Servo motor rotation angle accuracy
Note: answering the post in comments, not the original XY-problem.

The average output of solar panel tracking the sun is about 20% more when compared to fixed (at optimal angle for your location) solar panel. Which means you don't need anywhere close to that precision. Even the worst hobby servos are precise enough. The selection criteria should be torque, not precision.

Having said that, you would most likely need a modded servo with high-ratio gearbox, or a special slow high-torque servo. The size of a solar panel the regular hobby servo can rotate is about enough to power that servo + control device.