I went to HD, got a small sample sheet to experiment with. Looks very clear - nice!
Also got some Velcro. I'm thinking of using the sticky back type tape with the loop side, glued to the inside of the posts (close to the mosquito screen, perpendicular to the screens), in 1/2" width. Then a strip of the same loop sticky back on the edges of each sheet. Then I'd take a strip of double sided Velcro tape in a 1" width, fold it lengthwise so the hook side is half on the loop tape on the posts, half on the tape on the lexan sheets.

I don't want to glue the hook tape directly on the sheets for several reasons:
I'd have to mount the sheets on the outside of the posts (meaning the side facing the room). Aesthetics, and that would also require more lexan.

If the hook tape is not glued on, I just have to pull one end and strip it off, and roll it up for storage. The hook side won't pick up as much dirt during storage as if I stored the panels with the hook tape on in my dirty shed, and I wouldn't have to flex the panels to detach them.

Do you think that this is a good solution?
How well does Lexan hold up over the years? Is it really as clear as a window? I don't want to ruin my view from inside with anyhing murky. I've looked high and low online about simar setups to no avail, except in general terms. 

The porch is exposed to wind and there's no roof overhang.
The mosquito screens are 'permanently' attached, although I'm due for a rescreening soon.
I've found info on using lexan sheets w Velcro for storm windows and imroving insulation, but they were mostly attached with just small strips of Velcro here and there, not continuous tape all around. I'm wondering if it is overkill. The Velcro budget alone is close to $200. Haven't got the lexan budgeted out in detail, but I'm estimating $2500. It's a 3- sided porch with 100" tall openings, so the sheets have to be cut from very large sheets. Would be a lot cheaper had there been knee walls.  

I dont give your idea much chance of holding up during a wind storm , driving rain or hot sun. Lexan desplays a lot of movement with weather changes so the install has to allow for that.

If your dead set on doing it have frames built for the lexan fasten with screws being carefull / a lot of care to allow them to be backed off durning removal.
John Hyatt www.deckmastersllc.com

B. Your project will blow away,leak like a sob, look silly and be hard to store.

C. Not have the value ratio you want.

J.

Home Depot used to sell the coated product. I don't know if they still do. Their prices were high the last time I looked. You can usually do better a plastic supply house.

Polycarbonate can be worked with ordinary woodworking tools, including drills, saws, and routers. Polycarbonate is very strong and can take heavy blows (bullets in some cases) without shattering.

Acrylic, on the other hand, is not nearly as strong and cracks easily, but it does not cloud up like polycarbonate. Special techniques are required when working with it to avoid damage. Drilling a hole can result in cracks radiating from the hole.

My vote is for coated polycarbonate.