I noticed today when running my EG 4 inverters that are set up in SBU that the AC output varies wildly, from 104 volts to 140 or so on the LCD. I checked the panel with a voltmeter with the same result. My batteries are 100%. If I disconnect the solar input and run on batteries only the voltage reads a very steady 120 on both LCD's and my voltmeter. Does anyone see this with theirs?
EG4's in split phase output
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sunshine_eggo
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ncsolarelectric
Engineering Support CEO
Do you have a solid NG bond?
I can see if you don't have batteries or grid-connected, and you're running only on solar, then the output could drop to 104V if there isn't enough sun, but it should never go to 140V. If batteries are connected, I don't see how connecting PV will affect the output, that's why I think it's a grounding problem with your neutral to the panel.
I can see if you don't have batteries or grid-connected, and you're running only on solar, then the output could drop to 104V if there isn't enough sun, but it should never go to 140V. If batteries are connected, I don't see how connecting PV will affect the output, that's why I think it's a grounding problem with your neutral to the panel.
Thanks for the replies. It reads fine at 120 volts with the solar disconnected. My setup is below.
ncsolarelectric
Engineering Support CEO
I just see a dot.
I think you hit the nail on the head.I was running the system with the xfer switch in the main panel not switched on as this is a test. With that transfer switch not on and both bonding screws removed I would have no bond anywhere at this point true?
ncsolarelectric
Engineering Support CEO
Maybe there is a ground fault on the PV wires. Check your PV wires for short to ground/chassis/railings.
I have two EG4 inverters which are feeding a transfer switch that is in the main panel in the house where neutral and ground are of course bonded. Both inverter internal bonding screws are removed and the neutral, ground, and L1, and L2 from the inverters are kept separate and run directly to the xfer switch in the main panel. I have no AC input at this time. I followed Will and Ian's advice about removing the screws. Is this done correctly?
ncsolarelectric
Engineering Support CEO
If you hadn't removed the screws, it would've worked fine. Will saw some crazy stuff the first time when he removed both screws. If you're measuring voltage wrt ground, but you don't have an NG bond, the values will be bogus as it's floating on a capacitance with unknown voltage potential.
When I throw the xfer switch the bond should take place from the panel and my readings should be correct I assume.
ncsolarelectric
Engineering Support CEO
It's fine if you don't run the inverters when the transfer switch is not set to Inverter, but it isn't per code because with both screws removed, there is no NG bond except when the transfer switch is set to the inverter.
That makes sense, thanks. Should I re-install a bonding screw in one inverter as I saw suggested on here a while back? This is an interesting subject. Thanks for your time, sir.
ncsolarelectric
Engineering Support CEO
I would.
SignatureSolarJames
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3kw or 6.5kw?
ncsolarelectric
Engineering Support CEO
Did you check the string for ground faults? Ohm each cable to chassis and make sure there is no short to ground.
Here's what I have found so far.
I have two strings of 5 250w panels, I see no grounding issues and they each read approximately the same voltage output with a meter.
The strings go to a dual PV isolator switch mounted near the inverters and from there one string to each pv1 input on the inverters.
Connections are tight and the wiring at the switch to the inverters is correct.
If I run the inverters on battery only the 120V output is rock steady, if I connect the solar switch providing solar input to both inverters at their pv1 inlets, the output voltage swings all over the place on both inverters.
Now, If I disconnect one-panel string, It doesn't matter which one or which inverter and run it off one set of panels everything is fine. I have tried this with both inverters one at a time and both strings, to eliminate an inverter issue.
So, one PV string to either inverter, either string or inverter, it works fine, connect the second string of PV and the output is all over the map.
One odd thing I have noticed is that I have 32 volts at the output side of the Isolator switch even with the panels unplugged, it's coming from each inverter PV input line. I don't get that.
Both inverters are wired back to a transfer switch in the main house panel and bonded there only, that bond is connected whether or not the xfer switch is closed as it just closes L1 and L2.
And both inverter screws are still removed maybe this?
I have two strings of 5 250w panels, I see no grounding issues and they each read approximately the same voltage output with a meter.
The strings go to a dual PV isolator switch mounted near the inverters and from there one string to each pv1 input on the inverters.
Connections are tight and the wiring at the switch to the inverters is correct.
If I run the inverters on battery only the 120V output is rock steady, if I connect the solar switch providing solar input to both inverters at their pv1 inlets, the output voltage swings all over the place on both inverters.
Now, If I disconnect one-panel string, It doesn't matter which one or which inverter and run it off one set of panels everything is fine. I have tried this with both inverters one at a time and both strings, to eliminate an inverter issue.
So, one PV string to either inverter, either string or inverter, it works fine, connect the second string of PV and the output is all over the map.
One odd thing I have noticed is that I have 32 volts at the output side of the Isolator switch even with the panels unplugged, it's coming from each inverter PV input line. I don't get that.
Both inverters are wired back to a transfer switch in the main house panel and bonded there only, that bond is connected whether or not the xfer switch is closed as it just closes L1 and L2.
And both inverter screws are still removed maybe this?
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ncsolarelectric
Engineering Support CEO
Ask EG4, that's weird!
hi, I have the same problem with eg4 6k now. Started yesterday. If batteries are turned OFF, no issues from ac in to ac out. If batteries only, then I see the voltage fluctuations. Could it be related to bonding screw? Is there a video/instructions on how to change it?
I don't have pv. It was working perfectly yesterday morning. I have 4 wires coming from main panel to inverter and 4 going to sub-panel. I have double verified the wiring and it is correct as it was working yesterday. No response from SS
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ncsolarelectric
Engineering Support CEO
Easy solution. Don't remove the bonding screws. It's not necessary. It doesn't cause any issues having 2 N-G bonds. It causes issues not having any.
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