Leveraging SDGE TOU rates with an EV?

[J.P.M.]

As I have said before it all depends on where you are standing. Your big picture and my big picture are different and that leads us to have different objectives.
Process economics concerns itself with the production of goods and services. My objectives are more about the efficient consumption of goods and services and the allocation of resources to facilitate that. Picking the optimum rate is a subset of those objectives. Looking at rate differentials is just part of that process.

Some time ago I realized my consumption of energy was not limited to only the energy used to run my home. My transportation choices evolved from a succession of hybrids and plug in hybrids to the two EVs I currently own.

Yea, from where I'm standing, my objective in terms of economic analysis with respect to residential energy in all its subsets (with one aspect or subset being TOU rate impacts and EV super off peak charging to be one such subset) is getting the most long term bang for my buck.

I guess I'd have made you less ornery if I had written "solar process economics as a subset of engineering economics and using those methods to explore the implications of leveraging TOU rates for super off peak EV charging" instead of "process economics".

I've been around such subjects since the '70's and take what appears to me to be the longer and broader view of the subject as a basis for discussing the particulars of this thread.

[Ampster]

Yea, from where I'm standing, my objective in terms of economic analysis with respect to residential energy in all its subsets (with one aspect or subset being TOU rate impacts and EV super off peak charging to be one such subset) is getting the most long term bang for my buck.

I think our objectives are the same except mine is not limited to just my residence. My objective includes my EVs and the energy storage in my hybrid inverter.

I guess I'd have made you less ornery if I had written "solar process economics as a subset of engineering economics and using those methods to explore the implications of leveraging TOU rates for super off peak EV charging" instead of "process economics".

Ornery? I tried to be discrete about telling you that you were hijacking the thread on a topic in which you have no actual first hand experience. ie EVs and TOU rates. Later I posted a specific comment about that.

I've been around such subjects since the '70's and take what appears to me to be the longer and broader view of the subject as a basis for discussing the particulars of this thread.

Longer? Broader? Yes I am sure you believe your own press releases. If post count was the measure you have won the prize. The owners of this forum should recognize you for all the referrals that your posts have generated for their profit making enterprise.

I have been studying economics since 1962 and once chaired the International Banking Loan Committee of the second largest bank in California. I was part of a banking consortium that financed Quebec Hydro in its early stages. That gives me a global view that is different, that is all. Whether that is longer or more important is not material to this discussion.

[J.P.M.]

The title of this post is about leveraging TOU rates with an EV. Real world experience with EVs and TOU rates is probably more relevant to this discussion. If you want to discuss the broader issue of optimum alternative energy system design starting a new thread thread would give that topic a broader audience.

I appreciate the post subject. I wrote the paragraph you quoted as contextual to what followed that paragraph. If you had read the paragraph after that one, you might have seen where I framed the thread subject in a broader area of using rate gaming/time shifting to lower a total bill. The thread subject is one aspect of lower utility bills. I believe I understand super off peak rate EV charging well enough to see that the particulars of any advantages and particulars of time shifting of EV charging are no different than the advantages and particulars of time shifting of any load.

Part of what I'm trying to point out is that in the larger context of achieving the lowest cost of providing electrical service to a residence, shifting to super off peak times, EV charging needs to be viewed in the context of comparing all available rate plans for total annual bill and not simply the difference between rate differentials within a single tariff as the criteria for a rate plan choice that will impact all other tasks that make up a bill.

As I keep writing, if you want better accuracy, you gotta' run the numbers.

I believe Richard and I, and probably lots of others have a pretty good spreadsheet handle on how to do that in the larger context of finding the best rate plan for a particular situation of a particular user's tariff, annual usage and usage pattern - that is, finding the rate pan/tariff that results in the lowest annual electric bill.

Once the spreadsheet tools are available, the impact of adding an EV super off peak charging load as f(rate plan) and so it's impact on the total annual electric bill becomes an almost trivial task.

To not look at EV charging in the context of overall impact on annual bill seems shortsighted to me.

