Our PV solar panels have been installed for a year. We generated 10.75MWh of electricity. Our utility meter says we sold 7,373kWh of that back to the grid. And we used 6,880kWh from the grid. So net, we used 490kWh less than we produced! Our load is dreadfully mismatched with production. We are shipping 3/4 of our production to the grid and then taking it right back. Some of the mismatch is daily — we are at work when the sun is shining. Some of it is seasonal. The most likely culprit for the seasonal imbalance is the hot tub.
To verify how much energy we used, I had to figure out the Itron utility meter display. It’s anything but intuitive. The best resource I found was the Eversource FAQ. But while hunting around the internet, I found the generic Itron installation manual. It says the Itron meters use hall sensors to detect energy usage. According to this report, meters with hall sensors can systematically under-report energy usage. Obviously, whatever the meter says is how we are billed, so we will be billed as net zero. But I wanted to know “are we really net zero?” I did a quick comparison of a couple months of utility bills to data from my Sense monitor. They came out similar. So it looks like my smart reader is reasonably accurate.