I've never heard that Solar Shades are to be used on the exterior only and I've seen plenty of use on double pane windows within the house. If a shade had an insulating effect and was sealed along the edges or had sealed side tracks, then that would not be safe to use with double pane. Solar screens are just that.....screens. They go outside the window just as any other type of screen is used. Roller shades can be decorative lightweight window coverings, but the term 'roller' is also used for the Solar Shades since they are usually on some type of roller system. It sounds like Solar Shades will fit your need. Here is a link that might be useful: Interior Shades

Try here Just Blinds. They have a lot, so be prepared with a cuppa tea. I'm looking at 3/8" cellular for big window over sink and their price is very competitive-4 x 6 foot for $107. Another place that has worked for me is JCPenny - they run blind sales all the time. I got imitation grass roller blinds for less than $20 a window. They looked great and lasted three years with no visible wear. I was going to just re-install until we had to change out the windows.

Oh, my windows aren't as high as yours so that makes a big difference. Cordless is great but not if it means you'll fall out the window while straining to reach the top. My upstairs room has the BU only feature since the window is higher in that room & the top is unreachable and also I couldn't imagine a situation when I would need the top down. The downstairs room needed the TD/BU, for privacy and light control options, but I can reach the top of the window so it isn't a problem. And if I can reach the top then I'm sure all my guests can also. Wasn't there a recent post about power controlled window coverings for high, hard to reach spaces? It was a beautiful room with sky high windows and a lovely fireplace. Realistically, how often will you have to adjust the top? Frequent changes might make the cost of power control worthwhile. Infrequent might make using a pole, and finding a place to store it, tolerable. Or maybe someone else will have a better solution for you.

For privacy I think that the lattice suggestion is better than just a vine. Though Betty Corning covers the end of my deck which is ten feet wide it takes awhile to get to that growth and dies back at the end of fall. I like BC as it also has almost continuous bloom starting midsummer. Some people detect a faint aroma on their plants though I do not on mine. July 2016 BC in part shade--looks more impressive in real life. Two or three other less vigorous clematis also could like nice. These grow on one section of the 25' length of my deck. Hagley grows well on my north facing wall which is bright shade.