[DrChaos]

I appreciate the post subject. I wrote the paragraph you quoted as contextual to what followed that paragraph. If you had read the paragraph after that one, you might have seen where I framed the thread subject in a broader area of using rate gaming/time shifting to lower a total bill. The thread subject is one aspect of lower utility bills. I believe I understand super off peak rate EV charging well enough to see that the particulars of any advantages and particulars of time shifting of EV charging are no different than the advantages and particulars of time shifting of any load.

Part of what I'm trying to point out is that in the larger context of achieving the lowest cost of providing electrical service to a residence, shifting to super off peak times, EV charging needs to be viewed in the context of comparing all available rate plans for total annual bill and not simply the difference between rate differentials within a single tariff as the criteria for a rate plan choice that will impact all other tasks that make up a bill.

As I keep writing, if you want better accuracy, you gotta' run the numbers.

I believe Richard and I, and probably lots of others have a pretty good spreadsheet handle on how to do that in the larger context of finding the best rate plan for a particular situation of a particular user's tariff, annual usage and usage pattern - that is, finding the rate pan/tariff that results in the lowest annual electric bill.

Once the spreadsheet tools are available, the impact of adding an EV super off peak charging load as f(rate plan) and so it's impact on the total annual electric bill becomes an almost trivial task.

To not look at EV charging in the context of overall impact on annual bill seems shortsighted to me.

I don't disagree with you but as a first-order approximation (I'm a physicist not an engineer) I'd guesstimate that 90% of people with EV & Solar are heavy super-off-peak consumers, heavy off-peak generators, and light to zero on-peak consumers. An EV is the only big load that can be shifted to super off peak reliably. And then the gap between off-peak and super-off-peak will dominate the difference between rate plans.

A complete complex simulation will have better calibrated results but for rank ordering the plans, it's a good start.

[Ampster]

.....I'd guesstimate that 90% of people with EV & Solar are heavy super-off-peak consumers, heavy on-peak generators, and light to zero on-peak consumers. An EV is the only big load that can be shifted to super off peak reliably. And then the gap between off-peak and super-off-peak will dominate the difference between rate plans.

A complete complex simulation will have better calibrated results but for rank ordering the plans, it's a good start.

A good start indeed if a consumers results fit those assumption. I have been doing spreadsheet modeling of rate plans for seven years and that has been my conclusion as well. Your guesstimate is similar to my actual results in the past. I have bulleted the assumptions with my latest ten month results:

-Heavy super off peak consumption ( 3.4 mega Watt hrs)
-Heavy on peak generation ( 1.3 mega Watt hrs on peak & 1.7 mega Watt hrs off peak)

Overall I am a net consumer of 400 kilo Watt hrs for those ten months and expect that to grow in the next two months as I whittle away my $500 credit per my initial strategy. Last month I used 800 kilo Watt hrs at the super off peak rate. Even though I get free charging for one of my EVs, at this point it is not worth the round trip journey of 20 miles to charge that EV unless I am going past one of those stations and have a need to stop and charge.
I should emphasize that the above assumptions are critical to the predictability of that result. An occasional check is always worthwhile but I can now do it easily with monthly data and seven years of history.

[RichardCullip]

I don't disagree with you but as a first-order approximation (I'm a physicist not an engineer) I'd guesstimate that 90% of people with EV & Solar are heavy super-off-peak consumers, heavy on-peak generators, and light to zero on-peak consumers. An EV is the only big load that can be shifted to super off peak reliably. And then the gap between off-peak and super-off-peak will dominate the difference between rate plans.

A complete complex simulation will have better calibrated results but for rank ordering the plans, it's a good start.

Is there a typo in there when you state "heavy on-peak generators"? It seems to me that that should be "heavy off-peak generators". At least in the SDG&E area where the off-peak TOU period aligns best with mid-day high solar production.

[DrChaos]

Is there a typo in there when you state "heavy on-peak generators"? It seems to me that that should be "heavy off-peak generators". At least in the SDG&E area where the off-peak TOU period aligns best with mid-day high solar production.

