diy solar

diy solar

The "Meg" Build

You guys nailed it, I flipped the PV disconnect switch and there is now 0V from the dirt to aluminum. This is even with absolutely no sun out too.

It should also be noted, that leaving the PV array that is screwed to the roof of the trailer on, has no effect. It only has voltage potential when the panels on the shipping container are connected.
 
You guys nailed it, I flipped the PV disconnect switch and there is now 0V from the dirt to aluminum. This is even with absolutely no sun out too.

I have no reason to think the PV lines have anything to do with it, but try throwing the PC disconnect to off and see if the voltage is still there.
Although I’d be entirely in awe, entertained and fascinated if the 88V disappears with the PV neg(-) and pos(+) disconnected…
I don't think either of us really expected the PV to be the issue, but now we have a clue to work off of.

One thing to try to understand is if the shock is coming from PV power or someplace else. If the PV is connected in the night, do you still get the shock?

Tell us about the shipping container and the PV lines.
  • Is there any other electrical equipment in/at the container?
  • Is there a ground wire run with the PV power wires?
  • Please inspect the PV wires from the disconnect all the way to the panels. Look for any worn wires that might make a connection to something metal or to the ground.
  • 200ft is a long run, are the wires buried? Arial? Could something holding them in place have punctured the insulation?
  • What is the Voc of the PV string?
 
What brand panels?
Short from PV panel to its frame? Some old Trina panels had an issue, were recalled and replaced.

Your meter showed 101 VAC, not DC. So a bit puzzled.
Something about how a transformerless inverter is grounded could do that.
Or ripple on PV? 101V would be a lot. Check PV voltage on AC scale.
 
I don't think either of us really expected the PV to be the issue, but now we have a clue to work off of.

One thing to try to understand is if the shock is coming from PV power or someplace else. If the PV is connected in the night, do you still get the shock?

Tell us about the shipping container and the PV lines.
  • Is there any other electrical equipment in/at the container?
  • Is there a ground wire run with the PV power wires?
  • Please inspect the PV wires from the disconnect all the way to the panels. Look for any worn wires that might make a connection to something metal or to the ground.
  • 200ft is a long run, are the wires buried? Arial? Could something holding them in place have punctured the insulation?
  • What is the Voc of the PV string?
Nothing in/around the container with electricity. My RV is the closest thing to it with power.

There is 4 conductors running from the array (2x 6s2p arrays) to the RV (2 positive and 2 negative).

About 100ft of it is underneath rubber mats (like gym mats), and the other 100ft is wrapped in split loom. I will pull up the mats tomorrow and see if I can find any damage.

VOC is roughly 220v.

What brand panels?
Short from PV panel to its frame? Some old Trina panels had an issue, were recalled and replaced.

Your meter showed 101 VAC, not DC. So a bit puzzled.
Something about how a transformerless inverter is grounded could do that.
Or ripple on PV? 101V would be a lot. Check PV voltage on AC scale.
They are Trina panels, from SanTan.

When I did the test with the screwdriver, there was only 86V, so I believe it has something to do with the solar panels because the voltage was dropping from reduced sunlight. I can check more tomorrow if the voltage potential is higher during more sunlight. I will try and measure AC voltage right at the PV disconnect tomorrow and see what pops up.

How would the solar panels produce AC power?? Lol
 
How would the solar panels produce AC power?? Lol

MPPT charge controller draws pulses of current from capacitor charged by PV, so there is some ripple.
My GT PV inverters (and hybrids with high voltage DC rail like SolArk), draw sine wave current off that capacitor, likely much higher ripple.
Transformerless grid-tie inverters impose AC voltage waveform on the panel wires (At least 3-phase does, with a single-phase inverter across two lines of AC). That could occur in a split-phase design too.
Some cheap battery inverters produce +/- 60Vrms. If one leg was grounded to make 120VAC, battery would have AC imposed on it. PV coupled to battery would too.

Because your DMM showed 101VAC, I was puzzled by the fault being related to PV panels connected. So I'm speculating on what path could drive AC through them to chassis.
 
might need to bond the neutral to ground when off grid

Yes. Something like that may be needed, but it does not look like that is the issue the OP is facing.

As is typical with MPP, the manual does not explain its ground scheme. However, I suspect there is no N-G bond. Furthermore, there does not appear to be a dry-contact output like what is shown in the video for the Growatt.

