We recently installed a 7 kW system on our relatively new home in New Mexico. Since the house was almost new when we moved in, the meter only read about 13,200 kwh. We produce enough power that the meter actually spins backwards, (you can see a video of it here - not my house though). It's actually quite nice to watch kilowatt hour dials decrease over a week or so.
The system has been performing exceptionally well and we've produced about 3500 kwh from June to August yet we only used about 2200 kwh (this is good as we designed the system with net metering as the goal).. at this rate, our meter will "flip" back from 0 kwh to 999,999 kwh in around 3 years depending on how the winter months go.
In my neighborhood the meters are read by a "drive-by" system in which the utility collects the data via RF signal from a vehicle. My concern is that during one month I'll have 200 kwh, and the next month I'll have 998,000 kwh. So instead of having a negative kwh amount there is the possibility that we will actually be charged for one very very large month of consumption (about 100 years of electricity use in one month!!). Hopefully our utility would catch the error!
I am curious how the meters actually work and how the utility actually collects the information with net metering, ie how does the utility calculate my net excess generation?
I'm not too concerned about our system as the utility will probably just install a digital meter. Has anyone else had experience with net metering?