Study on NEM 1.0 vs. NEM 2.0

[sensij]

I guess you guys are right, each metered interval is 1 hour for residential customers. So I guess it will charge 2 cents per excess KWH each hours.

I don't know... your initial reading looks correct to me, the example you provided shows SCE calculating NBC charges on the net for the period (531 kWH), not the net for each hour, which appears to be 135+325+212 = 672 kWh. They do state "hourly" in the footnote of the example, so they've probably done just a good a job of muddying the waters as anything else we've seen.

[J.P.M.]

#7 specifically says, "Non bypassable charges (NBCs) are assessed on the net of kWh consumed in each metered interval of the current billing period

For most folks on T.O.U., in CA anyway, a metered interval is a period of no more than 1 hr. and usually 15 minutes, meaning either 24 or 96 metered intervals per 24 hour period.

[brucet9]

Can anyone explain how NEM2 works in SCE country? I tried calling SCE but got nowhere with the phone rep. All I could get was that for excess kWh SCE pays 2 to 4 cents.

Specifically, if I were to install enough capacity at 270 azimuth to equal my present annual consumption in kWh, All credits for deliveries to the Grid would be at peak rates (TOU-D-T 12pm to 6pm) winter/summer average $0.27/kWh. But 83% of my use would be during off peak times at $0.17/kWh, so average usage would be at $0.19/kWh. What happens at true-up? The difference, assuming usage exactly equals deliveries to the Grid, could be 7,000kWh x $0.08/kWh = $560. How much does SCE pay me in this case?

[sensij]

Can anyone explain how NEM2 works in SCE country? I tried calling SCE but got nowhere with the phone rep. All I could get was that for excess kWh SCE pays 2 to 4 cents.

Specifically, if I were to install enough capacity at 270 azimuth to equal my present annual consumption in kWh, All credits for deliveries to the Grid would be at peak rates (TOU-D-T 12pm to 6pm) winter/summer average $0.27/kWh. But 83% of my use would be during off peak times at $0.17/kWh, so average usage would be at $0.19/kWh. What happens at true-up? The difference, assuming usage exactly equals deliveries to the Grid, could be 7,000kWh x $0.08/kWh = $560. How much does SCE pay me in this case?

SCE only pays you if there is true volumetric overproduction.... if you actually export more kWh than you import netted over the entire year. The amount they pay per kWh is determined by the "Net Surplus Compensation Rate".

If you have an accounting credit at the end of the year because the energy you exported was more valuable than the energy you imported, but on a volumetric basis, you consumed more than you generated, that accounting credit is reset to zero at true-up.

[J.P.M.]

Can anyone explain how NEM2 works in SCE country? I tried calling SCE but got nowhere with the phone rep. All I could get was that for excess kWh SCE pays 2 to 4 cents.

Specifically, if I were to install enough capacity at 270 azimuth to equal my present annual consumption in kWh, All credits for deliveries to the Grid would be at peak rates (TOU-D-T 12pm to 6pm) winter/summer average $0.27/kWh. But 83% of my use would be during off peak times at $0.17/kWh, so average usage would be at $0.19/kWh. What happens at true-up? The difference, assuming usage exactly equals deliveries to the Grid, could be 7,000kWh x $0.08/kWh = $560. How much does SCE pay me in this case?

Your best shot at an answer is to rifle through all the written information fro SCE. There is a lot of things about NEM 2 - much more than can be explained here without the required brevity in this format causing confusion. basically, and this is no answer, it's similar to NEM 1.0 with a few changes. Still a decent deal in concept, but not quite as good as NEM 1.0. The way rate tariffs are being changed, which is somewhat but not entirely related to NEM 1.0 to 2.0 changes seems to be a bigger hit in terms of making PV less cost effective.

[brucet9]

If you have an accounting credit at the end of the year because the energy you exported was more valuable than the energy you imported, but on a volumetric basis, you consumed more than you generated, that accounting credit is reset to zero at true-up.

So that is the reason that PV installers suggest sizing the system to less than you actually use? 100% is better for the environment, but poorer ROI.

[ButchDeal]

So that is the reason that PV installers suggest sizing the system to less than you actually use? 100% is better for the environment, but poorer ROI.

