diy solar

diy solar

Ground Neutral Bond MPP LVX6048WP

Henderson

Solar Enthusiast
Joined
Jan 9, 2022
Messages
330
I've seen in this forum much discussion concerning neutral bonding issues with MPP off grid inverters (and Growatt offgrids). Would the MPP LVX6048WP have similar ground/neutral bonding concerns seeing that it's a hybrid inverter and not labelled as an off-grid?
 
Any AIO with grid pass through, could potentially have the issue. It depends on how the N/G bonding is handled by the AIO. And how you wire your system.
 
I believe that the 6048 is split-phase.
If only using one inverter, and keeping neutral and ground separated in the loads panel.
I think that it will work properly.
 
Yes, the LVX6048WP is split phase and the particular build will require 3 of them. Thanks.
 
With 3 units, there's a small ground loop between them. It can be dealt with by removing the internal bonding screw from two of the units. But, if you don't want to open them up, it not that big of a Hazzard. As long as the units are next to each other.
 
I would like to revive this thread as I am setting up an off-grid system with two lvx6048wp. Filter guy suggests removing the bonding screw in one of the inverters to fix this issue but Ian from watts247 says the following:
“Personally. I would not worry about GN bonding as the output is only bonded internally when in inverter mode as is required by NEC.”
I am not sure who to believe but am leaning towards removing the bonding screw in one of the inverters of it’s not hard to do.
What are others who are using two of the lvx6048wp (or the lvx6048 I guess)? If they are removing the screw can someone show me where that is?
Thanks in advance for the help as I am a novice in all this!
 
Removing the bonding screw from one of them, is the safest option. But, if they are right beside each other. And the wiring is very short. It's not a huge Hazzard. And, may not be worth voiding the warranty. It's located on the circuit board near the relays. (Identified with a ground symbol)
 
I have heard that if the inverters are close to one another it’s not so dangerous but I don’t really understand why that’s true. My inverters will be right next to each other and I don’t want to void the warranty so will likely go that route.
 
It's not so much the physical location but the length of wires between them. Short wires, with minimal connection points. Are less likely to develop a failure.
 
Thanks for clarifying that it’s the wire length that is important. Stupid question probably but when you say “wires between them” which wires do you mean?
 
I have heard that if the inverters are close to one another it’s not so dangerous but I don’t really understand why that’s true. My inverters will be right next to each other and I don’t want to void the warranty so will likely go that route.
For a pair of inverters that bond N-G under inverter power, there will be objectionable current between the 2 inverters on the EGC. There is a parallel path between the 2 units on N and G.

Go here, wiring for the LVX6048WP would be similar. https://diysolarforum.com/threads/mpp-lv6548-ground-neutral-safety.36241/post-462580
 
So I went to that post and tried to understand things....not very successfully....
I guess I am still trying to figure out what the risk really is if I just leave things as they are and if that is what some people are doing?
I don't really understand the 3 pole double throw diagram (I won't have a critical load panel just a main panel and I will not have any grid input/output. Also, not sure what differences there will be with split phase coming from each of the inverters) and what that does to solve the problem but that's because I am a novice here. I just want to make sure that things are reasonably safe but seem to be getting different answers from different people :(
 
With two inverters, each providing one leg of a split-phase system. There's no issue with current on the ground conductor, unless a neutral connection is lost.
 
I may be using the wrong terms but each inverter on the 6048 provides split phase (unlike the 6548 which has to be combined with another 6548 to produce split phase).
 
Nope, it was entirely my mistake.
Too much crap floating around in my head. lol
Another option would be to not ground one of the inverters. You would be relying on the bonding relay in that inverter to do it for you. But, you have to make sure that there is no metallic connection between the two inverters. Or this could create a parallel path.

Even though it would work, I don't like it.
 
So I went to that post and tried to understand things....not very successfully....
I guess I am still trying to figure out what the risk really is if I just leave things as they are and if that is what some people are doing?

The issue is to eliminate ground loops. I went back up the thread and as this completely off grid, you do not have a need for a 3 pole and you won't have a service panel. If you were tied to grid as backup, then the diagram would apply.


I don't really understand the 3 pole double throw diagram (I won't have a critical load panel just a main panel and I will not have any grid input/output. Also, not sure what differences there will be with split phase coming from each of the inverters) and what that does to solve the problem but that's because I am a novice here. I just want to make sure that things are reasonably safe but seem to be getting different answers from different people :(

If I was using multiple of these units, I'd daisy chain the EGC between units and run that to the main panel grounding busbar. I'm assuming the ground on each inverter is pass thru on input and output so makes it easy to daisy chain. Main panel would not have N-G bond but would have a grounding electrode at the main panel.

Neutrals to each inverter same length from main panel.

Bonding screw remains in each unit.
 
Ok so I want to revive this thread again as my system is now installed and I am concerned that it isn’t set up ideally with regards to G-N bond. Let me first say that I haven’t completely grasped the issue/problem with the G-N bond even after trying to educate myself so please be nice…I am admitting that I am not very knowledgeable and yet want to do things correctly/safely for my circumstances. My system is set up in a remote part of Baja so no grid power at all. I have 2 mpp solar lvx6048wp hooked up to three GSL 10kw batteries and have about 10kw solar. The system is running flawlessly though I have not moved in and really pushed it hard (I did a test running all five 1 ton 240v mini splits and it didn’t have any trouble with that though). Any way, I originally thought that the lvx6048wps had internal G-N bond in each unit but recently read someone’s post where they were told by mpp solar directly that the this model specifically did NOT have a G-N bond. So now I am confused as to how to set things up. I know I have some problems with how the local electrician set up the main panels and the two sub-panels because all three seem to have G-N bonded in the panel and that doesn’t seem right. There is not a lot of knowledge in Mexico around the G-N issue and these inverters are not commonly used there so I am not surprised to find they did it this way.
Here is a photo of my system:
1673131276880.jpeg
Batteries are all combined in the box above the batteries and the two inverter outputs are combined in the box circled in red and then that goes to the main panel. The blue circled box is for generator input which is fed into grid-in part of inverter (not generator in) as suggested by several posts on this forum. It’s not hooked up yet though so focusing on this G-N issue first.
So my questions are:
1. Do the 6048wps have a G-N bond in the unit?
2. Based on answer from above, how should main panel be bonded? 3. I am assuming that the sub panels should not have G-N bonded and I can get that fixed but want to confirm that I have that correct.

Sorry for such a long post but it seems like people are able to be more helpful when they have more details.
Thanks in advance,
Lori
 
Back
Top