SDG&E EV rates - EV-TOU-5 vs EV-TOU-2?

[J.P.M.]

On the NBC calculation, because I don't need to worry about it being on NEM 1.0, I forgot to mention how I checked the NBC calc I do for my DR-SES spreadsheets for new (non grandfathered) NEM 2.0 users.

So, FWIW:

Because I'm a bit slow on the draw a lot of the time, it took a while before it dawned on me that the answer or a way to check a spreadsheet (or any) calc done for NBC against what SDG & E thinks my NBC ought to be (and I believe is) right my nose - especially since I read and record all the POCO meter readings 1X/day about 20 minutes after I get up in the A.M.

I, and all I believe all NEM customers of SDG & E and most other CA POCOs for that matter, have meters that display a bunch of numbers. One of those numbers flashed on my meter's digital display is labeled "DEL". That's the # of kWh that have crossed the meter coming in from SDG& E since that meter was installed.

Now, according to everything I've seen and heard from the PUC, SDG & E and down to the solar vendors that I think have at least one eye and one balloon knot, all use language that can be paraphrased as something like: "Under NEM 2.0, new PV system owners will be charged NBC for every kWh that SDG & E sends (= delivers) to a new system owner." That's every kWh that crosses the meter from SDG & E's direction, that is "incoming" with the net +/- energy delivered or sent summed over every 15 minutes. That's not net over a billing period, but netted over every 15 minute period. That's one of the numbers I read/record every morning DUHH !?

So, if I read and record the meter "DEL" number at 23:59 hrs. local time just before one minute a new billing period starts and do that again one minute before the next billing period starts, and then subtract one from the other, I'll find how many kWh of my bill would get charged for NBC for the intervening period.

An example: My most recent billing covered the period 09/04/2019 to 10/03/2019.
Net usage for the period was -158 kWh. That agrees with my readings.
Tare number for my meter readings for the energy delivered for the billing period for the (09/04 - 10/03) billing period was 470 kWh.
Green button data sum of all positive (energy delivered) 15 minute kWh data for the same billing period was 466.595 kWh.
(FWIW, the same green button data shows I sent 576.66 kWh back to the POCO for the billing period. The system generated 806 kWh for the billing period , meaning ~ 806-577 = 229 kWh of system generation got used on site.)
I believe the small ~ 3 kWh discrepancy in the reading for delivered energy and the sum of the positive green button 15 minute data is explained by different times of when I read the meter to when the billing periods start and end. I'll take the small error and as this example may show, I believe summing all the positive values of the green button data is reflected in the sum of all the positive green button data. That (positive) sum is the amount of energy that is subject to NBC and what I would have been charged if I was a new (non grandfathered) NEM 2.0 customer.

[J.P.M.]

I've looked through this, but it doesn't help on the specific point, how to get the baseline credit with TOU (and solar producing in some TOU periods). I understand the NBC's take 15 minute data to compute and I don't bother.

http://regarchive.sdge.com/tm2/pdf/E...EDS_TOU-DR.pdf

I think without tiered components (e.g. EV-TOU2) I got fairly close in my own calculations as well. Also the question of what the city taxes and doesn't is vague but those amounts aren't so big.

and this is the big one for NEM-ST

http://regarchive.sdge.com/tm2/pdf/E...EDS_NEM-ST.pdf

here is the relevant texts in these.

a) Baseline Rates: If the customer is a net consumer over a billing period, the net kWh consumed shall be billed at the applicable baseline rates up to the billing period’s baseline allowance, with any excess kWh consumed billed at the applicable non-baseline rates charged other customers in the rate class. If the customer is a net generator over a billing period, the net kWh generated shall be valued at the applicable baseline rates up to the billing period’s baseline allowance, with any excess kWh generated valued at the applicable non-baseline rates charged other customers in the rate class. Any nonbypassable charges, as defined in Special Condition 1 of this schedule, shall be billed based on the kWhs consumed in each metered interval net of exports. b) Time-of-Use: If the customer is a net generator during any discrete time-of-use (TOU) period, the net kWh produced shall be valued at the appropriate TOU rates charged other customers under the same OAS. If the customer is a net consumer during any discrete TOU period, the net kWh consumed shall be billed at the appropriate TOU rates charged other customers under the same OAS. Any nonbypassable charges, as defined in Special Condition 1 of this schedule, shall be billed based on the kWhs consumed in each metered interval net of exports.


