MPP Solar LV1012 N-G Bond

[JAS]

as my 1012LV-MK does

Ahh?! I didn't catch your exact model before... Mine is a 1012LV-MS. Maybe that's a reason for yours bonding N/G and mine not?

 

[12VoltInstalls]

Ahh?! I didn't catch your exact model before... Mine is a 1012LV-MS. Maybe that's a reason for yours bonding N/G and mine not?

We do not know. Good little boys and girls test four things on inverters before they install them. I didn’t until OP question came up and I didn’t know the answer cuz I wasn’t a good little boy ?

 

[Zwy]

Ahh?! I didn't catch your exact model before... Mine is a 1012LV-MS. Maybe that's a reason for yours bonding N/G and mine not?

Does your unit have the Dry Contact Signal on the back panel? Refer to page 10 on the manual, it explains how this is used to control a relay external to the unit for N-G bonding purposes........

 

[JAS]

Follow up:

Finally got the front panel off to do more testing... Unit definitely has a floating neutral while on battery. (Tested Voltage right at terminals with the powerstrip disconnected)

Does your unit have the Dry Contact Signal on the back panel? Refer to page 10 on the manual, it explains how this is used to control a relay external to the unit for N-G bonding purposes........

Yes it does.

I also bonded the Input and Output Neutrals together with pigtails from the terminals. This did indeed take care of the problem! (With one caveat as per @Diysolar123 mentions above): As long as I keep the Input AC plugged in. (Regardless of whether grid power is present or not). If I unplug the cord, I lose my N/G bond.

Leaving the cord plugged in is not a problem for me. But, I haven't decided yet if I want to keep things this way or not.... I wanted to report that this setup does work. Just not sure I'm comfortable with the probable code violation of the whole thing????

 

[timselectric]

Which code violation?

 

[JAS]

Well, I'm not an electrician. But, I can't imagine any code inspector would be OK with a N/G bond that is dependent on not having a plug pulled from a receptacle... Then again, the fact that I have a non-UL listed inverter installed in my house would probably also not fly in my township

 

[12VoltInstalls]

Unit definitely has a floating neutral while on battery. (Tested Voltage right at terminals with the powerstrip disconnected)

Just for clarification- is this a recently acquired machine? And MS or MK model?

For sure with incoming grid completely disconnected on all three conductors my -MK unit was N-G bonded, also inverter G closed to grid G terminal.

I need to pull everything off mine and test proper.

 

[JAS]

Just for clarification- is this a recently acquired machine? And MS or MK model?

For sure with incoming grid completely disconnected on all three conductors my -MK unit was N-G bonded, also inverter G closed to grid G terminal.

I need to pull everything off mine and test proper.

Purchased about 6 months ago. MS model.

 

[ppmax5000]

New here, thinking about purchasing the LV1012 or LV2424 for a completely off-grid/no-grid solar+battery application to bring power to a shed. I love the idea, relative cost savings, and simplicity of these All-In-One units.

I have been following this discussion and another on this forum because I haven't been able to figure out how to wire these units between PV load box and an AC load box and carry a grounding electrode conductor clamped to earth ground rod throughout the system.

I happened to search through the manuals for both of these units for the term "ground" and the first hit in both manuals caught my attention. In both manuals this text appears in the SAFETY INSTRUCTIONS section (emphasis mine):

11. GROUNDING INSTRUCTIONS -This inverter/charger should be connected to a permanent grounded wiring system. Be sure to comply with local requirements and regulation to install this inverter.

Since there is no separate ground bonding screw on these units, doesn't the phrase above imply that these units "shall" be connected to grid power?

Out of curiosity, has anyone plugged a circuit tester into the AC output of these things when AC input is disconnected (battery power -> inverter)?

 

[JAS]

Out of curiosity, has anyone plugged a circuit tester into the AC output of these things when AC input is disconnected (battery power -> inverter)?

Yes, I have (buried somewhere towards the beginning of this thread). Lights on tester read "proper wiring". ?‍

 

[ppmax5000]

Thanks again JAS, much appreciated.

FWIW the post you referenced is #70

Did you get rid of your unit? Did you end up jumper AC IN and AC OUT Neutrals? It sounds like my use case is similar to yours...

 

[JAS]

Thanks again JAS, much appreciated.

FWIW the post you referenced is #70

Did you get rid of your unit? Did you end up jumper AC IN and AC OUT Neutrals? It sounds like my use case is similar to yours...

As of now, I have the Neutrals jumpered and that did resolve the "issue". However, it does require the AC input to always be connected in order for the N/G bond. (I've also thought about hard wiring it to a dedicated breaker in my main panel).

I'll probably keep the unit (as it seems I would have to pay the return shipping and that is just not worth it). But, not sure if I will keep it in the capacity I have it setup. IE: I may use it in a diy solar generator box or take it to my hunting cabin... (In which case, I would not keep the neutrals bonded)

 

[12VoltInstalls]

, it does require the AC input to always be connected in order for the N/G bond. (I've also thought about hard wiring it to a dedicated breaker in my main panel).

