Solar house produces power even after three days of rain

A solar-powered house that generated surplus power even after three days of rain — Team Germany’s “Cube House” — won top honours in this year’s Solar Decathlon.

The biennial competition, held by the US Department of Energy, invites university-led teams from across the US and internationally to compete in 10 contests, ranging from subjective elements such as architecture, market viability, communications, lighting design, and engineering, to technical measurements of how well the homes provided energy for space heating and cooling, hot water, home entertainment, appliances, and net metering.

This year’s winning entry was designed by a team from Darmstadt. It was the team’s second-straight Solar Decathlon victory, after winning the previous competition in 2007.

Second and third place went to the University of Illinois at Urbana-Champaign and Team California, respectively.

“This competition to build zero-carbon homes has been a tremendous undertaking and we have seen terrific efforts by all the teams,” said Deputy Secretary of Energy Daniel Poneman. “The ingenuity that comes from individual effort is the promise of our future.”

New to this year’s competition, the Net Metering Contest was worth 150 points towards the final results and was the most heavily weighted contest.  It challenged teams to generate surplus energy, above and beyond the power needed to run a house, which they fed into a power grid.

Team Germany earned 908.29 points out of a possible 1,000 to win the competition, followed by the University of Illinois at Urbana-Champaign with 897.30 points, and Team California with 863.08 points.

Other award winners include:

• Appliances: The University of Illinois at Urbana-Champaign earned the most points based on keeping a refrigerators and freezer cold, washing and drying 10 loads of laundry during the contest week, and washing dishes in a dishwasher five times during the competition – all on electricity generated only from sunlight. The team scored 93.53 out of 100 possible points.
• Architecture: Team California took first place in the Architecture contest and earned 98 points out of a possible 100. A jury of architects judged homes on the aesthetic and functional elements of the home’s design; ease of circulation among the public and private areas; integration of various spaces into a holistic design; generosity and sufficiency of space in the house; and the house’s design surprises meant to inspire visitors.
• Comfort Zone: Team Germany topped the contestants in the Comfort Zone contest, with 92 out of 100 points for maintaining indoor temperatures between 72 and 76 degrees Fahrenheit and relative humidity between 40 per cent and 55 per cent.
• Communication: Team California’s communications efforts, including communications plans, student-led tours, and team website, were judged best by the jury of website and public relations experts with a score of 69.75 points out of a possible 75 points.
• Engineering: The University of Minnesota won the Engineering contest, which was evaluated by a group of prominent engineers, who determined which solar home best exemplified excellence in energy systems design, energy-efficiency savings, creative innovations in design, and reliability of energy systems. The University of Minnesota scored 96 out of a possible 100 points.
• Home Entertainment: The Home Entertainment contest required students to use electricity generated by their solar houses to run interior and exterior lights, a TV, a computer, and a kitchen appliance to boil water.  Teams were also required to hold two dinner parties and a movie night for neighbors. The University of Illinois at Urbana-Champaign earned 92.62 out of a possible 100 points.
• Hot Water: The University of Illinois at Urbana-Champaign earned the maximum 100 points in the Hot Water contest’s “shower tests,” which aimed to deliver 15 gallons of hot water in ten minutes or less. Of course, the water was heated by the sun.
• Lighting Design: The University of Minnesota was named the winner of the Lighting contest where teams earned points based on an evaluation by a jury of lighting design experts. Jurors toured each house to evaluate the aesthetics, innovations, energy efficiency, user-friendliness, flexibility, and performance of the teams’ lighting designs. The University of Minnesota earned 72 points out of a possible 75 points.
• Market Viability: The University of Louisiana at Lafayette won the Market Viability contest, which evaluated whether the cost-effective construction and solar technology in a team’s design would create a viable product on the open market. Judges gauged market appeal based on three criteria: livability, feasibility of construction and marketability. The University of Louisiana at Lafayette earned 97 points out of a possible 100 as judged by the professional jury.
• Net Metering: Team Germany took the top spot in the crucial, 150-point Net Metering contest. Teams were awarded 100 points if the energy supplied to their home’s two-way electrical meter registered zero or less after all of the energy demands of the contest week. Each house in the 2009 Solar Decathlon was connected to a power grid and equipped with a meter that measured both its consumption and production of energy. When a team’s meter showed a negative number, the home had generated surplus energy — worth up to 50 additional points. Team Germany scored a perfect 150 points in this contest.

The application process for the next Solar Decathlon, to be held in fall 2011, has already begun.