Hello Leona, great to see you back with us.
I don't think there is an ideal position, as it will always be a question of ideal for what? A position that gives you maximum summer sunshine , might not give you good winter sunshine when the sun is lower in the sky. And do you want the sun blazing in all summer. Seems a bit non commital but I think you have to work out what you want this greenhouse for, and work the position out from there.

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From each according to his ability, to each according to his needs.