That doesn't answer to me how to combine. It says 'If a customer is a net consumer during any TOU period" (my situation), "the net kWh consumed shall be billed at the appropriate TOU rates charged other customers under the same OAS".

Which to me, seems like I should be getting baseline credit up to my full baseline allowance if the net consumption is less (as it is). But I don't. There is no provision I see anywhere that baseline allowances are somehow subdivided among TOU periods, nobody with TOU without solar generation ever experiences: "oh your net baseline allowance for this period was maxed out and you cant take your underbaseline use in other periods to this one".


(a) makes sense to me, it's the core of net metering, that generation needs to be treated just like consumption except for the explicit NBC's (I'm fine with that).

The concept of Baseline Credit or Baseline amount, which is calculated the same way BTW, is one that runs through all SDG & E tariffs that use tiers to wholly or partially establish a per kWh rate.

A bit of background: The baseline amount concept started many years ago with the idea that electricity is a commodity that should be available in subsistence (relatively small) quantities to everyone at a relatively low rate, sort of "this is the amount of electricity you need for basic subsistence".

To your conundrum of how to get the size of a baseline amount for any billing period, first off, remember what I've written and warned about SDG & E not making any of this easy. Part of the blame goes to the PUC which is a bureaucracy run largely top down and by committee. The utility rate structures are as they are partially for the same reasons that some say a camel is a horse designed by a committee.

To reach your goal of getting a baseline credit (or usage allowance - calc'ed the same way), you will need to know/find several pieces of information and then run some numbers.
Start out knowing that a baseline amount for an SDG & E residential electric bill changes every billing period.

Next, see/download the billing cycle schedule from SDG & E. Google "SDG & E + billing cycle schedule". download it. Look at it. Study it. Get familiar with it.
Note that the number of billing days and dates for any billing cycle period do not follow the calendar year or any adjacent month length.
Also, the number of days for any billing period and for any billing cycle change every year.

Next go to your SDG & E bill to get your billing cycle. Your billing cycle will be found on P.2 of your bill near the top of the page on the right side of the line that has your meter number.
Go to the billing cycle schedule and match/find your billing cycle in the left most column. That's your billing schedule.

Next, you will need three pieces of information:
- Your climate zone
- Time of year, summer or winter.
- Type of service, gas and electric or all electric.

I don't know why your referenced tariffs didn't include the necessary information to enable you to get a baseline size. So, I (just now) went looking and discovered that for some probably nefarious reason, SDG & E has removed the table that shows basic daily allowance from most of their current tariffs. However, that table is still shown as part of SCHs TOU-DR1 on P.U.C. sheet # 32156 - E, item 15, and TOU-DR2 on P.U.C sheet # 32157 - E, item 15. I intend to print those sheets until I find out W.T.F. is going on with the disappearance.

You can also get the # of billing days for your current billing cycle from P.2 of your bill, but that won't do you any good for a yearly bill and it'll change next year anyway. For next month's calcs, relying on the bill for the # of billing days won't work.

I'll use how to get my first billing period baseline allowance for calendar 2020 as an example of what you need to do. Follow the bouncing ball.

I'm billing cycle 3.
See the billing cycle sheet and find the first billing date for 2020 for billing cycle 3 to be Jan 6, and for that cycle and billing period that there are 33 billing days in the billing cycle.
Go to the mentioned table that's with schedule TOU-DR1.
- I'm all electric.
- I'm in the inland climate zone.
- The season is winter.
Put those 3 things together on the table and find that my daily baseline allowance for that billing period is 14.6 kWh/day.
Multiply the 14.6 kWh/day by the 33 billing days in the billing period to get the baseline billing period allowance for that billing period: 14.6 * 33 = 547.8. round up to 548 kWh.
Repeat the process for each billing period in the billing cycle using the appropriate arguments.

