Can I run a grounding wire 150ft from PV array to inverters?

[Goboatingnow]

Good write up on the subject from a reliable source

PV System Ground Fault Troubleshooting

Why DC ground faults in PV systems are hidden hazards you need to detect before it’s too late. Find the blind spots in PV systems. Solar ground fault troubleshooting.

www.fluke.com

 

[Goboatingnow]

The only DC ground fault detection that I am aware of does not measure imbalance like AC detection. It looks for actual voltage on the ground.

Nope , for example here’s Morningstar DC protection, it’s clearly stated it uses current imbalance

 

[timselectric]

Nope , for example here’s Morningstar DC protection, it’s clearly stated it uses current imbalance

I see.
I didn't think that anyone was using that type anymore. Because it can't detect a low enough leakage.
As pointed out in the write up you posted above.
But I guess some are still selling it.
Thanks

 

[Konvett]

It's the same ground for everything. There's not a dedicated PV ground terminal. It just needs to be connected to the rest of the grounding system.

I just spoke with Signature Solar who is the distributor of my inverter and they said under no circumstances should I connect a grounding wire from my solar arrays to my inverter. They said there isn't even a place to connect it because the only two ground lugs are for the AC input and output.

 

[timselectric]

I just spoke with Signature Solar who is the distributor of my inverter and they said under no circumstances should I connect a grounding wire from my solar arrays to my inverter. They said there isn't even a place to connect it because the only two ground lugs are for the AC input and output.

That's what I said above.

It's the same ground for everything. There's not a dedicated PV ground terminal. It just needs to be connected to the rest of the grounding system.

 

[Supervstech]

Again gentlemen the general is independant grounds are not interconnected. One ground point per system.

Code requires minimum TWO ground rods at service connection point, and additional are approved. As long as all are connected together.

Panel emf dissipation grounds doesn’t need to be tied to the main panel grounding circuits.

 

[Konvett]

It's the same ground for everything. There's not a dedicated PV ground terminal. It just needs to be connected to the rest of the grounding system.

Understood. So I can run this grounding wire from my panels and clamp it the the grounding wire coming off my service panel that goes into the earth ground rod?

 

[Supervstech]

Understood. So I can run this grounding wire from my panels and clamp it the the grounding wire coming off my service panel that goes into the earth ground rod?

You can. A rod at the panels is recommended.

 

[Konvett]

You can. A rod at the panels is recommended.

If I were to do a rod at the panels, would I need to connect it to the main service panel grounding then?

 

[Supervstech]

If I were to do a rod at the panels, would I need to connect it to the main service panel grounding then?

That depends on your SCC, and the panels. Some require a continuous ground conductor, some do not.

 

[Konvett]

That depends on your SCC, and the panels. Some require a continuous ground conductor, some do not.

What is SCC?

EDIT: I realize now you meant solar charge controller. I looked into my inverters manual (the EG4 6500EX) and called Signature Solar and they say just don't connect any ground wires to the inverter itself. So I'm really not sure what to do. This entire grounding discussion has me lost as to what to do.

 

[Goboatingnow]

I see.
I didn't think that anyone was using that type anymore. Because it can't detect a low enough leakage.
As pointed out in the write up you posted above.
But I guess some are still selling it.
Thanks

Morningstar threshold is 300mA ( it’s a call we’re you set the threshold )

Residual current methods are far better then other types

 

[timselectric]

Understood. So I can run this grounding wire from my panels and clamp it the the grounding wire coming off my service panel that goes into the earth ground rod?

You could, but I would run it into your service panel and connect it to the ground bar.

If I were to do a rod at the panels, would I need to connect it to the main service panel grounding then?

Absolutely yes. Per NEC.
But I would never recommend an auxiliary ground rod.
It will direct the gradient pulse from any nearby lighting strike to your house.

 

[Honuz]

I do not know your codes, i'm in Europe, my panels are 20m from the inverter, i got 2 ground rods, one under panels and one for the building. They are connected together and the buidling electrical box bonding is grounded to the building ground rod.
Do not know if i'm clear.
In case of an electrical potential happend, on the panels structure, in the electrical box, in the inverter... it will be directed to the least resistance rod, which COULD be whatever one depending on the season ... (humidity of the ground change), but in any case there is a path with the lowest resistance it can follow, by code it's < 30 Ohms, you can have a weaker ground but can't be > 100 Ohms, if it's > 30 Ohms you need a more sensible differential breaker.

