Adding a battery shunt to off grid setup- which side of shunt for earth ground?

MorganCarey

Solar Enthusiast
Joined
Jul 19, 2020
Messages
45
As the title states.

Which side of the shunt does the earth ground go on for the battery bank?

I know that all loads and charger goes on the opposite side of the shunt to the battery.

I would think the earth ground goes on the battery side of the shunt for proper metering of battery though?

Just looking for some confirmation here.
 

Steve_S

Offgrid Cabineer, N.E. Ontario, Canada
Joined
Oct 29, 2019
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Location
Rural NE Ontario Canada
Caution on TERMS !
Earth Ground is NOT the same thing as DC Negative.
Shunts go on the Negative Side, between the battery terminal and load side.
Battery Negative does not go to EARTH-GROUND, this is not AC power. Confusion arises thanks to vehicles where negative grounding to chassis occurs but that is different as it is not "earthed".

IF the Inverter is also a Charger then the energy flow in both directions is measured.
IF a Solar Charge Controller is installed, it would also be past the shunt on the inverter side.

[LOAD - Inverter]<----->(0-shunt-0)<---->[(-)NEG Terminal BATT]
[LOAD - Inverter]<------------------------->[(+)POS Terminal BATT]
 

Zil

Just another ass on the web
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May 27, 2020
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I was called out on that. On a building solar system, NEC requires lightning protection on all circuits including dc. I have not read that myself, but I was beat-up over it. That said, earth ground does not connect to the dc shunt. The battery end of the shunt only connects to the negative side of the battery bank, then all the negative dc returns are on the other side of the shunt. All the dc negatives must return to the battery through the shunt.
 

MorganCarey

Solar Enthusiast
Joined
Jul 19, 2020
Messages
45
Caution on TERMS !
Earth Ground is NOT the same thing as DC Negative.
Shunts go on the Negative Side, between the battery terminal and load side.
Battery Negative does not go to EARTH-GROUND, this is not AC power. Confusion arises thanks to vehicles where negative grounding to chassis occurs but that is different as it is not "earthed".

IF the Inverter is also a Charger then the energy flow in both directions is measured.
IF a Solar Charge Controller is installed, it would also be past the shunt on the inverter side.

[LOAD - Inverter]<----->(0-shunt-0)<---->[(-)NEG Terminal BATT]
[LOAD - Inverter]<------------------------->[(+)POS Terminal BATT]


Yes I am indeed talking about an actual earth ground. I'm certain I've seen multiple wiring diagrams in past reference the negative battery post being connected to earth in an off grid setup.

To clarify, the root of my question stems from the incorrect idea that I would indeed get electron flow from earth ground to the positive post of my battery, if given a path to do so.

Some googling has suggested otherwise. While I can't say I fully understand why I won't get electron flow in that situation on a DC circuit, I'm willing to take it at face value and move on with life. Lol.

The final debate seems to be, do I indeed connect earth ground on the negative side of the DC circuit at the shunt?

As I have said, Im sure I've seen multiple wiring diagrams suggesting that the negative terminal be earth connected. I'm going to have to go looking again.
 

SolarQueen

Making renewable do-able at www.alteStore.com
Joined
Dec 1, 2019
Messages
475
Location
Boxborough, MA
Ground and negative should be bonded at one point in the system. It is generally not at the shunt. Some charge controllers do it internally with their internal GFP, or if you have an external GFP breaker, it is done there. If not, there is generally a wire in your DC breaker box that goes between the negative bus bar and the grounding bus bar.

Edit: upon further reflection, the shunt is sometimes used as the negative busbar. If that is the case, then I'm changing my answer to yes, make the bond there, on the load side, not the battery side.
 
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