Regarding the integration of the Victron MP II 15000VA and an external inverter (MKS II 5kW)

[diotecenergy (Onur)]

Hello,

We have commissioned a Multiplus II 15000VA - Pylontech UF5000 system, currently off-grid. (The customer had existing PV panels at their facility with a capacity of 6.6 kWp). I connected it to a Cerbo GX and the system is working flawlessly.

The MKS II 5 kWe hybrid inverter we removed from the system is from 2018.
It has 8 x 12V 200Ah AGM batteries connected to it.

Currently, the 8 batteries and the MKS II inverter are outside the system, and I want to integrate them into this system.

My design for the Victron MP II is:
AC In: power grid
AC Out 1: uninterruptible loads
AC Out 2: household loads

If I connect this MKS II inverter and its batteries (no PV system) - as a completely separate system - to AC Out 2, can I charge them from the victron MP II(first PV then grid) and use them as an external system in the evenings?

Will I experience any frequency issues? What are your recommendations?
Our new system (diotec energy- Turkiye):

old inverters and batteries:

[MikeD (Mike)]

In my experience, the old batteries will not be worth re-using, and will just become a permanent drain on the new system.
It would be possible to use the old inverter to run an ‘external’ system, it would be better and more efficient to dispose of the second hand system and to extend the new battery system if needed.