Growatt 3000 LVM Inverter issues...

[Jim in NH]

I have a Growatt 3000 LVM hooked up to two 12 volt AGM 250 AH batteries in series for 24 volts. I also have 1400 watts of solar panels connected to it. I have been running in SBU mode with several critical loads on the inverter for several weeks.

When running in this mode my TACO heating system controller transformer hums loudly and I have burned up 3 16.5 volt alarm system transformers. When the transformer that I just installed 4 hours ago burned up I started checking voltages and noticed that the voltage at the outlets was fluctuating at 107 to 108 volts while the other outlets in my house on line power (not running through the inverter) were at around 118 volts.

When I switched the inverter over to UTL mode, the humming in the heating system controller transformer stopped. The batterie(s) were reporting 26.2 volts into the inverter when I switched modes from SBU to UTL. I rarely exceeded 25% of the inverter capacity and it is usually running at around 10%.

My little solar project/experiment has been quite a PITA.

The spike in the grip power in the graph below at around 12:30 is when I switched to UTL.

What's up with this thing??

 

[Jim in NH]

Update:

sales@watts247.com​	May 31, 2021, 9:37 PM (13 hours ago)
to me

Jim, please check that the output is set to 60Hz, very important! If it's 50hz, it will for sure burn up the transformers.

Let's start there

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Jim Graham​	10:51 AM (1 minute ago)
to watts247.com

Ian,

I confirmed that the unit is set for 120 volts at 60HZ.

I noticed that the output of the inverter when in SBU mode will fluctuate (while I was monitoring using a voltmeter), 108V to 128V. I noticed that when the TACO transformer was humming the voltage was at 128. I think that it was the high voltage that burned up my 16.5 volt alarm transformers. I do not think that these particular transformers are rated to much higher than 120 volts.

I have since switched the inverter to SOL mode. Since I did this, I have run for 24 hours and the voltage has remained around 118.

The documentation says that SBU mode will blend Solar and Battery to support the load. Whereas (if I interpret correctly) that SOL mode will switch between solar and battery to support the load (not blended)? Is that a correct assumption? Could it be that the blending is not working properly and delivers wildly fluctuating current to the loads?