How do I get the position of the sun?

I'm not quite sure if this is what you're looking for, but there is a way to get the LookVector of the sun. You'd use the function GetSunDirection ( ) and it will return a Vector3 Value

Note This is a function property of Lighting.

Here is a simple script:

local l = game.Lighting ---Lighting

local dir = l:GetSunDirection()
print(dir)

If you have TimeOfDay set to exactly 12, in will return the coordinates; -8.30329014e-008, 0.94978565, 0.312901378.

I hope this helped!