Solar Screens can be installed in the interior or more commonly the exterior side of your windows.  Solar screens cut down on glare and most importantly, heat gain inside the room.  A room whose windows are protected by retractable exterior solar screens will be much more comfortable without the direct sunlight passing through the window.  Your air-conditioner will run much less and your utility expense will decrease, sometimes as much as 20%.  Furniture and flooring will not be as subject to fading from the effects of direct sunlight.

In the winter the shades can be left up to receive the heat gain from the sun.