You can probably use something other than a photo cell. Some type of photo circuit that will close a relay and turn on a low RPM motor. Every time the sun shines in the bottom of the funnel the circuit turns on the motor and it moves forward out of the sun then stops. It moves forward all day long over and over moving out it the sun. At the end of the day it stops moving and at midnight a clock returns it to the starting point for the next day.