We put plantation shutters on the AZ house and have been thrilled with the difference in energy consumption. But, with what you mention as 24' window wall, plantation shutters are probably not an option. The theory is still valid...if you stop the sunlight from hitting all the surfaces in the room and heating the room up by radiant transfer, the room and the whole house will stay cooler in the afternoons/evenings and work your cooling system significantly less.