Leveraging SDGE TOU rates with an EV?

[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.

[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.

[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!

[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.

[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.

[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.

[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.

[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.]

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]

.....
The objective of an economic analysis for an alternate energy system can be viewed as the determination of the least cost method of meeting the energy need, considering both solar and non solar alternatives. ......

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.

[Ampster]

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. During the past decade my transportation choices have evolved from a succession of hybrids and a plug in hybrid to the two EVs I currently own. I put approximately 25,000 miles on those cars annually.

[J.P.M.]

It is a term that has been used on another forum frequented by EV drivers, I started using it here because it made sense with regard to solar and TOU rates. I did not invent it but my background in finance found it an appealing way to express the concept. When used as a noun it means the ratio of debt to equity. However in this context is is a verb, the meaning of which is, "to use (something) to maximum advantage." That quote is from a simple Internet search. In one sense it reminds me of the physics of a lever.

I hope that clarifies it. I can give more examples but the one I gave at the beginning of this thread still seems the simplest."buy low and sell high".

Thank you. I respect what you write in this post, but the way I learned process economics, it seems or feels to me that's sort of like throwing out the baby with the bath water.
Or at least not starting with the bigger picture:

The objective of an economic analysis for an alternate energy system can be viewed as the determination of the least cost method of meeting the energy need, considering both solar and non solar alternatives. For solar energy systems of any type, the goal is to determine the size of the solar energy system that gives the lowest cost combination of solar and the least cost electrical power option(s).

Once a system is in place and assumed fixed in size (at least for the near future), it would seem to me the discussion would shift to comparing various tariff plans to determine the one that results in the lowest total bill.

On the baby and bath water situation, what I think I'm reading from you and also from DrChaos looks like more but perhaps not total concern about finding the greatest differential cost/kWh from one tier to the next within a single tariff schedule rather than a comparison of total annual bills from a comparison of net annual bills from one tariff to the next or the lowest annual bill among all available tariffs.

[Ampster]

Can you explain how you see/define the concept of "leverage" as you use the term ?

It is a term that has been used on another forum frequented by EV drivers, I started using it here because it made sense with regard to solar and TOU rates. I did not invent it but my background in finance found it an appealing way to express the concept. When used as a noun it means the ratio of debt to equity. However in this context is is a verb, the meaning of which is, "to use (something) to maximum advantage." That quote is from a simple Internet search. In one sense it reminds me of the physics of a lever.

I hope that clarifies it. I can give more examples but the one I gave at the beginning of this thread still seems the simplest."buy low and sell high".

[J.P.M.]

I believe you are correct. Most people are not aware of their usage patterns. That is especially true for those that have fought to stay on tiered rates. EV owners by necessity have control over the timing of much of their consumption and don't have to do pages of analysis to find the optimum rate plan. I have to admit I did some extensive spreadsheet analysis until the concept of leverage became clear.

Can you explain how you see/define the concept of "leverage" as you use the term ?

[Ampster]

............
I bet my situation is common for people with EV & solar but not universal. .....

I believe you are correct that most people are not aware of their usage patterns. That may be especially true for those that have fought to stay on tiered rates. EV owners by necessity have control over the timing of much of their consumption and don't have to do pages of analysis to find the optimum rate plan. I have to admit I did some extensive spreadsheet analysis until the concept of leverage became clear.