I got my first bills and I started seasons on my game in late fall I turned on my thermostat to warmer costs more and my bill was $26,000!! haha (note to self set therm at cooler cost less!!)
Same thing happened to me although I was luckier I suppose, my Sims only owed just over 19,000. It's a cool way to raise bills for story purposes I guess but I think it's meant to only be used on "heat wave" or "freezing" days. Still, I have to admit I'm a little scared to use it again. X-D