Wattsun™ trackers utilize a patented, closed loop, optical sensing system to sense the sun's position and track it. The sun sensors, mounted on the controller chassis, feed information to the control electronics about the direct component of sunlight available, the diffuse amount of sunlight, the total amount of sunlight as well as the differential amount of sunlight on opposing sensors. Based on this information, the controller seeks to equalize the sunlight received by opposing sensors for each axis.

The controller circuitry automatically adjusts the tracker accordingly. It increases the sensitivity with increased direct sunlight; and decreases the sensitivity with scattered or diffused light as in cloudy conditions.This enables the tracker to eliminate undue hunting in cloudy or overcast conditions when sunlight is scattered. It also makes adjustments according to the total amount of light received by the sensors.

When powered directly from the PV modules, it will return to sunrise, at the first morning light through the use of its energy integration circuitry which enables the tracker to move with as little as 20ma of available current. This circuitry eliminates the need for any maintainence points such as batteries in the system. On dual axis models, the controller prioritizes movement of the Azimuth or East/West axis. It will first adjust the E/W axis to be on track, and then adjust the Elevation axis to position.