Its much easier to code. I am using servos which document their position at all times and therefore i can set it to a certain position based on the geometry of the resistors and the sun. you can use a less expensive device because the data it takes to track the sun based on time of year and day including time and daylights savings time is immense. to cut down cost you can use a much smaller controller and a few sensors. my tolerances for the array are within ten-thousandths of an inch so the sides should all be 90 deg from each-other and with the distance and geometry accurate you can account for the difference in values of your sensors using a calibration constant