Lighting with sunlight using sun tracking concentrators

The use of controlled beams of sunlight for lighting interior parts of a building is proposed as an economically attractive and practical option in a solar energy context. Sun tracking concentrators introduce beams of sunlight through holes in the roof. Inside, the beams can be relayed throughout the building by means of mirrors and lenses. Ideally cool lighting is obtained by using dielectric mirrors to separate the visible and ir parts of the solar spectrum. The ir can be used to generate electricity and usable heat in solar cells. Results of a preliminary experiment are given.