How important is grounding?
- Thread starter robknotts
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sparrowhawk
Christian Prepper
My understanding is if you put in a second grounding rod it's has to be almost right next to the first one. If it's not close enough to the first one then a lightning strike could send power through one of the grounding rods through the house to the other grounding rod which would be potentially dangerous and destructive. So more than likely you should use only one. And yes all the panels should be grounded together.
I'm no expert and there are many people on here that have a lot of expertise on the matter, but when I installed my panels that was the information I found. I almost made the mistake of adding a second grounding rod on the opposite side of my house which would have been a big no no.
ShaneC
New Member
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- Nov 3, 2022
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What @sparrowhawk said, when designing your system assume tens of thousands of volts might pass through your grounding system. Minimise the damage between lightning hit point and the earth by reducing the parts between the two. If you have two earth rods it will probably pass from hit point to both rods passing through everything in between potentially damaging it. I'd place one rod in the middle of the array that way even if lightning hits at the far end of the array it will only pass through half the array to get to ground.
How important is grounding... how important is your life? 
You need to bond all the panels together and connect it to your existing ground rod (generally same size as your PV circuits). If you add a ground rod at the panels, you need a bigger ground wire back to the existing, often a #4AWG or larger.
You need to bond all the panels together and connect it to your existing ground rod (generally same size as your PV circuits). If you add a ground rod at the panels, you need a bigger ground wire back to the existing, often a #4AWG or larger.
OffGridForGood
Catch, make or grow everything you can.
To be clear: The PV Array "earth ground" refers to a grounding cable/rod system from the metal racking and the PV panel frames. This needs to be earth-grounded and the important thing that is not really that obvious looking at a PV panel, the aluminum frames are anodized aluminum, and this coating is actually a rather good isolation from the base aluminum. Thus the use of WEEB washers(look them up). Under the NEC the Earth-ground for the PV array "may" be separate from the electrical earth-ground of your electrical system, OR it can be the same earth-grounding system. Often the choice boils down to how far is the PV from the rest of the electrical components? ie hundreds of feet away out in a field may lead to using a separate Earth-ground rod/cable for the PV frames and racks. There are many discussions on this forum about lightning and the potential to unintentionally invite a strike via the PV frames/racking and thus some choose to go with separate rod/cable for a remote PV array if they also feel they have very high lightning strike potential. Also see discusssions on lightning arresters. The general rule of 'one and only one ground' refers to the Earth-grounding electrode for the electrical system. This too is not necissarily "one single ground rod" as there are cases/regions where soil conditions may require more than a single rod or plate or other means to establish a suitable earth-ground. But once established, this earth-ground is then treated as a single earthing point electrically in your system, and importantly is bonded to Neutral at one (and only one) point at the first point of disconnect.
How important is grounding - yeah 'how important is your life' well said. Just know that the term 'grounding' has several meanings and is the source of much confusion. The general rule "one and only one earth-ground" is not actually quite correct when we include discussions of PV panel frame/racking earth-grounding where a separate system is also allowed.
To me, if your PV array is near-by and you don't live in Lightning-Alley use the same Earth-grounding for both the PV frames/racks as the electrical system earth-ground. That is my take on it.
How important is grounding - yeah 'how important is your life' well said. Just know that the term 'grounding' has several meanings and is the source of much confusion. The general rule "one and only one earth-ground" is not actually quite correct when we include discussions of PV panel frame/racking earth-grounding where a separate system is also allowed.
To me, if your PV array is near-by and you don't live in Lightning-Alley use the same Earth-grounding for both the PV frames/racks as the electrical system earth-ground. That is my take on it.
farmhand
Solar Enthusiast
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Non-code advice here:
When I moved onto this quaker commune it was struck 5 times in 7 years. The well tower was the target every time, plus we're on a hill. No one ever cared the top of the tower was blackened 3' down from hits over the century.
Keep in mind the 4 tower legs went into the ground 5'.
Once I started adding a mile of data cable & other technologies all hell would break out. I've seen sparks blow out of Brother printers, routers....
We tossed ground rods flipping everywhere!, Welded to the tower, farm house, cabin, pole garages, yes the array has another... bond & bonds & bonds. 7 rods total.
Have not been hit since, not in 15years. This grounding "network" also absorbs EMP from nearby stikes very nicely so not to build up a charge on the data runs.
Quattrohead
Solar Wizard
What is the rod distance required by the NEC away from the electrical panel? - E&S Grounding Ask the Experts
Generally speaking “best practice” would indicate that the closer you install the rod to the panel, the better
esgrounding.com
sparrowhawk
Christian Prepper
I believe that when you use more than one ground rod they have to be tied together and then to your service entrance with all the ground wires from your house and solar panels connected to the service panel. If you split up the grounds with some going to each grounding rod that's when you set up a potential for power from a lighting strike to travel from one grounding rod through the house to the other.
In my case I was going to add a second grounding rod and ground my panels to it. But if there was a lightning strike closer to that ground rod then the possibility of power flowing up that ground rod through my house to the other was a real risk.
I'm not sure what all the reasons for grounding solar panels are but I know one of them is to reduce the static charge that builds up on them. But I also know a lightning strike directly on the panels would overwhelm most if not all grounding schemes so that's not one of the reasons.
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So...the rack is grounded by 4 @ 2⅞" drill pipe. And the panels by being attached to rack. 3 strings of panels converge into one junction box attached to one leg of rack; is an additional ground rod for the JB needed here? How about the breaker panel 14' feet away?
