Multiple grounding rods for solar panel install and electrical devices?

[stevenforti]

Hello all,

My apologies forthcoming if this question has been asked and answered elsewhere

I was just wondering if I should use two separate grounding rods for my installation? One for my solar panel array wired in series and the other to the power shed I built to house the battery bank, inverter etc etc?

Or can I just use a single grounding rod and attach all of these items to it? Particularly worried about lightning here in Florida

thanks in advance for your help

 

[glandpuck]

Your array should be grounded with a grounding rod at the array. May be different if rooftop mounted. For the inverter and batteries, the NEC I believe now says that 2 grounding rods into the ground, at least 10 feet apart are connected together by a single wire like bare 6 AWG and brought into the inverter site. There should be a ground bar and all the equipment should be attached to this for safe grounding.

 

[stevenforti]

So is that a total of 3? 2 for the equipment and one for the solar panel array?

Ugh... getting one into the ground is bad enough

 

[glandpuck]

So is that a total of 3? 2 for the equipment and one for the solar panel array?

Ugh... getting one into the ground is bad enough

Well, if you are in an area of hard ground (I am in So Cal, rock hard ground), you have options. First, you should try renting a jackhammer like a 110 pounder and rent the ground rod bit for it. I have used this and even had 2 persons standing on it. Another option during construction is to use a mini excavator with a jack hammer attachment. If that stuff doesn't work, code will allow you to insert the rod at an angle where i believe it only has to go down something like 6 feet, but check with inspector on this. Also, if 10 feet into the ground not possible, you can dig a 36 Inch deep trench and lay it flat in the ground and connect it to wire. But make sure inspector approves due to the nature of the ground. You will not be the first person with this issue. Do not cut off the ground rod to make it look buried. Inspectors have an electrical meter and can tell if you cut it off. Better to leave the inches sticking out of the ground and get approval for cut off.

If this doesn't work, ask electrical contractor for help.

Yes, 3 ground rods.

 

[stevenforti]

Thanks for your advice, Gland.

I'll drive the rods in. I saw a video on youtube showing a water trick that looks promising

So if I understand you correctly I'm doing TWO rods for the electrical equipment linked to each other via 6 awg copper wire and then completely separate rod connected to my entire solar panel array. The solar panel array is going to be ground mounted via wooden frames by the way. I dont think that matters but thought I'd mention it

and this is all required even though I am maintaining complete autonomy from the grid?

thanks again

 

[Onehand]

Timselestric may have something to say about this. As far as I have learned, you want to bond all your panels and their racking together and run that ground line from the panels back to the inverters and land it on their common ground buss's, that is tied into the house mains ground buss, that goes to the ground rod outside your house.

Please correct me if I am wrong.

 

[timselectric]

No, no, no.
Do not isolate the array from your grounding system.
Unless you want to erect a fence around it. And post danger signs everywhere.

The solar array EGC (Equipment Grounding Conductor) must travel with the PV conductors to the rest of your grounding system. (One grounding system for everything)
If you choose to add an auxiliary ground rod at the array. (Allowed, but not recommended)
It must also be connected to the rest of the grounding system.

The auxiliary ground rod is not recommended. Because it provides a path to the rest of your equipment. For the gradient pulse created by a nearby lightning strike.

 

[stevenforti]

No, no, no.
Do not isolate the array from your grounding system.
Unless you want to erect a fence around it. And post danger signs everywhere.

The solar array EGC (Equipment Grounding Conductor) must travel with the PV conductors to the rest of your grounding system. (One grounding system for everything)
If you choose to add an auxiliary ground rod at the array. (Allowed, but not recommended)
It must also be connected to the rest of the grounding system.

The auxiliary ground rod is not recommended. Because it provides a path to the rest of your equipment. For the gradient pulse created by a nearby lightning strike.

So that's one ground rod with everything wired to it?

 

[Onehand]

Correct, one rod, back at the inverter(s).

I stand corrected below. Two rods means my house hasn't been code compliant for years with only one ground rod on the mains.

 

[timselectric]

So that's one ground rod with everything wired to it?

NEC requires 2 rods at a minimum of 6' apart. A single unbroken #6 AWG conductor from the main panel ground bar to both.
And all EGC's are connected back to the main ground bar.
These EGC's can be daisy chained through other devices or equipment. As long as the size is correct for each segment, along the way.

You can use this chart to size them correctly.

 

[stevenforti]

NEC requires 2 rods at a minimum of 6' apart. A single unbroken #6 AWG conductor from the main panel ground bar to both.
And all EGC's are connected back to the main ground bar.
These EGC's can be daisy chained through other devices or equipment. As long as the size is correct for each segment, along the way.

You can use this chart to size them correctly.View attachment 184039

I drew a quick picture of what I think you are trying to tell me

Can you look at it and tell me if I got it right before I end up killing myself or blowing up half of my backyard?

this system is going to be completely isolated from my house wiring

 

[timselectric]

this system is going to be completely isolated from my house wiring

It won't be feeding anything in your house?

 

[stevenforti]

It won't be feeding anything in your house?

No sir. My well pump, pool pump, hottub and septic tank pump. I will wire them all directly to the powershed I built with the off grid system

These items are all outside the house

 

[timselectric]

No sir. My well pump, pool pump, hottub and septic tank pump. I will wire them all directly to the powershed I built with the off grid system

These items are all outside the house

Then your drawing is correct.

 

[stevenforti]

Then your drawing is correct.

thank you so much.

So with this wiring I wont be killing myself or anyone in my family? It's ground mounted so I'm a little paranoid right now

thanks

 

[timselectric]

thank you so much.

So with this wiring I wont be killing myself or anyone in my family? It's ground mounted so I'm a little paranoid right now

thanks

Do you know what equipment you will be using, yet?
We need to see how it handles the N/G bond. Which is the beginning of your grounding system.

 

[stevenforti]

Do you know what equipment you will be using, yet?
We need to see how it handles the N/G bond. Which is the beginning of your grounding system.

solar panels X 10 will be wired in series
------------

JA Solar 535W Solar Panel 144 Cell Bifacial JAM72D30/MB – A1SolarStore

JA Solar 535W Solar Panel 144 Cell Bifacial JAM72D30/MB at A1SolarStore

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Inverter x 1
--------

10KW 48V Split Phase Solar Inverter

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sungoldpower.com

Batteries X 4 wired in series
---------

LiFePO4 12V 280Ah Lithium Iron Phosphate Battery | ECO-WORTHY

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[timselectric]

Batteries X 4 wired in series

It's not recommended to put BMS controlled batteries in series.
They will drift apart from each other. And require re balancing every few months. If you want a 48v system, use a 48v battery.

 

[stevenforti]

It's not recommended to put BMS controlled batteries in series.
They will drift apart from each other. And require re balancing every few months. If you want a 48v system, use a 48v battery.

Oh damn... I bought them already

 

[timselectric]

solar panels X 10 will be wired in series

10 will be too many. VOC is a do not ever exceed number.
9 might be ok, if you are in an always warm climate. (Depending on your record low temperature)