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MPP LV6548 Ground/Neutral Safety?

I am just going to walk out to my system and measure it.

Ok, just put 10,000W on my split phase configuration LV6548's and tested current and voltage drop across the grounding conductors. 0A with clamp meter and measured voltage drop across panel bus and my meter could not pick anything up at all. 0mV.

Did others who have current flowing on ground update their firmware yet? You need to update the firmware or you will have difference of potential, and current will flow. Especially when the output of these inverters is in series. Not sure what would happen if output was connected in parallel.
 
MT off grid said:
So if using two inverters to run two phase is where the problem still exists? Running one unit has all issues fixed?
Click to expand...
Running one unit for 120V will not have a problem with current on the EGC.

In parallel operation for 240V split phase, any imbalance between the two 120V legs will have current on the EGC equal to 1/2 of the imbalance between the 2 inverters. The other 1/2 of the imbalance will flow on the neutral.
 
Zwy said:
Any inverter that bonds N-G at the inverter and runs with a pair or more of units will have current on the EGC between the units, the current will be same amps as on the neutral.


It sure rolled around in my mind for days. At first I thought the phasing would prevent any current on the ESG or traveling thru one inverter to the other on neutral. But after some members tested this, it became apparent that current is following a parallel path on neutral and EGC between the inverters.

I will be installing a white wire instead of a green wire between the two inverters for the EGC. This would identify it could carry 1/2 of the neutral current. Probably print a label also indicating as such at each end. From the master inverter to main panel it will be a green wire.
Click to expand...
Ohhh ok I see the issue here. With imbalance. Sorry for my ignorance, I just did not have time to read all of the past posts. I see whatt you mean now.
 
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Will Prowse said:
I am just going to walk out to my system and measure it.

Ok, just put 10,000W on my split phase configuration LV6548's and tested current and voltage drop across the grounding conductors. 0A with clamp meter and measured voltage drop across panel bus and my meter could not pick anything up at all. 0mV.

Did others who have current flowing on ground update their firmware yet? You need to update the firmware or you will have difference of potential, and current will flow. Especially when the output of these inverters is in series. Not sure what would happen if output was connected in parallel.
Click to expand...
You need an imbalance between phases.
 
Will Prowse said:
How much current is flowing between the units on ground? I see there being an issue when the outputs are in parallel, but not so much when they are in series. Perhaps keeping them separate would avoid that current flow, but I still want a non-current carrying reference potential across the whole system. And some form of true earth ground, or electron sink.
Click to expand...
I am looking to buy one lv6548 but don't want any problems, the more I read the more I'm confused. I will be using a reliance 30216BRK transfer switch to connect to my house breaker panel
 
MT off grid said:
I am looking to buy one lv6548 but don't want any problems, the more I read the more I'm confused. I will be using a reliance 30216BRK transfer switch to connect to my house breaker panel
Click to expand...
Why not just buy a 6048 so you do not have any of these issues. 240V output. Add multiple units in parallel if you need larger capacity.
 
Will Prowse said:
Ohhh ok I see the issue here. With imbalance. Sorry for my ignorance, I just did not have time to read all of the past posts. I see whatt you mean now.
Click to expand...
I'll be anxiously awaiting an update with an imbalance.........
MT off grid said:
I am looking to buy one lv6548 but don't want any problems, the more I read the more I'm confused. I will be using a reliance 30216BRK transfer switch to connect to my house breaker panel
Click to expand...
Before you go to the Reliance, we have a whole thread about using one. Not ideal. You would be better served with a 3 pole double throw to switch neutral and a subpanel or critical loads panel.

diysolarforum.com

LV6048 output neutral-ground bonding?

Born and raised in California and relocated to ancestral roots in the Arkansas Ozarks 30 years ago. Made lots of money in Kansas City and Saint Louis. ? Funny.... I was raised in MO and went to CA to earn my money....
diysolarforum.com diysolarforum.com
 
Zwy said:
Running one unit for 120V will not have a problem with current on the EGC.