Yes of course, I fixed the typo!

[DrChaos]

A good start indeed if a consumers results fit those assumption. I have been doing spreadsheet modeling of rate plans for seven years and that has been my conclusion as well. Your guesstimate is similar to my actual results in the past. I have bulleted the assumptions with my latest ten month results:

-Heavy super off peak consumption ( 3.4 mega Watt hrs)
-Heavy on peak generation ( 1.3 mega Watt hrs on peak & 1.7 mega Watt hrs off peak)

Overall I am a net consumer of 400 kilo Watt hrs for those ten months and expect that to grow in the next two months as I whittle away my $500 credit per my initial strategy. Last month I used 800 kilo Watt hrs at the super off peak rate. Even though I get free charging for one of my EVs, at this point it is not worth the round trip journey of 20 miles to charge that EV unless I am going past one of those stations and have a need to stop and charge.
I should emphasize that the above assumptions are critical to the predictability of that result. An occasional check is always worthwhile but I can now do it easily with monthly data and seven years of history.

800 kWh super-off peak, and a net consumer over the 12 months? Seems like EV-TOU-5 might be right for you. $16 a month+NBC's and you get 9 or 10 c super off peak year round.

[Ampster]

800 kWh super-off peak, and a net consumer over the 12 months? Seems like EV-TOU-5 might be right for you. $16 a month+NBC's and you get 9 or 10 c super off peak year round.

It would but I live 500 miles north of SDG&E territory. I wish PG&E had a super off peak rate like that. I am grandfathered into EV-A with a super off peak rate around $0.14.
My biggest concern with PG&E is an increase in the fixed portion of the rate due to the settlements now taking place in their bankruptcy. I am not up to speed on the SDG&E rate increase involving a fixed fee but I am hoping it is not a trend.

[J.P.M.]

I don't disagree with you but as a first-order approximation (I'm a physicist not an engineer) I'd guesstimate that 90% of people with EV & Solar are heavy super-off-peak consumers, heavy on-peak generators, and light to zero on-peak consumers. An EV is the only big load that can be shifted to super off peak reliably. And then the gap between off-peak and super-off-peak will dominate the difference between rate plans.

A complete complex simulation will have better calibrated results but for rank ordering the plans, it's a good start.

Nor do I disagree with your estimate that a high number of folks with both EV and solar have the consumption patterns you claim. I also have no data to counter your claims even if I did disagree.

However, I still claim that using only the gap between off peak and super off peak rate for any tariff rather than comparing total estimates of annual bills for all tariffs being considered is shortsighted and may lead to annual bills that may well be higher than a more complete analysis would produce.

I also disagree with your claim that EV charging is the only big load that can be shifted to super off peak. Maybe a bit off topic but while I'll admit that the # of applications may be few but I can probably come up with a couple. One being the high mass/superinsulated dwelling I designed for a desert climate. Any required mechanical cooling would be done at super off peak times with the long thermal time constant allowing the building to coast through the heat of the following day while having low enough thermal hysteresis to maintain comfortable temp. ranges. Kind of like a thermal battery. Battery charging at super off peak hours may also be allowed by some POCOs.

Back on topic, given the relative ease of using a spreadsheet or two to get what's likely a closer est. of total annual bill for any/all considered tariffs and so a bigger picture of the effects of choices made seems, IMO only maybe, worth the small effort. However, because every situation and customer is different, that may remain a moot point.

It may be useful if only as a side note to maybe put some perspective on the relative #'s of EV owners in the population. There are ~ 2.6 EE7 million passenger vehicles registered in CA, including light trucks, and although reliable #'s seem hard to come by, a somewhat optimistic guess as of Sept. 2019 seems to point to somewhere in the vicinity of 6 EE5 plug in electric vehicles registered in CA at that time or ~ 2.3% or so of all registered vehicles, and BTW, CA has ~ 46 - 50 % of all plug in electric vehicle registrations in the U.S, giving the other 49 states a relative paucity of EV's. Because of the way you phrased it, while that doesn't necessarily invalidate your guesstimate , it does seem to put super off peak vehicle charging in a relatively small group.

