Decreasing heat in glass porch

You can call one of the tinting places in your area and ask them to put up some ceramic film that will reflect up to 95% of heat. That's what they use on cars now days and it works but kind of pricey. What it does, is blocking UV and IR from heating up your floor and furniture and unlike the regular tint/film, it will keep those window (glass) cool as well, preventing from radiant heat from seeping through.

Any of the following will help. You can do one of them or all of them:

• Tint and/or reflective coating on the glass.
• A light-colored fabric awning above the roof, attached to it, that rolls up electrically to the apex of the glass roof and unrolls, perhaps along tracks, to completely cover it or maybe even to extend further out over the lawn and shade the side windows too.
• Greenhouse-style vents at the apex of the roof, with fan to assist, pulling hot air up and out through the roof and hopefully cooler air in from entry vents near the floor
• Air conditioning, for example install a mini split here.