We only pay ~$8 connection fee per month for electricity since you draw from them during the night.
We had to pay for when the December bill came around because we were using more energy than we produced in Nov/Dec. Then we had to pay for the excess that we used through about March because the panels were covered in snow a lot during the winter. Since then, we've been producing more than we've used every month in the summer. The "zero" on the meter is when they actually connected the system, so it went positive in the wintertime and finally hit zero and is in the negative just recently. Whatever excess we produce this year gets credited toward the December bill. *I think* There were two different ways to set it up with Xcel, and that was to do it the way we're doing it, or to roll the credit's over I believe. I'll have to look into it more to see how it really works with Xcel, but we paid Solar City up front so we don't pay them a monthly fee on top of everything.