I had an idea while back. To take a 275 gal oil tank. Cause they are often free for the taking. Use an AC during the night to chill the contents (oil, or perhaps water). Using an evaporator within the tank. Insulate the tank, of course.
Daytime, either circulate the cold water through radiators with fans, or use another AC with the condensor in the tank.
That way, you'd be moving the BTUs outdoors at night when it's colder, and the unit wouldn't work as hard.
Seems like it would save money, dumping the heat at night.