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Array Grounding and Components Grounding

J

JamesTheCrow

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Joined
Feb 11, 2023
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Location
Atlantic Canada
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
 
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.
 
timselectric said:
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.
Click to expand...

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.
 
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.
 
Gotshocked! said:
Are you sure? Read all the comments.
Click to expand...
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! said:
Read his rebuttals, the comments on comments.
The solar panel frames are not powered.
Click to expand...
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 said:
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.
Click to expand...
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"?
 
Mark- said:
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"?
Click to expand...
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.
 
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.
 
Dauntless said:
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.
Click to expand...
The video is incorrect information.
You can't trust idiots on YouTube.
Driving a ground rod and connecting to it, doesn't ground anything. All exposed metal (panel frames, racking, raceways, and enclosues) should be connected to your grounding system. Provided by your electrical service panel.
 
It might be easier if we think about the grounding being done at the main service panel and any other grounding electrodes as auxiliary rounding rods that are bonded back to the ground. I use EMT for conduit and with the correct connectors can be run underground. It cost about the same as schedule 40 pvc and will provide some bonding. If you use a 10awg copper (green) equipment ground conductor 2023 NEC table 250.122 shows it can support up to 60 amps.
If going underground in conduit make sure the wire is rated for wet locations.
 
I can tell you one thing, if you’re not grounding with manufacturers instructions on any product, YOU HAVE NO WARRANTY PERIOD.
 
Willnaz said:
I can tell you one thing, if you’re not grounding with manufacturers instructions on any product, YOU HAVE NO WARRANTY PERIOD.
Click to expand...
The problem with WZRELB “reliable” and XYZInvt inverters is the documentation “instructions” vary depending on where you buy them. You can find WZRELB directions that say earth connection for pc board and output, but then with the exact same model on another site stating not to connect to earth ground.
My WZRELB 24v 5000w inverter has been earth grounded and neutral bonded at my main panel in a cabin for over 3 months and has been running my fridge, lights, blender etc. with no issues. This however is after checking and correcting the outlet polarity per the video.
In fact, when I take off my jacket or sweater and have static cling, I touch my fridge with the back of my hand to degauss. I’m glad my fridge is grounded in case a defrost happens to leak water onto the motor or other 120v circuits. I’d rather blow up a cheap inverter than have a safety risk with the fridge. I keep a spare 3000w around if needed which was hooked up prior.

1702488128296.jpeg
 
Add me to the confused pile.

Totally off grid system.

I have 6 panels ground mounted.

I have a WZRELB 3000W 24v inverter.

I can drive a copper rod into the earth nearby.

I can run grounding wire from the panels and the inverter to the copper rod.

Will that work? The inverter has a grounding bolt on the end of the unit. I will NOT be connecting that to my house grid system in any way. Will this work?

I am no electrician. My system has worked for years without being 'grounded' and with lead-acid batteries. But now I dropped the money for Lithium, I was hoping to do the grounding if necessary. But all I find are contradictory statements, instructions in bad English that muff the most important words like DO or DON'T and endless talk about floating, ground, neutral, hot, bonding, cases, and that WZRELB have all their internal wires criss-crossed. Do watch the video, don't watch the video, read the comments, don't tread the comments, they're all idiots, someone's gonna die.

Can I run a ground wire from the WZRELB to a copper rod in the earth? Can I attach my panels to that same copper rod?

Thanks!
 
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