Passive Solar - Its more than pointing the home south.

I was speaking with a friend who is planning to build a "passive solar" home off the grid. The plan is stick frame 2x6 walls, point the home south, cover the south wall with windows and sit back and enjoy. I asked them about the floor and the plan was to lift the home off the ground and use a crawl space. I asked them about their overhangs for the south and they hadn't thought that out yet. Although this home may meet there needs, as similiar home designs meet the needs of many people throughout the world today, to me a few simple changes could make this home REALLY efficient and comfortable. I will touch on a few of those in my next few posts including thermal mass, trombe walls, overhangs for south facing homes and glazing to livable square footage ratios.