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NEM-PS Annual True-Up Calculation [PG&E example]

aesculus

Still Trying to Figure This All Out
May 31, 2015
4,951
2,880
Northern California
I was having difficulty in understanding where all the elements came from in my annual true-up bill and reached out the both @miimura and @Redhill_qik for some insight. From our discussions a document was created that is copied into this post.

This document explains the factors that determine your annual true-up and where the numbers come from and how they are calculated. It was an exercise performed by @miimura, @Redhill_qik and @aesculus. The example system is 10 kW PV comprised of three arrays (one stand alone and two solar roofs) with two Powerwall 2s. The load side is ~4,000 square foot home with two heat pumps (about 2/3 of the way into the period they were replaced with variable speed units) and a Tesla Model X.

You can follow along on how we determined what was going on under the covers of the true-up bill to come up with the total value at the end of the year.

Data Collection​

First you will need to collect some data. At the minimum you will need your True-Up B/W bill. This can be found on the PG&E website (pge.com) after logging in with your credentials. You will not find the B/W bills in the Bill Payment and History area, that would be too easy. Instead, select the little pull down on the upper right that probably has your name such as Hi, Chris. Then select My Account and Services.

Scroll down to the Gas and electric Service information area and select your Service ID from the list (the one you are doing the True-Up for if you have more than one). This will bring you to the Service Details panel. Scroll to the bottom and note there is a dropdown labeled DOWNLOAD DETAIL OF BILL. Select the month of your true up bill. It is probably the top one unless you have waited to do this exercise. Note that the date will be the month prior to the true up month because the label the bills on the time due, not when they are produced.

In a few seconds the web browser should prompt you to save a pdf file with an undecipherable name. I would suggest you save the PDF using the format of pge_black_YYMM.pdf to easily identify the year (YY) and month (MM) for the bill. Optionally repeat this process for the preceding 11 months so you have an entire year of B/W bills. This is optional but it’s worth having your history saved. That’s all we need from PG&E so go ahead and sign out of your account.

Reviewing the True-Up Bill​

Open the PDF for your true-up month. At the top it should say “NEM PAIRED STORAGE ACCOUNT -
Annual True-Up
” and the second paragraph says “This is your annual True-Up period. Any unpaid energy charges, taxes or fees are due at this time”. If not, you have the wrong bill, so go backward or forward a month until you find it. Your annual true-up month is determined by the month that your PTO was granted or the month that you last had a change to your service.

For the purposes of this write up the customer is a net consumer with positive energy charges and PG&E is providing generation (non-CCA). If you are with a CCA there will be no mention of generation or Net Surplus Compensation, but the rest will be the same. If you are a net generator then you will likely owe nothing beyond the minimum charges for the current month and will have a positive Net Surplus Compensation if you have PG&E for generation.

The first page has the important BILLING SUMMARY table with your final annual true-up amount with three items listed, followed by the Net Surplus Compensation table and finally the SUMMARY OF CURRENT MONTH’s ENERGY CHARGES/CREDITS table.

tu1.jpg


Billing Summary table includes:
  • Minimum Charges – ($10.44) - This is the minimum daily charge (MDC) total for the current month
  • NEM True-Up Adjustment – ($280.74) - This is the calculated amount of money that you owe for the past year not including the MDCs for this month
  • Energy Commission Tax – ($2.32) - Tax on energy charges to fund the Energy Commission
  • Total Current Month's Electric Charges Due – ($293.50) - The sum of the three above items and what you own to PG&E for your annual true-up
Net Surplus Compensation (only for non-CCA customers) table includes:
  • Net Surplus Compensation – ($0.00) - The amount owed to you for exporting more than you imported PG&E services for this month
  • True-Up Total Net Usage – (0) - The amount of excess kWh that you exported
SUMMARY OF CURRENT MONTH'S ENERGY CHARGES/CREDITS table includes:
  • Current Month Energy Charge or Credit – (-$197.96) - This is the dollar amount of energy that you consumed or provided in net for the current month
  • Cumulative Energy Charges or Credits – ($405.75) - This is the total of cost or credit for all the energy
    consumed or sent to the grid during this 12-month period including the current month. This amount also includes Cumulative NBCs for the 12-month period
  • Current Month Non-Bypassable Charges – ($16.56) - This is the cost of the NBCs for the energy you imported during the current month
  • Cumulative Non-Bypassable Charges – ($340.96) - This is the total cost of the NBCs for the energy that you imported during the 12-month period including the current month
Each of these items is broken down in monthly form on Page 2 in the TRUE-UP HISTORY SUMMARY table:

tu3.jpg


At the bottom of this table, you can see your annual billing totals as well as the kWh breakdown for all imports, all exports, and the net kWh:
  • BILLED USAGE – (7,771) – The difference between imports and exports kWh
  • TOTAL CHARGES – ($405.75) - This is the same as the Cumulative Energy Charges or Credits from Page 1 is the sum of:
  • E84 BL CHG – ($403.43) - Everything but the Energy Commission Tax
  • E24 EC TAX – ($2.32) - Energy Commission Tax that is also on the Page 1
  • NON-BYPASSABLE CHARGES – ($340.96) - This is the same as the Cumulative Non-Bypassable Charges on Page
  • GRID ELECTRICTY USAGE – (14,256) – The total imported kWh for the 12-month period that require NBCs to be paid on
  • EXPORTED TO THE GRID – (-6,485) – The total exported kWh
  • SOLAR GENERATION ELIGIBLE FOR CREDIT - (-6,485) This number should be the same as the prior column or else PG&E thinks your system is not reported properly
The last number that we need to get is the total amount of MDCs that have been paid, well mostly paid, for the 12-month period and this can be found at the bottom of the True-Up Adjustment table

tu4.jpg


This table is poorly designed and is even worse if the tariff rate changed during the period as the software coder must re-used code for monthly totals instead of annual. Just ignore everything in the table except for the last row with the totals and the only number that matter is:

