Solar Energy, Collected, Concentrated, Transported, and Distributed as Light With No Energy Conversion Via a Hybrid Solar Lighting System

Hybrid solar lighting (HSL) is a technology in which sunlight is collected and distributed via optical fibers into the interior of buildings. Analogous to hybrid electric vehicles that use both batteries and internal combustion engines to power cars, hybrid lighting employs roof-mounted collectors to concentrate sunlight into flexible optical fibers and carry it inside buildings to “hybrid” light fixtures that also contain electric lamps. As the two light sources work in tandem, control systems keep lighting levels constant by dimming the electric lights when sunlight is bright, and turning them up as the sky darkens with weather conditions or nightfall. Data indicate that on a bright, sunny day the power consumption for lighting can be reduced by 50% or more. Today, lighting in U.S. residential and commercial buildings consumes close to 5 quadrillion BTUs of primary energy and one-fifth of all electricity. In commercial buildings, one-quarter of all energy demand is for lighting. With a forecasted doubling of commercial floor space by the year 2020 comes an urgent and growing need to find more efficient ways of lighting our nation’s buildings. Typically, less than 25 percent of the electrical energy consumed for lighting actually produces light; the rest generates heat, which increases the need for air-conditioning. Unlike conventional electric lamps, the sunlight from HSL systems produces virtually no waste heat. A nationwide field trial program is under way to provide system performance data and user-feedback essential for the successful commercialization of HSL. Field trial installations include San Diego State University, San Diego, CA; Pacific Northwest National Laboratory, Richland, WA; Sacramento Municipal Utility District, Sacramento, CA; Wal-Mart, McKinney, TX; Aveda Corp., Minneapolis, MN; Staples, Long Island, NY; Braden’s Furniture, Knoxville, TN; Multipurpose Research Facility, Oak Ridge National Laboratory (ORNL), Oak Ridge, TN; University of Nevada-Las Vegas, Las Vegas, NV; Hybrid Lighting Laboratory, ORNL, Oak Ridge, TN. This paper describes the field trial program and summarizes the results to date from the field trial installations.