Tier 1 usage or credit size for each billing period (and calc'ed the same way, BTW) == the baseline allowance * 1.3.

The disappearance of the table is a bit troubling to me as the daily baseline allowances have been dropping some since AB 327 and NEM 2.0 took hold and have changed a bit in the past before that.

Without the table, or some other way to know what the daily allowance is a priori, I and others who play with this crap will be S.O.L.

Take what you want of the above. Scrap the rest.

[DrChaos]

While I can get very close on a bill to a T.O.U. tariff that doesn't have a tiered rate laid over it, it's also quite likely that I'm under some incorrect assumptions or misunderstandings about how SDG & E handles billing under a T.O.U. tariff that does have a tiered rate laid over it and that makes my method of backing out the credit for tier one usage in any billing period simplistic and incorrect.

....

I honestly look forward to your thoughts and Richard's as well. If you're so inclined post (and/or send to me) an entire bill with name, address and acct. # removed with your climate zone and whether or not you're an all electric user, along with your green button data for the period covered by that bill, and I'll figure it out by adding the option for tiered rate overlay for my T.O.U. billing method..

I/WE may need some mod cooperation for that one. (Mods: how about it ?)

Respectfully,

I've looked through this, but it doesn't help on the specific point, how to get the baseline credit with TOU (and solar producing in some TOU periods). I understand the NBC's take 15 minute data to compute and I don't bother.

http://regarchive.sdge.com/tm2/pdf/ELEC_ELEC-SCHEDS_TOU-DR.pdf

I think without tiered components (e.g. EV-TOU2) I got fairly close in my own calculations as well. Also the question of what the city taxes and doesn't is vague but those amounts aren't so big.

and this is the big one for NEM-ST

http://regarchive.sdge.com/tm2/pdf/ELEC_ELEC-SCHEDS_NEM-ST.pdf

here is the relevant texts in these.

a) Baseline Rates: If the customer is a net consumer over a billing period, the net kWh consumed shall be billed at the applicable baseline rates up to the billing period’s baseline allowance, with any excess kWh consumed billed at the applicable non-baseline rates charged other customers in the rate class. If the customer is a net generator over a billing period, the net kWh generated shall be valued at the applicable baseline rates up to the billing period’s baseline allowance, with any excess kWh generated valued at the applicable non-baseline rates charged other customers in the rate class. Any nonbypassable charges, as defined in Special Condition 1 of this schedule, shall be billed based on the kWhs consumed in each metered interval net of exports. b) Time-of-Use: If the customer is a net generator during any discrete time-of-use (TOU) period, the net kWh produced shall be valued at the appropriate TOU rates charged other customers under the same OAS. If the customer is a net consumer during any discrete TOU period, the net kWh consumed shall be billed at the appropriate TOU rates charged other customers under the same OAS. Any nonbypassable charges, as defined in Special Condition 1 of this schedule, shall be billed based on the kWhs consumed in each metered interval net of exports.


That doesn't answer to me how to combine. It says 'If a customer is a net consumer during any TOU period" (my situation), "the net kWh consumed shall be billed at the appropriate TOU rates charged other customers under the same OAS".

Which to me, seems like I should be getting baseline credit up to my full baseline allowance if the net consumption is less (as it is). But I don't. There is no provision I see anywhere that baseline allowances are somehow subdivided among TOU periods, nobody with TOU without solar generation ever experiences: "oh your net baseline allowance for this period was maxed out and you cant take your underbaseline use in other periods to this one".


(a) makes sense to me, it's the core of net metering, that generation needs to be treated just like consumption except for the explicit NBC's (I'm fine with that).

[J.P.M.]

I'm glad you could understand my rambling thru an explanation of how I handle the NBC data. Glad to have helped.

It only took me working thru the first 4 months of bills and banging my head against the keyboard when things didn't add up to figure out a method that matches SDG&E's values. The first two months of effort had me convinced that SDG&E was using a random number generator to get their NBC values. Now I have a better understanding, or at least a workable approximation, of what they are doing to get the monthly NBC value.

Understood.

