Hmm, last time when i did my home the 4 core 16mm price is the same as 25mm two core armored steel. I did mine around 25Meters from incoming to DB Cost less than RM700 if i m not mistaken.

you can do like me, get electrician to pull additional 4 core wires for 3 phase ready, not necessary you need to apply with tnb straight for 3 phase. as i say for single phase shall suffice if you are loading 50% as per said items, get TNB to change incoming fuse to 100A, and at the DB you can used 63A units. if you are running 3x1 HP + 2xWH simultaneously will not cause problems, at max you are pulling 12A+30A for those items.

i have no idea about the circuitry of seda/solar, any one doing this can share here as well. can learn