I have power for a humidifier, a shutter fan, two internal fans, and water with a misting system, also have a small heater that can heat the GH when it is at 30F outside (maybe lower temps too, haven't tried it). I also have a little misting system under the shelves and wet the rock floor every morning and evening.
The shade cloth is stapled to the inside so no wind problems. I have it permanent all on the roof, halfway (from the bottom down) on the south side, and a roll up piece of cloth on the west side.
If you see room for improvement please let me know!