For the past electric bills to be useful you'll also need to know what temperature the family kept the home, if they kept it at that temperature when they were home from work or all of the time, if all of the family members work the same job schedule and if the electricity is only one when people are home from work or school. You'll also need to know whether some appliances or the water heater are gas and how new they are. New Energy Star appliances cost less to use.
This is a tough question to get an answer on from AEP. It used to be that they would share this information with realtors or home buyers without another thought. Not the case today.
Without access to the previous home owners and their knowledge of the monthly expenses for utilities, there isn't a way to know previous use.
Of course, it wouldn't be too hard to find friends or family with electric heat pumps and electric water heaters and ask them what their usage and bills are like.
Hope that helps