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| 'Solar 7' nears completion in a Cambridge, Mass., parking lot near the Massachusetts Institute of Technology. The house is
now displayed on the Mall in Washington, D.C. Solar 7 |
Students compete to design solar homes
Full-size 'Solar Decathlon' entries populate Washington's Mall Oct. 12-19.
from the October 11, 2007 edition
Page 2 of 4
Skeptics are invited to visit Greg Sachs's house at the US Merchant Marine Academy in New York. It was the New York Institute of Technology's entry to the 2005 Solar Decathlon.
Mr. Sachs, a professor at the merchant marine academy and founder of its alternative-power program, helped design aspects of both the NYIT and USMMA houses two years ago. Part of his reward was getting to keep the house and see how it works for everyday living.
"Something I teach my students," Sachs says by phone, "is that we've been through the Industrial Age and the Information Age. Now we're entering the Age of Energy. This is going to be the defining thing for our generation: How can we power our lives and homes with something other than fossil fuels?" The decathlon hints at how homes may function.
Result: a negative electric bill
Sachs has a negative electric bill. His home produces more than he uses, so he sells the excess back to the power company. That could be the reality for anyone living in any of the homes in Washington's "solar village." Some came from as far away as California and Colorado, Spain and Germany to be in the competition.
All the homes are powered exclusively by solar and designed to operate off the electric grid. But they must produce enough power to juice up an electric car.
This year, Sachs is working with NYIT and MIT (where he's a distance grad student) on their photovoltaic systems.
The MIT students built Solar 7 in a vacant MIT parking lot, hanging up sketches and calculations on the side of a makeshift metal arch. A banner hanging on it reads, "If it exists, it must therefore be possible."
The team lives by its motto, taking existing technology – some of it brand-new – and adapting the energy-efficient products to the typical American home.
"These houses are innovative because they're bringing all these things together – the products, the materials, the engineering, the architecture – into one integrated system that looks and operates pretty much like a normal house," says Santa Clara's Bickford. "It's about finding the best blend of sustainability."
Two factors determine how well the houses will perform, says Kurt Keville, adviser to the MIT project and a researcher at the university. One is the house's load: how much energy the house needs for everyday functions.
In MIT's case, their house features all Energy Star appliances (Energy Star is a government program to promote energy-efficient products) to keep the load down. Other schools will try different tactics, says Keville, which his team won't see until the competition.
The second determinant of a house's self-sufficiency is how much solar energy it can produce. The MIT and NYIT teams have boosted the efficiency of their solar arrays 10 percent by using a new kind of current inverter. Inverters take the DC power generated by the solar cells and convert it to AC.
MIT's 42 solar panels can generate 9 kilowatts of energy per hour in ideal conditions, while the average home in Massachusetts requires only 25 kilowatts per day. The extra wattage is mainly to show the best they can do since it's a "concept" home, says Jim Dunn, MIT's technical adviser.
MIT's team analyzed the winners of the 2002 and 2005 decathlons to help guide their design. They decided that the rainstorms at the 2005 event were less likely than the heat wave at the first decathlon. So the team decided on an efficient solar array and extensive use of passive solar.
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