Array Grounding and Components Grounding

[JamesTheCrow]

Hi all,

I'm trying to wrap my head around grounding our PV componenents. Would appreciate your input on this.

Context

We're still connected to the electrical grid. At the moment, we only have a home battery backup, since I haven't installed the solar panels, yet. This panel-less system connects to our house's transfer switch to tide us over during outages. At 7.2 kW it's enough to run most appliances, even our deep well pump (but not everything at once, of course). Sans panels, our PV system consists of

• 2x Ecoflow Delta Pros: PV inputs connected to two busbars; AC out connects to our house's transfer switch via the double voltage hub (split phase)
• 3x 48V, 100Ah server rack batteries: connected in parallel to the aforementioned busbars
• 4x SCC: not connected, yet (but to be connected to the same busbars once I've installed the solar panels)
• 1x 48V 20A battery charger: connected to the busbars

I plan to spread the solar panels into five arrays across three locations on our property:

• Array #1: ground mount; 6 340W panels in 3S2P config: 113.4 V, 19.52 A; 250 ft run
• Array #2: ground mount; 6 340W panels in 3S2P config: 113.4 V, 19.52 A; 250 ft run
• Array #3: ground mount; 6 340W panels in 3S2P config: 113.4 V, 19.52 A; 250 ft run
• Array #4: RV roof mount; 10 180W panels in 5S2P config: 119.2 V, 18.42 A; 100 ft run
• Array #5: ground mount; 6 355W panels in 3S2P config: 121.8 V, 22.5 A; 150 ft run (this won't be connected to a SCC, but rather be used for mini splits powered by both solar and AC)

Questions

1) How do I go about grounding the solar panels?

Assumptions:

1. Since I'm going to build the ground mounts with lumber, I plan on using grounding clamps to connect each array's panels with grounding wire.
2. Having read @FilterGuy 's primer (thank you), it's my understanding that I have to run grounding wire from each solar panel array to our house's grounding rod (i. e. the grounding rod that our service panel is grounded to).
3. What size would I need for the grounding wires for 250 ft and 100 ft runs, respectively?

2) How do I go about grounding the remaining PV components?

Assumptions:

1. I plan on running grounding wire from each SCC to the negative busbar. And from the negative busbar to the grounding bar of our service panel.
2. I assume there's no additional grounding required for the Delta Pros, since they're being grounded via their connection to the transfer switch.

I'm really stumped on this. Looking forward to your feedback. Thank you.


James

 

[timselectric]

All exposed metal (solar panel frames, junction boxes, conduit, and equipment enclosues) are to be connected to the existing grounding system. EGC (Equipment Grounding Conductor) size is based on the current rating of the circuits feeding or passing through the equipment. If the EGC is exposed (not in conduit) to physical damage. The minimum size requirement is #6.

 

[JamesTheCrow]

All exposed metal (solar panel frames, junction boxes, conduit, and equipment enclosues) are to be connected to the existing grounding system. EGC (Equipment Grounding Conductor) size is based on the current rating of the circuits feeding or passing through the equipment. If the EGC is exposed (not in conduit) to physical damage. The minimum size requirement is #6.

Thanks.

Please bear with me in spelling things out by verifying my assumptions

Assumption 1:
The existing grounding system would be the grounding bar in our service panel that connects to our house's grounding rod.

Assumption 2:
If so, than my assumptions in my original post would be correct.

 

[timselectric]

The existing grounding system would be the grounding bar in our service panel that connects to our house's grounding rod.

And anything already connected to it.
Once you connect something to the grounding system. It also becomes part of the grounding system.

 

[JamesTheCrow]

Thanks, man. If you can do it, I can do it. I'll take your word for it

 

[Gotshocked!]

I don't believe you want to ground those panels. Watch but more importantly, read the comments.

 

[timselectric]

I don't believe you want to ground those panels. Watch but more importantly, read the comments.

Well, that guy's an idiot. lol

 

[Gotshocked!]

Well, that guy's an idiot. lol

Are you sure? Read all the comments.

 

[Wattsinwattsout]

He lives in Texas, possibly where there are no building code requirements or a lack of inspectors. A few things to consider, if you are tied into the grid already your system is most likely permitted. If adding panels will require inspections you will need to ground the panels. If lightning does strike it’s better to have them grounded than to have the flash current run through your PV cables to the charge controller/inverter. If you do have an issue, like lightning, fire or short circuit and damage the grid power it’s best you have the system inspected for insurance reasons.

There may be alternative ways to ground them with a seperate ground rod if they are kept at a large distance from the main sustem.

 

[Wattsinwattsout]

Are you sure? Read all the comments.

There are plenty that explain the risks of high voltage panel arrays. Go back and read them again. For an RV or Auto the rubber tires make it a floating ground situation. A home or cabin with an earth ground system should have all equipment casing grounded as well as solar panel cases or frames.
He does make a good point about having a taller lightening rod away from your home and system to attract lightening first but the rest seems to be geared toward RV owners.

 

[Gotshocked!]

Read his rebuttals, the comments on comments.
The solar panel frames are not powered.

 

[timselectric]

Are you sure? Read all the comments.

Absolutely 100%. And the comments showed that he's creating more idiots. I hope that they are successful in suing him, when someone gets hurt or killed.

 

[Wattsinwattsout]

Read his rebuttals, the comments on comments.
The solar panel frames are not powered.

The frames are not powered until there is a short, then it’s doomsday if they are not grounded. Bird turds on panels can cause shorts and fires, hail damage, kids throwing rocks. There are lots of ways to electrify an otherwise safe panel.
Agian if you’re in an rv with rubber tires that’s one thing but if it’s a house or cabin earth ground for insurance purposes or to pass inspection is required.

 

[timselectric]

Read his rebuttals, the comments on comments.
The solar panel frames are not powered.

And the purpose of grounding them is to make sure that they never will be.

 

[HalfBaked]

There seems to not be a forum consensus on this issue.

 

[Gotshocked!]

The seems to not be a forum consensus on this issue.

I'm not one that you should consider being a part of a consensus regarding anything electrical. I'm just trying to figure out a system for myself.

 

[Mark-]

All exposed metal (solar panel frames, junction boxes, conduit, and equipment enclosues) are to be connected to the existing grounding system. EGC (Equipment Grounding Conductor) size is based on the current rating of the circuits feeding or passing through the equipment. If the EGC is exposed (not in conduit) to physical damage. The minimum size requirement is #6.

Thanks.
What about surge suppressors mounted at the solar panel array(s). Should the ground connection be to a rod in the ground or a connection to the "existing ground system"?

 

[timselectric]

Thanks.
What about surge suppressors mounted at the solar panel array(s). Should the ground connection be to a rod in the ground or a connection to the "existing ground system"?

Usually the existing grounding system.
But I have heard arguments for connecting it to a dedicated ground rod. And I haven't found a reason for that to be a problem.

 

[Mark-]

Usually the existing grounding system.
But I have heard arguments for connecting it to a dedicated ground rod. And I haven't found a reason for that to be a problem.

Thanks.

 

[Dauntless]

Watching the video and reading all the comments above, everyone seems to be saying the same thing as I understand it.
Both the video and comments above could be more clear however.
One of the confusing issues is that people will sometimes refer to DC negative as a ground. Not the same thing at all, as mentioned above and in the video.
Essentially, all metal frames, cases, etc need to be grounded. I put a new ground rod for each on my two sets of panel arrays. The combiner box lightning surge protector is connected with #6 bare Cu wire to the ground rod, as are the panel racks and frames.