A Solar thread

This could well the be the start of quite a long thread about a solar installation starting from scratch. I don't know too much about solar at this time but am quite well versed with residential electrical installation.

The first task at hand is to do away with the overhead electric and internet cables shown in the image below and replace with buried 16mm2 NYY cable from the meter and then coming out of the ground and up the exterior of the wall.

After a visit to PEA office in Khon Kaen city center I was told it is ok to join the NYY cable with the 16mm2 THW copper cables that go up into the roofspace to my consumer unit in a cabinet on the wall using a good quality 2P 63a breaker. (I like that I can isolate the entire property using this)

Given this is a north facing wall and that a concrete slab running the length of the house there will be poured shortly it seems that could be a good location to build a secure enclosure for inverter / batteries / etc. If it turns out that it's not ideal to have that stuff outside it can also go inside the house in the room the other side of the wall there where I plan to put the cabinet.

The first thing I want to ask about is how big should the cabinet be? I was thinking it should be a lockable steel one with an ip 65 or better rated plastic combiner box inside? I haven't yet worked out how the inverter gets connected to the incoming mains / tails to the consumer unit, what breakers and other things do I need to put in that cabinet so that it is ready to accept an inverter?

Am I right in thinking the DC breaker / isolaters for the incoming cables from the panels can also go in this cabinet?

Any advice is most welcome thanks!