Leveraging SDGE TOU rates with an EV?

[DrChaos]

Yea. Don't know how that will wring out as it winds it's way through the lobbies and cloakrooms of the CPUC.

If it does become reality in some form (?), and depending on how it's structured, and similar to the ways NEM rate/T.O.U. time restructuring lowered array cost effectiveness by ~ 22 - 25% or so, such a charge may wind up as another example of some of the risks of oversizing an array based on assumptions of increasing array cost effectiveness from rates that are assumed to only go up, and that such an assumption is not a always a slam dunk or the only thing that affects an electric bill.

If that $38 min. charge/billing period is against usage, and again, depending on how it's structured, for this oversimplified example only, that could reduce the value of an array's first $ 38 worth of generation per billing period to zero. That is, the $38 charge might well be there regardless of the amount of any PV generation.

It will have the perverse incentive of encouraging needless consumption and probably fossil fuel use.

[bcroe]

It will have the perverse incentive of encouraging needless consumption and probably fossil fuel use.

Agreed, no charge should remove the incentive to be less wasteful and save energy. Decades before
my solar, I had many an electric bill under $20. Back then all agreed (at least to the public) it was best
to minimize consumption. Now everything is oriented to guarantee extracting as much $ from the
customer regardless of consumption. One reason I went solar was to avoid all these extra charges
that I see keep expanding on any monthly account. I avoided that by eliminating connection to the
gas company, but cannot operate here without net metering with the electric co. Bruce Roe

[SunEagle]

Agreed, no charge should remove the incentive to be less wasteful and save energy. Decades before
my solar, I had many an electric bill under $20. Back then all agreed (at least to the public) it was best
to minimize consumption. Now everything is oriented to guarantee extracting as much $ from the
customer regardless of consumption. One reason I went solar was to avoid all these extra charges
that I see keep expanding on any monthly account. I avoided that by eliminating connection to the
gas company, but cannot operate here without net metering with the electric co. Bruce Roe

Unfortunately I feel most POCO's are trying to justify additional charges due to their loss of customers that use to purchase as much power as they had before because of installing solar. The sad part is the loss to the POCO due to local solar power generation is less then what they get with the additional charges to all customers.

Remember the POCO stocks are an investment to some and the investors expect increasing returns or they go somewhere else with their money. It is a bad economical spiral for the POCO to keep providing more to their investors then other business investments as well as their promise to keep the lights on for their customers.

[J.P.M.]

It will have the perverse incentive of encouraging needless consumption and probably fossil fuel use.

It may well do that. I agree. It may also do more.

My point however, was that there is always uncertainty in assumptions about the future with respect to residential PV. In those assumptions, cooking in the idea that because rates will always increase (which seems a reasonable bet IMO), while not considering or ignoring that the POCO will likely do what it can to it's best benefit (which seems another reasonable assumption IMO only), and in so doing make PV less cost effective, may not be the best set of assumptions.

While not disagreeing with you, in what ways do you all think residential users, PV owners and others, will see/perceive such an increase in the min. billing period charge that would possibly encourage them to consume more electricity ?

Also, what possible impact(s) do you see on the go/no go decision for those residential POCO customers who may be contemplating adding PV ? Bigger arrays ? smaller ? No/forego PV for now ? Changes in PV project budget $$'s ? Other, such as more conservation in lieu of PV ?

[J.P.M.]

Back to the original question: I am in SDG&E with solar and an EV. My solar generation, over a year, is about net even with my consumption including an EV. I don't yet have air conditioning.

I chose the TOU-DR-P rate. I think it is optimal for my condition. More specifically: in summer months there is a 10c difference between "off-peak" (when most generation happens) and super-off-peak (when I would charge the EV and consume the most), so I can accumulate credit faster than energy use. Additionally, there is only a 1c increment for the on-peak, when I may use electricity and solar generation is low to zero. I like not having to stress too much about the on-peak hours.

The issue though is that there is a large penalty rate for the Reduce Your Use days, which are called occasionally on very hot summer weekdays (no guarantee but nearly always true)---a $1.16 increment to rate between 2 to 6pm on those days. Summer 2019 there were none, Summer 2018 there were four. But as they were 2-6pm, as I planned to totally minimize consumption on those times they ended up being a very good generating bonus as I had net generation during those hours, maybe $15 in credit per RYU day!

