Date: Mon, 05 Jan 2009 16:07:58 -0500
From: Nicholas Ponzio <npon...@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
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