When we first moved into our house about 15 years ago, our first electric bill was $160!! I called my mother to find out what hers was and it was at least half that. Our homes are similar square footage.
I was on the phone with the electric company several times stating that no one was even home 12 hours a day, How can it be this high? I did this several months in row.
During the 5th or 6th phone call, one operator told me how to narrow down where all the electricity was being sucked up:
Go to your breaker box/electrical panel and shut everything off.
Put one switch on and check your electric meter (usually on the outside of the house) to see how fast the numbers are spinning or changing.
Shut off that switch and go to the next, having only one switch on at a time.
It took a lot of running up and down my basement stairs, but within 15 minutes, we discovered that our well pump was running way too much. We had it checked and there was a crack in the pipe that was causing the pump to run 24 hours a day!!
The next month, our bill was about $80!!
You could use this same method to see how much your dehumidifier is sucking up also.
We run ours from April through September. We do see an increase, but the basement (carpeted) starts to smell funny if we don't.
Good Luck!