I used sketchup to analyze the shadow on the courtyard and help to optimize the location of our merry-go-round.
Here is the shadow study about Dec 23, the day receiving least solar energy.
Here is the shadow study about Jun 23, the day receiving most solar energy.
Obviously the further the merry-go-round is away from the house, the less shadow it would receive. It will be more energy efficiency. But the heat it lost through conduction from the panel to the tank will be increase at the same time. So we need more quantitative study about this tradeoff.