If right now you're worried about DC wiring for inside the house, just use 14 AWG romex and you'll be fine. Unless you're running something REALLY big.
The only thing that sucks about using romex for DC is that there is a third conductor that you don't need. But that could play in your favor as well. Use the bare wire for ground (negative) and the black and white wires can both be positive for 2 different circuits.
If you're a novice when it comes to home electrical, the big box stores have some good books on it. Wiring up an AC breaker box from scratch, especially when you have generator inputs, etc, can be very confusing if you don't have experience. Grounding alone can be very confusing. And whether or not you are subject to inspections, you want to follow the NEC because it exists for a reason. Mostly so you don't burn the house down!
Make sure all your junction points are in boxes that can be accessed when the walls are finished (NONE hidden behind walls!), use staples every couple feet and at every box entry, use strain relieve on your boxes, and you should be good to go.
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