1-axis and 2-axis solar trackers

Abstract

A one-axis sun position tracking device with its rotation axis parallel to the rotation axis of the Earth, rotates perpetually at a constant speed in the opposite direction of the Earth's rotation. This device comprises a shaft that is aligned to the Earth's polar axis, one or more crossbars are rigidly attached to and perpendicular to the shaft, solar energy collectors are mounted on the crossbar and could rotate around the crossbar that defines declination angle. A self-latched declination angle adjustment mechanism keeps the declination angle constant at most of time. A drive mechanism keeps this solar tracker to rotate perpetually. An automatic and abrupt declination angle change will keep the declination angle updated to correct value each day. A similarly configured two-axis tracker that continuously updates its declination angle by a mechanism derived from a differential coaxial rotation. Two independent driving mechanisms control the speed and / or duration of the two coaxial rotations, and are programmed to eliminate all tracking errors from various sources.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims the benefit of provisional application Ser. No. 61 / 269,462, filed 2009 Jun. 26 by the present inventor.FEDERALLY SPONSORED RESEARCH[0002]Not applicableSEQUENCE LISTING[0003]NoneBACKGROUND[0004]1. Field[0005]This invention relates to solar energy collections, specifically to sun position tracking that is used in sunlight concentration and collection.[0006]2. Prior Art[0007]Sun position tracking is very important to solar energy collection, especially for solar concentrators. Different implementations have been invented, they could be categorized as 1-axis tracking and 2-axis tracking. 1-axis tracking is simple, however, it is commonly believed that 1-axis tracking has a poor tracking capability, that is not true in a special case; 2-axis tracking can have a very good tracking accuracy, however, it is usually very complicated because of the coupled rotation of 2-axis.[0008]Most 2-axis tracking methods are using local ...

AI Technical Summary

Benefits of technology

[0016]The proposed apparatus has a rotatable shaft orientated substantially parallel to the rotation axis of the earth. One or more crossbars are rigidly and perpendicularly attached to this shaft, solar energy collectors are mounted on these crossbars and could rotate around these crossbars to define different declination angle. Those solar energy collectors are connected to a set of gears by a mechanical link, and different position of the gears determines the declination angle of the solar energy collectors. One gear in the gear chain is usually latched, for example, by a spring load ball against a notch, which causes the whole gear chain and the declination angle to be kept at a fixed position. When correctly forced at the correct time, the latched gear will be unlatched, turned to the next correct position, and reapply the latch. In this example, the spring will be compressed, the ball yields its way of blocking the notch so that the gear could rotate until the ball falls into the next notch; at that time, the external force is removed and the spring loaded ball latches the gear at the new position, which defines the next declination angle for the solar tracker.

Problems solved by technology

Of course we have to set the next correct declination angle for the next day, a manual adjustment is tedious, a continuous adjustment is an overkill as others already proposed in the prior arts and is unnecessary.

In order to further improve sun position tracking, this non-continuous declination angle adjustment is not enough.

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