We have a window about that large in our master with a view and lots of sunlight. We went with a motorized lift cordless cellular shade that runs off of batteries. To me it is cleaner and better at blocking light than 3 individual ones and less hassle to move 3 up and down.

Are you saying that each pane of glass is too wide? Wider than 48 inches?

The whole window is too wide to get one shade, unless I call in a professional. The total is about 120".

The mullions between the panels are thick enough that 3 separate units should cover and look fine. Be aware regarding the cellular/thermal coverings though that while they will provide some efficiency improvement, they will make the windows colder which could create or exacerbate condensation issues... Any window covering can do that of course, but the better it insulates, the colder the window will be (ie: more condensation).

Great point that I never thought about. Thank you.