Another shed conversion! - Update and question

Snap

From everything I have read solar doesn't make sense financially. If it's eco credentials driving your thinking, IMO the most cost effective way is to select a good energy supplier and go the oil filled rads route. They are very cheap to run. The people who built this place put an AC unit in it. It is, to be fair, great when it gets very hot, but not really necessary. Good for getting the place warm quickly too. Can't believe it is anything but expensive to run though.