Upgrading System, Found Grounding Issues

RicoWarner

New Member
Joined
Jul 10, 2021
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2
Hi all - doing major overhaul and upgrade since had multiple failures in system this last winter. It originally was installed by contractors...and Ron Swanson is right about contractors.

Anyway, multiple grounding issues appear to be present. Would ask folks *in the know* to authoritatively weigh in on them.

*starting at the ground-mount PV's, there is one grounding rod for the two array frames. Presumably, this is to provide an Equipment Ground Conductor (EGC).
>For one, it looks like could add a second 8' copper rod bonded to the first for more reliable equipment ground.
>For another, they then bond this EGC to a green conductor that goes some 30' to the combiner box and then is bonded to the DC Negative Bus (that batteries, inverter/charger, and CC connect to).
? 1: should the DC side have a separate SYSTEM ground (NOT equipment ground) than the AC side?
? 2: or should I disconnect this bond, so it is solely an equipment ground and not a DC System ground?
? 3: does the inverter/charger effectively bond the DC Bus and the single-point ground for the house together, by way of battery negative and inverter's connection to the AC neutral bus on output side (which runs to house's SINGLE-POINT BONDING OF *NEUTRAL* TO HOUSE GROUND)?

*Looks like house's single-point ground (near electrical panel, bonded to neutral) is an 8' copper rod driven into ground. I want to do star configuration and drive in a couple more rods, attaching them to the main one.

*regarding the backup generator, it uses a floating neutral, relying on the house's single-point ground and single neutral connection to ground, when it is powering the inverter/charger.
>as such, the frame is a floating ground, and I believe I should additionally drive a ground rod in near where it runs, so I can ground the generator frame.

As such, for those keeping count, that would be the single neutral-bonded ground for the house AC side, plus an equipment ground for both the solar panels and the generator.

? 4: this goes against concept of single-point ground...but both gen and solar panel frames would be unsafe without equipment grounds. The Power Distribuyion System from Schneider keeps the DC Bus separate from the groundBus, suggesting...it needs to be separate.

? 5: there is concept of Ground Loops if have more than one ground. Do the equipment grounds then form ground loops?

Thanks in advance for any authoritative info!

Richard
 

Warpspeed

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Jun 11, 2021
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44
The basic philosophy behind a safety grounding system is to prevent an electric shock hazard from being created should the "hot" side of the system find its way onto any exposed metal parts.

To be able to do that, the earth stake (or whatever) needs to be located right at the power source, and connected to both one side of the electrical system, and any exposed metal. So yes, you ground your solar electrcal -ve and solar metal frames right at the solar panels, which is the power source.

Likewise your main house wiring back at the power board is regarded as the power source, so both neutral and ac ground (green wire) should be bonded to an earth stake or a cold water pipe.

So there will be two quite independent grounding systems, dc solar, and ac house wiring. And these grounds should not be connected together.

An ac generator, from the electrical safety aspect is just another household appliance. Like any other household appliance the ground system and the neutral system should be kept separate at the appliance, and three pin plugs and sockets used. An ac generator cannot become "alive" unless its plugged into something, and if it is, it will have a safety ground going back to the main power board.

What happens at the inverter is a very debatable subject.
Which ground should the inverter metal frame be connected to ?
There may be specific regulations in your part of the world that cover that, but a common sense view might be you ground to either the house ac ground, or the solar dc ground, depending on which is the highest and most dangerous voltage.
 
Last edited:

DerpsyDoodler

Photon Sorcerer
Joined
Jan 10, 2021
Messages
1,635
The basic philosophy behind a safety grounding system is to prevent an electric shock hazard from being created should the "hot" side of the system find its way onto any exposed metal parts.

To be able to do that, the earth stake (or whatever) needs to be located right at the power source, and connected to both one side of the electrical system, and any exposed metal. So yes, you ground your solar electrcal -ve and solar metal frames right at the solar panels, which is the power source.

Likewise your main house wiring back at the power board is regarded as the power source, so both neutral and ac ground (green wire) should be bonded to an earth stake or a cold water pipe.

So there will be two quite independent grounding systems, dc solar, and ac house wiring. And these grounds should not be connected together.

An ac generator, from the electrical safety aspect is just another household appliance. Like any other household appliance the ground system and the neutral system should be kept separate at the appliance, and three pin plugs and sockets used. An ac generator cannot become "alive" unless its plugged into something, and if it is, it will have a safety ground going back to the main power board.

What happens at the inverter is a very debatable subject.
Which ground should the inverter metal frame be connected to ?
There may be specific regulations in your part of the world that cover that, but a common sense view might be you ground to either the house ac ground, or the solar dc ground, depending on which is the highest and most dangerous voltage.
How does this logic apply in a mobile application? Chassis is considered "earth" in this aspect. I have a single common ground bus that i plan on chassis grounding all components through (scc, inverter, solar panel frames, dc circuit ground). Inverter has a built-in transfer switch. By default, neutral bond switches between chassis and shore power on the inverter, depending on which source is in use.
 

Warpspeed

Solar Enthusiast
Joined
Jun 11, 2021
Messages
44
Vehicles and aircraft obviously cannot be directly grounded, and that does not really matter.
In each case, the metal frame of the vehicle can be considered to be ground and serves the exact same purpose.
 

MrAubin

Solar Enthusiast
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Jul 17, 2021
Messages
73
If your equipment is in the vehicle and you want to chassis ground your solar equipment ex... Charge controller, inverter, then you have to also ground the solar battery to the vehicle. And your solar panel frame grounds remain at thier separate earth ground staked into earth. Maybe install a lightning arrestor at the solar battery Incase the vehicle is hit by lightning. I've read the batteries won't bother each other as thier both DC. Hope this helps spark some more thoughts.
 
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