Hi David--I haven't gotten my bill yet since the chiller was installed, but am told that it will likely add roughly $50 to my electric bill. Of course, this figure would depend on what size chiller you buy and what kind of pull down you are looking for. Naturally, the larger the pull down the more the unit will be running. If you are planning to buy one, try to get one that is bit larger than what you actually need. It will run more efficiently and cost less in electric bills in the long run. Plus, if you ever decide to upgrade to a larger system, you won't have to purchase a larger unit down the road. I have roughly 300 gallons all told and could have gone with the 1/2 hp unit, but the difference in cost between them (the 1/3 hp and the 1/2 hp) was large so decided to stick with the 1/3 unit. I believe it sucks up as much electricity as a regular refrigerator.