Putting in backup systems isn't cheap, but it can be done. When it takes 6 years or more for some plants to get to maturity I think it's worth it.
I have two independent electrical supplies into the greenhouse, each feeding a seperate set of systems with one of each key service (ventilation, circulation, heating, fogger). One board has just one each of the newest of these and should be the most robust, the other has older equipment and non-essential stuff as well (lights, etc).
To cope with total electrical failure I have a non-electric gas heater on pilot, and my latest development is I have just bought a unit which connects to a 12V battery and switches over to it in case of mains failure. This should keep my fans and foggers going for about a day or so.
I can discuss details offline if anyone is interested.