INFRARED PHOTOVOLTAICS FOR COMBINED SOLAR LIGHTING AND ELECTRICITY FOR BUILDINGS

摘要

A concept for indoor illumination using sunlight is described. For this system, a tracking concentrator on the building roof follows the sun and focuses sunlight into a light guide. A system of transparent light guides distributes the sunlight to interior rooms. In this system, a cold mirror splits the solar spectrum into visible light for indoor illumination and infrared radiation which is directed to an array of GaSb infrared sensitive photovoltaic cells which then generate electricity. It is shown that each Watt of visible sunlight displaces two Watts of electricity which otherwise would be used for florescent lighting and air conditioning. The savings from this displaced electricity can then pay back the cost of the concentrator, tracker, and light guides in approximately three years. Meanwhile, the GaSb cell array converts the concentrated infrared energy to electricity with an electric power density of one Watt per square cm. This power density is one hundred times higher than available from a planar silicon cell, thus easily allowing PV electric power production at a capital cost of under $1 per Watt.