question

Anyone please?

the US2000 is rated at 25 amps continous with max 50 amps and a peak of 100 amps. in general you do not install the fuse equal to the max amps you plan to pull. as most fuses are rate to blow at that amps and so you would generally size it 25% more. In this case Victron suggest a 200 amp for the inverter so there is no need to go over 200 amp on the battery. I would be looking at a minimum of 150 amp for the battery but would most likely go with 200 amp for both the battery and the inverter.

For the mppt I would be installing fuses or dc breakers on the panel wiring before it goes into the mppt and then I would install a 125amp fuse on the Lynx.

The Pylontech modules have 25mm2 cables rated at 120A. The fuse you use should be sized to protect the cable. In your situation I would use two sets of Pylontech cables with maybe a 100A or 125A fuse on either set. The MultiPlus could draw in excess of 120A so your single set of cables would now be overloaded. (remember to use a fuse rated for 48V systems, normal mega fuses are usually rated at 32V).

Use the recommended fuse rating and cable as in the manual for the MultiPlus.

The MPPT 250/100 can accept 35sq cable which generally has a current capacity of 240A so you can pick a fuse size between 100A and 240A. 150A would be fine I'd imagine. If you use a lesser cable then a smaller fuse will be needed.

Keep cables short and with well sized cross sectional area. The fuse is essentially there to protect the cables from catching fire. To protect the electronic equipment I think you need to select fast blow fuses. Not official advice but probably not far off the mark.