 

[timselectric]

I do not know your codes, i'm in Europe, my panels are 20m from the inverter, i got 2 ground rods, one under panels and one for the building. They are connected together and the buidling electrical box bonding is grounded to the building ground rod.
Do not know if i'm clear.
In case of an electrical potential happend, on the panels structure, in the electrical box, in the inverter... it will be directed to the least resistance rod, which COULD be whatever one depending on the season ... (humidity of the ground change), but in any case there is a path with the lowest resistance it can follow, by code it's < 30 Ohms, you can have a weaker ground but can't be > 100 Ohms, if it's > 30 Ohms you need a more sensible differential breaker.

Electrical faults don't go to earth. (This is a misconception) they go back to the source.
A ground rod doesn't connect the grounding system to earth. It connects the earth to the grounding system. This is so that if a fault finds its way to earth it can travel up the ground rod and back into the grounding system. Then back to the source, so that it can clear the fault. A ground rod at the array is an auxiliary ground rod, in the US. NEC allows but doesn't require auxiliary ground rods. (And they are not recommended by anyone who understands why)
If lightning strikes the earth near the array. It creates a high voltage DC pulse gradient. This pulse radiates from the point of the strike. And dissipates over distance. Due to the high resistance of the earth. If you place two rods in the earth. The grounding conductor between them has a much lower resistance. The pulse will travel up the closest rod and follow the conductor to the house. This pulse can fry electronics. (Inverter, TV, computer, microwave, and any other electronics)

 

[Honuz]

Electrical faults don't go to earth. (This is a misconception) they go back to the source.
A ground rod doesn't connect the grounding system to earth. It connects the earth to the grounding system. This is so that if a fault finds its way to earth it can travel up the ground rod and back into the grounding system. Then back to the source, so that it can clear the fault. A ground rod at the array is an auxiliary ground rod, in the US. NEC allows but doesn't require auxiliary ground rods. (And they are not recommended by anyone who understands why)
If lightning strikes the earth near the array. It creates a high voltage DC pulse gradient. This pulse radiates from the point of the strike. And dissipates over distance. Due to the high resistance of the earth. If you place two rods in the earth. The grounding conductor between them has a much lower resistance. The pulse will travel up the closest rod and follow the conductor to the house. This pulse can fry electronics. (Inverter, TV, computer, microwave, and any other electronics)

Maybe i did not used the correct vocabulary
All my devices metal parts are bonded together through a cable and 2 rods that are in the ground. The dc part of my circuit is "floating", i think it's the word in english.
Then on my AC side, the neutral is grounded on the same rods
It look something like that :

PV : Panels
Batterie : Battery
Convertisseur : Inverter
Circle : Differential breaker

 

[timselectric]

Maybe i did not used the correct vocabulary
All my devices metal parts are bonded together through a cable and 2 rods that are in the ground. The dc part of my circuit is "floating", i think it's the word in english.
Then on my AC side, the neutral is grounded on the same rods
It look something like that :

PV : Panels
Batterie : Battery
Convertisseur : Inverter
Circle : Differential breaker

View attachment 117116

Yes, that's a typical setup.
The only thing that I wouldn't do is the auxiliary ground rod. I'm not sure what your regulations are there. But, in my opinion. You should only connect to earth at one location. (Near the main service) so that you don't provide an alternate path for the gradient pulse.

 

[Honuz]

Yes, that's a typical setup.
The only thing that I wouldn't do is the auxiliary ground rod. I'm not sure what your regulations are there. But, in my opinion. You should only connect to earth at one location. (Near the main service) so that you don't provide an alternate path for the gradient pulse.

In our country if the ground pole is more then 100 Ohm, some other poles can be added, if the pole is 2m long, then the next pole need to be at least at 2m from the others, but they advise to put them at twice the length of the pole = 4m for a 2m pole. And those poles are connected together.
On each pole we add this "isolator" , which permit to test the pole resistance by disconnecting it from the circuit.

