OT Firemen unable to tackle fire effectively due to solar panels on roof

[harry]

They could be running at up to 1000 volts. DC Mine run at up to 750 volts. But only when the sun shines. But they can't be turned off except by covering them.

[John Williamson]

When I was working at a filling station a long time ago, I was told that the fireman's switch cut power to the whole of the forecourt. So, pumps, lights and any other stuff outside the main building. Basically, anything that could cause a spark in the area of the pumps.

[harry]

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The panels always generate in sunlight. You can isolate them but not shut them down.

[ARW]

Would it surprise you that pub beer cellars seem to have more stringent electrical regs than a petrol station?

[polygonum]

Never seen a beer cellar at a petrol station...

Oh! I see what you mean. :-)

[Mr Pounder]

Yes. Tell me about it.

[Martin Brown]

Dunno. I'd want some kind of isolator. Water and electricity don't mix!

That or a Woods metal fuse that melts and breaks the circuit if it gets too hot. A single panel on its own doesn't pose any threat apart from mechanical as a slip/trip hazard or if it falls off the roof.

I believe they have analysed the potential risks in detail but I don't know what they concluded. Much of what is out on the web is specific to US building codes and being wooden they go up like matchwood!

[The Natural Philosopher]

I am fairly sure a sledeghammer would turn them off..

[PeterC]

Nowadays the firemen need some way of dealing with this problem - I wonder if spraying with a thick layer of foam would work.

[polygonum]

And might cause a bit of broken glass...

Hot topic: lessons on reacting to a solar panel fire By Greg Spanoudakis |

10 April 2012

"One simple first step is to inform the local fire department that your building has been fitted with solar modules. Often, firefighters only learn that the building is equipped with a solar system when they arrive on the scene. This is a problem because solar rooftop installations demand a different approach both in terms of safety and because traditional extinguishing methods do not apply to electrical systems. Not only does the rooftop position, risk of falling glass and slippery surfaces of the modules need to be considered, but so too does the system?s high DC voltage."

Has everyone here with solar panels informed their local fire people? What would the fire people do with the information?

[Tim+]

Put you on the fireman's equivalent of the "do not resuscitate" list? ;-)

Tim

[Andy Champ]

At first sight, I thought don't be silly.

But on second thoughts - do you mean really opaque, sticky foam? That would leave the panels in darkness?

Andy

[polygonum]

With the dangers involved, I wouldn't blame them. Sounds a bit like using a defib without shouting "Clear!".

[Andrew Gabriel]

and they're not rated for 1000V DC.

There are solar panel versions with remote switching

but I don't know if UK fire authorities will recognised them.

[newshound]

I was originally assuming that the sort of stuff they spray on crashed planes would do the job but, on reflection, although it would catch all the IR it would probably still let perhaps half of the shorter wavelengths through. I expect Martin will be along in a minute with a definitive answer.

[harry]

They still work with a thin layer of snow. A thick layer of snow shuts them down.

[harry]

The idea put forward at the link is drivel. The panels are still generating however isolated.

A slight danger arises if water is sprayed on them of electrocution. The danger is slight because they are weather/waterproof as is all the wiring and connections. This would only be damaged if the roof was already seriously on fire.

There are no other hazards. Certainly nothing to stop them entering a building. If they shut off the main electric supply, the inverter would shut down. The wiring from the panels to the inverter would still be live in daylight. There might be a case for using say MICC cable for this wiring.

The only other thing that could be done is to break up the "chain" of panels. The individual panels only run at 30 or 40 volts.

[harry]

Just looked at the video on that link. Absolute drivel. But American, what do you expect?

All solar panel in the UK are already fitted with an isolator. But it doesn't cure the problem discussed here.

[Andrew Gabriel]

It should not be impossible to come up with a suitable product. A foam with an opaque black dye and something to make it stick to inclined self-cleaning glass and stay there in a fire, and nothing flammable in the propellent or foaming agent.

The trouble may be that application of such a product may render the house beyond viable repair, in which case it may not save much over letting it burn to the ground as seems to be the norm around the world for solar panel homes at the moment, after rescuing anyone inside.

When I was holidaying around south of France in 1970's, I saw

3 solar furnaces, the two larger ones being hillsides covered in large moving mirror arrays which focused the sun on a point to generate lots of heat, which was used in various ways to generate electricity (or just to melt things for fun, such as car engine blocks). When I first saw the mirrors, my thought was, what do they do if the mirror array loses power and can't keep the sun focused on the right spot? When I saw the target, it became obvious there was no such protection - burn lines all over the concrete around it where the mirror array had obviously got stuck and the sun's focus moved off target. I thought at the time a simple drop-down roller blind at the top of each mirror would solve that problem. The same goes for solar panels.

Another option might be to short out the solar panels in an emergency so there is no high voltage (just high current). However, a number of existing installations have caught fire due to the connection resistances in the junction boxes at nornal operating current, and that is very much more likely to happen when the array is shorted out.

[Ian Jackson]

Is that why beer's more than twice as expensive as petrol?