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Grounding my off grid pv system

 
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I live in a dry clime where the soil does not conduct electricity very well. I would like to connect my battery negative to several earth ground rods, but have read warnings about creating "loops". As long as all my rods are connected to the same circuit ( batt neg), will ground loops still be a problem for me?
 
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Hi Art, welcome to Permies!

Art McConnell wrote: As long as all my rods are connected to the same circuit ( batt neg), will ground loops still be a problem for me?



This should not cause a problem. Ground loops could still be a problem if for example you're running audio/visual equipment components which are each grounded at their power source (electrical plug) and then also connected to each other with some kind of cable containing a ground, making a loop.

The best way to run multiple ground rods, and you may know this already, but run one long unbroken ground wire from one ground rod clamp to the next, with each ground rod at least 8 feet away from the next. You mentioned an arid climate, and may I suggest finding the longest ground rods you can get. Hope this helps!
 
Art McConnell
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Thank you. Yes, I had thought about a ground level 6 ga wire connecting the 3 ground rods I currently have. Currently, only one of these is connected to my batt neg. One grounds my mobile home frame, and the third one grounds my solar array mount. I have also considered sinking another ground rod very near my septic tank lateral, where there must be elevated levels of moisture in the soil. Any advice on this idea?
 
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steward
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Art McConnell wrote: Any advice on this idea?



There are interesting and bizarre phenomenas that can occur with electricity (stray voltage is one phenomena, it's fascinating*) and I don't understand how they happen and occur, but one thing that is not advisable (for grid sourced power) is having separate grounds for different things. A good friend of mine is an electrical engineer, and works for a electrical utility, and I just built a new home, and I asked him if it would be good for me to give my well pump its own ground rod out by the well head, in addition to the ground rods at my house. He said it was a bad idea, and mysterious things can happen, and I can't remember the details of what he explained could happen and how. He advised, to only have one point of grounding for a home. Multiple ground rods all connected together is a good idea, as quality grounding is important.

one of these is connected to my batt neg. One grounds my mobile home frame, and the third one grounds my solar array mount



I'm not an electrician, engineer or solar guy. There are some solar guys here on Permies and I hope one will chime in on this, but from what has been explained to me and what I understand, perhaps seek advice of a solar professional about the panels and the batteries having separate grounds, instead of sharing one common grounding point.



*I read an article about stray voltage, written by an engineer who spent a part of his career diagnosing stray voltage sources. The strangest one that he ever witnessed and was unable to solve, was an Amish barn, many hundreds of feet from any utility grid power source, and metal tools and items inside this barn somehow had low voltage current in them.
 
                                  
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I believe the problem with separate ground rods for each load is a phenomenon known as "step potential", where the possibility of each ground rod being at a different voltage potential exists.  This is avoided by creating a "ground array" where multiple ground rods are linked together and a single ground is connection is taken to the breaker panel.  In very arid/dry climates installations such as electric utility sub-stations this is avoided by driving multiple ground rods in a grid pattern and connecting them together with bare copper conductors.  
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