Solar7

Oct 18, 2007 09:37 GMT  ·  By
MIT students, faculty and volunteers designed and built the house. Once completed, the house was broken down into modules to be taken to the Solar Decathlon in Washington, D.C.
   MIT students, faculty and volunteers designed and built the house. Once completed, the house was broken down into modules to be taken to the Solar Decathlon in Washington, D.C.

The electricity bill gives you a headache every time. What if it could simply disappear? After all, the Sun offers its energy for free and we use it all the time. The solution could be the solar houses, that heat water, dry laundry and power an electric car for free, with the help of sunlight.

MIT students have created an entirely solar-powered house, called the Solar7, for the Department of Energy's annual Solar Decathlon.

An entire village of Solar7 and other types of solar houses are exposed at the National Mall in Washington, D.C. on Oct. 12-20. Each 800-square-foot home is the work of a different university team (amongst which winners of past editions like Georgia Tech, Universidad Polit?cnica de Madrid, Santa Clara University, Universidad de Puerto Rico and the University of Colorado at Boulder) and are assigned to 10 categories based on energy efficiency, design and marketability.

Each model must accomplish the needs of the average American family: keep enough warmth (but not to be turned into a solar oven); have enough light for rainy days; warm water for showers; be handicapped-accessible; and accumulate enough energy for making a dishwasher and an electric car work; and employ accessible building materials and technologies. "You can't yank something out of the lab and throw it up on the roof. You have to use production-grade products." said Kurt Keville, faculty advisor to the MIT project.

Retaining heat is perhaps the most important challenge for a solar house. For this purpose, the Solar7's south-facing wall is built in a 1-foot-(30 cm) thick sandwich-like square tile structure. Two opaque plastic squares represent "the bread" and the filling is water and thermal insulating gel. The gel passes the sun's energy from the outside through the water inside the house.

The windows have three glass panels and krypton gas acting as insulator, limiting the lost heat. Several photovoltaic cells cover the south-facing roof, storing the energy in 24 batteries with an overall power of 70 kilowatts and which can deliver electricity to the house for 48 hours.

The Georgia Tech's model has roof panels that move following the sun's position.

The hot shower contest challenges the teams to come with showering water with a temperature rise to 110 ?F (43 ?C), or cooking the dinner for each team's neighbors employing the stored energy for powering appliances. Each team has to wash and dry a towel load, as well.