Protecting screened in porch in the winter
I have a screened in porch with 5 screens that have openings of 4' wide by 5' high and am looking for a solution to protect it during the winter (Massachusetts). I tried the plastic on the outside of the windows - you know how that went. Then we built frames for the inside and that's okay, but I am wondering if there is any type of system, that we could either construct or purchase, that I could just attach to the outside in the winters and cover with glass or plexiglass. I really don't want to put windows in, that would defeat the feel of the room to me. I have looked on line but really haven't found what I'm looking for. The room is sided on the outsied and there is probably 8 inches of space between each window.
Thanks for your help!