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MPP SOLAR LV 6048 - OPEN NUETRAL?

jhm08021990

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Jan 19, 2022
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We bought this machine a year ago and have been using it with little to no issues up until 2 days ago. A front load washer was turned on then ensued a popping noise and burning smells. We are not connected to a grid so everything is powered by batteries. Outlet testers in the house show open nuetral and open ground and all gfci are flashing red lights. Everything looked fine on the LV6048(I'll be pulling codes today soon) so we called an electrician out to see if they could help determine if the wiring in the home had gone bad(it is 2 years old, so of course that wasn't the problem) and they said the inverter has something going wrong inside of it with the nuetral wiring that's allowing too much electricity to flow into the house from the nuetral wire and it fried our fridge, washing machine, and many lights... how do I fix this issue? Can I bond the nuetral ac out to ground ac out?
 
If the burning smell was coming from the inverter then I would not use it.
I would contact the company that sold it to you and file a warranty claim.
 
If too much is flowing in on the neutral wire, where is it going? Cuz whatever comes in has to go out somewhere. Is this a 240 volt split phase inverter?
 
If you have 240 split. If 120 circuits share a neutral, and the neutral opens somewhere in the circuit. Your 120 could go to 240, and cook things. If the whole house opens a neutral, that would be bad. A loose neutral could cause voltage swings over 120. I would disconnect the inverter from the the house and test it. if the inverter checks out. Then I would run the house off a generator or grid, to find problems.
 
If you have 240 split. If 120 circuits share a neutral, and the neutral opens somewhere in the circuit. Your 120 could go to 240, and cook things. If the whole house opens a neutral, that would be bad. A loose neutral could cause voltage swings over 120. I would disconnect the inverter from the the house and test it. if the inverter checks out. Then I would run the house off a generator or grid, to find problems.
So this sounds like the problem... but how does an open neutral just randomly happen after a year of using things? We had an electrician come out and tell us that the issue was coming from the inverter. How can i test the inverter for an open ground?
 
If too much is flowing in on the neutral wire, where is it going? Cuz whatever comes in has to go out somewhere. Is this a 240 volt split phase inverter?
Yes it is and I've only got one neutral for the ac output on the lv6048. We are off grid and had somebody build a junction box with one 100 amp breaker and a generator plug to run a generator to power the house that I'm now using to plug the solar into by cutting a 240v generator extention cable in half and connecting the wires to the lv 6048 and the plug to the generator plug.
 
So this sounds like the problem... but how does an open neutral just randomly happen after a year of using things? We had an electrician come out and tell us that the issue was coming from the inverter. How can i test the inverter for an open ground?
It could be a loose connection. Unplug the output of the inverter. This maybe over you head. Test your voltage output from each hot to neutral. It should be close to 120. If that checks out, then put a load on it and check the voltage again. If you can run the house from a gen then see if you have the same problems when you are on generator power. Can you ask the electrician exactly what he tested and found. What voltage did he find on the neutral? I’m an electrician and like troubleshooting .Sometime it’s hard to understand what the problem is without being there looking at things. But I’m happy to help point you in the right direction. Your electrician may have already done that but it’s hard to determine with little information.
 
See I was thinking this could be the issue as well! The culprit I would think to be the generator plug outside of the house that is connected to the junction box. How can I test and verify that? Just take it apart and tug test the wires? If one of those were loose would it cause that issue? I'm asking what all the electrician said they did and I'll report back.
 
It could be a loose connection. Unplug the output of the inverter. This maybe over you head. Test your voltage output from each hot to neutral. It should be close to 120. If that checks out, then put a load on it and check the voltage again. If you can run the house from a gen then see if you have the same problems when you are on generator power. Can you ask the electrician exactly what he tested and found. What voltage did he find on the neutral? I’m an electrician and like troubleshooting .Sometime it’s hard to understand what the problem is without being there looking at things. But I’m happy to help point you in the right direction. Your electrician may have already done that but it’s hard to determine with little information.
He did not say what he tested but told my wife the inverter was the issue and that there was something wrong with the nuetral on it... voltage is steady until compressor on fridge turns on then fluctuates from 108v to 130v and stops when the compressor turns off on the fridge... lights flicker when compressor turns on as well then stops with it. Generator has usual small light fluctuations and compressor causes no change with that.
 
I have two MPP 6048's now, but started a couple years ago with just one, paired with just one 100Ah server rack battery.
Internally each MPP6048 is really just two 3kW inverters side by side.
This is how they can supply 120 & 240 with just a single unit, each 3kW inverter is making 120 volts, just 180-degrees out of phase with each other. To my understanding this is not the same as systems that rely on an auto-transformer, which if it cuts out, the result is 240vAC where 120vAC should be. Ian has a good video on this issue and the consequences.

With just one 6048 I found it was touchy to run/start a high load on a single phase, with nothing (or nearly nothing) on the other phase. ie, trying to start my funace fan on L1 (120vAC) while there was literally zero load on L2 a single MPP6048 went into fault on 'out of balance load'. I was able to 'fix' this by just putting my shop lights on L2 to reduce the out of balance. Each 6048 has a max output of 27.3A total, based on the loads you describe, I can imagine the front load washing machine may have been turn on about the same time as your fridge did a cycle, and if these are both on one leg (ie say both these are on L1) then the start up surge may have been too high. This may never have happened during the first two years you have used the equipment, since it is just chance the fridge and washer both start at the same time, or Fridge running a cycle just as the washer was started. It is not just chance to have two large loads on the same leg (ie L1) this can be changed in the electrical panel so the two are split to L1 and L2.
The MPP have an internal relay that closes during inverting (running on battery) I wonder if this relay got cooked/overloaded.
I learned ealy on, and it is in the MPP manual that the 6048 needs at least 200A available from battery. My first set up only had 100A battery, and this caused issues with larger loads, like seeing the vAC drop below 120 during starting a motor (like a large fridge compressor). When I added a second 100A rack battery, this issue never happened again. You don't say how large the battery pack you are using is, perhaps it can't supply 200A to the inverter, which dropped the voltage, which increased the amperage and blew up something. This shouldn't happen, in my experience with my units, they will shut off power if overloaded, beep warnings, and turn on red fault lights, maybe trip the reset breaker on the bottom of the unit near the AC output.
 
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