1. Field of the Invention
This invention relates to sun-tracking apparatus and methods for solar energy collectors, and more particularly to light sensitive control mechanism for controlling the drive of sun-tracking apparatus.
2. Problem
A problem of solar energy collectors is the decreased efficiency of such collectors which do not track the sun. Insolation received by a collector that tracks the sun during the summer is as much as three times as great as the insolation received by a stationary solar energy collector, and during the winter is as much as twice as great as the insolation received by a stationary collector. To solve the problem of maximizing insolation on a solar energy collector, therefore, it is necessary to mount the collector for movement to track the sun and to control movement of the tracking apparatus to track the sun reasonably precisely.
3. Prior Art
Prior solar energy collectors have usually been stationary, although the direction of some has been adjustable. It has been proposed to mount a solar energy collector for rotation about a vertical axis to adjust the azimuth and for tilting to adjust the altitude so as to point the collector toward the sun, especially during midday hours, but practical and economical drive and control mechanism for effecting the rotation of a base turntable and tilting of the collector relative to the base has not been available. Note the discussion of solar cooking at page 527 of volume 12 of the McGraw-Hill Encyclopedia of Science and Technology.
Sophisticated tracking mechanism for tracking the sun, planets or stars by automatically rotating a turntable about a vertical axis for azimuth adjustment and tilting a target about a horizontal axis for elevation adjustment is shown and described at pages 52 and 53 of volume 13 and at pages 737 and 738 of volume 1 of the McGraw-Hill Encyclopedia of Science and Technology.
Fully computerized control mechanism for trackers must be programmed differently for different latitudes of the earth's surface, as well as for different days during the year. Such programming is, therefore, very complex and expensive.