Adding new stand alone different brand MPPT controller to existing off grid Solar system

[Madonit]

Hi Guys
I have a Bluesun inverter(BSE6KL1) with 2 mppt internal controllers maxed out with solar, ac/in is connected to a generator and its connected to about 55 kw of lithium batteries. I wish to add more solar for winter months and want to do the concept of a 'dump' array, so add a stand alone mppt controller with its own array and connect directly to batteries(via its own CB).
When I asked bluesun about this, they said they would not recommend it, but would not give me an explanation as to why. The inverter cannot be daisy chained, so my only other option would be to get a brand new inverter which is a very expensive option.
Does anyone have any experience with this sort of solution and what issues could there be, I just cant find out why the bluesun dont like this solution?
thank you
Mardi

 

[DougfromdaUP]

I have been doing this all winter, using a EG4 100 amp 500Voc charge controller in addition to my SolArk 12k. It works fine.
I set the voltages, both bulk and float, a little lower than the SolArk. The EG4 switches to the float voltage before the SolArk, which gives a slower finish to the bulk charge, and doesn't charge at all during the float phase till the battery voltage falls a tiny bit below the SolArk float.

 

[Madonit]

I have been doing this all winter, using a EG4 100 amp 500Voc charge controller in addition to my SolArk 12k. It works fine.
I set the voltages, both bulk and float, a little lower than the SolArk. The EG4 switches to the float voltage before the SolArk, which gives a slower finish to the bulk charge, and doesn't charge at all during the float phase till the battery voltage falls a tiny bit below the SolArk float.

Thanks Doug and your mppt is completely standalone, so its own CB and seperate battery leads to your bank and therefore no communication to your SolArk 12 at all?
Thanks

 

[DougfromdaUP]

Yes, it has no communication. All it knows is the battery voltage.