to connect the old MPPT 100/30 for the new solar curtain, you can use JTS XT60 plugs for the battery side. So you can remove and store the MPTT anywhere. The XT60 is designed for a volatga of 500V DC and continous current of 30 Amps, peak current 60 Amps.
For the PV panels, you can use a flat PV-cable going through a slightly opened window.
It’s not the nicess solution like an outdoor mount point, but a good one for temprory usage.
There are also adpater capble MC4 to XT60. I connemnt not using XT60 for PV panle and for battery connection. It can be mixed up and the pannels directly connected to the battery.
I would put the MPPT 100/30 in a box with two different fast plugable connectors for battery and PV on it.