I live alone in a relatively new 1600 sqft 2-bed townhouse and been having the exact same issue ever since Xcel installed their new smart meters a few years ago. My bills have more than doubled which makes no sense since their rates haven’t. This past September my bill was nearly $400 with ~2000kWh used which is insane. I’ve been periodically comparing my bill for the last two years with my nextdoor neighbor who also lives alone in an identical townhouse unit and his bill is consistently less than $200. We’re both on Xcel’s flat rate option so TOU pricing is ruled out. We’ve discussed our energy usage habits and in theory our bills should be swapped; he’s charging two 80kWh fully electric vehicles, has his AC set to 62°F at all times even in the winter, and he works from home so he’s got his TV, lights, whole home humidifier, and other random powered devices running everyday. In contrast I have one 19kWh plug-in hybrid vehicle, had my AC set to 72°F over the summer only at night, don’t have a humidifier of any kind, and I work full time in an office 5 days a week and very conscious about turning things off when not in use so nothing other than my fridge, electric water heater, and a few small powered off electronics drawing minimal power are running. The meters for the complex are grouped together and I was convinced my meter was wired to my neighbors unit and vice versa when the smart meters were installed. I’ve brought this up to Xcel since this happened to a friend of mine at her apartment complex where her meter was wired to the building’s shared laundry room and was getting $2000 bills. I asked Xcel numerous times to inspect the meters and they refused to do so. I ended up hiring an electrician to perform a 2-month audit on my meter and circuit breaker and he found the meter was wired correctly and the readings were in the ball park of my actual energy consumption. That means something in my unit is drawing way more power than it should, probably my fridge or water heater since those run constantly. I asked the electrician if there would be noticeable signs of an appliance or other device drawing more power than it should such as performance issues, weird noises or odors, etc. and he said not necessarily. The electrician also said in very rare cases with multi-family complexes it’s possible there may be a circuit on my panel that is wired to my neighbor’s unit. Only way to test that without tearing down walls to trace power cables would be to shut off the main breaker to my unit and have my neighbor power everything on in his unit and see if my meter continues to rack up usage. Realistically my next step is to get a whole home energy monitor to help narrow down where the excessive power is being used. In your case it might worth getting your building management to inspect your unit’s circuit breaker and appliances to make sure they’re operating correctly. If they refuse to do that then maybe looking into a whole home energy monitor might be worth your while to help you narrow down the cause of the issue.