We designed for passive solar, and also installed a solar hot water system (inset, also visible on the dormer roof).  Our house is more properly called "sun tempered" since we're not trying to maximize how much passive solar we use.  Still, we believe we get about 25% of our heat from passive solar, just by putting extra windows on the south side, and super-insulating the house.  Most of our windows have overhangs to keep out the summer sun.  Although some windows don't have overhangs, we had no overheating problems for five years.  If we ever have a problem, we will hang exterior bamboo screen on eyehooks.