In photovoltaic systems, trackers help minimize the angle of incidence (the angle that a ray of light makes with a line perpendicular to the surface) between the incoming light and the panel, which increases the amount of energy the installation produces.
Single-axis solar trackers rotate on one axis moving back and forth in a single direction. Different types of single-axis trackers include horizontal, vertical, tilted, and polar aligned, which rotate as the names imply. Dual-axis solar trackers continually face the sun because they can move in two different directions.
The use of solar trackers can increase electricity production by around a third, and some claim by as much as 40% in some regions, compared with modules at a fixed angle. In any solar application, the conversion efficiency is improved when the modules are continually adjusted to the optimum angle as the sun traverses the sky. As improved efficiency means improved yield, use of trackers can make quite a difference to the income from a large plant. This is why utility-scale solar installations are increasingly being mounted on tracking systems.
There are, however, some disadvantages of solar trackers. Adding a solar tracking system means added more equipment, moving parts and gears, that will require regular maintenance and repair or replacement of broken parts. Also, if the solar tracker system breaks down when the solar panels are at an extreme angle, the loss of production until the system is functional again can be substantial. A solar tracker is also more prone to be damaged in a storm than the actual panels.