Parallel Rosies not sharing generator charging

[Wirenut]

I have an off grid system installed with 2 Rosie inverters in parallel. The AC input is a 14 kW generator. When generator charging the Rosies don't share equally. Also, sometimes, not long after a generator auto start charge cycle is completed there is a fault code for AC overload on L1.
I've attached 3 pictures. One shows the FW in each component. Left and Right are two different MNGP2 displays. Master is the master Rosie. Rosie is the slave Rosie.
The others pictures are summary's of the inverters activity on the same day when a generator auto start occurred to charge the batteries. As you can see, one Rosie took in over 7,000 watts for long enough to take in over 49 kWh. The other Rosie shows all zeros for the same day.
I thought maybe the parallel threshold was set to high at 40% but I didn't think that affected charging, just inverting. I changed the parallel threshold down to 25%. At the time the generator wasn't running and total load on the inverters was about 1 kW. When I lowered it to 25% the slave inverter came on which seemed strange with such a low load.
Any ideas are appreciated. I don't know if this is multiple problems or if they are related.
Thanks for your help.

[Brucey]

How are the Rosies wired together?

[Wirenut]

The master has the MNE300Rosie-240P100 breaker panel under it. The slave has the MNE300Rosie-240F panel under it. They are wired together with #6 THHN conductors between the boxes. The generator input connects to the AC input of the 240P100 box with #4 THHN conductors.

[FNG]

A few things here in no order:

1- I would update firmware on the Rosies, A lot of work was done for generators late in 25/ early in 26
2- Looks like the second Rosie is off maybe, It should wake up if parallel threshold is set but to be sure try turning parallel threshold to off
3- Parallel threshold percentage is on either leg. For example if set to 20% and L1 loads to 700 watts that's 20%

[Brucey]

A few things here in no order:

1- I would update firmware on the Rosies, A lot of work was done for generators late in 25/ early in 26
2- Looks like the second Rosie is off maybe, It should wake up if parallel threshold is set but to be sure try turning parallel threshold to off
3- Parallel threshold percentage is on either leg. For example if set to 20% and L1 loads to 700 watts that's 20%

To clarify on the parallel threshold setting, this allows you to just have the Master Rosie on and additional slave parallel unit(s) will power up if the threshold is exceeded? Is there a timer before the slaves shutdown after load drops below threshold?

Very cool.

[Brucey]

A few things here in no order:

1- I would update firmware on the Rosies, A lot of work was done for generators late in 25/ early in 26
2- Looks like the second Rosie is off maybe, It should wake up if parallel threshold is set but to be sure try turning parallel threshold to off
3- Parallel threshold percentage is on either leg. For example if set to 20% and L1 loads to 700 watts that's 20%

To clarify on the parallel threshold setting, this allows you to just have the Master Rosie on and additional slave parallel unit(s) will power up if the threshold is exceeded? Is there a timer before the slaves shutdown after load drops below threshold?

Very cool.

I emailed Midnite support on this and got a response within 3 minutes

Once load on a leg drops below the threshold for about 60 seconds the additional slave units will power off

[Wizbandit]

I have an off grid system installed with 2 Rosie inverters in parallel. The AC input is a 14 kW generator. When generator charging the Rosies don't share equally. Also, sometimes, not long after a generator auto start charge cycle is completed there is a fault code for AC overload on L1.
I've attached 3 pictures. One shows the FW in each component. Left and Right are two different MNGP2 displays. Master is the master Rosie. Rosie is the slave Rosie.
The others pictures are summary's of the inverters activity on the same day when a generator auto start occurred to charge the batteries. As you can see, one Rosie took in over 7,000 watts for long enough to take in over 49 kWh. The other Rosie shows all zeros for the same day.
I thought maybe the parallel threshold was set to high at 40% but I didn't think that affected charging, just inverting. I changed the parallel threshold down to 25%. At the time the generator wasn't running and total load on the inverters was about 1 kW. When I lowered it to 25% the slave inverter came on which seemed strange with such a low load.
Any ideas are appreciated. I don't know if this is multiple problems or if they are related.
Thanks for your help.

"Stacked" Rosie inverters do not share loads ( and apparently charging) equally when there is AC IN I'm told.  Things like AC IN wire lengths may cause voltage drops between inverters and the balance issues.  To properly balance AC IN operations (and SELL MODE, which is not yet available) will take "Closed Loop" communications between all inverters which does not happen with the present firmwares...

We can hope the engineers will find time to add this feature in the future but it does not seem to be effecting very many installations right now so it's low priority.

[Brucey]

I have an off grid system installed with 2 Rosie inverters in parallel. The AC input is a 14 kW generator. When generator charging the Rosies don't share equally. Also, sometimes, not long after a generator auto start charge cycle is completed there is a fault code for AC overload on L1.
I've attached 3 pictures. One shows the FW in each component. Left and Right are two different MNGP2 displays. Master is the master Rosie. Rosie is the slave Rosie.
The others pictures are summary's of the inverters activity on the same day when a generator auto start occurred to charge the batteries. As you can see, one Rosie took in over 7,000 watts for long enough to take in over 49 kWh. The other Rosie shows all zeros for the same day.
I thought maybe the parallel threshold was set to high at 40% but I didn't think that affected charging, just inverting. I changed the parallel threshold down to 25%. At the time the generator wasn't running and total load on the inverters was about 1 kW. When I lowered it to 25% the slave inverter came on which seemed strange with such a low load.
Any ideas are appreciated. I don't know if this is multiple problems or if they are related.
Thanks for your help.

"Stacked" Rosie inverters do not share loads ( and apparently charging) equally when there is AC IN I'm told.  Things like AC IN wire lengths may cause voltage drops between inverters and the balance issues.  To properly balance AC IN operations (and SELL MODE, which is not yet available) will take "Closed Loop" communications between all inverters which does not happen with the present firmwares...

We can hope the engineers will find time to add this feature in the future but it does not seem to be effecting very many installations right now so it's low priority.

Having identical length wiring for ac input to parallel inverters is best practice.