Well, I think you need plan on the most likely contingencies. In this area (Austin, anyway), I don't think we have ever had a power outage of more than 6 or 7 hours. If we have a power outage of a week, then I think I am just going to throw up my hands and assume a total loss. It is going to be pretty expensive to get a generator that will run an air conditioner.

So, my guess is that it might be better not to run the lights, since things can survive without that for a few days and they generate heat. I would run my pumps, skimmer (part time), chiller, and fridge (to save the food).