Some active trackers use clockworks to approximately follow the sun’s azimuth. Normally a homebrew solution, these clockworks need to be manually set each morning to face the rising sun before being powered up. As a result, they are not quite as accurate as trackers that employ optical controls.
Tracking can be even more inventive, and the Home Power crew has seen it all—from arrays mounted on a turntable with ropes on opposite sides so that the system owner can move the array by manipulating the ropes from inside the home, to a water-powered tracker that moved by the changing weight of water-filled buckets purposefully built to leak at a specific rate. Way back in HP17, we included an article on how to build your own photo-sensor controller to operate a 12 VDC windshield wiper motor to turn an array. This controller could also operate a modern actuator to move the array.
Tinkerer beware: One problem with manual tracking is that neglecting to move the array means that modules could spend a large part of the day faced away from the sun—resulting in the exact opposite of the desired effect.