arguably a very important key to sustainable living. And if we could figure out how to universally prevent fires, it would already be on the table. In the meantime, designers and engineers are going to have to work out some safety factors, and more importantly, begin a comprehensive education program with emergency personnel for how to safely destroy their product.
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If you ask me this is just b.s. trumped up to try create negative sentiment for solar. Instead they should go fishing off of say, Fukashima Japan.! We are living in a Fuk'ed up world where people think that nuclear is safe and solar or wind is not.
The beauty is.that there is an incredibly simple solution: electrically controlled relays that open the connections between the panels. Could easily be accomplished with products readily available to electricians.
Easy Peasy
The IEC standards for PV are already fairly severe (and in some aspects rather poorly designed standards), and as a result they are in part responsible for high prices... I'm not suggesting the standards should go, but if the wrong people get it into their heads that we need to legislate further requirements, we'll set back the agenda a bit further....
That said, as mentioned microinverters could be an option, but they are quite pricey... and reliability/affordability isn't really there strong suit right now... but it'll happen.
For the minute, we could always just roll out a big old Nomex blanket...
On the electrical safety side, microinverters are the way to go for rooftop PV systems. There is no high voltage series connection of the modules. Each module is independent of the others. One AC disconnect near the main service meter is the only requirement for electrical safety in a fire.
As far as the problem with cutting holes in the roof, well anything mounted on a rooftop presents that problem such as solar hot water or even HVAC components. Just be careful up there.
Incidentally, Why is DHS researching this instead of the myriad federal, state and private fire safety research facilities?
Incidentally, Why is DHS researching this instead of the myriad federal, state and private fire safety research facilities?
I design in the solar industry, and yes, much work is being done to adapt PV design principles to the other needs of structures, including fire resistance, and fire protection. The newest release of the 2012 NFPA 1 Fire Code contains specific guidelines for the placement of solar modules on roofs, which mostly focus on making sure there is easy access to the edges of the roof, and that there are sufficient locations for creating vents. It is based on the CAL FIRE guidelines which were put into place several years ago for California projects.
Not all jurisdictions have adopted the 2012 NFPA 1 yet, and many departments still need training on it, but it is a big step in the right direction.
http://www.ul.com/global/documents/offerings/industries/buildingmaterials/fireservice/PV-FF_SafetyFinalReport.pdf