by Billy Ludt(associate editor of Solar Power World)
Since the Earth’s rotation relative to the sun is not the same all year, with an arc that will vary by season, a dual-axis tracking system will consistently experience greater energy yield than its single-axis counterpart since it can follow that path directly. A dual-axis solar tracker produces 30 to 45% more energy yield than fixed-tilt solar systems.
Dual-axis trackers are used more in residential and smaller commercial applications but are beginning to see utility-scale deployment. Each of these trackers is installed atop a single elevated post to account for the greater range of angles the installed panels will reach. Dual-axis trackers can hold upwards of 20 panels per unit.
With higher elevation, panels aren’t as easily accessible for cleaning. However, with more headspace, dual-axis trackers leave the ground underneath open for other purposes, such as agriculture or even carports.
It’s a largely unexplored market segment, but tracking solutions for rooftops are starting to surface as well. These roof trackers operate somewhat like dual-axis trackers, rotating on a carousel-style track at the bottom of their racking, and adjust panel angles to follow the sun more accurately than single-axis trackers.
Following the sun
Solar trackers use different drivers, software, and physics to track the sun’s location. Active trackers use drivers, which are motors linked to sensors reacting to light from the sun or following GPS coordinates of its position. Some tracker models have separate, smaller PV panels specifically to power the driving system.
Passive trackers rotate using compressed gas and liquid that passes between channels in the driver from exposure to sunlight.
Most solar trackers have five-year warranties for drives and controls and 10-year warranties for racking. In the last several years, tracking systems companies have made operational improvements to their systems, developing monitoring software for preventive maintenance and optimizing angles for higher energy yield. Tracking technology will continue to evolve, helping installers maximize the power output of solar projects.