AC voltage from array ground to main panel ground.

[42OhmsPA]

Scenario -
Was going to hook array ground from roof mount to main distribution panel since I never got around to it earlier. Heard a faint buzzing when the wire came in contact with panel frame and grabbed a meter.
Reading 24VAC between the array ground and main panel ground, 0VDc between the 2. Reading 0VAC between neutral and ground, they are not bonded in the panel.
Sun set hours ago. Wire was coiled up out of the way for weeks and system has been working fine, except for flickering lights when the washer agitates.

Setup -
200A US Split Phase Grid main to main panel lugs, inverter fed from main panel, inverter supplies entire house and is the only AC connection to the entire house.

TP6048 / LVX6048 / EG4 6K / Voltronic...

2 9s arrays of 315 w Q cells, one W the other S, fused and paralleled to the inverter. Ground wire in question is on the house roof above.

Thoughts?
I'm still a rookie and can't think of anything, especially since I don't get any voltage from N to G.

 

[42OhmsPA]

Still can't make sense of this one.

 

[Shimmy]

• Are all the lights that flicker on the same circuit?
• Do you have a clamp ammeter that can go around the incoming phases and neutral?
• Is there a neutral connection on the surge arrestor?
• Is the behavior the same if the inverter is isolated (Off, AC input/output open, battery open, no PV)?

You might have a pinched neutral or a neutral-hot reversed on a fixture (I have something similar happening via an electronic transformer for some MR16 lights that I can't find anywhere). If that is the case, shut off the breakers one at a time to see if the condition continues.

First step is to try to eliminate potential sources of ...the potential.

 

[PreppenWolf]

Any chance a nail/screw during install pierced a line in the attic?

 

[Hedges]

I think people have had AC voltage coupled through PV +/- wires to array. Array frame should be grounded back to system.
Try completing the (ground) circuit with a light bulb, then check voltage across it.

 

[42OhmsPA]

• Are all the lights that flicker on the same circuit?

Yes, the inverter is powering the whole house. There are 2 other panels that feed off the panel being fed from the inverter.

• Do you have a clamp ammeter that can go around the incoming phases and neutral?

I could likely rearrange some wires to be able to go around both. What would this help diagnose? I'll grab my better meter I left at my brother's when go into town.

• Is there a neutral connection on the surge arrestor?

No, it's wired per midnite instructions. 2 legs to breaker, 1 to ground.

• Is the behavior the same if the inverter is isolated (Off, AC input/output open, battery open, no PV)?

I'll check it shortly once the sun is up enough for loads to run off solar only.

You might have a pinched neutral or a neutral-hot reversed on a fixture (I have something similar happening via an electronic transformer for some MR16 lights that I can't find anywhere). If that is the case, shut off the breakers one at a time to see if the condition continues.

First step is to try to eliminate potential sources of ...the potential.

Thanks you for the help. Now that you mention a N H reversed, I did notice an LED bulb that seems to have a slight glow to it when the switch is off. I will dig into that further.

I just can't figure out how there was no voltage between N and G in the main panel but there was voltage between main panel ground and array ground in the dark.

 

[42OhmsPA]

Any chance a nail/screw during install pierced a line in the attic?

No. The array ground is in new metal conduit from the array to the interior just before the main panel. The only changes I made on the AC side was pulled the main grid feed from a panel upstairs to the panel pictured above.

 

[42OhmsPA]

I think people have had AC voltage coupled through PV +/- wires to array. Array frame should be grounded back to system.
Try completing the (ground) circuit with a light bulb, then check voltage across it.

Will do, have a few old A19 bases laying around.
I remember reading a few posts about AC on PV. I suppose I should have metered the PV wires as well, I'll do that when it gets dark tonight.

 

[42OhmsPA]

With inverter running in solar / battery mode, meter reads 20vac between grounds mentioned. No ac between PV+ - at breaker, 306vdc.
I'll work on more of the above later.

Something else interesting, I think it's due to the sun angle and shitty panel angle.
I saw a peak of ~2600w from the panels around noon, array is 5600w. SA is also only showing around 8a from the panels. I either have a string dead or I'm only getting 50% of output.

 

[12VoltInstalls]

Now that you mention a N H reversed, I did notice an LED bulb that seems to have a slight glow to it when the switch is off.

This issue of reversed H and N should not matter. Whether by switching H/L or switching N,once the switch opens there is no more circuit. There could be capacitance in the LED assembly leading to a brief time of residual glow, or temporary phosphorescence in the diodes.

This typically only (mostly?) happens with “120VAC” LED bulbs. LEDs are ALL direct current at very low voltages up to ~12VDC nominal with some operating safely at 24VDC nominal (usually with reduced projected calendar life). 120VAC LEDs operate by rectifying AC and either by sophisticated electronics (Sometimes) or by using a simple resistor in lower-priced options then supply the intended voltage. There can be residual energy stored in these circuits until it bleeds down.