Thanks, a lower wall height than the formula derives at would be better. I have modified my drawing to a 1.8m wall height (that's the standard wall height on the shed), but with a higher 100 cm roof.
Also, I would probably just go with sliding the whole roof off towards one end of the shed...it will take up more of a footprint, but it would be cheaper to manufacture and automate the sliding of the roof (for a set and go to bed setup..with perhaps some cloud/rain monitoring). It would also give me more flexibility with the 180 degree line of sight (without the roof ridge supports).
http://130.95.21.121/pbrowne/Ob2.jpg