MPP Solar LV1012 N-G Bond

[timselectric]

In an off grid system. It's perfectly fine to install a fully grounded system, or a fully non grounded system. There are benefits to either. I have installed both, most of which are in an industrial environment.
I prefer a grounded system. But, when installing an ungrounded system. I always install a ground detection system. As an early warning system.
Of course, if you (speaking in general) are going to be connected to the grid. You don't have a choice. You have to match whatever the grid system is.

 

[thetimbo]

Thanks to all who replied. Sorry, I have one last question for timselectric :
To clarify the lightning point, my thought had been to screw a lay-in lug to each PV panel, then run the 6g wire down and to my rod where all my system's grounds are tied. But you feel that lightning protection should best be entirely separated from the electrical system's ground rod. And is best not earthed at all. But if one had a auxiliary rod for lightning, it should be tied back to the "main" rod.
Is this correct?
Thanks so much.
Tim

 

[timselectric]

my thought had been to screw a lay-in lug to each PV panel, then run the 6g wire down and to my rod where all my system's grounds are tied.

This is the required electrical grounding.
This is not lightning protection.

But you feel that lightning protection should best be entirely separated from the electrical system's ground rod.

Yes, they are two separate systems.

And is best not earthed at all.

No, lightning protection must be earted to function, as the path of least resistance to earth.

But if one had a auxiliary rod for lightning, it should be tied back to the "main

If it's an auxiliary rod, that's connected to the system's equipment. (Ground lugs,enclosures,solar panels, structural framing, water and gas pipes) it's an auxiliary electrical system's ground rod........ Then Yes
If it's part of a lightning protection system. (Completely separate from the electrical system)....... Then No

 

[thetimbo]

I must be confusing ordinary equipment grounding (the PV panels) to my common ground rod, and a lightning protection system.
You've been a great help. Thank you.
Tim

 

[timselectric]

Grounding is always a confusing process.
For everyone.
So many different things, fall under that word. lol

 

[JAS]

ahh, good thought. I do have one of those testers and did use it previously. However, can't remember if I did the test on battery AND if I tested with the AC input disconnected. I'll check again this weekend

Follow up... Confusing!

On Bypass (AC connected from my main service panel), I get:
H-N = 120V
H-G = 120V
N-G = 0V
Receptacle tester shows correct wiring

On Battery (AC disconnected), I get:
H-N = 120V
H-G = 100V
N-G = 20V
Receptacle tester shows correct wiring

What is going on with that?!?! (Oh, I did have a small load on it while testing. Does that make a difference?)

 

[timselectric]

Oh, I did have a small load on it while testing. Does that make a difference?

Yes

 

[timselectric]

Follow up... Confusing!

On Bypass (AC connected from my main service panel), I get:
H-N = 120V
H-G = 120V
N-G = 0V
Receptacle tester shows correct wiring

On Battery (AC disconnected), I get:
H-N = 120V
H-G = 100V
N-G = 20V
Receptacle tester shows correct wiring

What is going on with that?!?! (Oh, I did have a small load on it while testing. Does that make a difference?)

It appears that you have a N/G bond, in bypass mode.
But not, in battery mode.
Need to verify, with no load connected.

 

[12VoltInstalls]

It appears that you have a N/G bond, in bypass mode.
But not, in battery mode.
Need to verify, with no load connected.

Warning Will Robinson!

It appears to me that the other poster that said this switches bond was incorrect with the information.
I haven’t had a chance to test mine thoroughly but I have other info that suggests G is open and not switching to bond. Customer right now I’ll write more tonight.

 

[JAS]

It appears that you have a N/G bond, in bypass mode.
But not, in battery mode.
Need to verify, with no load connected.

So with no load on, I get slightly better...

H-N = 120v
H-G = 110v
N-G = 10v

Is this "normal" or do I have a faulty unit?

 

[JAS]

Also, this is what I got from MPP Support when I asked about N-G bond:

---------- Forwarded message ---------
From: MPP Solar Inc. <support2@mppsolar.com>
Date: Wed, Feb 9, 2022 at 11:58 PM
Subject: Re: 1012LV-MS, 92412105100096- Neutral Ground Bonding Question
To: (removed) <support@mppsolar.com>


Hi Jeff

Based on the original design of the unit, when the unit works in the battery mode, the AC output N-G terminal will be short. When the unit works in the line mode, the N-G terminal will be open.

I hope it helps you.

Thank you.
Best regards,
Andy Y. ¦ Support Team, MPP Solar Inc.
support@mppsolar.com ¦ www.mppsolar.com

 

[Bud Martin]

What is the output connected to, outlet strip with surge protection?
My 1012
1) without AC connected (not plugged into my utility outlet), inverter switch is OFF, the resistance at the AC output terminal checking between N and G <1 Ohm (my meter probe wires resistance).
2) When on Inverter mode, no AC connected, N-G shows in mVac, H-G = 120Vac, H-N = 120Vac.

BTW, when you say 'AC disconnected' does it mean all 3 wires are disconnected from the utility panel?

 

[JAS]

What is the output connected to, outlet strip with surge protection?
My 1012
1) without AC connected, inverter switch is OFF, the resistance at the AC output terminal checking between N and G <1 Ohm (my meter probe wires resistance).
2) When on Inverter mode, no AC connected, N-G shows in mVac, H-G = 120Vac, H-N = 120Vac.

Yes, I have a power strip wired into it. Why would that affect battery only mode? (ByPass mode tested as expected)

 

[JAS]

BTW, when you say 'AC disconnected' does it mean all 3 wires are disconnected from the utility panel?

Yes, I have an extension cord wired to the AC In and I keep it plugged into a receptacle coming off of my main service panel. For these tests, I just unplugged it.

 

[timselectric]

Yes, I have a power strip wired into it. Why would that affect battery only mode? (ByPass mode tested as expected)

In bypass mode, it passes the H, N, and G, through.
Along with its N/G bond.
In battery mode, it disconnects the H, and N.
And bonds the inverter N to G.
At least, this is how it should work.
The power strip, possibly has a lighted switch, or surge protection circuitry. This will give false readings on your meter.

 

[JAS]

The power strip, possibly has a lighted switch, or surge protection circuitry. This will give false readings on your meter.

Wouldn't that give the same false reading when the unit is in ByPass though as well?

I guess when I have more motivation, I'll open the panel and check right at the terminals. (It's a pita getting those small screws back in. I think I drop one every time and have to spend 10 minutes finding it)

 

[timselectric]

Wouldn't that give the same false reading when the unit is in ByPass though as well?

Not if you have a true N/G bond.
So, I'll assume that you don't in battery mode.

 

[JAS]

Not if you have a true N/G bond.
So, I'll assume that you don't in battery mode.

Well, that sucks . I'm basing my setup on the fact that I have a N/G bond coming out regardless of battery or ByPass mode. So that implies this unit could only be useful with a generator input (one without a N/G bond) and then the N/G bond could be done at a panel after the unit. That being said, I don't think I'd want to use it regardless with it leaking voltage to the ground...

I have an email in to both MPP Solar and Ian at Watts247, where I bought it. I'll see what they say. But, if it's "normal", I'll have to try to sell this unit and get something the next tier up...

 

[timselectric]

Jumper the input neutral and output neutral together.
Problem solved.

 

[timselectric]

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