I built a 4-season greenhouse for 8000 ft. elevation: bitter cold winter and lots of sun in summer. I second the idea of using shade cloth and automatic vents to keep the ambient air temps lower when the sun's out. Don't know the optimum temp range for hydroponic water, but suspect it can vary with direct sun and high air temp.
For some practical stuff and photos, look for my posts in the Share Photos of Your Greenhouse thread.
The thread "Please share photos of your greenhouse" in
Greenhouses forum