But most new homes got their ground wire burried around the house, when the slab is builded, like this :

 

[timselectric]

In our country if the ground pole is more then 100 Ohm, some other poles can be added, if the pole is 2m long, then the next pole need to be at least at 2m from the others, but they advise to put them at twice the length of the pole = 4m for a 2m pole. And those poles are connected together.
On each pole we add this "isolator" , which permit to test the pole resistance by disconnecting it from the circuit.

Yeah, here in the states. We are now required to install 2 rods at the service 6 ft apart. Connected together, but still one location.

But most new homes got their ground wire burried around the house, when the slab is builded, like this :

Required here also. We call it a Uffer (not sure if that's how it's spelled) ground. It's actually in our foundations.

 

[Checkthisout]

Yes, that's a typical setup.
The only thing that I wouldn't do is the auxiliary ground rod. I'm not sure what your regulations are there. But, in my opinion. You should only connect to earth at one location. (Near the main service) so that you don't provide an alternate path for the gradient pulse.

Best practice would put lots of ground rods at the solar array and code would require an equipment grounding conductor run back to the charge controller/service entrance/main whatever.

How on earth do you do subpanels in detached buildings without adding grounding rods when code requires it?

 

[Checkthisout]

Electrical faults don't go to earth. (This is a misconception) they go back to the source.
A ground rod doesn't connect the grounding system to earth. It connects the earth to the grounding system. This is so that if a fault finds its way to earth it can travel up the ground rod and back into the grounding system. Then back to the source, so that it can clear the fault. A ground rod at the array is an auxiliary ground rod, in the US. NEC allows but doesn't require auxiliary ground rods. (And they are not recommended by anyone who understands why)
If lightning strikes the earth near the array. It creates a high voltage DC pulse gradient. This pulse radiates from the point of the strike. And dissipates over distance. Due to the high resistance of the earth. If you place two rods in the earth. The grounding conductor between them has a much lower resistance. The pulse will travel up the closest rod and follow the conductor to the house. This pulse can fry electronics. (Inverter, TV, computer, microwave, and any other electronics)

Who is making this stuff up?

Put lots of grounding at the array. If the array can ground through it's metal posts, that much better. And of course as per code, run an EGC back to the service entrance panel and bond to neutral.

 

[Checkthisout]

Again gentlemen the general is independant grounds are not interconnected. One ground point per system.

You guys are starting to freak me out.

Where did this myth get started and what does code say about subpanels in detached structures?

 

[timselectric]

Put lots of grounding at the array. If the array can ground through it's metal posts, that much better. And of course as per code, run an EGC back to the service entrance panel and bond to neutral.

You go right ahead and do that, if you want.
I prefer to keep my electronics working. When a lightning storm happens.
Also, there should only be one N/G bond in a service.

 

[Checkthisout]

You go right ahead and do that, if you want.
I prefer to keep my electronics working. When a lightning storm happens.
Also, there should only be one N/G bond in a service.

Agree on the Neutral/Ground bond. That's code and it makes sense.

Totally disagree about not having a separate earthing system for a remotely mounted array and even one mounted on a roof. Do we ground lightning rods through the electrical system? If not, why not?

What does code say about ground rods in subpanels and outbuildings?

Where are you getting the idea that ground mount solar arrays should not have their own lightning protection system? Would you apply this same line of thought to a HAM radio tower? Satellite dish? Cell antenna?

Whoever started the line of thought that there should be only one earth connection in an electrical system should have to play the role of the DOC in back to the future and complete the connection between the clock tower and the delorean...only in real life and see if they prefer the lightning rod be grounded at the clock tower or through the delorean.

Total silliness.

 

[timselectric]

What does code say about ground rods in subpanels and outbuildings?

This is not a sub panel.

Where are you getting the idea that ground mount solar arrays should not have their own lightning protection system?

This is not lightning protection. That's would be an entirely different system.

Would you apply this same line of thought to a HAM radio tower? Satellite dish? Cell antenna?

No, because they are not powered by the electrical system. So, equipment grounding wouldn't directly apply.

No comment on the rest of your statements. Because this isn't a clock tower or a DeLorean.