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Good Gosh, more grounding and NEC

Dr. Dickie

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Jun 7, 2021
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Here is what I have (I don't have much hair for pulling it out trying to understand this).
Basically, I have an array, then 20 feet away a shed which contains the solar charge controller, battery, inverter. Inverter is a sungold 6kW split phase. It feeds two hots, neutral, and ground about 180 or so feet to the garage where is goes into the solar electrical panel.
I have put a ground rod in at the base of the array to server as DC ground for array and shed (both equipment and system). The solar charge controller (Midnite) bonds the ground to DC negative for ground fault protection (only point).
I think, based on what I read and see, that NEC requires that I bond the DC ground system to the AC ground system at the inverter.
The inverter has AC ground at house service bonded to the case (6 AWG run), so equipment ground is taken care of for the inverter there.
IF I bond the DC ground system to the AC ground system, then I have a two ground points on the comnined ground system (which I understand is bad due to possible lightening voltage potentials).
However, the DC ground is already hooked to the inverter due to the neg ground bond in the solar charge controller.
I could remove the ground at the array and run everything off of a single point ground coming from the house service ground. But that would mean a run of about 200 feet to get the array grounded.
I will say that we have very conductive ground, as I measured zero resistance from house ground to array ground which is over a 100 feet away.
Does NEC require the two grounding systems (DC and AC) be bonded into only a single ground conductor? I think it does.
If so, should I ditch the second ground rod, so only a single point ground (I am pretty sure I know the answer). However, this would mean that ALL potential voltages at the array and shed would have to flow through the entire system (inverter, solar charge controller, etc) from DC system, to AC system, to house service ground. That does not sound so great to me.
It seems to me, people are saying, if lightening strikes near the array, that will elevate the potential at the one ground rod, and so current will travel along the ground system, through the equipment, to the other ground site and that will cause damage.
But that implies that it is okay for lightening to strike the array (elevated metal structure, much more likely), and allow a HUGE current to travel along that very same path, through equipment, to house house ground, damaging everything along the way. As appose to offering a closer path to ground.
I am not trying to me a smart ass, just stating it the way I see it and wonder what I am missing here--I really do want to learn this stuff, as I can always do something better if I understand versus just doing what folks say to do.
Thanks for any and all help.


Okay, after watching Mike Holt again, I think he may have won me over:


I buy the argument that the ground rod will not protect against lightening strike, but can only make a possible problem.
I am learning.
 

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I think that the idea is that you bond the frame of the panels to a ground rod near the array if you want to, but do not bond the panel electrical output to that ground rod. The frame ground is then a supplemental system, and is separate from the actual electrical system, which should still be bonded at your AC grounding point.

My interpretation of bonded aerial spikes or burr balls is that they help dissipate local charge, thus possibly preventing the lightning strike at that location. The sharper the spike, the better it does at dissipating static charge.

I have a stiff horizontal wire just above the top line of my panels that I wrapped with many smaller wires cut at an angle. The spikes are about 3" long and a few inches apart. It looks like barbed wire gone wild. I did it mostly to keep birds from sitting on the top bar and pooping on my panels, but I also grounded it to a bare wire down the pole and into the ground. If it helps protect against both, that's great.
 
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