MPP Solar LV2424 - Utility connection has voltage when not backfeeding

[oglife]

So I've been experimenting with my parallel LV2424 units, and noticed that the utility connection ports (when disconnected from grid) show a voltage of up to ~0.8 volts on each unit. The units in parallel have read as high as ~1.8 volts. I have the grid-tie feature disabled in settings, and would thus expect the utility hookup to always read at zero volts.

I mentioned this to a friend, who works for our local electric co-op but is not an electrician, who suggested that this would make connecting these inverters to the grid unsafe, as when that voltage reaches the transformer it will be stepped up to somewhere in the neighborhood of 110-120 volts. They stated that the co-op would not allow these devices on the grid if they produce more than zero volts at the meter.

I was hoping to be able to use the grid bypass & charging features of the unit, but I'm now concerned. I know the unit isn't UL-listed, but I assumed that only related to the grid-tie/backfeed functionality, and had read on these forums that the LV2424 is expected to receive a UL listing in 2020 anyway.

Could any other MPP owners chime in? Do your inverters show a non-zero voltage on their utility connection ports? Perhaps I have some induced voltage, or another problem?

 

[ytwytw]

Do you have the white color unit or green color unit?

 

[oglife]

Green.

 

[nosys70]

you will probably not able to measure this voltage if you put some load on the wires.
no way that 1V is converted to high voltage by a gris transformer

 

[ytwytw]

I have the green one as well, I measured the AC input plug, 0V
(under load, battery is charging as well from solar)

 

[silgen]

To reach 120v from 2v, you need a 60:1 transformer which will reduce current at the same ratio. Not sure if it is a concern.

 

[oglife]

you will probably not able to measure this voltage if you put some load on the wires.
no way that 1V is converted to high voltage by a gris transformer

To reach 120v from 2v, you need a 60:1 transformer which will reduce current at the same ratio. Not sure if it is a concern.

This was my assumption. I'm just a hobbyist electrician, but I figured with any load the voltage would be pulled down to nothing. I also assumed that even if it was stepped up at a transformer, there'd be even less available current. Glad to hear others say the same.

I have the green one as well, I measured the AC input plug, 0V
(under load, battery is charging as well from solar)

Thanks for the report. Very odd that both of my units read above 0V. They are powering loads and being charged by solar, but the AC input side has no other load on it (the inverters were the only devices connected to this meter).

So I may still have to contend with the voltage reading to pass an inspection if I want these hooked to the meter. Maybe I should just wire a light socket in parallel, and stick an LED bulb in it? That way when the meter is disconnected, the bulb pulls the voltage to zero, and the reading should be 0V at the meter socket.

 

[BiduleOhm]

So I may still have to contend with the voltage reading to pass an inspection if I want these hooked to the meter. Maybe I should just wire a light socket in parallel, and stick an LED bulb in it? That way when the meter is disconnected, the bulb pulls the voltage to zero, and the reading should be 0V at the meter socket.

That's what I would do too