Single Axis Solar Trackers

There are three types of single-axis solar trackers. When viewed from the ground, the axis of rotation is horizontal, and in HSAT systems, the solar panel is lined up parallel to the axis of rotation. The axis of spin in VSAT systems is straight up and down from the ground. Because VSAT systems follow the sun around a vertical axis, they need more room than HSAT systems to keep the yield from being affected by shading. There are also tilted HSAT (HTSAT) systems on the market. These have mounted solar panels so that they tilt at the best angle along the horizontal line.

Horizontal Single-axis Trackers (HSAT)

Horizontal type of trackers are designed with a horizontal axis of rotation parallel to the ground. These trackers can share posts at both ends of the rotation axis, which helps reduce installation costs. HSATs are particularly suitable for regions with low latitudes. 

Field layouts using horizontal single axis trackers offer flexibility, requiring only parallel alignment of rotation axes to position the trackers appropriately. The energy production-to-cost ratio can be maximized by determining the optimal spacing, depending on local terrain, shading conditions, and the time-of-day value of the energy produced. Backtracking is one method used to calculate the panel disposition.

In horizontal trackers, the module’s face is typically aligned parallel to the axis of rotation. As the module tracks the Sun, it sweeps a rotationally symmetric cylinder around the rotation axis. The system comprises a long horizontal tube supported on bearings mounted on towers or frames. The tube’s axis runs on a north-south line, and solar panels are mounted on the tube, allowing it to rotate and track the Sun’s apparent motion throughout the day.

Horizontal Single-axis Trackers with Tilted Modules (HTSAT) follow the same principle as HSAT, but the modules are installed at a certain tilt rather than being mounted flat at 0 degrees. This configuration is often preferred in high latitude locations. HTSAT offers the advantages of vertical single axis trackers (VSAT) while occupying less land space. Consequently, it reduces the overall cost of solar projects.

Vertical Single-axis Trackers (VSAT)

Vertical trackers have a vertical axis of rotation with respect to the ground. These trackers rotate from East to West over the day, making them more effective at high latitudes than horizontal axis trackers. Field layouts for VSATs must consider shading to avoid unnecessary energy losses and optimize land use. 

However, optimizing for dense packing is limited due to the shading patterns throughout the year. Typically, the face of the module in vertical single-axis trackers is oriented at an angle with respect to the axis of rotation. As the module tracks the Sun, it sweeps a rotationally symmetric cone around the rotation axis.

Tilted Single-axis trackers (TSAT)

Tilted trackers include all trackers with axes of rotation between horizontal and vertical orientations. The tilt angles of these trackers are often limited to reduce wind profile and decrease elevated end height. With backtracking, they can be densely packed without shading perpendicular to their axis of rotation. 

However, the tilt angle and latitude limit the packing parallel to their axes of rotation. Similar to horizontal trackers, tilted single-axis trackers have the module’s face aligned parallel to the axis of rotation. As the module tracks the Sun, it sweeps a rotationally symmetric cylinder around the rotation axis.