timselectric
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And then the inverter is grounded to the service ground bar, hopefully.
Can I run a grounding wire 150ft from PV array to inverters?
- Thread starter Konvett
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Well, the AC Input will be my service panel from my utility company, which is earth grounded. But my AC Out is not earth grounded as it's just a critical load panel. Does that seem proper?
timselectric
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The critical loads panel should be grounded.
But not bonded. Should be separated from the neutral. Hopefully your inverter takes care of this.
timselectric
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By grounded...
I mean a ground wire from the inverter or main service panel. Not to a ground rod.
I mean a ground wire from the inverter or main service panel. Not to a ground rod.
So you're saying I should earth ground the critical load panel and keep the ground and neutral bus bars separate within it?
Ah, got it, got it. I currently have a ground from critical load to inverter and inverter to utility service panel (which is earth grounded). I should still keep my ground and neutral bus separate in my critical load panel though?
timselectric
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Yes
Out of curiosity, could you share with me why the critical load panel grounds and neutrals can't be bonded?
If you have two bonds in the house then the ground wire between the two will essentially just be like a parallel neutral wire (so current will be flowing on it).
It may be worth noting that there is only a single breaker in the utility service panel. It feeds the AC In in the inverter.
timselectric
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One breaker is all that is required. The N/G bond is required to be at or before the first means of disconnect. Which is the first breaker or disconnect from the meter. In a residential service, this is usually the main service panel. And this can only be in one location to avoid a parallel path. And neutral current flowing on the ground conductor.
Man, I've been sooo confused about all of the ground/neutral bonding discussions all over this site until it just clicked. Of course - this makes way more sense.
tldr: be able to disconnect neutral-ground-bonded panel from everything else after it, and ensure that you won't have current on ground (for safety).
Vigo
Solar Addict
So aside from all issues of code and legality, im trying to figure out which purposes we are attempting to serve with this ground conductor..
If lightning strikes your array and the lowest resistance path to ground is across your MPPT, *bad stuff*. So a grounding rod at the array OR a conductor back to 'house' ground would protect against equipment damage there, i guess. Ground rod would probably be a bit better due to the extra ~200' of wire in the other option.
If your inverter is putting AC voltage your PV circuit (which is apparently common?), and you were to come in contact with it because you had unplugged the PV and assumed the house-side line was dead without checking, etc.. then whether you get the privilege of experiencing that AC voltage basically comes down to what else you're touching and whether it presents a low enough resistance 'path back to source'. In that scenario having a local ground rod would make the ground you're standing on (assuming ground mount because we're talking about driving ground rods) and basically everything sitting on the ground, a better path back to source than if there were no ground rod there at all... so not helping.
But, if you had a dedicated ground conductor then ONLY the PV framework, mounting rails, and that actual conductor would be a 'good' path back to source and the rest of the ground you're standing on would be a pretty poor one considering the 150'. Unless your ground mount is on metal posts driven into the ground in which case, not much better because unless you took steps to electrically isolate the panels from their mounting system then the local dirt itself would have a good path back into your dedicated grounding conductor through the mount!
So the dedicated ground conductor is preferable (again, regardless of laws/code) because while it does a slightly worse job of protecting from lightning, it does a better job of protecting you from AC faults that may exist on your ostensibly DC circuit if you also happen to not be wearing shoes?! What am I missing here? I feel like there must be a better reason than that.
If lightning strikes your array and the lowest resistance path to ground is across your MPPT, *bad stuff*. So a grounding rod at the array OR a conductor back to 'house' ground would protect against equipment damage there, i guess. Ground rod would probably be a bit better due to the extra ~200' of wire in the other option.
If your inverter is putting AC voltage your PV circuit (which is apparently common?), and you were to come in contact with it because you had unplugged the PV and assumed the house-side line was dead without checking, etc.. then whether you get the privilege of experiencing that AC voltage basically comes down to what else you're touching and whether it presents a low enough resistance 'path back to source'. In that scenario having a local ground rod would make the ground you're standing on (assuming ground mount because we're talking about driving ground rods) and basically everything sitting on the ground, a better path back to source than if there were no ground rod there at all... so not helping.
But, if you had a dedicated ground conductor then ONLY the PV framework, mounting rails, and that actual conductor would be a 'good' path back to source and the rest of the ground you're standing on would be a pretty poor one considering the 150'. Unless your ground mount is on metal posts driven into the ground in which case, not much better because unless you took steps to electrically isolate the panels from their mounting system then the local dirt itself would have a good path back into your dedicated grounding conductor through the mount!
So the dedicated ground conductor is preferable (again, regardless of laws/code) because while it does a slightly worse job of protecting from lightning, it does a better job of protecting you from AC faults that may exist on your ostensibly DC circuit if you also happen to not be wearing shoes?! What am I missing here? I feel like there must be a better reason than that.
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timselectric
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This is only electrical system grounding.
Lighting protection is a whole different animal.
Lighting protection should never be connected to what you want to protect. It's installed around what you want to protect.
The way I'm grounding my panels to my service panel is by attaching grounding lugs to the rails. Is that the correct way to do it for electrical system grounding?
timselectric
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Yes, if the panels to rails connection is rated for grounding. (AKA weebs)
timselectric
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Wiley WEEB-9.5NL Washers for pole/ground mounted solar panels
Wiley Electronics WEEB-9.5NL washers for pole or ground mounted solar panels
www.altestore.com
I'm using IronRidge rails with their UFO clamp which is supposed to bond the panels to the rails.
Vigo
Solar Addict
But… aside from your inverter putting ac on your PV circuit (which couldnt even happen if your mppt and inverter weren’t the same box), why would the PV array need to be electrically grounded? Im still missing something.
Goboatingnow
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Most codes do not support multiple connected earth ground points within a domestic situation.
This is present a particular ground point carrying ALL ground fault currents , to a particular ground point. This could include your neighbours ground faults.
Hence if you install a separate ground point that’s fine. But that protective ground wire should NOT be connected to the rest of the domestic grounding system. There is typically only ONE central grounding point increasing this is a neutral PE connection point , this then relies on the power company neutral grounding practices and not your “ dodgy “ local grounds.
For example I can’t install a high power EV charging station if I have ground rod based earthing as the loop impedance is too high. I must have neutral earth wire bonding instead.