In parallel operation for 240V split phase, any imbalance between the two 120V legs will have current on the EGC equal to 1/2 of the imbalance between the 2 inverters. The other 1/2 of the imbalance will flow on the neutral.
Click to expand...
So of I use my reli
Will Prowse said:
Why not just buy a 6048 so you do not have any of these issues. 240V output. Add multiple units in parallel if you need larger capacity.my hous
Click to expand...

Will Prowse said:
Why not just buy a 6048 so you do not have any of these issues. 240V output. Add multiple units in parallel if you need larger capacity.
Click to expand...
I thought about that but #1 I don't want to feed my entire house with solar #2 the city wants me to keep everything UL listed and since that is almost impossible or at the least very expensive I need to use a generator transfer switch so that my batteries and inverter are considered a temporary power source, if I do it that way then all I need to do is get the transfer switch instalation inspected and they don't care what I plug into the transfer switch
 
Will Prowse said:
Why not just buy a 6048 so you do not have any of these issues. 240V output. Add multiple units in parallel if you need larger capacity.
Click to expand...
If you have more than one 6048 hooked to the system in parallel, the current on the EGC will still be there. More than one N-G bond in the system (each inverter under inverter power) and there will be 1/2 the neutral current on the EGC. It's a parallel path.
 
Zwy said:
I'll be anxiously awaiting an update with an imbalance.........

Before you go to the Reliance, we have a whole thread about using one. Not ideal. You would be better served with a 3 pole double throw to switch neutral and a subpanel or critical loads panel.

diysolarforum.com

LV6048 output neutral-ground bonding?

Born and raised in California and relocated to ancestral roots in the Arkansas Ozarks 30 years ago. Made lots of money in Kansas City and Saint Louis. ? Funny.... I was raised in MO and went to CA to earn my money....
diysolarforum.com diysolarforum.com
Click to expand...
I was going to use it because I already own it and can't afford to spend money on more equipment
 
MT off grid said:
I was going to use it because I already own it and can't afford to spend money on more equipment
Click to expand...
Then use the method I outlined in the linked post. You will need all neutrals run to the Reliance on a neutral busbar that is not bonded.

The Reliance 310C does not switch neutral and as such there will be a ground fault as the N-G are bonded at the main service panel.

If you intend to treat the Reliance 310C as a subpanel and run loads off it continously, then you simply run neutral from main panel to inverter AC input, then from inverter AC output to the Reliance 310C. Do not have a neutral between the main panel and Reliance 310C. All circuits powered by the Reliance 310C will need their neutral returned to a neutral busbar in the Reliance 310C. This neutral is not to be bonded to ground.
 
Zwy said:
I'll be anxiously awaiting an update with an imbalance.........

Before you go to the Reliance, we have a whole thread about using one. Not ideal. You would be better served with a 3 pole double throw to switch neutral and a subpanel or critical loads panel.

diysolarforum.com

LV6048 output neutral-ground bonding?

Born and raised in California and relocated to ancestral roots in the Arkansas Ozarks 30 years ago. Made lots of money in Kansas City and Saint Louis. ? Funny.... I was raised in MO and went to CA to earn my money....
diysolarforum.com diysolarforum.com
Click to expand...
Ok! Your argument totally makes sense to me now. I get it.

But I just put a 3000W imbalance on my two inverters. One leg was running two 1500W loads, and still no current on ground conductor! Now I am actually confused. I see your logic and why it would have current on ground now (sorry I was slow to understand). I then disconnected one load and only ran 1500W on one leg, and still no current. I did not think it would change anything, but just wanted to verify.

I do not see how the firmware would affect this. Two bonds, one ground. Imbalance. Imbalance should flow on neutral and ground, and that's bad. I just don't understand why I am not seeing any current.
 
I will have to think about this one for a bit. I did test to see if ac output g-n were bonded after I updated the firmware. Bond was present, no voltage between ground and neutral on both units. So strange. There has to be a piece of the puzzle that we are missing. Hmm.

I really wish there was no bond in the unit, or you could control it with a relay. Then have a separate non current carrying ground for the cases, then create your own, single bond at the panel.
 
Zwy said:
Then use the method I outlined in the linked post. You will need all neutrals run to the Reliance on a neutral busbar that is not bonded.

The Reliance 310C does not switch neutral and as such there will be a ground fault as the N-G are bonded at the main service panel.

