How to calculate sun position?

[oab_nor]

For starters, you can try with just using altitude since blinds only move on one axis. Blinds should be perpendicular to current sun position. Then you can tweak it by checking azimuth so you don't adjust blinds when there's no direct sunlight.

Tanks, maybe  i'm just making it too complex.  
There should, of course, be a 1:1 relation between sun altitude and  slate position (e.g. 0-100%) – regardless of azimuth and orientation of the blinds/window.