Re: The next digs the last digs
First, before you settle on any one thing, do your research. What looks good on the surface may not be so great in practice, or have diminishing returns as far as value for dollar.
Consult with an architect who is familiar with green and energy efficient construction. This person will know what is available in the area in which you wish to build and may have options that you have not thought about.
There is more to solar than placing PV cells on your roof. There is also solar water heating, passive solar heating, solar lighting, and other forms. The area you are planning to build may have "greenergy" programs available to help defray the cost of construction. For instance, in my area the local utility will subsidize the installation of a solar electric system, in return you will be connected to the grid and any electricity that you do not use will be put out onto the grid and you will be paid for it. I have heard that the best part of a system like this is watching the meter run backwards!
Instead of a boiler to heat the water for your radiant floor, a solar heater may be the better route. The types of materials you build with will also make a big difference in your energy costs. So, again, I would recommend consulting with local tradesmen with green construction experience.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!