20 solar homes

The 20 houses on the mall need to run entirely on the sun and perform normal household tasks, such as running appliances and supplying hot water for washing dishes and laundry.

All of the buildings use both solar-photovoltaic (PV) panels that convert sun to electricity and solar-thermal systems that make hot water. All of the homes also have batteries to store electricity for when the sun isn't shining.

The Georgia Institute of Technology, with its "Icarus" house, took a novel tack on solar photovoltaics.

It has three rows of solar panels on the roof that have motors that change the angle of the panels to maximize the amount of sunlight that comes in. Team members also chose to build a "solar wall" covered with solar PV.