Does anyone here have a clever electrical backup system to cool there greenhouse in the case of an electrical failure? I'm thinking I might need something like that.

I don't have one myself, but I remember seeing an idea for one...

Three car batteries wired in parallel, a trickle charger, and an automotive power inverter. Dunno how many amps your cooling system draws, but I imagine this setup could give you at least a moderate amount of protection.

--Stephen

Am I missing something? What about a generator?

Am I missing something? What about a generator?

Sure, but they are fairly expensive depending on how much you need to run, and how big they are.

There are also solar powered fans. Greenhouses won't overheat at night.