I noticed that the Xantrex Warranty does not cover voltage surges from lightning strikes. I imagine this is typical of any inverter manufacturer warranties.

Does Xantrex or anybody else have specific recommendations regarding surge arrestors? I know many installers have used the Delta SOV arrestors, but a Home Power #107 article implied that their UL listing had been pulled. I called Delta and they said their products were "UL Recognized" implying that the lack of UL listing was due to the applicable UL standard being rewritten.

I live in Southern California where lightning storms are rare but inspectors check to make sure every panel is grounded, so a PV Array is a pretty good sized grounded conductor on the roof that would seem to be vulnerable to all kinds of voltage surges.

Any info or recommendations would be appreciated.

Anyone heard or tried the "porcupine" style of charge bleeders ?

no good here: http://www.kn4lf.com/kn4lf60.htm

but others swear by them here: http://porcupine.w4zt.com/


and a quote:
"Absolutely, when you hear thunder ground out your antenna(s) unplug your radio station equipment and leave the radio shack. Secondly, no matter how much lightning protection and grounding you have implemented it's probably not enough."


http://www.lightningsafety.com/

mike,
though i agree that a porcupine could draw off a lightning attack, if you will forgive the terminology, but most inspectors will not recognize this as adequate protection for one's solar setup. if the lightning where to hit the porcupine instead of the pvs, the emp would still be impressed upon the solar setup so more than a porcupine and a good ground wire is needed for some means of stopping it is still warranted. a gas discharge protector may be acceptable to them if the lightning is minimal in the area as was said. there are no guarantees, but they aren't looking to guarantee no damage, but adequate efforts in its suppression or prevention.
though he made no mention of radio equipment that i saw, my using a further analogy to describe why the porcupine is not enough would be like me saying i have a 100ft tree next to my house that goes 60ft higher than my antenna so i won't need any precautions in grounding or suppression efforts for my antenna or solar setups. that would be 100% wrong and it could be said the tree and the porcupine could draw the lightning to the area putting the equipment at risk that way too. i do believe small charges are dissipated by such a device and could reduce the chance of a full strike, but in the event of a full strike it may go straight to the porcupine rather than a quarter mile down the road too.
henry,
yes, i remember our discussions on this and i would expect you to throw in your 2 cents, but i don't think he will be able to convince his inspectors of your argument against grounding the pvs.
also, i have made mention of using diodes as a means of sending higher surges to ground in the past. i've not heard it mentioned anywhere else, but a diode does have a reverse avalanche point they term as piv as you know. diodes do take huge surges too, which is also a plus. your thoughts on this and has anybody heard of the reaction to this type of protection in regards to the nec if they were ever presented with it? yes, the diode may have to be a higher power diode to begin with as in having say a 3-5amps forward or better current rating, but in my view it is viable and comparable to other devices used in protection. a 50piv diode would trip somewhere in and around that 50 volt point making it better than an mov or sov for tripping sooner than the 250v or higher voltage for the mov or sov would trip at. diodes also have other higher piv ratings too for those systems that may need a higher trigger point voltage. gas is best at low trip high current points, but once fired it is useless for another goround for sure. mov/sovs can also burn out or explode too on the first goround as well as a diode, but these 2 types of protection have a better survival capability for a second, 3rd, 4th, etc. shot than the gas does depending on the surge amps flowing.

Delta makes what look to be good arrestors, i.e. Delta LA302 DC Lightning arrestor. The response time is good and several of these devices are much cheaper than most other equipment or your house. Place ground rods as close to the protected equipment as possible. Grounding info for ham operators is applicable and can be found easily. Search the web for "lightning protection" along with "solar panels" or "antenna" or "wind turbine".

Lightning is unpredictable and a direct strike will most likely damage something regardless of the level of protection. The real point is protection from near by strikes which are far more likely and more frequent than a direct strike.

The diode idea is good, with a parallel arrestor, it is even better. The diode will breakdown fast and the arrestor will follow quickly behind providing bulk current protection. There is an advantage provided for this parallel system by the wiring from the panels - the current through the wires can not change instantaneously! So the voltage breakdown for the protection devices precedes the large current surge to follow nanoseconds later.

It is better to keep the protection devices outside your house and in metal enclosures. The surge from a strike can cause explosive and/or incendiary results in protection devices (usually very short lived). I have seen evidence of a direct lightning strike nearly vaporizing a 12 AWG ground wire connected to an arrestor. The damage was minor and the arrestor did it's job (self-sacrificed), but the evidence below where the wire was showed that a wood surface may have been ignited. Fortunately, only the arrestor died in that strike.