Off Grid shed connected to RV getting shocked

[yettieu]

I have a concerning situation with my off grid setup and getting shock from my RV chassis after a storm and heavy rain .

Overview:

a solar array feeds into a shed that houses the inverters, batteries , ac panel. I have a RV plugged into this building and after a heavy rain the RV started getting charged (shocked my dogs and the door lock was tingly to the tough). I'm getting 60 vac and 58vdc when testing earth ground to the frame of the RV. If I turn off the PV breaker in the building (day or night) then the issue goes away. This is a new issue and have been off grid with this setup for almost 2 years.

The setup:

The Array is 12k, each panel has the frame connected by 6awg ground which goes to the combiner box that goes to a ground rod.

The Combiner Box has 2 sets of PV wire are in conduit to the inverters located in a shed 90 feet away. (no grounding wire from the combiner box to inverter shed)

The shed has 2 growatt 5000 inverters that have PV breakers as well as battery breakers for the 48V eg4 battery bank

The 2 growatts feed their line 1, line 2, and ground to a "inverter combiner" panel that have 2 breakers one for each inverter which combines and feeds into a breaker on the AC panel

A midpoint transform also feeds into the AC panel.

The AC Panel in the shed has the neutral and ground bonded, there is a ground rod to the AC Panel ground bar

I have an 50amp RV panel on the exterior of the shed and the RV is park a few feet away over the buried PV lines.

I'm unsure if i should connect the Array ground to the inverter combiner panel ground or remove the bonded ground/neutral screw in the AC Panel?

Thanks in advance for advice

 

[ksmithaz1]

If it's a new problem I would suspect an issue on the RV backfeeding to ground. Unplug the RV test ground at the outlet for the RV to earth. should be zero, should read 0 to N and ~120v to L1 and L2. You should not see DC anywhere earth to plug,N,L1,L2. Then find the problem on the RV and fix it.

 

[timselectric]

. (no grounding wire from the combiner box to inverter shed)

This is why you are getting shocked.
Your array is not grounded. (It's just connected to earth)

 

[Hedges]

The 2 growatts feed their line 1, line 2, and ground to a "inverter combiner" panel that have 2 breakers one for each inverter which combines and feeds into a breaker on the AC panel

A midpoint transform also feeds into the AC panel.

The AC Panel in the shed has the neutral and ground bonded, there is a ground rod to the AC Panel ground bar

I have an 50amp RV panel on the exterior of the shed and the RV is park a few feet away over the buried PV lines.

I'm unsure if i should connect the Array ground to the inverter combiner panel ground or remove the bonded ground/neutral screw in the AC Panel?

Known problem, some inverters impose AC on PV+/-, which capacitively couples to PV frames.
Need a "ground" wire from PV frames back to inverter chassis.

Will wrote about this, and several forum members had the issue.

Separately, you have 230V only European model inverters. They may have L/N rather than L1/L2, and their "N" (one of your "L") bonded to ground. A bonding screw needs to be removed in that case.

Further issues arise if you connect grid power to the inverters, or maybe generator power. But I think it can be made OK for purely offgrid.
Preferred approach would have been 120/240V split-phase inverters.

If you have 2x Growatt and an auto-transformer, have to consider whether autotransformer could be overloaded, and whether it can disconnect by breaker to protect itself from overheating, in which case neutral is lost and 120V loads can get excessive voltage. This can be made to work, but you have to understand the issues and design around them.

 

[yettieu]

This is why you are getting shocked.
Your array is not grounded. (It's just connected to earth)

I ran a ground wire from the PV Array combiner box to my the ground in the panel the growatts combine into, and the charge to the RV went away but the SL1 growatt is throwing a 51 over current error, but the other HST growatt is doing fine

 

[timselectric]

I ran a ground wire from the PV Array combiner box to my the ground in the panel the growatts combine into, and the charge to the RV went away but the SL1 growatt is throwing a 51 over current error, but the other HST growatt is doing fine

Try a reboot.
Not sure if that will clear it up.
Do you know how much current was flowing, at the time?

 

[timselectric]

Error #51 is over current or surge.
If it was a surge, a reboot should clear it.

 

[yettieu]

Known problem, some inverters impose AC on PV+/-, which capacitively couples to PV frames.
Need a "ground" wire from PV frames back to inverter chassis.

Will wrote about this, and several forum members had the issue.

Separately, you have 230V only European model inverters. They may have L/N rather than L1/L2, and their "N" (one of your "L") bonded to ground. A bonding screw needs to be removed in that case.

Further issues arise if you connect grid power to the inverters, or maybe generator power. But I think it can be made OK for purely offgrid.
Preferred approach would have been 120/240V split-phase inverters.

