Replace existing inverter or add to it

[Stable Idiot]

Hi, I currently have 6.6kW of panels with a 5kW Fronius Primo inverter that is ~5 years old and still working well.
Where I'm located has a 5kW export limit to the grid for single phase. Voc of each of the 2 strings is 480V and 400V

I'll soon have ~15kWh of batteries (48V LiFePO4 setup) to incorporate into this system. Am I better to:

1. Have a sparky completely replace the Fronius inverter with a hybrid (like a Deye inverter)?

2. Keep the Fronius, but have a sparky install a transfer switch and some other off-grid inverter/charger?

One problem is that most electricians here don't want to install a inverter that I supply (and get for a great price) and prefer to sell me something at a very marked up price or completely replace the system with some brand(s) they prefer.

 

[sunshine_eggo]

Assuming you have to deal with regulatory issues in swapping out your grid-tie setup, I would choose 2.

 

[Stable Idiot]

Thanks. That's a good point.
I'll do some further reading here to try and work out what to get for that option.