SDG&E's NBC Calculation for NEM-ST

[J.P.M.]

I was rooting around in my 15 min green button data and noticed that for the 8,760 x 4 = 35,040, fifteen minute periods ending @ 2400 hrs. 08/12/17, 192 of those 15 minute periods, the kWh recorded as zero, that is (I presume) missing data.

Looking back at what my SDG & E meter shows for what they sent to me("DEL"), and what I sent to them ("REC") for the green button data and what meter tare readings for the same dates show:

"DEL" or sent to me from the POCO:
green button data = 4,653.89 kWh
meter subtraction = 4,846 kWh

difference = 4,653.19 - 4846 = -192.11 kWh between what the green button data shows they sent me and what their meter shows.

"REC", or sent from me to the POCO"
green button data = 6,314.89 kWh
meter subtraction = 6521 kWh

difference = 6,314.89 - 6,521 = 206.11 kWh between what the green button data shows I sent to the POCO and what the meter shows I sent to the POCO.


On the "DEL", the meter subtraction values were 17,902 - 13056 = 4,846 kWh.
On the "REC", the meter subtraction values were 26,099 - 19,578 = 6,521 kWh.

Note that the number of missing data = 192 is about the same as the "delivered" 192 kWh. I believe that may be coincidence.

Since I was a net generator, the lost 192 data points, if randomly distributed (which I note, I have not checked with respect to randomness), might perhaps explain why the absolute value of the differences in "REC" data is less than the absolute value of the "DEL" data.

Perhaps Charlie's and Sensij's meters and green button data sources are doing some of the same, and that may be were the small # of extra kWh/billing period comes from - that is, maybe some billing adjustment takes place after the billing period closes when the difference between the meter reporting and green button data may go trough some sort of reconciliation.

Just a thought.

[sensij]

Another month, another bill. Calculations are still holding up, and at this point, I'm ready to complain about the taxes and fees being excluded from the minimum bill. Since those values *are* included in the NEM charges, and consume NEM credits to offset, it makes no sense to me that they are excluded from the minimum bill calculation and charged again in the total electric service charge where they are no offset-able by credits.

In other words, the only explanation that holds up right now for the minimum bill calculation is that taxes and fees are charged twice... once in the offsetable charges, and once in the non-offsetable charges. That can't be right.

I had 3 kWh of additional NBC charge this month. It doesn't match the difference between 15 min imports and hourly imports like I had speculated after my last bill, since that difference this time is 4.7 kWh. I'll go back to the Imported and Exported channels of data captured in PVOutput and see if any other ideas hold water.