This. 100% This.

I had solar installed this summer, but I didn't see any change in my first two bills. At the time I thought that I was just paying for my previous usage before the panels were installed (I have found that my bill is a month or so behind my actual consumption). But then I got a bill that completely overlapped with after the panels were installed and it was so far off that I called RI Energy.

They said the bill was based on an estimate and that they'd send someone to read the meter. Come to find out I had overpaid the bast two bills by several hundred dollars! Between the credit and the solar panels I haven't had to pay my electric bill in months, but it's super shitty that they would have happily kept taking my money unless I had said something.

tl;dr - Read the fine print on your bill. If it says "estimated" give RI Energy a call. They may be ripping you off.