You mentioned that you haven't tackled generation yet. When/if you do, holler back w/any questions. I'm believe I'm better at engineering design than spreadsheet design. I didn't examine any billing or rate schemes until after I'd gotten PV generation dialed in pretty good, and I didn't do that until after massaging the solar resource data I've been fiddling with since the mid '70's.

My goal for the bill generation was a necessary part of the overall goal to have a general method of being able to model a potential PV system's output and then optimize that PV system and its output for it's cost effectiveness and have the method be general enough to be applicable to any SDG & E residential customer given that user's pre, or estimated future gross electrical usage for SDG & E customers. To do that, I needed knowledge of SDG & E billing practices, schedules and how NEM works with all it's twists and turns.

Up until the addition of tiered rate schemes laid over a TOU schedule, I've largely achieved that goal, but appreciate that nothing stays the same forever. The tech./engineering part of the PV is fun for me, but I'd say the time and frustration of learning what wound up being a lot more than I wanted about POCO billing and the time spent on it were not things I particularly enjoyed. But, paraphrasing what Gus McCrae said, I always like to get where I started out for. Sometimes, when I think about all of it and where it started for me, something Bob Seger wrote comes to mind: "Wish I didn't know now what I didn't know then".

Back on topic.

[Ampster]

Like J.P.M., I work with the 15 min interval data available from SDG&E.

.........

To make the data easy to handle I do some spreadsheet magic with look-up tables (with Excel's vlookup function), to assign the 15 min data to the proper TOU period. I then use Excel's Pivot Table capabilities to add everything up in a neat summary table. Once I get the proper monthly sums for the On-Peak, Off-Peak, Super Off-Peak and NBCs I apply the proper SDG&E cost for each component resulting in a match to the closest penny.

.....

I learned something too. I have been using Pivot Tables in Google Sheets but forgot about vlookup. That will make comparing different TOU rate periods easier. I am grandfathered into PG & E EV A rate for a while but it is good to know what my alternatives look like.

[RichardCullip]

I just learned something I wish I'd learned sooner. Thank you.

I'm glad you could understand my rambling thru an explanation of how I handle the NBC data. Glad to have helped.

It only took me working thru the first 4 months of bills and banging my head against the keyboard when things didn't add up to figure out a method that matches SDG&E's values. The first two months of effort had me convinced that SDG&E was using a random number generator to get their NBC values. Now I have a better understanding, or at least a workable approximation, of what they are doing to get the monthly NBC value.

[J.P.M.]

Like J.P.M., I work with the 15 min interval data available from SDG&E.

I download the CSV version which opens up in a Excel spreadsheet just fine. I can match SDG&E's NBC values to the nearest whole number by summing up the 15 min kW data that are greater than zero, ignoring any 15 min period when I was generating more than I was using. The resulting sum needs to be adjusted at the end of the billing period by subtracting any On-Peak, Off-Peak or Super Off-Period totals that are positive. So far, this method of handling the NBC component has let me match the last 5 months of my SDG&E bills to the nearest penny.

To make the data easy to handle I do some spreadsheet magic with look-up tables (with Excel's vlookup function), to assign the 15 min data to the proper TOU period. I then use Excel's Pivot Table capabilities to add everything up in a neat summary table. Once I get the proper monthly sums for the On-Peak, Off-Peak, Super Off-Peak and NBCs I apply the proper SDG&E cost for each component resulting in a match to the closest penny.

That being said, I'm on the TOU-DR rate schedule and don't have to worry, so far, about any above baseline values since I've been a net producer each month since I turned on my system in April..

I just learned something I wish I'd learned sooner. Thank you.

[RichardCullip]

Like J.P.M., I work with the 15 min interval data available from SDG&E.

I download the CSV version which opens up in a Excel spreadsheet just fine. I can match SDG&E's NBC values to the nearest whole number by summing up the 15 min kW data that are greater than zero, ignoring any 15 min period when I was generating more than I was using. The resulting sum needs to be adjusted at the end of the billing period by subtracting any On-Peak, Off-Peak or Super Off-Period totals that are positive. So far, this method of handling the NBC component has let me match the last 5 months of my SDG&E bills to the nearest penny.

