The sun will damage your fabric. I had bookcase shelving for my fabric and had to throw a lot away and do some creative cutting on a lot of it. I got rid of them and bought cupboards to keep my fabric in. It works great, and protects the fabric. Fabric costs too much to let the sun damage. By the way, I live in Michigan, and the sun is not seen as often as in the warmer climates and I only have one window in my sewing room.
Sue