I was looking back at reddit posts (while deleting them), and I realized I’d written a book worth of stuff about this topic. I would write it all again, if it is helpful. But for a brief synopsis of “how it works”, here is what one does:
Assess power needs - look at your living standard and catalog all the devices you power, and estimate the time they operate - power is measured in watts, and time in hours. Multiply to get watt-hours; then divide by 1000 to get kilowatt hours. Compare with your utility bill.
I went for a compromise: my house is equipped with 24 V DC cabling (PC PSU sockets as wall sockets) and likewise has a 240 V inverter.
Small stuff that is always on (router, alarm system) connects to the DC lines with DC/DC converters. Also: circulation pump, LED lights, 3D printer, small battery chargers - these use DC.
Most rooms have fairly limited wiring, so a huge amount of copper wasn’t spent… except in the direction of the water tank. In that direction, wires are massive because my opportunistic heat storage system (when the season is cold and excess solar energy becomes available) also uses DC.
Big stuff (charging the car, pumping heat or irrigation water, drilling, welding, cutting) uses AC.