To make the data easy to handle I do some spreadsheet magic with look-up tables (with Excel's vlookup function), to assign the 15 min data to the proper TOU period. I then use Excel's Pivot Table capabilities to add everything up in a neat summary table. Once I get the proper monthly sums for the On-Peak, Off-Peak, Super Off-Peak and NBCs I apply the proper SDG&E cost for each component resulting in a match to the closest penny.

That being said, I'm on the TOU-DR rate schedule and don't have to worry, so far, about any above baseline values since I've been a net producer each month since I turned on my system in April..

[J.P.M.]

Well, I think that's what I thought too, but it doesn't work for me.

I am well under the Tier limit in any accounting. Say I have 150 kWh consumption on super-off-peak. -200 generation on off peak, and maybe net -10 generation on peak.

My tier 1 is somewhere around 300 kWh. I would expect the line that said "Baseline Adjustment Credit" to equal 150 * the current BaselineAdjustment Credit per kWh figure on my rate plan, which is TOU-DR-P, and that value is .10404. It never is. It's almost always noticeably lower. It's possible the difference is added to my NEM credits that get rolled over, but I'm not sure. I've made spreadsheets and attempted to replicate the various portions of the bill but this one I never can.

I have my new bill today: on peak -7, off peak -252, super off peak 196. So multiplying 196 by .10404 gives $20.39. On my statement it is a credit of $15.19. I can't replicate that from anything in the rate sheet and various combinations of consumption/production, signed and unsigned. My NBCs are $6.14 so that's not the difference either.

What is PUC 23286-E btw? I am looking at the rate sheets, and I see no update since 2019-06-01. https://www.sdge.com/total-electric-rates

196 * 0.07571 gives $14.89, and not $15.19.

1.) I'm not trying to duck out on this, but have you called SDG & E and asked them W.T.F. ? Back in the day, I called them so often I got to recognize some of them by voice. Some of the folks were more knowledgeable than others, but if I stayed professional, persistent and most of all friendly, I usually and eventually got an answer or enough information from climbing the chain of command to figure it out.

2.) Still not trying to duck out, even though it may look that way, as I wrote a couple of posts back, I've not back calc'ed a tiered T.O.U. bill, but the method I use gets very close and consistent for non tiered T.O.U tariffs except for some NBC diff. That, as I described, I'm pretty sure comes from my combining of 15 minute periods into 1 hour periods for the 8,760 hour spreadsheets I use. I may not be correct on my idea of how to handle a tiered rate credit on a T.O.U. tariff, but If I get a copy of a tiered rate bill, I bet my method can be adjusted to make a tiered rate credit work with a T.O.U. tariff bill.

3.) On your question: "What is PUC 23286 btw ?". My apologies. I created an typo error and missed that error when I checked for errors before pulling the trigger. I actually wrote "...PUC sheet No 32286-E...". The correct PUC sheet number is: PUC 33286 - E. To your perhaps larger question, it is one of the tariff sheets you'll find if you Google "SDG & E + Current and Effective Tariffs". That will get you to the SDG & E Tariff Book. Choose schedule TOU-DR. that chosen screen will get you most of the information you'll need to get a per kWh rate for charges and credits on a 15 minute basis, including grandfathered rate times and rates. I say most because you'll still need to calc an NBC rate and know how to apply it to a usage if you don't already know how.

The tariff book is my bible for SDG & E rates and the published authority for tariffs and what goes into generating an SDG & E bill. What you're quoting and using, and I again mean no disrespect here, while it has current rates, by itself, it does not have all the information necessary to back calculate a bill, notably how the calculate a base period or T.O.U. times. I guess my questions might be: Do you use the tariff book ? Also, how do you calc a baseline period ? It looks to me that you may not be aware of everything that can effect a bill, or when some of those things may not apply or change. I say (write) that because it looks to me that you are encountering at least some of the same questions and frustrations and missed things SDG & E doesn't tell us or is vague about that I had when I first started doing what you're now doing. FWIW, I finally just bit the bullet, read all the tariff information, quit trying to cut corners and did it the hard way. Then I back calc'ed a bunch of bills, picked up more information SDG & E wouldn't/couldn't d tell me and learned some of the stuff I'm sharing now.

