A solar tracker is a useful addition to some types of solar energy systems. The principle behind a solar tracker is simple. Solar collectors work most efficiently when pointed directly at the sun. Unfortunately, the position of the sun in the sky changes throughout the day. The tracker turns the solar array throughout the day to follow the path of the sun. Overnight, the tracker resets to the far east to prepare for the next day. Professional quality solar trackers cost quite a bit because they are designed for large scale installations, such as solar power plants. Nonetheless, you may wish to build your own solar tracker for a small system.
Solar tracking systems have four main parts: the motor, controller, rotor, and optical sensor. There are several different designs, and not all actually have optical sensors. For example, some solar trackers are controlled by a complex programmable logic device. Periodic angular steps are calculated for the months and days of the year. A timer controls vertical and horizontal rotation of the tracker. Other designs use LEDs as transducers. The LED generates a small voltage when exposed to sunlight. Several LEDs are mounted on a ring and a computer program constantly tests the output of the diodes. The sensor is tilted in the direction of the highest voltage. If you do not have the electrical or programming skills to replicate these systems, you can build your own tracker using pipes and a satellite antenna motor.
Step 1 - Design System
Sketch out the proposed tracker to determine the dimensions of pipe and number of fasteners you will require. The finish design will consist of two vertical pipes of different heights spanned by a diagonal length of pipe. The solar panel is fastened to this pipe, as well as the antenna rotator. The vertical angle is fixed by the placement of the vertical pipes, so choose the best angle for the whole year. The horizontal angle is controlled by the rotator.
Step 2 - Sink Foundations
Dig holes at the location of the vertical posts and fill them with concrete. Mount the posts in the holes. Bolt the casters to the tops to form an eyehole.
Step 3 - Build Frame
Drill holes near the ends of the diagonal pipe and mount it to the casters using the wheel bolts and washers. Mount the rotator onto this pipe with a u-bolt. Place a second diagonal pipe directly into the rotator, and mount the opposite end with the antenna bearing a few inches from the top of the lower pipe. Bolt and clamp the pipes together.
Step 4 - Mount Solar Panel
Fasten the solar panel to the frame. Place the aluminum bar across the back and bolt it to a chain link post bracket. Place a piece of rubber between the bracket and pipe.
Step 5 - Wire and Program Controller
Power the motor with batteries or low voltage wiring. This should be convenient with a photovoltaic tracker. Obtain a programmable remote and set appropriate angle steps for the hours of the day.