Along the discussion of the DC home, a good inverter and maybe dedicated DC outlets. Maybe just feed outlets directly from solar/wind battery bank.
I'd add switchable glass windows to go "opaque" whenever I wanted, at least in the bedrooms.
Running low voltage DC over long distances properly is difficult, as you need bigger wiring, switches, fuses, etc. I'm not sure I'd want to do a lot of home wiring with it. Modern inverters are relatively efficient and fairly reliable. I would say that the way to go would be to pick out a few circuits for 'critical' loads you would like to be able to supply backup power to or run off grid, and run them into a separate sub panel. You could either just wire this into your main panel during construction, or install a battery/inverter system right away that would act like a big UPS to the loads on the sub panel. You can get inverters that will work with batteries, but push excess power from solar/wind into the grid while the grid is up. If it goes down, you can run your critical loads on battery power.
For some low voltage things I'd maybe consider a separate, smaller PV system and locate it close to the load, maybe for something like garden lights or ham radio gear.
Higher voltage DC is an interesting idea, especially since you could probably run a lot of switching supplies off of it - some data centers do this. However you need special switches and fuses to be able to interrupt it. I'm not sure 120/240 VDC is something I'd want in my home.