[RE-wrenches] fire safety vs. fire hysteria?

[boB Gudgel]

> Date: Mon, 05 Jan 2009 16:07:58 -0500
> From: Nicholas Ponzio <nponzio at buildingenergyus.com>
>
>
> I just got this email forwarded from a coworker that volunteers as a
> firefigher. Your comments are welcome:
>
>   
I agree that fire access may be restricted, but a bunch of this report I 
would say is definitely hysteria..

> Forwarded Message:
>
> The thing to know with solar panels are that they cannot be shut down -
> they are ALWAYS ENERGIZED.
ALWAYS energized ?  REMOTELY possible at night if something is 
backfeeding I suppose.
>   And they are energized with up to 600 volts
> of DC current.
    600 Volts of Current, eh ?


>   For example, you cannot put an ax through them to open
> up a roof to vent - your putting the ax through 600 volts.  If fire is
> infringing upon solar panels on the roof it will compromise the
> integrity of the panels.
I suppose if the one or a few panels is more important the the whole 
house...

>   You then have 600 volts of live electrical
> energy - and what don't you do when you have live electrical energy? -
> you don't put water on it.  Even if the roof burned through and the
> panels fell into the structure, unless the panels were destroyed
> (de-energized) by the fire and/or falling into the structure, they can
> still have the potential to be live,they  have to be treated as such and
> have the potential of 600 volts of DC current.
>   
I don't think you would have 600 Amperes of Voltage after the panels 
have fallen through the roof, would you ?
Doesn't fire shade modules ?

> A basic solar system consists of:  The solar panels themselves; a
> combination box; a disconnect box; and a inverter.  The panels all feed
> into a combination box.  The combination box (which is almost always
> located on the roof) takes in all the energy and sends it to a
> disconnect box.  The disconnect box takes the energy and then sends it
> into the inverter which converts the DC current into AC current.  From
> there the AC energy "pushes" into the structure's normal electrical system.
>
>   
Something that could be done is to short out the array at the box (Break 
before Make of course)

> The combination box has fuses in it that come from the solar panels
> themselves.  If you access that box, you can pull all the fuses inside
> and "kill" anything after the combination box.  But remember the panels
> are still live and have up to 600 volts in them.  If you "kill" the
> energy at the disconnect box - anything up to that box is still
> energized - the solar panels, the combination box, the line going from
> the combination box into the structure and into the disconnect box are
> all still energized.  The power company pulling the meter for normal
> service has no effect whatsoever on the solar panel system - it is all
> still live and has up to 600 volts of DC current.
Third time's a charm...   Is that 600 AC volts of DC current or the other way around ?

>   The only "good" thing
> when it comes to the disconnect box and the inverter is that they need
> to be co-located with the normal service panel for the structure and
> each should be marked as appropriate.
>
> Even if it's nighttime and the solar panels have not been exposed to
> direct sunlight for several hours, they still are energized and can kill
> you.  It is estimated that the panels would need to be covered with an
> opaque tarp for 7-10 days before the panels will "de-energized" down to
> minuscule levels. 
OK, I'm starting to think that this letter belongs on SNOPES.

>  (although the handouts specify that this is an option
> for safety steps - it is not accurate per the presenter)
> In closing there are people who have greater minds and resources than we
> do in developing a process to safely handle fires which may involve
> these systems - such as the NFPA, OSHA, etc.  Per the presenter, the
> situation - and these organizations, are now starting to become aware of
> the potential problems.  So far in the State of NJ, there is no recorded
> injury to a Firefighter being caused by coming into contact with a solar
> panel system.  Ironically, New Jersey comes in 2nd when it comes to
> solar panel system installations in the nation, behind Califorina.
>
> The final question which was asked really put things in prospective -
> someone asked that since Califorina is number one when it comes to Solar
> Panel Syatem installations, "...what do their Firefighters do when a
> structure fire involves these systems?"  Answer was "... they let it burn!"
>
> Please, I'm not suggesting that we adopt this strategy.  But the reality
> is - I really don't have an answer and it seems as if the Fire Service
> industry, nor the Solar Panel Companies, don't either.
>
> Just - please be aware and please be careful if you roll up to a
> structure where a solar panel system is installed - bottom line, if can
> kill you.
>
>
> <End Forwarded Message>
>
> Is this even possible? "Even if it's nighttime and the solar panels have
> not been exposed to direct sunlight for several hours, they still are
> energized and can kill you.  It is estimated that the panels would need
> to be covered with an opaque tarp for 7-10 days before the panels will
> "de-energized" down to minuscule levels. "
>
> And are there documented cases where firefighters let a house burn
> because it had PV on the roof?
>
> Thanks again,
> nik
>
>   
This sounds reminiscent of  those first letters regarding  NEC Wind  in 
the state of Washington from L&I.

I think they really need to re-think their wording just a little bit.

Merry New Year !
boB