The remark about wear and tear on the LDRs out in the sun's damaging rays, and all weathers set me thinking...
a) In ANYTHING you design that will be outdoors, design it for easy replacement of damaged parts. They WILL need replacing... sooner than you hope!
b) Are LDRs the way to go? Probably... but I wondered if maybe temperature sensors embedded in small blocks of black epoxy might do just as well, and be more robust?
c) Of course, while I would be the first to applaud anyone wanting to have fun creating a solar tracker... how cool! (I've wanted to build one for years).... if I just wanted my solar panels oriented correctly, I would put my faith in Mr Newton. The geometries of the earth's relationship to the sun are entirely predictable, and a program can be written to point the panels in the right direction without any light sensors. Sorry to be a bore. Do remember on BIG advantage of the track-by-light-sensor approach, though: It doesn't need an accurately set RTC (time of day clock) to work.
d) A KISS point: You really only need the expense, complexity, etc, etc needed to "tip" the panels left and right around one axis of rotation day by day.... to track the sun across the sky. You may want to mount everything on a second axis of rotation to compensate for the sun's height above the horizon at noon, to compensate for the seasonal variation in that axis... but this adjustment can be done manually with whatever you want to use during your routine servicing of the panels. The rate of change in this axis is slow.