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 the interior of a building. The benefits of HSL include money savings, increased office productivity and agricultural development. Sunlight Direct, manufacturer of HSL systems, is conducting beta testing at 12 locations across the United States. The Sacramento Municipal Utility District was one of the first to facilitate HSL testing. The hybrid solar lighting system is composed of three main parts. These parts are the solar collector, the optical fibers and the hybrid luminaires. Solar collector The solar collector looks like a satellite dish; but instead of receiving a TV signal, it captures 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 harsh weather conditions. Secondary Mirror: The small reflective dome protruding from the center of the dish. Another mirror used to reflect and focus light. Fiber optic receiver: the small tube in the center of the dish. Connects to optical fibers and transmits light through them. Solar Collector Function Sunlight reflects off the primary mirror and focuses on the secondary mirror. From there, the light beam bounces back to the fiber optic receiver. A tracking system inside the collector calculates the position of the sun using a global positioning system and local time. Throughout the day, the solar collector repositions its dish to follow middle of paper...... can be saved through the reduced air conditioning load, saving the homeowner a total of 8,000 kilowatt hours each year. Studies show that customers are more likely to shop in stores that offer natural lighting rather than electric lighting; customers considered electrically lit stores dull. Natural sunlight makes a room appear brighter. Other studies have found a strong correlation between natural lighting and improved academic performance, as well as office productivity. Skylights provide natural lighting at an affordable price, but they have several disadvantages compared to hybrid solar lighting. Skylights do not filter the sun's heat and are not capable of distributing light over large areas. Since HSL systems use fiber optics, multiple floors of the building can receive natural sunlight. Dormer windows are limited to upper floors only.