I have a situation where I require extra panels. The North roof is full and only have an East-west roof.

The thought is the use the first MPPT for the north-facing roof and the second MPPT for the east roof.
The Sunsynk would continue to use the BMS to the battery.
The Victron MPPT would connected to the west roof and feed the batteries direct.

If this is viable, how would I set up the Victron values?
I would probably use the Cerbo S for remote admin.

I would appreciate only solid technical advice together with evidence and values,

Please don't muddy the water and reply with opinions.

7 hours ago, IanO said:

I have a situation where I require extra panels. The North roof is full and only have an East-west roof.

The thought is the use the first MPPT for the north-facing roof and the second MPPT for the east roof.
The Sunsynk would continue to use the BMS to the battery.
The Victron MPPT would connected to the west roof and feed the batteries direct.

If this is viable, how would I set up the Victron values?
I would probably use the Cerbo S for remote admin.

I would appreciate only solid technical advice together with evidence and values,

Please don't muddy the water and reply with opinions.

You’re asking for solid technical advice with evidence and values that’s fair. But you haven’t provided enough system data for anyone to give that level of answer.

Before this can be evaluated properly, please provide: Exact Sunsynk inverter model. Battery brand/model, voltage, and max charge current allowed by BMS

Current PV string configurations (modules per string + Voc/Imp values)

Intended west-roof string layout and amount of panels(kwp)

Whether the Victron will run standalone or via Cerbo S with DVCC

Running Sunsynk MPPTs together with an external Victron MPPT charging the same battery is technically possible but only if charge control authority and current limits are clearly defined. Otherwise you risk voltage conflict and current stacking.

Perhaps add the area you reside in if you need values of yield as it's no use quoting in Gauteng and you in the Cape. Winter there is like being in darkness compared to Gauteng😂

I have used this external method with success.

11 hours ago, IanO said:

I have a situation where I require extra panels. The North roof is full and only have an East-west roof.

The thought is the use the first MPPT for the north-facing roof and the second MPPT for the east roof.

I think you don't need an additional MPPT. Connect the west roof panels in parallel with the east roof panels. This will not overload the MPPT since the east and the west panels will never deliver full power at the same time. I have such a situation and write from experience. Condition is however that east and west panels are of the same type (same number of cells).

13 hours ago, IanO said:

Please don't muddy the water and reply with opinions.

Not going to get much response with this attitude - sorry, that's just an opinion 😁 Keeping quiet now...

Easier probably to just get a grid tie inverter connected to the Aux port, the Sunsynk will control production on the grid-tie and you can get as many extra MPPT's as you want.

There is a max size you can connect to the AUX port, half the inverter size if I remember correctly.

1 hour ago, Sc00bs said:

Easier probably to just get a grid tie inverter connected to the Aux port, the Sunsynk will control production on the grid-tie and you can get as many extra MPPT's as you want.

There is a max size you can connect to the AUX port, half the inverter size if I remember correctly.

Would you mind explaining this to me. I have a 5kW Sunsynk as well as a 3kVA Axpert (both still to be installed). What are the advantages

1 hour ago, dax021 said:

What are the advantages

If the Sunsynk controls a grid-tie or hybrid inverter on the aux port, it will still manage total solar pushed back into the house while on grid and it will utilise all solar for the battery while off grid.

I suspect your Axpert is an off-grid/UPS type inverter. This means that it can only use solar for downstream loads.

3 hours ago, dax021 said:

Would you mind explaining this to me. I have a 5kW Sunsynk as well as a 3kVA Axpert (both still to be installed). What are the advantages

Is the 3kW Axpert a 48V?

The input via Aux port can only be a grid tied or true hybrid.

I would settle for a grid tied with internal MPPT tracker instead of separate MPPTs. Solis 4G mini comes to mind and they are super reliable.

Edited February 28Feb 28 by Scorp007

Yes, Axpert 3kVA, so 2.4 kW 48V. So the reason for connecting like this is purely for the extra MPPT, am I correct? If this is the case, I would rather keep the aux port for a generator as I think I will have enough PV capacity on the Sunsynk's two MPPT's. On advice from others on this forum, I can fit 12 x 600W panels in two strings E and W

5 hours ago, dax021 said:

Would you mind explaining this to me. I have a 5kW Sunsynk as well as a 3kVA Axpert (both still to be installed). What are the advantages

Axpert's usually aren't grid tied, they are off grid inverters with an option to connect to the grid, they don't sync to grid frequency.

You could connect Axpert for essential loads and Sunsynk as grid-tie so save on energy. In outages you will lose out on solar panels.

Thanks all. What I didn't mention is that there are 5 bloody DB's in this house daisy chained, each one feeding the next, so going to be a nightmare to connect the inverter.