This is the winter building section which shows how the low winter sun interacts with the building's form. The solar thermal panels (which generate hot water for the domestic hot water system and tie into the HVAC system) are angled to be optimized in the winter when the hot water is needed most.
The overhangs are arranged on the south facing windows to allow a maximum of sunlight into the house for passive solar gain.
The only thing required to achieve a home powered by the sun is some smart design. For another project, architect Nate Kipnis identifies the roof angles that will be required during the winter ...
There are a number of sites that offer a calculator for determining sun angles and optimal positioning of collectors. Just google "sun angle calculator" or something similar. But I think yours is more of an architectural question. Typically, my preference is to build a 3D model of the project in Sketchup ( http://sketchup.google.com/intl/en/ ) and position the model in Google Earth to study how the sun moves across the project at various times of day and night and throughout the year. I can then adjust the architectural elements to to get the amount of sun and shade I want. A very early study of the sun across the south face of a project is shown in the image -- look at "sketchup" for floorplans