At this point we are having difficulties with the electronic tracker.  It gets confused by the reflections from the parabolic collector...  We would like to go to a small computer (Raspi?) with a sun tracking program instead of having to rely on the electronic tracker.  Since we would like to use the Raspi for hot water monitoring and uploading to the net, we figure we might as well use it for the solar tracking as well.  The unit is mains connected so we do not rely on solar for the electricity.