eg4 6500EX offgrid, 4 inverters: Anyone have it working?

[rebible]

The problem:
when the system switches to the generator (utility) at least one inverter will throw a F60 power feedback error within the first 1/2 hour of running off the generator.

System:
is 4 inverters split phase , 12 eg4 batteries (60Kwh), gobs of solar, and a 20KW generator.
The generator is a new Kohler.
The wiring is "textbook" clean with over sized conductors used everywhere.
While on solar or battery the system seems solid with minor flickering on some LED lights and occasional ups alarm beeps. Pretty much what we expected:
Current is shared as it is supposed to be and the voltage regulation is good .. As a side note the flickering is also almost eliminated with 4 vs 2
Inverters are programmed SBU and 50 amps charge from utility.

BUT,
if the system tuns on the generator with the NO contacts (or we manually have the generator already running) within about 1/2 hour 1 inverter on each phase will set the F60 fault and shutoff charging and output. The other two inverters keep running but the battery charging rate is now 50% and a total system shut down and restart is necessary to get everyone happy again.

If we run the same experiment with just two inverter everything is honky dory.

I have put in a trouble ticket to signature. The units have only been in use about 1 month, but this seems like a design bug in the software.

From what I can determine the current sharing between the units in parallel is accomplished by adjusting the unit output voltages. (If you isolate one inverter from the load it slowly goes to 130V while the unit under load drops to 110V). Evidently with the utility input from a generator the current sharing feedback loop glitches.

 

[Samsonite801]

Here is some more reference about the error (Page 16):

https://www.mppsolar.com/v3/catalogs/PIP-HS_MS%20Parallel%20Guide.pdf

Not sure if this is related, but what is the status of your N-G bond screws inside the inverters? Do you have one inverter bonded, both bonded, or none bonded and using Setting option 42... Wondering if there could be two N-G bonds, perhaps you're getting objectionable ground current on grounding and bonding paths, leading to noise on the communication / current sharing cables..

Wondering if there is any relationship to this thread:

EG46500EX F80 when grid is added.

Hello all! My system consists of 2 eg4-6500ex's in split 240v, 6 eg4 lifepower 4's, 16 Q Cell panels(400 watts), and 16 Boviet panels (370watts). The system has been up and running without issue since July 22 of this year. We've had several cloudy days recently so I manually switched the...

diysolarforum.com

FYI, to whom it may concern:
@EG4_Jarrett

Actually, I just remembered, when you're on generator power, the N-G bond inside inverters should be open (while inverters are in bypass), so does your generator or generator circuit somewhere upstream of the inverter input provide an N-G bond? (since you need to have exactly one N-G bond)

 

[EG4_Jarrett]

The problem:
when the system switches to the generator (utility) at least one inverter will throw a F60 power feedback error within the first 1/2 hour of running off the generator.

Units are on when this happens?

Is the generator connected to all inverters or just one?

 

[rebible]

I appear to have solved it.

long story short. There was generator current and output current being shared on the generator neutral lines. This is obvious in retrospect.

Long Story:
our property was serviced by 3 meters 1/4 to 1/2 mile apart (1:the barn,well , auxiliary buildings, 2: two wells, the lake pump, 3:and the house)
We have done the solar installation centralized in the barn.
This required running new buried AC wiring from the barn to the house (600ft) and from the house to the lake (300 ft).
We already had the backup generator adjacent to the house and the propane so we are using it for the solar.
We kept the automatic transfer switch (last resort backup for the house) and wired the generator to both it and the solar inverters.
This was done with 3 conductor direct burial service entrance wire.

Thus, there are two 3 conductor cables between the barn and the house/generator. L1,L2,N to the house and L1,L2,N to the generator.
Since the auto transfer switch is two poles the house N and generator N are tied together.
I also had tied the House Neutral (Inverter out N) to the generator N at the barn (Jumped between the two panels.)

When I broke the "neutral loop" at the barn everything now seems to work.

I know everyone is going to be freaking out about what is bonded to earth ground and where. According to NEC when the sub-panels are separated by these distances they should be separately bonded and there is no need for a ground wire between them.
The house/generator Neutral is earth ground bonded at the house and the inverter grounds are bonded to earth ground at the barn.


Picture of install below. (yes there are 5 inverters. was going to do 3 phase, but my well pump saver was unhappy with 120 degree L1 &L2. So right now it is a spare)