I have added some info about the new Arduino Mega Based Sun Tracking / Heliostat program’s sun position calculation accuracy to the “Checking the Output Error of the Arduino Sun Position Calculations” page. You’ll have to scroll down towards the bottom to find the in depth stuff. A quick summary of it though is as follows.
Sun Position Error:
The maximum deviation from the sun is 0.0262 degrees.
The average deviation from the sun is 0.0061 degrees.
Heliostat Reflection Error at 10 Meters:
Max Error = 0.0046 meters
Average Error = 0.0011 meters
Not too shabby. 
I still need to do the real life testing of these calculations, but it’s looking good so far.