One partial solution is to use shore power to turn of a normally closed contactor that creates the Neutral-Ground bond. The only problem *might* be that if the shore power is plugged in but the inverter is on battery for some reason, there could be two N-G bonds.
 
Short from PV panel to its frame? Some old Trina panels had an issue, were recalled and replaced.
They are Trina panels, from SanTan.
It seems highly probable the problem is identified!!! The last test would be to disconnect the PV at the panels and see if the problem goes away.

Safety recalls often live long past the warranty. The OP should see if he can get the panels replaced.

BTW: it is problems like this that gave rise to the PV ground fault protection requirements in the NEC. As much as I hate all the dang NEC requirements.... I have to admit that they are there for a reason.
 
It seems highly probable the problem is identified!!! The last test would be to disconnect the PV at the panels and see if the problem goes away.

Safety recalls often live long past the warranty. The OP should see if he can get the panels replaced.

BTW: it is problems like this that gave rise to the PV ground fault protection requirements in the NEC. As much as I hate all the dang NEC requirements.... I have to admit that they are there for a reason.
I will be doing lots of testing tomorrow to try and identify if there is a single panel causing the problem.

I wonder what the process would be of getting a replacement panel? If it is even possible.
 
last test would be to disconnect the PV at the panels and see if the problem goes away.
I’ll freely admit I don’t have the experience and knowledge of filterguy and I’m not opposing this at all BUT I’d take the 10/15 minutes and verify neutral/ground tie (or not) with the inverter(s) anyway, both disconnected from the RV black and white circuits AND connected. The results should be the same; if not the same then test A/B with just the white then just the black (continuity). But that’s sometimes weird to do as some equipment with motors can display zero ohms or close enough to zero that results can be a lie. Anyways… That should scare out a crossed hot/neutral - though it’s highly unlikely from your reports and defies the symptom.

But I am fascinatedly awaiting the report of 1) if there is no shock in dark or disconnected from PV; and 2) if there is a faux AC feedout from the panels to the earth which then completes a circuit when hand on camper through body to earth is positioned.
 
I’d take the 10/15 minutes and verify neutral/ground tie (or not) with the inverter(s) anyway, both disconnected from the RV black and white circuits AND connected.
I would be interested in this too....I suspect there is no Neutral-Ground bond and that can be dangerous. However, even if it is lacking the bond, I don't think it is causing the problem the OP is asking about
I will be doing lots of testing tomorrow to try and identify if there is a single panel causing the problem.
Any update??? We are very curious about what you find.
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even if it is lacking the bond, I don't think it is causing the problem the OP is asking about
Ya, I was actually trying to imagine some feedback or ‘poor’ short- lacking the bond would make the feedback zap impossible I think

You probably nailed it anyway. It was just a fun little death trap.
 
Appliances can have some leakage to "ground", meaning the protective ground wire of a 3-prong plug.
Most things these days are electronic, and they have EMI filters with capacitors to ground. Which can inject some milliamps. Too much of that and even GFCI trip. Mostly, could be enough to feel. (This happens to be a current professional topic for me, so I've been doing measurements and looking at waveforms and spectrums.)
That still doesn't explain why vehicle chassis would have AC voltage relative to mother earth.
 
That still doesn't explain why vehicle chassis would have AC voltage relative to mother earth.
There could be a couple of possibilities. As you rightly pointed out, a charge controller can create a large ripple or even pulses on the PV line. There could be a couple of possibilites.

* A pulsed DC voltage could appear as a positive AC voltage to a voltmeter. The VOC of the PV is 220V and the measured 'AC' was around 100 so the numbers are about right for this. It would be interesting to see if the voltage registers as a DC voltage as well.

* If there is an inductive or capacitive coupling someplace in the system... it could show up as an AC voltage.
 
I found 83.3v AC and 59.99Hz from earth to RV just now. Now I'm pulling up these super heavy mats looking for punctures...
 
Frame grounded to earth shouldn't cause it. Something with AC voltage driving leakage current into earth, that's AC voltage relative to frame, would make frame carry voltage.
If very low current I suspect capacitive coupling.
 
I disconnect the PV wires from the Array (200ft away) and still have 54V AC between rv and earth.

For the hell of it, I connected back to the grid with 50a supply, and low and behold, only 216mV between rv and earth, and no shocking when I touch it.

So does this mean I need to bond neutral/ground when not connected to grid power?
 
That, and connect ground to a rod driven into the earth.
(depending on moisture content. The first U.S. soldier death in Iraq was electrocution while taking a shower.)
 
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