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12/04/2006 01:15 PM     print story email story      

Hybrid Solar: Coming Soon?

Hybrid technologies are the new kid on the block. In addition to hybrid cars, emerging technologies combine hydrogen with wind, and solar with lighting.

25% of the electricity used in the U.S. powers indoor lights, and inefficient ones at that. Three quarters of the electricity drawn by incandescent lights is completely wasted, and worse than that, the heat they reflect increases the need to cool buildings by 10%.

A hybrid solar lighting (HSL) project, with the potential to vastly increase lighting efficiencies, is on track to enter commercialization in early 2007.

Developed by the federal Oak Ridge National Laboratory (ORNL), HSL technology places 4-foot wide mirrored dish solar collectors on the roof that track the sun with the help of a GPS receiver. The collector focuses the sunlight onto 127 optical fibers, which act as flexible light pipes to deliver the electricity to indoor light fixtures. Each collector powers about eight hybrid light fixtures, which spread the light in all directions through diffusion rods, illuminating about 1,000 square feet.

What makes it a hybrid? HSL control systems continually monitor that amount of natural light that's available and switch between artificial and natural light as needed. On cloudy days, and in the evening, the fixtures use standard electricity.

ORNL researchers found they could also capture the thermal portion of the sunlight by adding an additional mirror. The heated energy is sent to a photovoltaic panel or a solar hot-water heater instead of to the light fixtures. The mirrors reflect infrared energy and ultraviolet waves, reducing both heating and cooling costs. 

Duncan Earl, an ORNL researcher and co-inventor of the technology, formed for-profit Sunlight Direct to commercialize HSL. ORNL licensed the technology to the company, and together they are in the midst of beta-testing with 25 facilities across the U.S. It's being tested at a New York Staples store, Aveda's corporate headquarters in Minneapolis, at a San Diego State University office building, Wal-Mart and the Long Island Power Authority, for example.

Earl plans on making HSL available for sale in commercial buildings in early 2007, and for the residential market within a couple of years. The price is still a hefty $24,000 for a HSL system, but Earl expects the price to drop rapidly as more systems are manufactured.

Utilities are also evaluating it to determine how long the payback would be and how much reliable  light HSL generates. So far, most users are excited about the technology?s prospects, finding it provides steady, high quality light.

And thanks to federal tax credits, Sunlight Direct's entry into the commercial market will get a lift from the 30% tax credit available through 2007.

Besides the energy benefits this technology offers, it makes natural light more available to inhabitants of buildings of all kinds. It's widely accepted that natural light is important to overall health; artificial light, on the other hand, has been shown to be associated with depression and other negative health effects. Daylighting is a key feature of green building - HSL takes it a step further because it can be used beyond ambient lighting to provide highly directional, product lighting.


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