Just suppose the sun is at a certain position, and the slats are closed enough to keep the sun out. Then imagine you rotate your house. Then you don’t need to reposition your slats, as the rotation of the house is parallel to the slats. The same is true when not your house rotates but the sun. So the position of the slats is independent of the azimuth and equals the altitude, ie always perpendicular to the sun.
The azimuth does determine the time the slats shall be lowered or raised. As your hous faces 187, the slats shall be lowered between (187-90) and (187+90).
