This year's contest was the fifth since the decathlon was first launched in 2002, at a time when solar power was still a tiny, hothouse business. Since then, solar energy has taken off, growing into a multibillion-dollar industry, with more than 3,000 megawatts of installed solar power in the United States alone.

While much of the U.S. installed capacity is powering commercial buildings, solar homes have also moved toward the mainstream as builders like Arizona's Meritage Homes roll out entire net-zero-energy subdivisions at prices comparable to standard construction.

During the 2011 decathlon, 19 teams, including four from universities outside the U.S., spent a week in mid-September erecting their homes in the National Mall's West Potomac Park in Washington, D.C.

In the days that followed, they competed for points in ten categories: architecture, market appeal, engineering, educational communications, affordability, "comfort zone" (indoor temperate and humidity), hot water systems, appliances, home entertainment, and energy balance.

Some of the houses in this year's competition echoed market trends in at least a couple of ways: the cost of the homes and a holistic approach to green building.

Nearly half — nine out of 19 houses — were estimated at less than $300,000 to build. This year's entries were about 33 percent less expensive than the 2009 solar homes, according to decathlon organizers.   >>>