Solar Panels

[westie101]

This report is interesting and possibly something not really thought through.

Even disconnected from the mains the output of any solar panel will always be live (except when it is dark) and needs consideration!


http://www.sunshinecoastdaily.com.au/news/school-blaze-probe-delayed/2354692/?ref=hs

SOLAR panels on the roof of the fire-damaged Bli Bli State School were a roadblock for investigators looking into the cause of Friday night's blaze.

Unable to enter the building until power to the solar panels was cut

 

[ban-all-sheds]

"Unable to enter the building until power to the solar panels was cut"

The power to the panels comes from the Sun.

Not much they can do to cut that other than a large blackout awning or putting the Sun on the other side of the Earth....

 

[ericmark]

We rely on the inverter shutting down and with a fire the inverter I suppose could become damaged in a way which prevents it shutting down. Also of course cables between panels and inverter are always live.

There are now strict rules on how inverters must auto shut down but there must be some which slip through. In the UK in order to get the government payout the panels have to be installed by registered installers but without that payout I am sure there would be more DIY and use of non approved inverters.

It would be interesting to know why the inverters did not auto shut down? Since in USA it could of course be the only source of power and may have not been using grid tie inverters.

 

[JohnD]

Friday night's blaze.

The sun might not have been shining on Friday night.

 

[bernardgreen]

The sun might not have been shining on Friday night.

But it was on the Saturday when the forensic team were ready to examine the building.

A fire fighter friend tells me that solar panels present significant hazards to fire fighters due the inability to shut them down. With a panel capable of delivering several kilowatts into fire damaged cable / equipment there is a significant risk of electric shock and / or re-ignition of the fire.

 

[ericmark]

Friday night's blaze.

The sun might not have been shining on Friday night.

Would the fire light cause the panels to give an output?

 

[ericmark]

The sun might not have been shining on Friday night.

But it was on the Saturday when the forensic team were ready to examine the building.

A fire fighter friend tells me that solar panels present significant hazards to fire fighters due the inability to shut them down. With a panel capable of delivering several kilowatts into fire damaged cable / equipment there is a significant risk of electric shock and / or re-ignition of the fire.

I have seen where there is a danger to the fire fighter fires are just left to burn themselves out. Does having solar panels fitted mean that the fire fighters will just stop the fire spreading and no try to save the house. This is rather worrying.

 

[AdrianUK]

I did find a report, done by UL in the US, about such risks to firefighters.

They conducted some quiet extensive tests, trying different methods to cover the panel or to try & isolate them, with some quiet frightening results.

Even trying to sever the cable between panels & the inverter is not without danger - a solar panel will quite happily drive its rated current into a short circuit indefinitely

the When I'm back at work tomorrow, I'll try to append a link to that report.

Here is the link: http://site.ul.com/global/documents...rials/fireservice/PV-FF_SafetyFinalReport.pdf

Adrian

 

[Adam_151]

I would have thought that if fire crew could cover the panels over with a spray of foam then that might be the best way to make safe.

Of course the solar edge system is better, panels normally have a voltage of 40v ish and connected in series to give voltage sin the range of 300v-800v seen at inverter inputs, With the solar edge system, each panel + and - are connected to a control module behind the panel and the modules are in series. No voltage comes out the string until the modules are instructed to bring the panels into circuit. When the power to the inverter drops out, the signal drops and the string circuit is broken and there is no voltage over 45v anywhere. The modules are expensive and the inverter costs more however it is more efficient as shaded modules can be compensated for and no longer affect the current flow through the whole string etc.

 

[AdrianUK]

I would have thought that if fire crew could cover the panels over with a spray of foam then that might be the best way to make safe..

The UL reported suggested that spray foam was next to useless & any effect that it did have had 'worn off' in under 10min as the foam thinned & dissipated

 

[Monkeh]

Just read that report, quite interesting, but mostly expected results.

http://site.ul.com/global/documents...rials/fireservice/PV-FF_SafetyFinalReport.pdf

The only sure way to make a solar panel dead is a 100% light blocking tarp.

 

[JohnW2]

The only sure way to make a solar panel dead is a 100% light blocking tarp.

I imagine that there is some scope for similar issues to arise with other forms of 'unstoppable power' - e.g. large banks of batteries, or even wind/wave/whatever generators if things go wrong and one can't 'deactivate' them? (and I won't even mention nuclear power ).

Kind Regards, John

 

[bernardgreen]

It does seem a light proof cover is the only way to ensure a solar panel is shut down.

Even a 40 volt 250 watt panel would be a hazard if its lead out cable was damaged. 250 watts concentrated into a few inches of damp charcoal ( after the fire has been put out ) will create an ignition source to restart the fire.

Many places have a fireman's switch that turns off the supply to things like petrol pumps and illuminated displays. Maybe something similar should be built into solar panels.

 

[EddieM]

The only sure way to make a solar panel dead is a 100% light blocking tarp.

I imagine that there is some scope for similar issues to arise with other forms of 'unstoppable power' - e.g. large banks of batteries, or even wind/wave/whatever generators if things go wrong and one can't 'deactivate' them? (and I won't even mention nuclear power ).

Kind Regards, John

You can shutdown nuclear reactors, indeed modern ones have to be "encouraged" to keep going.

 

[JohnW2]

You can shutdown nuclear reactors, indeed modern ones have to be "encouraged" to keep going.

One can, provided the control systems are intact. I presume that can get rather more difficult if the control systems have been damaged or destroyed by fire - is there a 'manual' way of doing it. In any event, as I said I "wasn't mentioning" nuclear power

Kind Regards, John