It looks to me that we currently approach this task differently. I do 8,760 hours and apply the SDG & E inputs that affect each hourly rate to get a net cost for each hour per kWh they send me, and a net price per kWh for what I send back to SDG & E. I'm pretty sure I've got some error by combining 15 minute increments into 1 hour increments, but it seems the error is small and I think I know (perhaps foolishly) where that error comes from. I get very close for T.O.U. tariffs that do not have a tier component. And, while I'm probably missing or not understanding some of what you're doing, and that's my bad and my ignorance, but it looks to me what you're doing is looking at a bill with the goal of matching what you're charged, and I'm wondering if you have all the information you need to do that and if you do, if you are applying the tariff rules correctly.

While I can get very close on a bill to a T.O.U. tariff that doesn't have a tiered rate laid over it, it's also quite likely that I'm under some incorrect assumptions or misunderstandings about how SDG & E handles billing under a T.O.U. tariff that does have a tiered rate laid over it and that makes my method of backing out the credit for tier one usage in any billing period simplistic and incorrect.

FWIW, one other respectful suggestion I have for your consideration (if you don't already know about green button data and haven't already done this) is that you download all the 15 minute green button data for a billing period and then spreadsheet it with the per kWh charge and credits with those charges and credits adjusted for everything that the tariff your using ads/subtracts/multiplies/changers to that hourly rate.

I honestly look forward to your thoughts and Richard's as well. If you're so inclined post (and/or send to me) an entire bill with name, address and acct. # removed with your climate zone and whether or not you're an all electric user, along with your green button data for the period covered by that bill, and I'll figure it out by adding the option for tiered rate overlay for my T.O.U. billing method..

I/WE may need some mod cooperation for that one. (Mods: how about it ?)

Respectfully,

[DrChaos]

I'm as confused about your bill as you are. I was feeling pretty confident, perhaps even cocky, about my understanding of SDG&E's billing details. Not anymore, as there is something about your current bill that doesn't make sense to me. Like you, I can't make the numbers work.

It's probably a curiosity, or coincidence, that the difference btwn the expected generation credit ($20.39) and the actual generation credit ($15.19) works out to be exactly 50kWh times the baseline adjustment of $0.10404. Is it possible that thru the magic accounting process that SDG&E uses that you went over your baseline by 50kWh?

The amount of the credit always seems to be a round number of kWh times the credit rate, but figuring out that # of kWh is eldritch magic. Is there some prorating of baseline per hour or TOU period?

That doesn't make sense and would be against NEM rules that say that NEM is treated like regular billing.

My previous bill is +5 on peak, -243 Off Peak, +215 super off peak. Baseline Adjustment Credit is $ -18.52.

I would expect (5+215)*.10404 = 22.89

18.52 / .10404 = 178.00xxx So they think I got 178 kWh of credit previous month.

This month they think I get 146 kWh. Where the heck does that come from? It's been a mystery for a year. TOU periods are the same so if there were a per-period baseline cap, I would have expected the same number.

My baseline allowance is 288, and 1.3 times that is 374.4

[RichardCullip]

I have my new bill today: on peak -7, off peak -252, super off peak 196. So multiplying 196 by .10404 gives $20.39. On my statement it is a credit of $15.19. I can't replicate that from anything in the rate sheet and various combinations of consumption/production, signed and unsigned. My NBCs are $6.14 so that's not the difference either....

I'm as confused about your bill as you are. I was feeling pretty confident, perhaps even cocky, about my understanding of SDG&E's billing details. Not anymore, as there is something about your current bill that doesn't make sense to me. Like you, I can't make the numbers work.

It's probably a curiosity, or coincidence, that the difference btwn the expected generation credit ($20.39) and the actual generation credit ($15.19) works out to be exactly 50kWh times the baseline adjustment of $0.10404. Is it possible that thru the magic accounting process that SDG&E uses that you went over your baseline by 50kWh?

[DrChaos]

I believe this as described below works. HOWEVER, I'm On sch. DR and at this time, all of my neighbors that I cooperate with who have PV are either on sch. DR like me or on DR-SES which is a straight T.O.U schedule. I therefore have not yet checked my method against an actual bill.