If you intend to treat the Reliance 310C as a subpanel and run loads off it continously, then you simply run neutral from main panel to inverter AC input, then from inverter AC output to the Reliance 310C. Do not have a neutral between the main panel and Reliance 310C. All circuits powered by the Reliance 310C will need their neutral returned to a neutral busbar in the Reliance 310C. This neutral is not to be bonded to ground.
Click to expand...
Is the 310c and the 30216BRK (what i have) built the same? I'm still new to electrical so I will need to read your response and do some research to understand what you are saying
 
MT off grid said:
So of I use my reli



I thought about that but #1 I don't want to feed my entire house with solar #2 the city wants me to keep everything UL listed and since that is almost impossible or at the least very expensive I need to use a generator transfer switch so that my batteries and inverter are considered a temporary power source, if I do it that way then all I need to do is get the transfer switch instalation inspected and they don't care what I plug into the transfer switch
Click to expand...
Oh! The LV6548 is not listed. It is only UL 1741 certified. I highly doubt it will pass inspection (unless you live in a very relaxed regulation area).

I think what you need is a sol ark. They have ground neutral relay and you can program it to do whatever you wish. That would be much better for you! UL 1741 too, so it would pass any inspection.
 
Will Prowse said:
Oh! The LV6548 is not listed! It is only certified. I highly doubt it will pass inspection (unless you live in a very relaxed regulation area).

I think what you need is a sol ark. They have ground neutral relay and you can program it to do whatever you wish. That would be much better for you! UL 1741 too, so it would pass any inspection.
Click to expand...
I thought about that but waaay out of my price range plus everything else would still need UL listed (panels, wire, combiner box, inverter etc etc
Etc, im kinda stuck with the 6548 because of price, im just not sure how it would all work with my transfer switch
 
MT off grid said:
I thought about that but waaay out of my price range plus everything else would still need UL listed (panels, wire, combiner box, inverter etc etc
Etc, im kinda stuck with the 6548 because of price, im just not sure how it would all work with my transfer switch
Click to expand...
Gosh ok I understand now. Dang that is a tough one!!

Or you could use an ac coupled system but yes, price would be an issue. Hmm.
 
Will Prowse said:
Ok! Your argument totally makes sense to me now. I get it.
Click to expand...

It takes awhile, I didn't understand how it was possible at first as Filter Guy had brought it up. Then some members started checking and sure enough, the current was present.

Will Prowse said:
But I just put a 3000W imbalance on my two inverters. One leg was running two 1500W loads, and still no current on ground conductor! Now I am actually confused. I see your logic and why it would have current on ground now (sorry I was slow to understand). I then disconnected one load and only ran 1500W on one leg, and still no current. I did not think it would change anything, but just wanted to verify.
Click to expand...

Interesting indeed, when I originally discussed this, I thought each phase would have current return directly to the inverter that had the imbalance.

Will Prowse said:
I do not see how the firmware would affect this. Two bonds, one ground. Imbalance. Imbalance should flow on neutral and ground, and that's bad. I just don't understand why I am not seeing any current.
Click to expand...
It should be there.

It could be possible the firmware changed the N-G bond in the slave inverter. Only one inverter bonded. Would you see 0V potential on the slave then? Good question.
 
Will Prowse said:
Gosh ok I understand now. Dang that is a tough one!!

Or you could use an ac coupled system but yes, price would be an issue. Hmm.
Click to expand...
I'm getting so overwhelmed with it all that I'm about to give up, I have panels on the way so now I'm not sure what to do, still learning but trying to work with a small budget and a transfer switch that I already own, I know how to do my own electrical work but when it comes to adding a power source and making it safe I'm getting confused, maybe if you have time LOL you can look into how my design of using a reliance 30216brk transfer switch and a LV6548 would work or not work, local electricians won't help due to UL and NEC requirements
 
MT off grid said:
I thought about that but waaay out of my price range plus everything else would still need UL listed (panels, wire, combiner box, inverter etc etc
Etc, im kinda stuck with the 6548 because of price, im just not sure how it would all work with my transfer switch
Click to expand...
Are your critical loads all 120V? If so, then you could run just one LV6548 and not worry about it.
 
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