Hi Guys

Really hope someone can help me with my issue.

I recently had a second inverter installed in parallel. My issue I have is as per below.

The slave inverter will always charge the batteries between 400-500watts, will even take some grid to do so if there is not enough solar. Where the master will stop charging when there is not enough solar. 

So the salve will use more grid as it uses the extra 400-500watts for the charge (even is the timer are set to 50% and the batteries are over 50% it still charges)

Timers as all correct

Batteries are connected to a bus bar and then to the inverters

Inverters are connected with the yellow cable from Sunsynk and both inverters parallel dip switches are "on"

Your help will be much appreciated!

I have also had issues with the slave in my parallel setup.

I can't remember how the charging behavior was, but when the system was running on grid, the slave had a consistently higher draw from batteries than the master (0.8A vs 0.2A). And in general, when connected to grid, the slave seemed to run slightly different than the master. All cables same length, so not an installation issue.

I was in contact with Sunsynk, who looked into the data and agreed that there was something odd. But they wanted me to send in both inverters for testing in their lab, leaving me completely without a system at home. And that I have not done yet.

I am now running disconnected from the grid for most of the time and am ignoring the issues for now...

@Zeus-JKR: Please post some more info/photos as well as data/graphs of your system, so that we can see more details on how your system behaves

@wolfandy Sorry for only replying now but I was not home.

 

Ok so what I have found is 2 issues.

1.The Master and slave does not split the grid/load load 50/50, the slave uses almost 890w more than the master when the load is higher.

2.The slave see's the batteries as 0.5V higher than the master.

 

I Connections.

Comms cable in Master parallel B and Slave Parallel A

CT Coil on master only

So I really do not know what to change as I have tried all settings.

When running on batteries only the load and use is split 50/50

Please if anyone can shed some light.

 

Thank you

 

 

 

 

 

Edited December 24, 20241 yr by Zeus-JKR

17 minutes ago, Zeus-JKR said:

2.The slave see's the batteries as 0.5V higher than the master.

In my system, both report the same battery voltage. How are your batteries connected to the inverters? 

18 minutes ago, Zeus-JKR said:

1.The Master and slave does not split the grid/load load 50/50, the slave uses almost 890w more than the master when the load is higher.

When running on batteries only the load and use is split 50/50

If I understand correctly, your system also runs ok when only on batteries but has unexpected behavior when connected to grid - is that correct?

The batteries are connected to a bus bar and then to the inverters

Yes if ons batteries everything in 50/50 but when on grid the split is not even close to 50/50 (not sure if this is normal or not)

Looks like your PV Arrays are not equally split? Can you comment? Usually if the PV Arrasy are not an equal split the machine that has more PV power available will work harder. 

1 hour ago, Steve87 said:

Looks like your PV Arrays are not equally split? Can you comment? Usually if the PV Arrasy are not an equal split the machine that has more PV power available will work harder. 

Hi Steve87

Correct my strings are split in 6x 460 and 10x 460 panels due to shading from a neigbours tree. The bigger array is on the slave inverter.

The slave will also work harder on grid at night when no PV is available but only on grid, as said when on batteries the load is split 50/50

If it is the case that the one works harder than the other and there is no issue with it then I leave it as is as there is no ill effect that I can see other than the numbers that is not equal.

There is no adverse effects. Try this to be absolutely sure. Switch off the Solar PV on the Slave for a few minutes, then observe the results. You will find the Master doing most of the work. This is a Sunsynk/ Deye thing. Voltronics and just about every other manufacturer I have cross paths with don't behave like this. Took me a long time to make this observation. We had a site that had some major issues & was back & fourth with machines in parallel then not...

2 hours ago, Zeus-JKR said:

The batteries are connected to a bus bar and then to the inverters

That's the way it should be. Same cable lengths to each inverter from busbar?

I am getting the same voltage reading on both inverters. Max. 0.1V difference

 

 

 

 

 

 

1 hour ago, Zeus-JKR said:

The slave will also work harder on grid at night when no PV is available but only on grid, as said when on batteries the load is split 50/50

I also get something weird running on grid. My Total Load is relatively even split:

 

However, when looking at my Essential Load, the Slave is carrying a higher load than the Master:

 

And for some reason, the Master is reporting a Non-Essential Load while the Slave is reporting a negative value for Non-Essential Load. This is particularly strange as I have no load connected to Non-Essential. It appears that the Master is pushing current across to the Slave:

When disconnected from the Grid, Non-Essential Load is 0.

Are you seeing something similar in your system?

 

The other thing I have noticed is that the Slave is drawing significantly more from the batteries when running on Grid:

Does this also occur in your system?

Edited December 24, 20241 yr by wolfandy

Hi Steve

 

Thanks I did it but with a very weird result, the slave still uses more grid but then also starts using some battery just like 320w. Which is absolutly wrong as the timers are off.

So the master charges the batteries and the slave uses them.

My system was 100% with a single inverter.

 

@wolfandy

I hane no non essntial there was just one short spike

Below is my graphs 

 

 

Thanks @Zeus-JKR

16 minutes ago, Zeus-JKR said:

On the battery current, when you zoom in on the time period that your system is running on Grid (e.g., 02h00 - 04h00), is the battery draw still the same for both inverters?

 

16 minutes ago, Zeus-JKR said:

 

Strange - so we both get a higher Essential Load on our Slave, but seemingly caused by different things...

 

Have you raised this with Sunsynk Support? Are you also based in SA?

@wolfandy yes also from SA in Pretoria.

 

Yes battery current still the same between 2 and 4.

I have not yet contacted Sunsynk as my installer will handle that. But to be honest if this is not going to effect the system in future or blow it up I am going to ignore it as everything works.

The thing with Sunsynk is they are going to say send in the inverters and not doing that right now.

I am just one of those number guys and thats why I picked it up, knowing my friend he would of never noticed it as it works and that's all hahahaha 

Thanks for all the replies so far lets hope both of us get a solution or the systems does not blow up and just keep the lights on

 

 

Hi

Just want to find out is this correct of maybe my issue?

The master shows die batteries BMS but the slave inverter does not, please see below and advise if this is normal or not.

 

1 hour ago, Zeus-JKR said:

The master shows die batteries BMS but the slave inverter does not, please see below and advise if this is normal or not.

Same on my side. I think this is because the BMS is only connected to the Master - and the Master does not seem to communicate the details to the Slave

Thank you good to know