Wow! Oh Wow! What an outstanding quilt. It's colors are perfect for making the room glow with warmth.
I too had the same concern as others with regards to the light affecting the fabric over time, even if using this quilt just during the winter months. I would suggest checking and getting some window film, the type that keeps out uv rays. This could be fashioned and attached to a frame(s) that fit inside the window area. This would help preserve the colors and the fabric as it is used over time.
You might also want to check with a local window manufacturing or installation company. They may have some glass that is specially treated for uv rays.
My dad made some plexiglass inside storm windows for very large windows. Some were 8+ ft across. These windows had three sections for each inside storm. They were completed removable for taking outside to clean with soap and water using the water hose. The frames had magnetic strips attached on one side with the other attached to the other magnetic strip on the wall. He put up a thin metal frame support so that the inside section could be removed when wanting to have the windows open. Something similar could be used with uv protection products.
Pam M