Are you trying to totally block the sun or simply shade and keep out the heat.
To shade and keep out the heat I made window covers out of black sun blocker material sold
in hardware stores. It's like the material that big rigs use on their windows
. I sewed tape all around the edges. I then removed a screw from the window frame and ran it through a piece of velcro before putting it back in the frame. I took the opposing velcro and sewed it to the window cover in a spot to match the one on the window frame. I did this top and bottom. I simply stretch the cover across the window attaching it to the four pieces of velcro. It keeps the sun out and quite a bit of heat as well. I can see out just the same but no one can see in unless it's night time with a light
Here's picture from the inside to show you can see out. Then a picture of one of the covers. It's wrinkled from being folded in the cupboard but stretches out nicely on the window. It looks like a tinted window from the outside.