Hi @brian.chatagnier, I put together a checklist of ways to check accuracy here. The challenge is that most of the latter, more accurate techniques, are not possible without a smart meter. You still have a human reading the meter so you have to hew to the periods and readings they deliver if you want to do a comparison.
One question for you since you don’t have a smart meter - does your meter even run backwards when your solar is producing ? Many meters don’t run backwards - we had to get a special net meter when solar was installed.