I've used one outdoors. Originally covered my hoop house in the tropics with 6mm plastic sheeting but that thing was a sauna. Switched and had decent results with a green 70-ish percent (light blocked) shade cloth. The more shade, the less light, which obviously isn't ideal. But it's still the sun and the sun doesn't fuck around when it comes to growing plants. You'll get results, even though they aren't as big as they could be.
But depending on where you are, it might not bring the temperature down that much. No experience with temps quite that high.