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Q: How does a hybrid solar lighting (HSL) system work?
A: Imagine being able to light your home or office most of the day, and on most days, with sunlight, but not the kind that comes through the windows. That's what hybrid solar lighting (or HSL) systems are being developed to do. Prototype HSL systems are made up of roof-mounted concentrators that collect and separate the visible and infrared portions of sunlight. The visible portion of the light is distributed through large-diameter optical fibers to hybrid luminaires. (Hybrid luminaires are lighting fixtures that contain both electric lamps and fiber optics to distribute sunlight directly.) Unlike conventional electric lamps, the solar component of HSL produces little heat.
The remaining "invisible" energy in the sunlight, mostly infrared radiation, is directed to a concentrating thermo-photovoltaic (solar) cell that very efficiently converts infrared radiation into electricity. The resulting electric power can be directed to other uses in a building. When sunlight is plentiful, the fiber optics in the luminaires can provide all or most of the light needed in a particular area. But when there is little or no sunlight, sensor-controlled electric lamps turn on to maintain the desired illumination level.
Independent cost and performance models suggest the overall affordability of solar energy could be doubled or tripled by using this new hybrid approach. The multidisciplinary R&D effort involved in developing HSL includes several industrial and university partners. Other Resources:
Other Resources: To learn more about the research being done in HSL, please visit Oak Ridge National Laboratory's Hybrid Solar Lighting Web site.
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Q: Who is doing research in hybrid solar lighting (HSL)?
A: Research that's under way now at Oak Ridge National Laboratory (ORNL) in Tennessee could lead to entirely new, highly energy-efficient ways of lighting buildings using the power of sunlight. In addition to providing light, HSL would convert sunlight to electricity much more efficiently than conventional solar technologies. In commercial buildings, lighting consumes more electric energy than any other use. And lighting accounts for more than a third of all the electricity consumed for commercial use in the United States. Typically, less than 25% of that energy actually produces light; the rest generates heat, which increases the need for air-conditioning. So, ORNL is developing a system to reduce the energy required for lighting and the air-conditioning loads associated with it, while generating power for other uses—for example, heating or cooling the spaces in buildings.
The HSL concept, originated by ORNL's Jeff Muhs, separates and uses different portions of sunlight for two applications — interior lighting and distributed power generation. This concept takes advantage of two facts. First, the luminous efficacy (or light output per unit of energy, expressed as lumens per watt) of the visible part of the solar spectrum is more than double that of electric lamps. Second, photovoltaic (solar) cells, and especially thermo-photovoltaic cells, are very efficient in converting the infrared portion of the spectrum to electricity. You may contact Jeff Muhs, 865-574-9328 to discuss opportunities to demonstrate HSL technology.
Other Resources:
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