However, I've checked the general method I use for T.O.U. bill generation/checking against some actual DR-SES billing and my method does seem to accurately reproduce an electric bill, except for being a bit off in the NBC adjustment for reasons known and described in a post elsewhere on this thread.

The general method I use is to consider/treat each of the 8,760 hours in a year by itself, put in the rate for each individual hour, things that affect those rates for each hour, SDG & E delivery for each hour, and solar generation for each hour, and other things including but not limited to things NBC, taxes, all by and for specific hours. A lot of what looks like a huge task is made a lot easier by the fact that most of it is a copy job.

The hard part for me was (and still is) keeping straight what could be copied from what couldn't be copied from one row/week/billing period/season to another.

To do it right also forced me to dig really deep into, and to really understand SDG & E and by association a lot of other POCO's billing and tariff methods (but by no means as well for the other POCOs).

Adding a tiered rate credit for each hour as applicable against a billing period's hourly rate for that hour over part of a variable number of hours per billing period is no more than something else to add that "other things for that hour" list.

I'll use sch. TOU-DR for example purposes here. The method and logic ought to work for any SDG & E T.O.U. rate tariff that has a tier scheme laid over it.

I use 8,760 rows on all my rate, use and generation spreadsheets, one for each hour in a year. If you use a different method and logic than I do, what I describe may not and probably won't work for you.

For T.O.U. tariffs that have a tiered rate laid over the top of them, I first figure the baseline allowance for any billing period as determined by the tariff sheets and my climate zone and that I'm an all electric customer and if that row's date is in summer or winter. See the SDG & E tariff sheets for those details if you have not already done so.

I then multiply that baseline amount by 1.3 to figure out how big tier one is for that billing period. Note that the baseline amount and so tier one size is different for each billing period.

Then, for all the electricity that comes in from SDG & E for that billing period, AND until that electricity totals up to the tier one level for that billing period, the per kWh rate for any such hour is reduced by the credit amount shown on the tariff schedule. Per cal P.U.C. sheet No. 32286-E submitted 08/01/2019, effective 11/01/19, that per kWh credit = $0.07571/kWh for summer deliveries and $0.06898/kWh for winter deliveries.

Once the tier energy allotment is received from SDG & E for that billing period, the tier one credit is removed, controlled by an "if" statement using the tier one allotment for that billing period and the monthly running total delivered electricity as arguments. The tier one credit is then restored at the beginning of the next billing period as appropriate for that billing period.

Well, I think that's what I thought too, but it doesn't work for me.

I am well under the Tier limit in any accounting. Say I have 150 kWh consumption on super-off-peak. -200 generation on off peak, and maybe net -10 generation on peak.

My tier 1 is somewhere around 300 kWh. I would expect the line that said "Baseline Adjustment Credit" to equal 150 * the current BaselineAdjustment Credit per kWh figure on my rate plan, which is TOU-DR-P, and that value is .10404. It never is. It's almost always noticeably lower. It's possible the difference is added to my NEM credits that get rolled over, but I'm not sure. I've made spreadsheets and attempted to replicate the various portions of the bill but this one I never can.

I have my new bill today: on peak -7, off peak -252, super off peak 196. So multiplying 196 by .10404 gives $20.39. On my statement it is a credit of $15.19. I can't replicate that from anything in the rate sheet and various combinations of consumption/production, signed and unsigned. My NBCs are $6.14 so that's not the difference either.

What is PUC 23286-E btw? I am looking at the rate sheets, and I see no update since 2019-06-01. https://www.sdge.com/total-electric-rates

196 * 0.07571 gives $14.89, and not $15.19.

[J.P.M.]

What is that adjustment? I can't get it to match any numbers on my bill.

I believe this as described below works. HOWEVER, I'm On sch. DR and at this time, all of my neighbors that I cooperate with who have PV are either on sch. DR like me or on DR-SES which is a straight T.O.U schedule. I therefore have not yet checked my method against an actual bill.