There are also ~ 7 EE6 single and attached dwelling units in CA. If each of those ~ 600,000 plug in electric vehicles is charged using power from a single family or attached dwelling electric meter, that works out to ~ < 9% or so of the residential electricity customers in CA who are, by your declaration, the only (residential) users of large amounts of super off peak electricity.

[Ampster]

However, I still claim .......
I also disagree .........
Maybe a bit off topic.....
.......it does seem to put super off peak vehicle charging in a relatively small group.

My comments in this thread have been designed to help EV drivers or potential EV drivers see the possibilities of leveraging TOU rates to their advantage. They may be a small group but globally they are a rapidly growing segment of automobile ownership.

[J.P.M.]

My comments in this thread have been designed to help EV drivers or potential EV drivers see the possibilities of leveraging TOU rates to their advantage. They may be a small group but globally they are a rapidly growing segment of automobile ownership.

I don't doubt your good intentions. You also won't get an argument (not agreement - that was a typo/brain fart) from me about the idea that EVs are a growing portion of the automobile market and thus responsible for a lot of increased super off peak residential electricity demand.

However, I am of the opinion that there's a better way to save all users money, including EV owners. That way is looking at the effects that all available tariffs will have on total annual electric bills rather than what you seem to be narrowly focused on, that is, what you call leveraging of rates with super off peak to off peak rate differential being what looks to me to be the sole criteria.

My other point was only to note and maybe keep in mind that super off peak sales for EV charging are, at this time anyway, a relatively small segment of most CA POCO's sales, and, because CA EV use is roughly about half the total U.S., that leaves what would seem to be the remaining half of the of the U.S. EV market and (presumably super off peak) electricity sales to be spread among the other 90% of the U.S. population that doesn't live in CA..

Maybe not getting too parochial and myopic about EVs and CA's love of them may be something to think about.

Not everyone lives in the land of fruits and nuts like you, me, Richard and DrChaos.

It may also be worth considering, maybe in another thread, what would/may/possibly happen with respect to POCO TOU rates, tariffs and policies if use at what are now super off peak times really rises for whatever reason - lots of EVs/charging, distributed residential energy storage is suddenly seen as an advantage to the bottom line of utilities and super off peak charging becomes common or encouraged by the POCOs, whatever. If Super off peak use rises enough will super off peak rates then rise ? Will TOU rates equalize to the point that TOU becomes an anachronism ? What effect would all that have on the grid's capacities ?

[Ampster]

.....
It may also be worth considering, maybe in another thread, what would/may/possibly happen with respect to POCO TOU rates, tariffs and policies if use at what are now super off peak times really rises for whatever reason - lots of EVs/charging, distributed residential energy storage is suddenly seen as an advantage to the bottom line of utilities and super off peak charging becomes common or encouraged by the POCOs, whatever. If Super off peak use rises enough will super off peak rates then rise ? Will TOU rates equalize to the point that TOU becomes an anachronism ? What effect would all that have on the grid's capacities ?

That is a subject that interests me but I don't think it would get much traction on this forum. There is another forum where those regional issues have been discussed more extensively and with input from a diverse cross section of industry professionals and consumers. The discussion on this thread has seen less than ten people post.

[RichardCullip]

That is a subject that interests me but I don't think it would get much traction on this forum. There is another forum where those regional issues have been discussed more extensively and with input from a diverse cross section of industry professionals and consumers. The discussion on this thread has seen less than ten people post.

This is also a subject I’m interested in. Care to share the forum you referenced?

[Ampster]

This is also a subject I’m interested in. Care to share the forum you referenced?

I am no sure I can post a link but it is called the tesla motors club forum. The specific sub forums that I spend my time on are Tesla Energy, the regional California Forum and the Energy, Environment & Policy Forum. I have been a member there since 2012 when I bought a Toyota RAV 4 EV which had a Tesla drivetrain. I was active in a RAV 4 forum and some of the posters there, also referred to the broader discussions on the Tesla forum.