Growatt 6K cause power outages at night

[terrango]

Hey guys,

I have a strange problem going on with one of my growatt inverters.
So i have 2 growatt 6K split phase units and 1 EG4 6000ex (just for reference).

Both Growatt units have solar and are drawing from the same battery bank.
Both units have been working issue free for 2 years.
Each unit feeds a separate sub panel and the load at peak is 50%.
Battery bank size is 1200ah about 57,000 watt hours.
Battery bank drops about 20% over night currently under summer conditions. Lots of capacity left.

So what has changed, well one unit and this is only at night, starts having voltage issues.
The voltage will show 119v at the receptacle and then it will randomly drop to 96v and back up to 117v and on and on and on.
This happens all throughout the night. Come morning when solar is available, everything is 100% normal again.

Now the other growatt inverter which is connected to its own panel, has zero issues, no drops in voltage, it runs like a champ.
The EG4, runs without issues.

I have tried moving the AC output on the affected inverter to another subpanel and the problem follows.
There is no error codes that show up on the inverter.
The inverter shows everything is operating normal, but its not.
Im not sure what to check with this unit.
I am planing to move everything over to the EG4 once i receive my second 6000ex and parallel the unit.
However i would like to get this growatt unit working so that i can use it elsewhere.

Anyone have ideas as to what to check next?
There isnt any warranty left as it is just passed the 2 year mark.

 

[DIYrich]

My guess is that the circuit in the growatt that boosts battery voltage to 240+ (or 120+) volts is going bad. The MPPT for PV may have a separate circuit that adjusts the PV voltage to the internal 240+ (or 120+) volts for the inverter, which it why it works when solar is available.

 

[Brett V]

Carefully check your battery connections, fuse or circuit beaker. Are you getting any error codes? do you have some sort of remote monitoring installed like the Growatt WiFi dongle or Solar Assistant? I highly recommend Solar Assistant for Growatt products.

 

[petr1ab]

Hi. I have some similar (maybe same issue) with my GW SPH 5K in off grid configuration. Once battery is charged and there is a very low load (less than 200W), the system starts switching on AC backup output. I found out that there is a problem with output voltage regulation. Voltages is suddenly increasing until overvoltage protection reached and the output regulation restarts by SW reset. Video shot hre :
GW SPH 5K output regulation issue

Once i increase the load the issue dissappear until load goes low again. The only way to avoid is restart the inverter.

There is ERROR 409 and 416 reported in growatt server.

Can u confirm having the same trouble?

 

[terrango]

Hi. I have some similar (maybe same issue) with my GW SPH 5K in off grid configuration. Once battery is charged and there is a very low load (less than 200W), the system starts switching on AC backup output. I found out that there is a problem with output voltage regulation. Voltages is suddenly increasing until overvoltage protection reached and the output regulation restarts by SW reset. Video shot hre :
GW SPH 5K output regulation issue

Once i increase the load the issue dissappear until load goes low again. The only way to avoid is restart the inverter.

There is ERROR 409 and 416 reported in growatt server.

Can u confirm having the same trouble?

My issue isnt exactly the same. The voltage does fluctuate once the sun goes down between 116V-121V but that is still within the voltage range.
I hooked up my other 6KW Growatt inverter and it doesnt have the same issues. I also tested everything with my EG4 inverter and it works as it should. So i think in my case DIYrich is correct that there is a problem with the switching on the one inverter.

I am not getting any error codes. I havent installed any monitoring devices. Im sort of on the fence about it as i am, switching everything over to EG4 in the next month or so anyway. Ill probably just send the faulty unit out for repair with Microgreen solar in Canada.