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Photo of two students wearing hard hats, who are installing long glass tubes in vertical rows along metal fittings on the outside of their team's house.

Nansen Yu and Myra Wong of Cornell University install evacuated tube collectors for heating water on their team's house. A metal tube with fins inside the glass tubes collects the sun's heat, transferring it to water that passes through the tubes, thereby heating the water. The tubes use an internal vacuum to prevent heat loss.

Solar Decathlon 2007

Hot Water

(100 points)

This contest demonstrates that solar hot water systems can supply all the hot water that households use daily for bathing, laundry, and dishwashing. Teams score points in the Hot Water contest by successfully completing "shower tests" over 4 days of the competition. They aim to deliver 15 gallons of hot water (110°F/43.3°C) in 10 minutes or less.