Why do I still get a bill from the utility company if my system is offsetting all of my usage?

The utility generally applies a minimum charge for their service of between $15 and $20, depending on a few different variables. On the months when you use more electricity than normal, your utility will provide you with any extra kilowatt hours you need, and usually the extra credits you had in the bank (Net Energy Metering) will offset this extra usage. Learn more about Net Metering here.