However, I've checked the general method I use for T.O.U. bill generation/checking against some actual DR-SES billing and my method does seem to accurately reproduce an electric bill, except for being a bit off in the NBC adjustment for reasons known and described in a post elsewhere on this thread.

The general method I use is to consider/treat each of the 8,760 hours in a year by itself, put in the rate for each individual hour, things that affect those rates for each hour, SDG & E delivery for each hour, and solar generation for each hour, and other things including but not limited to things NBC, taxes, all by and for specific hours. A lot of what looks like a huge task is made a lot easier by the fact that most of it is a copy job.

The hard part for me was (and still is) keeping straight what could be copied from what couldn't be copied from one row/week/billing period/season to another.

To do it right also forced me to dig really deep into, and to really understand SDG & E and by association a lot of other POCO's billing and tariff methods (but by no means as well for the other POCOs).

Adding a tiered rate credit for each hour as applicable against a billing period's hourly rate for that hour over part of a variable number of hours per billing period is no more than something else to add that "other things for that hour" list.

I'll use sch. TOU-DR for example purposes here. The method and logic ought to work for any SDG & E T.O.U. rate tariff that has a tier scheme laid over it.

I use 8,760 rows on all my rate, use and generation spreadsheets, one for each hour in a year. If you use a different method and logic than I do, what I describe may not and probably won't work for you.

For T.O.U. tariffs that have a tiered rate laid over the top of them, I first figure the baseline allowance for any billing period as determined by the tariff sheets and my climate zone and that I'm an all electric customer and if that row's date is in summer or winter. See the SDG & E tariff sheets for those details if you have not already done so.

I then multiply that baseline amount by 1.3 to figure out how big tier one is for that billing period. Note that the baseline amount and so tier one size is different for each billing period.

Then, for all the electricity that comes in from SDG & E for that billing period, AND until that electricity totals up to the tier one level for that billing period, the per kWh rate for any such hour is reduced by the credit amount shown on the tariff schedule. Per cal P.U.C. sheet No. 32286-E submitted 08/01/2019, effective 11/01/19, that per kWh credit = $0.07571/kWh for summer deliveries and $0.06898/kWh for winter deliveries.

Once the tier energy allotment is received from SDG & E for that billing period, the tier one credit is removed, controlled by an "if" statement using the tier one allotment for that billing period and the monthly running total delivered electricity as arguments. The tier one credit is then restored at the beginning of the next billing period as appropriate for that billing period.

[RichardCullip]

Have you been able to successfully replicate the SDG&E billing on a rate-plan that involves both tiers and time-of-use? I cannot do so for TOU-DR-P.


I think these two rate plans are best for solar + EV users. I'm on TOU-DR-P. For you I might start with that with the EV for a year, and if @ the true-up yearly the hard money cost is more than $250 I would switch to EV-TOU-5. How much do you consume now without EV?

A couple of good questions. My current solar output exceeds my demands from SDG&E's grid. I have a decent excess each month, averaging about 250kWh per month for the last 5 months. That will drop once winter arrives. That being said I haven't had to deal with handling the second tier situation as I have always been solidly below the Tier 1 upper limit. This makes my calculation a bit easier.

I can handle bills that span two months with different rates. With my SDG&E billing schedule I normally get the bill near mid-month. The upcoming Nov bill should be based on 20 days under the Oct the schedule and the remaining 10-11 days under Nov's rate schedule. I will calculate the 20 days of use in Oct under Oct's rate schedule and the other 10-11 days of use under Nov's rate schedule. Add the two sub-totals together and I should match SDGE's total bill.The rate schedule for NBC's is the same for each month so I don't have to split NBCs btwn the two months. I will just use Oct's NBC rate multiplied by the NBC kWhs.

Of course, in my situation, since I am currently a net generator, my bill will be the monthly minimum so I could take the easy way and just multiple the number of days times the Minimum Rate per Day (currently $0.338 per day) but what's the fun in taking the easy way.

[DrChaos]

For other T.O.U. rates that have a tier scheme laid over them, the billing periods come into play as additional adjustments to the hourly rates both charged and credited with both reduced for all tier one usage in a billing period.

What is that adjustment? I can't get it to match any numbers on my bill.