A pinhole camera to track the sun position

An innovative and simple method, exploiting a pinhole camera to perform the sun tracking, is proposed. The tracking technique has been applied to a sunlight collection system, based on solar concentrators coupled to optical fibres. Using an equatorial configuration, the movements to align the optical collectors in the sun direction are preformed in two directions: on the temporal axis and on the declination axis. The methodology to track the sun position employs a double guiding system that uses two complementary procedures. The first one provides the preliminary orientation, then the second realises the fine positioning and adjustments. The first tracking system is of passive type and it drives the motors to correctly orient the head every day of the year. The second one is of dynamic type and it employs an optical pointing system. The core of this active tracking system is the sun pointer, which works as a double pinhole camera without lenses. The pointer has two sensors, with decreasing Field of View, that are used in sequence, improving the precisions of the sun tracking. The sun tracking technique has been applied to a system for illumination of internal spaces installed in a museum, where it has been tested in working conditions.