Solar Tracking Controller

Solar PV panels operate at their greatest conversion efficiency when the incoming light rays strike the panel’s surface perpendicular to the plane of the panels. Considering that the sun is a constantly moving light source, this would occur only once per day with a stationary installation! However, a mechanical system, known as a solar tracker, can be used to constantly move the PV panel to directly face the sun. Solar trackers typically increase the power generated by a solar array from 20% to as much as 40%.

There are many variants of solar tracker designs, involving different approaches and technologies for moving the PV panels to follow the sun. Fundamentally, however, solar trackers can be divided into two basic types: single-axis and dual axis.

Defining the motion of a tracker to follow the sun can be crudely accomplished using “open loop” controls. These controls calculate the sunrise to sunset movement of the sun based on the time of year and geographic latitude of the installation, and develop a motion program to move the PV array accordingly. However, environmental loads (wind, snow, ice, etc.) and accumulated positioning errors make open-loop systems less desirable (and less accurate) over time. There’s just no guarantee that the tracker is actually pointed where the controls think it should be.

Using position feedback improves the tracking accuracy and helps ensure that the solar array is actually positioned where the controls dictate it should be, based on time of day and time of year, and especially after meteorological events involving strong winds, snow, and ice.

Obviously, the tracker’s design geometry and motion mechanics will help determine the best solution for position feedback. Five different sensing technologies can be employed to provide position feedback on solar trackers.

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