If you have 2x Growatt and an auto-transformer, have to consider whether autotransformer could be overloaded, and whether it can disconnect by breaker to protect itself from overheating, in which case neutral is lost and 120V loads can get excessive voltage. This can be made to work, but you have to understand the issues and design around them.

these were from Signature solar and the us version but im wondering about the bonding screw is in them still

 

[timselectric]

these were from Signature solar and the us version but im wondering about the bonding screw is in them still

It's not in those models.

 

[Zwy]

I have a concerning situation with my off grid setup and getting shock from my RV chassis after a storm and heavy rain .

Overview:

a solar array feeds into a shed that houses the inverters, batteries , ac panel. I have a RV plugged into this building and after a heavy rain the RV started getting charged (shocked my dogs and the door lock was tingly to the tough). I'm getting 60 vac and 58vdc when testing earth ground to the frame of the RV. If I turn off the PV breaker in the building (day or night) then the issue goes away. This is a new issue and have been off grid with this setup for almost 2 years.

The setup:

The Array is 12k, each panel has the frame connected by 6awg ground which goes to the combiner box that goes to a ground rod.

The Combiner Box has 2 sets of PV wire are in conduit to the inverters located in a shed 90 feet away. (no grounding wire from the combiner box to inverter shed)

The shed has 2 growatt 5000 inverters that have PV breakers as well as battery breakers for the 48V eg4 battery bank

The 2 growatts feed their line 1, line 2, and ground to a "inverter combiner" panel that have 2 breakers one for each inverter which combines and feeds into a breaker on the AC panel

A midpoint transform also feeds into the AC panel.

The AC Panel in the shed has the neutral and ground bonded, there is a ground rod to the AC Panel ground bar

I have an 50amp RV panel on the exterior of the shed and the RV is park a few feet away over the buried PV lines.

I'm unsure if i should connect the Array ground to the inverter combiner panel ground or remove the bonded ground/neutral screw in the AC Panel?

Thanks in advance for advice

N-G bond in RV, I've been there. https://diysolarforum.com/threads/p...ain-breaker-due-to-distance.66653/post-839280 If you have N and G on the same busbar, you get a parallel path. If you have the AC panel in the RV N-G bonded, it creates a parallel path.

As mentioned, you do need an EGC from PV array to system grounding.

 

[timselectric]

N-G bond in RV,

It shouldn't have one.
But, I'm assuming that this is a manufactured RV.
If it's a home made RV, anything is possible.
Assuming things have gotten me in trouble, before.

 

[Zwy]

It shouldn't have one.

Correct.

But, I'm assuming that this is a manufactured RV.
If it's a home made RV, anything is possible.
Assuming things have gotten me in trouble, before.

You know how things "happen".

I'll put my money on an N-G bond or some type of conductivity between N and G.

 

[Hedges]

An extra N-G bond somewhere isn't going to raise voltage to the point of causing a shock.
It does produce "objectionable current", some neutral return current flowing through chassis/ground.
If neutral opens and ground opens, only then would line voltage appear on chassis.

Shock from chassis would be due to other problems, not N-G bond in wrong place.

58VDC sounds like full battery voltage. By the way, is that +58V or -58V?

Bonding of all chassis and frames to a ground wire and ground rod ought to eliminate voltage on chassis. Might trip a breaker or overload inverter if there is another faulty connection somewhere.

 

[timselectric]

I believe that the issue was between the ungrounded array and the grounded RV.
It was solved by grounding the array.

 

[Zwy]

An extra N-G bond somewhere isn't going to raise voltage to the point of causing a shock.
It does produce "objectionable current", some neutral return current flowing through chassis/ground.

An extra N-G bond will produce hot skin if G is bonded to chassis due to the parallel path. Current will pass thru a person if the ground contact is enough to conduct electricity.

Take it from my personal experience, it might not be noticeable until one day it is.

There have only been a few times I ever was shocked so far. One was very young, open hole on side of fuse panel that was used as a switch on a water heater. I put my finger in there. I wasn't very old at the time, but I sure remember it.

Next time was hot skin on the work trailer, I posted a link for that story.

Next was an open neutral when I had the wrong neutral wire. Luckily not much load on it.

This thread is a classic example of hot skin.

I believe that the issue was between the ungrounded array and the grounded RV.
It was solved by grounding the array.

I see he added a ground but now has an overcurrent. I don't consider the "problem" is fixed.

Problem appeared after a heavy rain, so the ground contact is important. Current is finding a path back to source from the RV.

 

[timselectric]

I see he added a ground but now has an overcurrent. I don't consider the "problem" is fixed.

The ground problem is fixed.
Haven't heard back about the over current error.
Could have just been a glitch. Or could be something else.
Just have to wait until we hear back.

 

[yettieu]

The over current was due to a diode board in my 247 watts PV combiner box was fried. I ordered a replacement diode board they have, meanwhile I by pass it with fused mc4 splitters and the error went away. The shock looks like it was from not having a ground wire from the Array to the Inverters' combiner panel I ran a ground and everything has checked out and running good.

Thanks Everyone for your suggestions and comments!