Just a thought - as the panels have a lot of metalwork and are
presumably at earth potential what are the added lightning risks?. Will
they "attract" lightning? If so, then should they have a heavy earth cable
into a ground rod?
Actually have a look at the mitigation measures taken in Cape Canaveral for
deflecting lightening there. T they seem to just use soem avarage looking
towers or posts with wires strung between them, and yet things still get
hit. No I think its a lot more to do with the conductivity of the air in
between one point and another and that is very random and overwhelms the
small differences in the size or earthyness of aerials and arrays.
I had the highest aerial in the area for many many years and was never
struck once, but other houses down the hill from me were so its rather like
a lottery, I never won those either.
From the Sofa of Brian Gaff Reply address is active
"DerbyBorn" < email@example.com> wrote in message
On Wednesday, July 31, 2013 9:58:29 AM UTC+1, Brian Gaff wrote:
Also the ionization of the air (leading to the conducting path and therefor
e the lightening) depends on the local field gradient. That is strongest n
ear pointy conductors, where the field lines converge, and that's why light
ening conductors often have spikes on top.
On previous house .. mine didn't vapourise instantly, it took a lot of
energy, blew the telly and burnt a large slot through the cast iron
guttering .... it had been simply run down roof tiles, & over guttering
by previous owner.
I slept through it, only found out in morning when a large part of telly
was the other side of the room.
Hardly any more then what they already are. Your average lightning
discharge has usually travelled a few miles, runs at millions of volts
and at tens of kilo-amps so a bit of wire on the roof?..
What usually happens is it will take whatever route or routes it can
find to get to ground wherever they are. TV aerials usually get
vaporised particularly the aerial cable. Bricks can be blown out of
walls, light and power circuits can be very seriously damaged and so
What a decent lightning conductor does is to SHUNT the lightning
currents past the house to Earth thus giving it a very direct path to
Normally done with a Copper or Ally earthing "tape" some 1 inch by
eighth and a few deep driven electrodes info the ground. This needs to
be a lot more substantial then the usual rod for earthing purposes. The
lightning conductor needs to be of as low impedance as possible even a
kinked bend around a gutter can present a point where the current can
After that grim diatribe you might like to read a section on the Furse
website that outlines the protection of PV systems!..
Many years ago I read that the primary purpose of a lightning
conductor was to _prevent_ lightning strikes, by in effect 'short
circuiting' the static charge building up in the cloud layer before it
gets high enough to arc to earth. Apparently the current passing in a
lightning conductor before a lightning flash can be very high, an
indication that this shorting process is happening. If the flash
actually occurs, it can be interpreted as the lightning conductor
having failed to achieve its intended primary purpose.
Having said that, I find it hard to believe that when lightning
conductors were first used, short circuiting the cloud was the
original intention. They only discovered that much later. I would
think the original intention was as you describe, to carry the current
to earth down a path that would cause least damage to the adjacent
Lightning conductors do nothing of the sort.
If you actually look at them you will see they have a fusible link just
in case they get struck.
They actually reduce the chances of being struck not prevent the damage
if they are.
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