grounding safe or unsafe

mahendra

hi everyone! i have a quick question i have an off grid pv system 12v nominal and every thing i.e all grounding is on a single ground rod is this safe. will lighting surges reenter my system and cause damage if yes. what are the components that should be on separate ground rods.thanks in advance this forum has been really helpful to me in improving my system.

icarus

Re: grounding safe or unsafe

I am NOT a grounding expert. That said, I would ground the PV panels speparqtely, with the PV ground as far from the electrical system ground as possible. Not that I think it will. Make much diffrence in a direct lightning strike, but you want to avoid sending lighting into the building and the electronics.

I have my PV, steel chimney, and vertical radio antenna bonded together, and then off to a good ground using #4 copper.

With a direct hit, all bets are off.

Tony

mahendra

Re: grounding safe or unsafe

thanks while you claim not to be an expert you certainly know more than me.So that said you are saying i should have a separate ground rod for the arrays and a separate one for charge controllers battery bank and inverter.Am i correct

icarus

Re: grounding safe or unsafe

That's the way I would do it, but others may disagree. I also run my ground wire into the lake on a copper clad rod, since I am on granite and can't drive a good rod. Many people have suggested that that is a bad idea, as a lightning strike near in the water could flow back up the wire. True, but lightning in the water dissipates pretty quickly, and in 75 years we haven't lost a building to lightning using this technique.

I don't know your situation, but a small battery based system probably doesn't need a ground on the battery side, but it (in most cases, see also ground loops) will not burn any thing.

Tony

mahendra

Re: grounding safe or unsafe

ok icarus that was helpful.but i would be happy to hear what the other experts say about this too

icarus

Re: grounding safe or unsafe

Absolutely!

Tony

niel

Re: grounding safe or unsafe

if the pvs are fairly near the main ground rod then attach all to that ground rod. if far away (greater than about 75ft or so and this figure is not critical) then you can have a separate rod as the ground resistance will help prevent some problems from arising like inducing ground loop voltages.

in the case of close in and separate rods, tony's logic doesn't really hold much credibility as the emp will be induced in everything anyway at some pretty high levels of voltage. now once the lightning hits the ground it is very unlikely to travel back up any other ground wires to your equipment as lightning will seek the path through the soil itself. as i mentioned, the separate ground rods close in and unbonded will create stray voltage loops known as ground loops and can create more problems. one ground rod is desirable and when more than one rod is used close in it is a good idea to bond them electrically with thick bare copper wire buried between the rods.

icarus

Re: grounding safe or unsafe

That is not the first time, (nor will it likely BR the last!) that my logic lacks credibility! I will defer to others in most every case.

Tony

mahendra

Re: grounding safe or unsafe

thats ok its good to have different ideas or logic thats real progress isnt it. i appreciate all the advise thank you people

tmarch

Re: grounding safe or unsafe

"tony's logic doesn't really hold much credibility"

hmmmmmmmm

niel

Re: grounding safe or unsafe

tmarch wrote: »

"tony's logic doesn't really hold much credibility"

hmmmmmmmm

i may not have explained it all well, but that's right as there should normally be only 1 grounding point.