Father in Law made a set of these about 5 years ago for our windows [4 windows on the bottom floor] - grey mesh material purchased from home depot/lowes. Self-taping fasteners/snaps from an online retailer - about .60 per fastener/snap, and the tooling to install the snaps onto the mesh material.
Definitely notice a significant heat reduction during the summer months + privacy from the nosy neighbors.
The only problem I've seen so far is when the self-taping screw fails to stay in the new style windows [1/4" plastic frame] - typically if it's very window - only option is to drill a new hole and move the snap over. There is also the chance for the plastic frame to become damaged.
Adhesive Studs with 3M super hold VHB adhesive would be the best route to go for the new style 1/4" plastic window frames.