Years ago, my dad built the first solar home in the southern part of the state. It was built from the ground up to be efficient, from the materials used, to the appliances, to the insulation in the walls, to the sky lights. I don't remember a lot, but the attic was filled by the solar collector. The home would run off the solar panels completely on a moderately sunny day. A few days of cloudy weather, and it required power from the grid. The people who bought the house said their annual electric bill was less than $5.
Last summer, I helped set up an existing home with solar panels. My opinion is that the house needs to be built to be efficient. The cost of installing such a system in an existing house will never be recovered by the current owner.
