My first thought is, "why 12V?" Do you have a pre-existing reason to select that voltage?
If you don't, I'd suggest going for a higher voltage - 24 or 48V - especially if you want to take a house completely off-grid. (Although just what that entails could vary - do you intend to completely forgo an inverter and 120VAC appliances and such?)
In my case, my primary usage is already 12V (ham radio bench) so I chose to stay with that. Were it not for the radios, I'd definitely have chosen a higher voltage - probably 48V. Even as it is, I still occasionally consider that idea. I just can't quite bring myself to run an inverter then power supply back to 12VDC for the rigs, though!
Raising the voltage drops the wire size requirements considerably, as the amperage to do a given amount of work goes down. It also means a small voltage drop isn't the huge killer it might be at 12V. I am frequently amazed - and frustrated - at how large of a wire I wind up needing for some tasks just because of voltage drop.
It can also mean more power from a given device in some cases. Solar charge controllers often can run at 12, 24 or 48V - but will pass the same amount of current at each one. So my 80A charge controller will only supply 960W max on my 12V system, whereas if I were to change it to 48V it could supply 3840W.