Comment DC electrical system (Score 1) 557
I'd add some kind of DC electrical system. AC power is fine for moving electricity over long distances, powering motors, heaters, etc. However, all electronics need DC. Life without AC->DC adapters on every damn piece of electronics would be great. (Yes, maybe you'd need some external DC->DC adapters, but lots of things already can be powered by a USB port -- meaning 5 V.)
AC is especially dumb for solar: you have DC power source (a solar panel) which you then turn into AC power which gets converted back to DC for your electronics, LED lighting, etc. What a waste!
There have been some recently work on in-home DC power systems, although I haven't followed it closely (since I'm in no danger of owning a home soon).