Which isn’t a bad thing. That you need to connect it to an electrical system that it derives the neutral ground bond from isn’t a bad thing. As long as you avoid wiring and such a fashion that you create a ground loop that is perfectly fine. It seems ideally suited to that

I'll probably keep the unit…not sure if I will keep it in the capacity I have it setup. IE: I may use it in a diy solar generator box or take it to my hunting cabin... (In which case, I would not keep the neutrals bonded)

If you have an in a hunting cabin you should have a breaker panel anyway. The breaker panel that it feeds could/would contain the neutral ground bond. If a generator is connected to it in which the neutral and ground are not connected, then that would still be fine.
At the end of the day it can be wired safely. What makes this a ““ problem ““ is the fact that the instructions both lack direction on grounding specifics and don’t even mention the concerns as far as I can tell. The tone of this discussion in the thread could easily be misinterpreted as if there’s something wrong with the unit, but I think that that would be a shortsighted conclusion. The unit does what it should as far as providing power - the instructions are the problem imho.

I would be overjoyed if it appropriately switched the – G bond from internal closed to internally open with the neutral ground bond passed from grid source to the supply output. My unit may do that safely but I need to be at home long enough to test the output properly and assure there is no current on the ground conductor(s). I’ll do that eventually.

Don’t throw out the baby with the bathwater.

 

[JAS]

The biggest "problem" I see with my particular unit (aside from the lack of instructions or even knowledge from support) is that there is very little room to jumper the neutrals inside the unit. I got it done. But, boy is it tight. It just doesn't feel like the unit was designed for that kind of "wiring work around"...

 

[12VoltInstalls]

there is very little room to jumper the neutrals inside the unit

Agreed. I’d be likely to use a 4-square box and make it there if I did what you did.

I personally would (should say will) use a three-position center-off three-conductor switch to act as a transfer switch if it tests necessary.
This would allow me to handle the N-G pass from Grid when grid is selected, or isolate from grid and carry the bond appropriate to the unit.
But I’d agree it SHOULD handle all that properly within itself

 

[thetimbo]

Sorry for the delay. My solar outbuilding needed extensive mods that took much time.
The "bottom half" of my 1012lv system is installed (sans solar panels), and I can say that there is definitely no N/G bond on the unit while on battery.
So, I'm left to make the bond in my single breaker sub-panel, all off-grid. I've run a ground wire from that panel to a centralized ground Bus in a second mini-fuse box, where my PV wires will descend and also be grounded.
My question is, will the N-G bond function from a second box (distance is two feet)?

Thanks for your patience.
Tim

 

[JAS]

If you have an in a hunting cabin you should have a breaker panel anyway. The breaker panel that it feeds could/would contain the neutral ground bond. If a generator is connected to it in which the neutral and ground are not connected, then that would still be fine.

Turns out I am thinking of doing just this...

Question: Does the MPP need grounding (not bonding) if feeding the breaker panel in the cabin (and that panel is both grounded and has the N/G bond)? If so, how?

 

[12VoltInstalls]

Turns out I am thinking of doing just this...

Question: Does the MPP need grounding (not bonding) if feeding the breaker panel in the cabin (and that panel is both grounded and has the N/G bond)? If so, how?

Off-grid operation I believe all the MPPs connect ground to neutral internally and automatically. If gen gets connected and starts running I believe it opens that N-G as with any other input power.

I would prefer the N-G in the AIO for totally off-grid, and bridge it at the genset if you have a generator in mind.

Various NEC codes require a ground rod for any system but I do not believe that the circuit requires a ground rod mechanically. I’m not an EE or elecktricionne but that is my opinion. Wire everything properly safety/3-wire grounded and my opinion is that is a safe system.

 

[JAS]

I believe all the MPPs connect ground to neutral internally and automatically

It does appear from reports that all newer models do. But, that is not the case on my 1012 MS. (See above posts in this thread). So in my case, feeding the AC in with a generator (no N-G Bond), it makes more sense to keep the N-G Bond in the main panel.

In addition, since the MPP units do not have a grounding lug on the case, they need to get their ground from the AC in. But, in the case of a portable generator feeding the AC in... How do I ground it?

 

[12VoltInstalls]

It does appear from reports that all newer models do. But, that is not the case on my 1012 MS. (See above posts in this thread). So in my case, feeding the AC in with a generator (no N-G Bond), it makes more sense to keep the N-G Bond in the main panel.

In addition, since the MPP units do not have a grounding lug on the case, they need to get their ground from the AC in. But, in the case of a portable generator feeding the AC in... How do I ground it?

You answered your own questions.

Prove again to yourself that your MPPSolar 1012 does not make a N-G bond and do that bond in the main distribution panel.
If the generator is ‘open’ leave it open and run the safety ground back to the panel along with everything else.

As far as a copper rod 8’ in the dirt- if the generator chassis is exposed to dirt or other “grounded” item/surface; that IS a potential ground loop in a fault. So I’d attend to that as well.