Hybrid Solar LightingIntroductionHybrid Solar Lighting (HSL) is a type of lighting system that combines natural solar lighting with standard electric lighting. This system directs pure sunlight into a building. Benefits of HSL include saving money, increasing office productivity, and agricultural development. Sunlight Direct, a manufacturer of HSL systems, is conducting beta testing in 12 locations across the United States. The Sacramento Municipal District was one of the first to facilitate HSL testing. The hybrid solar lighting system consists of three main parts. These parts are the solar collector, optical fibers and hybrid lighting fixtures. Solar collector The solar collector resembles a satellite dish; but instead of receiving the television signal, it collects sunlight. The collector is installed on the roofs of buildings as shown in Figure 2. Three main parts make up the solar collector: Primary mirror: the large reflecting dish (about 4 feet in diameter). Made of plastic and built to withstand adverse weather conditions. Secondary mirror: The small reflective dome that protrudes from the center of the dish. Another mirror used to reflect and concentrate light. Fiber optic receiving unit: the small tube in the center of the dish. It connects to optical fibers and transmits light through them. Solar collector function Sunlight is reflected on the primary mirror and concentrated in the secondary mirror. From there, the light beam bounces into the fiber optic receiving unit. A tracking system inside the collector calculates the sun's position using a global positioning system and local time. During the day, the solar collector repositions its dish to follow... half the paper... savings can be made due to the reduced air conditioning load, saving the owner a total of 8,000 kilowatt hours each year. Studies show that customers are more likely to shop in stores that offer natural lighting instead of electric lighting; Customers considered electrically lit stores boring. Natural sunlight gives the impression of a brighter room. Other studies have found a strong correlation between natural lighting and increased academic performance, as well as office productivity. Skylights offer natural lighting at an affordable price, but they have several disadvantages compared to hybrid solar lighting. Skylights do not filter the heat of sunlight nor are they capable of distributing light over large areas. Because HSL systems use fiber optics, multiple floors of the building can receive natural sunlight. Skylights are limited to upper floors only.