Active & Passive Trackers
Tracking can increase a PV array's power production from 10 to 50 percent depending on the season and location.
Active trackers such as WattSun track the sun from east to west using electronic sensors and motor or actuator drives. During partly cloudy conditions, the tracker fixes on the brightest area of the sky, capturing the maximum amount of sunlight available.
Passive trackers such as Zomeworks uses no motors, no gears and no controls that can fail. The sun's heat moves liquid from side to side, allowing gravity to turn the Track Rack and follow the sun.
While Passive trackers are advantageous in that they have little components to fail we have found that in some locations with extreme cold temperatures the trackers are slow to follow the sun in the morning until the liquid heats up.
UPDATE: As of 1st Jan 2019 Zomeworks are no longer accepting new orders. They are looking to either sell company or may discontinue trackers completely.