Previous Billed Amounts – ($122.69) - This is the total of MDCs that have been billed monthly and it also includes the current month MDCs even though they have been billed or paid for yet

This table also matches up with the other numbers in the tables we talked about previously:
  • Calculated Cumulative Amounts – ($405.75) - Same as the Cumulative Energy Charges or Credits from Page 1
  • Calculated Used Amounts – ($403.43) – Same as the E84 BL CHG
  • Other Billable Charges – ($2.32) – Same as the Energy Commission Tax from Page 1
  • Current Billed Amounts – ($280.74) – Same as the NEM True-Up Adjustment from Page 1

Calculating the Annual True-Up Amount​

There are some if-then statements that are used to evaluate how this is calculated that are fall into the following cases:

Case 1 - Cumulative Total Charges or Credits ($405.75) is greater or equal to the Cumulative Non-Bypassable Charges ($340.96):

In this case you pay the Cumulative Total Charges or Credits ($405.75) minus the Previous Billed Amount ($122.69) plus the unpaid Minimum Charges ($10.44) from the current month which equals $290.50. Now since PG&E likes to make things confusing to the reader, they split out the Energy Commission Tax of $2.32 from Cumulative Total Charges or Credits which gets you the numbers in the first table.
  • Minimum Charges – ($10.44)
  • NEM True-Up Adjustment – ($280.74) = ($405.75 - $2.32 - $122.69)
  • Energy Commission Tax – ($2.32)
  • Total Current Month's Electric Charges Due – ($293.50) = ($10.44 + $280.74 + $2.32)
Case 2 - Cumulative Total Charges or Credits ($200.00 for instance) is less than the Cumulative Non-Bypassable Charges ($340.96):

In this case you pay the Cumulative Non-Bypassable Charges ($340.96) minus the Previous Bill Amount ($122.69) plus the unpaid Minimum Charges ($10.44) from the current month which equals $228.71. In this case there is no Energy Commission Tax on the NBCs, so the first table would look like:
  • Minimum Charges – ($10.44)
  • NEM True-Up Adjustment – ($218.27) = ($340.96 - $122.69)
  • Total Current Month's Electric Charges Due – ($228.71) = ($10.44 + $218.27)
Case 3 - Cumulative Total Charges or Credits (-$958.22) is less than the Cumulative Non-Bypassable Charges ($57.91) which is less than Previous Billed Amounts ($122.69)

In this case you have already paid in more in Previous Bill Amounts ($122.69) than you owe for Cumulative Non-Bypassable Charges ($57.91) , so the your annual true-up is just the unpaid Minimum Charges ($10.44) so the first table would look like:
  • Minimum Charges – ($10.44)
  • Total Current Month's Electric Charges Due – ($10.44)

Cumulative Charges, NBCs and Price Arbitrage with Export Everything​

A passing note from @redhill_qik:
You mentioned that you are using the Export Everything mode from your Powerwalls, like some others here, and I have always been skeptical of this. In your case you have an undersized system for your usage and imported 14,256 kWh which accumulated $340.96 in NBCs vs the Cumulative Total of $405.75 that included those NBCs, so the difference is only $64.79. Pricing arbitrage through exporting more during would at best save you that $64.79, but some of that will be offset by needing to import more due to the charging efficiency loss or even more if you are using the Charge from Grid mode.

So, you can see in my scenario I really have only left $64.79 on the table and I just started using Export Everything in the last few weeks so it was not a part of the above model. In my case it may not be worth the wear and tear on my system since I am only getting about $60 extra money. I would just be throwing money away to PG&E if I sent back more. My plan is to monitor my exports vs imports month by month and make sure I stay reasonably close to what I achieved this year. And the advantage of my true-up time in July means I have some very productive months prior to “tune” my return to PG&E to maximize my monetary value.
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Moderator
Nov 28, 2018
15,842
20,543
Riverside Co. CA
(moderator note)

I want to thank @aesculus for taking the time to write this up, and thank @aesculus , @miimura and @Redhill_qik for their efforts here. This also falls into the type of information that would get easily lost, so I am going to sticky it.

I believe the information and methods used can be helpful to many, both PGE customers, and because the methods are spelled out, non PGE customers, which is why I am taking this step even though the information presented is about one utility.

Thanks again for the time and effort spent here, and being willing to share it.
 
Last edited:
I would like to highlight the bit about using Export Everything to reduce your Cumulative Energy Charges and Credits through price arbitrage. People that are considering this should take a close look at how their Cumulative Non-Bypassable Charges compares with the CECC as the CNBC amount is included in the CECC. If your CNBC amount is higher than your CECC amount then reducing the CECCs by using Export Everything will no effect and may cause you to import even more kWh which will increase your CNBC amount.
 

Nosken

Active Member
Jan 15, 2015
1,146
1,147
Lincoln, CA
I think "gone away" meant no longer available to be selected as a TOU. I don't know of any plan to remove the grandfather status for current EVA customers.
I got the mail from PG&E that mine is going away. It is 5 years since my connection. I thought I read that there was a firm date that everyone would have to migrate to EV2. I am still looking for where I read that. Last enrollment to EV-A was in 2019.
They make it sould like it will be a benefit--"Longer hours of low cost"--Yea, right. My over production will be 50% of what it was on EV-A.
1659055695282.png
 

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