No,. Anything over 100% has lower ROI, The part under 100% has higher ROI

[Mike7381]

Can anyone explain how NEM2 works in SCE country? I tried calling SCE but got nowhere with the phone rep. All I could get was that for excess kWh SCE pays 2 to 4 cents.

Specifically, if I were to install enough capacity at 270 azimuth to equal my present annual consumption in kWh, All credits for deliveries to the Grid would be at peak rates (TOU-D-T 12pm to 6pm) winter/summer average $0.27/kWh. But 83% of my use would be during off peak times at $0.17/kWh, so average usage would be at $0.19/kWh. What happens at true-up? The difference, assuming usage exactly equals deliveries to the Grid, could be 7,000kWh x $0.08/kWh = $560. How much does SCE pay me in this case?

Basically SCE don't pay really pay anything for excess energy export to the grid at the end of your 12 months perioid, here is why. SCE pay you 2.5 cents base on the current "Net Surplus Compensation Rate". But NBC costs 2 cents, so only half a penny each KW. so I believe sizing your system around 90% if you use more at offpeak, size it at 105% if you use more at peak, that 5% basically is to cover the difference between your offpeak credit and on peak consumption.

[sensij]

Here you go:
20170724120135.pdf

Next month, I'll be in the situation with NEM credit carry forward, although the basic shape will look the same (Peak is net generation, Super-Off peak is net consumption, and Off-peak something in between.

In this bill, the NEM Credits (Shown as "Applied credits", since none are carried forward) look like the following. -93 kWh was the net for the month in the peak period.

UDC contribution = -93 kWh * 0.14184 = -13.19
EEEC contribution = -93 kWh * 0.35243 = -32.78
DWR-BC contribution = -93 kWh * .00549 = -0.51
State surcharge tax contribution = -93 kWh * 0.00029 = -0.03
State regulatory fee contribution = -93 kWh * 0.00043 = -0.04
San Diego Franchise fee contribution = 0.0578 * (UDC contribution + EEEC contribution) = -2.66
Others Franchise fee contribution = 0.0688 * (DWR-BC contribution) = -0.04

The sum of those numbers adds up to the 49.25 credit shown on page 4.

The NEM charges, on the other hand, are calculated accounting for NBC's. Off-peak + Super-off peak net consumption = (124 + 328) = 452 kWh

UDC contribution (subtracting NBC's) = 452 kWh * (0.14184 - 0.01191) = 58.73
EEEC contribution = (124 kWh * 0.09604) + (328 kWh * 0.04651) = 27.16
State surcharge tax contribution = 452 kWh * 0.00029 = 0.13
State regulatory fee contribution = 452 kWh * 0.00043 = 0.19
San Diego Franchise fee contribution = 0.0578 * (UDC contribution + NBC contribution + EEEC contribution) = 5.28
Others Franchise fee contribution = 0.0688 * (DWR-BC contribution) = 0.17

The sum of these numbers matches the 91.67 shown under NEM charges on page 4.

NEM Charges can be offset by NEM credits, which is valid since none of the non-bypassable charges were included in the offsettable NEM charge calculation. The NEM balance after the credits are netted against the charges is 42.42, which is greater than (0.329 * 32), so the minimum charge won't apply at this time. However, that 42.42 remains to be carried forward to next month, when I will have sufficient NEM credits to cover it, and also roll credits ahead to August. On my next statement, a minimum charge will apply, but the true whole minimum charge total won't be resolved until true-up.


That leaves the non-bypassable charges.
DWR-BC contribution = 452 kWh * .00549 = 2.48
Other NBC contribution = 452 kWh * 0.01191 = 5.38

Total NBC's = 7.86

This number is not shown directly, but implicitly agrees with the (192.14) line shown in "Additional charges/Payments" on page 4.
-200 EV credit + 7.86 NBC charge = -192.14

The combined total of all these numbers:
42.42 - 192.14 = -149.72, which matches the statement balance on pages 1 and 4.




Unfortunately for the OP, this is all SDG&E specific, and I have no idea how much of this is applicable to PG&E.

