Do not install a solar system in your home without first doing an energy audit. An energy audit will assess your energy needs and will help you utilize savings before installing a solar system. The last thing you want to do is install a solar system to pay for energy you are wasting.
The best time to incorporate solar power into the design of a home or building is in the initial construction. Windows are best facing south to let maximum sunlight (hence greenhouse heat) in during the winter. Likewise, avoid windows facing directly into the summertime sun to keep things cooler, so less power is needed for fans or air conditioning. The maximum roof space, however, should always get sunlight exposure.