This topic is old news for those of you with those big, west-facing-mountain-view windows. They create an inferno for you in the summer. You may have even spent thousands on beautiful floor to ceiling blinds to shut out the sun.
However, unless the shades are physically outside the window, they are relatively ineffective. Once the sunshine comes in the window, it stays inside as heat.
So the shades must be on the outside.
The easiest, quickest, and least expensive way to install an exterior window shade without completely ruining the view just might be from Screenmobile. They are a national franchise, and I've used the local branch often for conventional screen replacement, and found them to be a good solution for an annoying problem.