from solar nation

A neat update on this years Solar Decathlon:

The Team to Beat

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Darmstadt's title defense at the Solar Decathlon

Who is the 'team to beat' at the 2009 Solar Decathlon? It would have to be the Technische Universitat Darmstadt, aka Team Germany, and for the usual host of reasons: they won last time.

The Darmstadt students are well aware of the pressure they face in retaining the silver trophy of the Solar Decathlon, and it shows. Their 2009 entry is one of the most singular sights in the whole solar village, looking as much like an outsize lacquered ebony music box as a livable home. In fact, think of a cube draped in one large solar panel, top and sides, and you'd have a pretty good realtor's description of the home.

What you'll see at the Darmstadt site if you make the (very worthwhile) journey to the National Mall between now and October 16th is a two-story building envelope almost completely covered with thin-film PV panels with a total capacity of some 19 kW. That figure is so much in excess of normal requirements for an 800-square-foot house that the designers have dispensed with a solar hot water system; all the power for heating, cooling and lighting the building comes from the electricity generated by the panels -- crystalline silicon on the roof and thin-film copper indium diselenide on the walls.

As is now common with Solar Decathlon houses, the German entry features a building optimization system. This system monitors all electricity-using machines and systems in the house against the power available from the solar cladding, and can adjust energy use automatically or on command. It can also alter the position of window louvers to vary the amount of solar heat admitted. And the house's walls are made up of vacuum insulation panels, aided by phase-change material in the drywall, to maintain comfortable temperatures.

It's quite clear, considering the cost of the materials and sophistication of the systems used, that such a house would not fit in the 'affordable housing' category. Nor would the German students argue the point. Their philosophy was to "push the envelope with as many new technologies as possible", which creates a dichotomy as far as Solar Decathlon principles are concerned. On one hand, the competition's DOE sponsors want to see designs that can be reproduced, in whole or in part, in the homebuilding market. If a house produces twice as much power as it needs, as the Darmstadt house does, it pays a penalty in construction cost. This may make the design unmarketable, or confine it to a niche at the top end of the market;* (according to Solar Decathlon organizer Richard King, even the average cost of this year's houses is $490,000). On the other hand, DOE knows that what counts as high-end innovation today can become common currency in the market tomorrow, and that it's only by pushing the envelope today that we can bring about revolutions tomorrow.

How the Solar Decathlon juries parse this dichotomy in the next week may determine whether the prized trophy stays with the Darmstadt students or finds a new home until 2011.




*By contrast, the Rice University house is specifically designed to be used in a low-income home project. After the competition it will be transferred to Project Row Houses, a local community development organization in Houston, for rebuilding in the city's Third Ward.