September 27, 2006—The Department of Energy’s (DOE) Oak Ridge National Laboratory (ORNL) says the forecast is looking sunny for the hybrid solar lighting systems it has developed, with 25 either currently installed or soon to be installed.
Preliminary data from field units show potentially significant energy savings in lighting and maintenance costs, as well as environmental benefits, says ORNL. In addition to financial incentives such as a 30 percent tax credit, the higher quality of natural light reportedly leads to increased productivity and improved sales in retail outlets.
The hybrid solar lighting technology uses a rooftop-mounted 48-inch diameter collector and secondary mirror that track the sun throughout the day. The collector system focuses the sunlight into 127 optical fibers connected to hybrid light fixtures equipped with diffusion rods visually similar to fluorescent light bulbs. These rods spread light in all directions.
One collector powers eight to 12 hybrid light fixtures, which can illuminate about 1,000 square feet. During times of little or no sunlight, a sensor controls the intensity of the artificial lamps to maintain a constant level of illumination. The technology provides peak light output during the hours of the greatest demand for electricity, which saves energy and money and can reduce brownouts.
The system can save about 6,000 kWh per year in lighting and another 2,000 in reduced cooling needs for a total of 8,000 kWh annually, according to Sunlight Direct estimates. Over 10 years, for parts of the country where the utility rates are 10 cents per kWh, that can result in savings up to $8,000 per hybrid solar lighting unit.
For large floor spaces—100,000 to 200,000 sq. ft.—this translates into energy cost savings of between $1 million and $2 million over 10 years, according to Sunlight Direct. Operation and maintenance savings could account for another $300,000 in savings over the same period.
For more information visit ORNL or Sunlight Direct.
