diy solar

diy solar

Growatt MPP 24 volt inverter error 81

tucsonjwt

New Member
Joined
Sep 29, 2019
Messages
85
I am installing a Growatt MPP 24 volt system in my utility trailer. I just turned it on for the first time and I am getting an 81 error "solar utility" error, with a green flashing light and a buzzing sound.

I have two strings of 2 solar panels each going into the Midnite Solar combiner box. I have each string connected to a Midnite Solar 12 amp DC circuit breaker. Each string reads 92.9 volts and 8.1 amps. However, the output at the main buss bar where the two circuit breakers connect reads 92.9 volts but only 8.1 amps. Shouldn't the combined output be 16.2 amps? I don't know if this is causing the error.

I do have a Midnite Solar SPD installed on the combiner box and the blue light is on. Also, I have the solar panels grounded to the ground buss bar in the combiner box, the ground wire from the SPD connects to the same ground bar, then a ground wire runs from the combiner box ground buss bar to a bolt on the trailer frame (I guess this would be a reference ground.)

Does anyone have thoughts about what I am doing wrong? A pic of the combiner box is attached.

Thanks for any help you can give this newbie.
 

Attachments

  • Solar combiner box.jpeg
    Solar combiner box.jpeg
    122.4 KB · Views: 4
I forgot to mention that I have 4 Battle Born 100 AH batteries (2 strings of 2 batteries connected together for 24 volt output.) I am reading 26.8 volts output from the battery bank into the inverter.

I think I have the wires connected properly and all of the connections to everything seem to be tight.
 
The MPP display just flashes once through all features quickly, so I really can make out what it is displaying. It just shuts down after about 30 seconds of flashing light and buzzing sound. All I can make out is the "solar utility" error with an image of a solar panel. Do you think there is a problem with the solar input? It seems like I should be getting 16.2 amps input but I only read 8.1 on the main combiner positive buss bar.
 
The MPP display just flashes once through all features quickly, so I really can make out what it is displaying. It just shuts down after about 30 seconds of flashing light and buzzing sound. All I can make out is the "solar utility" error with an image of a solar panel. Do you think there is a problem with the solar input? It seems like I should be getting 16.2 amps input but I only read 8.1 on the main combiner positive buss bar.
I do not know how you are measuring current input if the AIO is not working. You do not get current without a load. The fact the MPP is just flashing would seem to indicate a mistake in wiring. Do you have polarity correct?
 
The photo of my combiner box shows the wiring. Red wires from solar panels to the DC circuit breakers, black wire from the solar panels to the negative bus, black output wire to the negative bus, red output wire to the main positive bus. Red combiner output wire goes to the PV + on the Growatt, black combiner output wire goes to the PV - on the Growatt. Connections seem tight.

Currents draw was measured when the inverter iwas turned on. Current was measured between the positive terminals on the circuit breakers and the negative buss bar, and between the main buss positive buss bar and the negative buss bar. Is the inverter drawing power during the startup process and trying (but failing) to power the inverter on?

I am completely new to this, so anything is possible. I have some considerable experience with residential AC systems, but have no experience with DC.

I do have 4 solar panels - 2 strings of 2 panels, each string of two is wired together in series so the voltage goes up (92.9 volts total input). Both strings (+ &- wires) go from the solar panels to the combiner box without any intermediate terminals or splices. I suppose I could have gotten wires crossed on the roof, but wouldn't that mean I would have no voltage at the combiner box?
 
Is it possible that having the ground from the solar panel racking attached to the same ground bar in the combiner box that the SPD and ground wire to the trailer frame are attached to might be a problem? Maybe some kind of unintended feedback loop through the combiner box enclosure?
 
I would advise disconnecting the MPP and remove the PV wires. At that point you should be able to turn it on from the batteries (through the normal battery hookup) and check to see if it is working. Double check voltages with your meter all the way from the panels observing polarity.

Incidentally there should be no current flow at all if the MPP is disconnected from the PV wires unless you are shorted out someplace.
 
Last edited:
I disconnected the PV wires at the MPP and still got the same 81 error code when I turned the inverter on.

I found 81 in the owners manual:

Explanation/Possible cause Host Loss 1. Check whether the parallel communication cables are connected well.
2. If the problem still exists, please return to repair center.


The display says "solar utility" but the owners manual does include this statement for the 81 error code.

I think the parallel communication cables refer to a dual inverter 240 volt set up, but I only have one (120V) inverter.
I have an email in to Watts24/7 where I purchased this unit. I hope he can help me.

I bought this MPP about 2 years ago but it has been in storage because health issues prevented me from getting the system installed.
I think my warranty just ran out recently. I hope Watts 24/7 can help.

I know that I am totally new to all of this so I am likely making errors along the way, but it is always possible that I have a defective inverter.
I don't know which is worse.;)
 
Yeah that don't look good in terms of being a defective inverter. I had hoped it was simply a wiring mistake based on your information of the fault being connected to the solar input.
 
Back
Top