I just got my 2nd bill. The math I've outlined in the post quoted here worked right out of the box, which was encouraging. The only new wrinkle was a line item for NBC's on just 3 kWh, adding $0.06 to the bill that isn't part of any calculation in my spreadsheet right now. I'll get to work trying to figure that out, hopefully whatever I find explains @CharlieEscCA's observations too.

I am really thinking right now that the NBC charges will be adjusted at some point in the future through some kind of billing correction, after the CPUC gets through their next round of hearings on this. That doesn't stop me from hoping against all odds that the existing method being used on my bills now remains.

I'll post screenshots later.

[brucet9]

Wow! Could they make it any more complicated?

[CharlieEscCA]

I just got my 2nd bill. The math I've outlined in the post quoted here worked right out of the box, which was encouraging. The only new wrinkle was a line item for NBC's on just 3 kWh, adding $0.06 to the bill that isn't part of any calculation in my spreadsheet right now. I'll get to work trying to figure that out, hopefully whatever I find explains @CharlieEscCA's observations too.

Like I've said before, I've given up on figuring out where the number of NBC kWh is coming from. Add to that, when I take the stated 3/1/2017 published tariff rates for off peak, semi peak, and peak times the the reported kWh in those categories, I get a slightly different $ value than my bill shows -- thus I've basically given up on having my spreadsheet exactly match the actual bill. Since it's close enough, and the NBC charges are in my favor, it's no longer worth my time and effort to understand it.

[sensij]

Ok, so one way I can get to a 3 kWh NBC adjustment is by comparing my imports summed over each 15 minutes (415 kWh) to my imports netted over each hour (412 kWh). It might just be a coincidence, and would certainly be difficult to tie in any logical way to the way the calculation is presented, but it would be interesting to see what that relationship looks like on CharlieEscCA 's data.

Stated more clearly (hopefully)... if the 15 min data shows consumption, it is included in the 15 min interval sum. If the total over the hour shows net consumption, that is included in the hourly interval sum. The hourly sum is smaller than the 15 min sum, because there are some 15 min import periods that get knocked out by generation in some of the other 45 min of that hour.

[CharlieEscCA]

Ok, so one way I can get to a 3 kWh NBC adjustment is by comparing my imports summed over each 15 minutes (415 kWh) to my imports netted over each hour (412 kWh). It might just be a coincidence, and would certainly be difficult to tie in any logical way to the way the calculation is presented, but it would be interesting to see what that relationship looks like on CharlieEscCA 's data.

I'll give this a try over the weekend. I'm assuming you took the green button data and then did the summing of net's over the two different intervals. I'm pretty good in Excel, so I should be able to get this done.

[sensij]

I'll give this a try over the weekend. I'm assuming you took the green button data and then did the summing of net's over the two different intervals. I'm pretty good in Excel, so I should be able to get this done.

Yes, I used the data downloaded from "my energy use". I prefer the spreadsheet export over the Green Button format, but the data are the same. The difference is visible on most days. For example, on 6/26, if I just sum up the positive values in the raw data (which is at 15 min resolution), the total is 6.62 kWh. When I add the four 15 min readings together for each hour (netting the positive and negative raw data), I get positive values for hours 0-6, and hours 19-23, and the sum of those is 6.37 kWh. Most hours are either all import or all export, but at sunrise and sunset, there are hours with both positive and negative values in the 15 min data.

Even more explicitly, for hour 6 on 6/26, I have the raw data

6:00 +0.060
6:15 +0.145
6:30 +0.005
6:45 -0.085

The sum of imports on a 15 min meter interval is 0.060+0.145+0.005 = 0.210 kWh
The sum of imports netted over the hour is (.210-.085) = 0.125 kWh

Again, might be a red herring, but at least its something to try...

[CharlieEscCA]

Yes, I used the data downloaded from "my energy use". I prefer the spreadsheet export over the Green Button format, but the data are the same.

Looks like I have to contact SDGE. My data is messed up because of a meter swap. The data I can export stops at the meter swap that was required because the prior meter would not take the NEM reprogramming.

sdge1.JPG

I can see data beyond 4/25 in the charts -- this is how I pull daily data into my spreadsheet I maintain.