Ground wiring technique?

Re: Ground wiring technique?

"I plan to put a number of panels up on my roof, and as I understand it, they each need to have their frames grounded, in such a manner that if I remove one panel for any reason, the others will remain grounded."


roderick,
it is not necessary to have each individually done as a short daisy is feasable as long as it does not windup zig zagging your roof. it must seem to flow in a direction going towards the downlead for your ground. in fact that doodad is perfect as you could run a solid wire run rather than individual connections with lugs, which amounts to more of a resistance in the path. when a pv is removed just unscrew that ground lug to keep your wire run intact for the rest of the pvs. if it is not a smooth flow towards the ground, like when using 2 series runs of pvs, you could use a terminal block and combine the 2 with the wire going to ground. in fact, one of those wires could be a continuous run from the pvs(running through each doodad lol) and through the terminal block and straight to the ground with the second string's ground attaching to the terminal block. if terminal blocks aren't viable for you, run each string to ground with its own ground wire, but connected to the same ground rod. in cases where 2 rods are to be used you must use a bare solid copper wire buried in a straight line(if possible) to connect each rod electrically together using at least #6, but if you use a larger wire for the ground wire then use that size or bigger for this underground interconnection. no sharp bends should be on either the ground wire or ground rod interconnections as this presents a weak point to the wire with the possibility of lightning jumping off from that point. i hope this helps you, but if you have anymore specific questions concerning this please ask.

Re: Ground wiring technique?

frank,
not all of them provide the hardware. unisolar doesn't anyway.

Re: Ground wiring technique?

What about soldering and crimping is that acceptable?

Re: Ground wiring technique?

it appears i wasn't clear enough as frank is correct. you can use a terminal block, but it shouldn't be with your other connections at all as that is a deviation from the flow towards that ground and even if it doesn't deviate by some wild outside chance it induces an emp into your + and - leads, if you're lucky enough that it doesn't jump straight to them as wire insulations usually breakdown at about 600v. i was talking of using the terminal block in open air or even mounted to the frame of the last pv inline before going down to the ground. remember the flow i was telling you as it must flow from the pvs, either they be paralleled or seriesed like a daisy chain, always moving towards the ground as straightly and short as possible without any sharp bends. never route it near other wires if at all possible and never into or under a house.

Re: Ground wiring technique?

that's not very wise of them to put a ground rod under the house as a direct strike has to continue through the house to get to the ground making everybody and all appliances in the house possibly within it's path. even a close by strike may follow a path into the house to go through that rod which is a low point of resistance to the earth. if it were me i'd challenge that law as a rod outside driven to below a level that the basement floor is at would be better by far. that way it doesn't go through the house, but around it. if they'd insist on keeping the law i'd drive one in from the outside that is longer than the depth of the rod under the house and interconnect them. it would then be more apt to follow the longer deeper rod placed from the outside(at least you'd hope it'll follow the second rod).

Re: Ground wiring technique?

just how accessable is the main utility ground rod to your pv system ground? if it is possible to run the ground wire from the pv system to that point that would be best. as to the connection into the box do what you have to do as i had said not to route near other wires if at all possible. their design forces you to do it.
if the utility ground is too far away or not convenient for your pvs to run to i do recommend the 2 seperate rods and interconnecting them underground to make them as one. this is fine that the rods could even be on opposite sides of a home as long as the bare solid heavy gage wire is connecting them underground. you don't always have to dig the soil up as many places can use just a piece of wood like a small length of plywood hammered into the ground and pulled back out leaving a small width hole that could be done the entire length to bury the interconnecting wire in. this does become difficult where concrete is in the way, as in steps and driveways. that interconnecting wire is also like having a longer ground rod as it gives more metal to soil contact area