There are two main types of solar trackers, single-axis and two-axis.
Single-axis
Single-axis solar trackers follow the sun from sunrise to sunset as it moves in the sky through the day from east to west. They are called a single-axis trackers as the mechanism only rotates in one plane around a single axis. The axis can be oriented so that the cells stand up at a tilt (called a polar axis) or lie flat (called a horizontal axis). Horizontal axis’ are more suitable for small latitudes , whilst polar axis are more suitable for larger latitudes
The advantages of single-axis trackers are that they are less complicated, and thus less expensive. As can be seen in the figures below, single axis trackers capture much of the benefit of solar tracking. In locations closer to the equator where the sun’s arc through the sky is less variable through the day and through the seasons, single-axis trackers are particularly effective.
Single-axis horizontal trackers are also structurally more rigid and stable, and hence less likely to be damaged during storms. In addition to the normal single-axis options, a new solar PV technology has been developed called Tubular solar, where the shape of the cells themselves are cylindrical, allowing the cells to capture the maximum amount of light as the sun goes through it’s daily cycle.
Dual-axis
Dual-axis, or two-axis, trackers follow the sun completely. The two axes of rotation allow the tracker to position the solar cells directly perpendicular to the sun’s ray all the time. As they are able to adjust for the sun’s height as well east to west rotation dual-axis trackers fully adjust for seasons as well as adjusting to face the sun as it sits low in the horizon at sunrise and sunset, and high in the sky in the middle of the day.
Dual-axis trackers capture the full extent of the sun, but they are slightly more complex and hence a little more expensive. Dual-axis trackers make more of a difference at greater latitudes where there is substantial seasonal variation in the sun’s height and arc.
