Solar Implications

So you didn't buy a solar panel because you realized the energy contribution would not be significant enough to offset the cost. If you had built your home from Autoclave Aerated Concrete you could have reduced total (yes that is total) energy consumption by up to 50%.
Now imagine what that small solar array could contribute, relatively speaking. Now use architectural features to lower energy costs. Perhaps you could install solar tube lighting. At the very least you could implement compact florescent lights. Surely an energy wise construction would include a tankless water heater. The point is that it is perfectly reasonable for a new structure to be powered completely off the grid with out significant increases to cost (atleast during the day). This has far reaching implications as you consider that every model for the future of transportation ultimately inflicts higher demands on the established power grid. That's right all of them - Hydrogen production requires electricity - ethanol production can be ran off the grid but that subtracts signifcantly from overall plant output - and batteries (my personal favorite)....well naturally they require grid power.