SDG&E rates here: (bookmark this page!): https://www.sdge.com/total-electric-rates

If I were to be a heavier consumer, e.g. with significant AC use, then the EV-TOU-5 rate would be optimal---as there is a huge gap between generation hours rates and super-off-peak (EV charge time) rates, and this gap is present year round. At the cost of $16 per month of hard money that can't be offset with generation, plus the non-bypassable charges, so maybe $25 per month? The upside would be that I would earn large generation credit from rate arbitrage that could be used for AC or other consumption.

For TOU-DR-P the combination of minimum bill and NBC's + taxes results in a net minimum hard money bill of about $12 per month.

I think the best rate plans for EV+Solar users in SDG&E are TOU-DR-P and EV-TOU-5.

Note there is also TOU-DR rate (not really advertised) that is like the other TOU rate that SDG&E is pushing, but with a lesser gap from on-peak to off-peak. But the gap from off-peak to super-off-peak is more like 6c vs 10c, similar to EV-TOU-2 and DR-SES (which are almost the same).

What tools do you use that led you to the conclusion that TOU-DR-P is the optimum for you ? Are they quantitative tools ? Spreadsheets ? Other ?

When I found out, and pretty much what I'd already guessed as a blinding flash of the obvious, that most of the residential PV decision for most folks was financial, I then saw an important part of the decision process would require a way to accurately compare what a residential electric bills would be both before and after PV additions under various available tariffs, with considerations for knowing or at least defining things as unknowable for the future.

Took a while to get there, but now I've got methods to estimate bills for SDG & E at least for me and most any residential SDG & E customer in a way that I believe allows for reasonably accurate and quick bill generation based on use, with or without solar generation and comparisons.

Since most every situation and best solution is different, or at least perceived as different by most every electrical customer, such tools might be useful in the decision making process.

Just wondering what tools you use that led you to the conclusion that those two tariffs were optimum or best for EV + Solar users.

I'm also interested in maybe learning some new tricks or things I might improve upon in my bill generation algorithms.

[scrambler]

Since most every situation and best solution is different, or at least perceived as different by most every electrical customer, such tools might be useful in the decision making process.

Just wondering what tools you use that led you to the conclusion that those two tariffs were optimum or best for EV + Solar users.

I'm also interested in maybe learning some new tricks or things I might improve upon in my bill generation algorithms.

I personally built a basic spreadsheet that uses hourly usage data from my POCO and hourly production data (from PVWatt before install, from solar reporting after). I can customize the spreadsheet to take into account different rate schedule and prices, as well as what operating mode the solar system is running (including with or without a battery system).

Defending on the NEM system it would need to be customize further as the buy back is different with each. the spreadsheet right now is PG&E with or without MCE (who has a better buyback than PG&E).

What I noticed using the spreadsheet is that with the recent change with EV rate and schedule, the gain from buyback actually went down in my configuration.

It sounds like you may have gone a step further, can you describe what you did?

[Ampster]

...
Just wondering what tools you use that led you to the conclusion that those two tariffs were optimum or best for EV + Solar users.

I'm also interested in maybe learning some new tricks or things I might improve upon in my bill generation algorithms.

Have you overlaid some scenerios of a two EV family who drives say 50 or 100 miles a day and therefore could consume 25 kWhrs per day at off peak?

[scrambler]

Have you overlaid some scenerios of a two EV family who drives say 50 or 100 miles a day and therefore could consume 25 kWhrs per day at off peak?

I have not done that either as there was no need for me as I already have 2 electric cars, but that would be farily easy to add.

Changing consumption profile would require for me to create a second component where I would customize hourly data for the whole year based on different user scenarios.

I could for example create a side spreadsheet that would take the existing Hourly usage data of someone who doe not have electric cars, then automatically add daily electric car charging number to it based on a few variables like car efficiency, daily miles, charging only at night or day and night etc…

That hourly data could then feed the existing spreadsheet that compute the solar/battery / grid usage.

[DrChaos]

Remember the POCO stocks are an investment to some and the investors expect increasing returns or they go somewhere else with their money. It is a bad economical spiral for the POCO to keep providing more to their investors then other business investments as well as their promise to keep the lights on for their customers.

This is a good reason in my opinion to have municipally owned utilities. In California, the municipal utilities, (LADWP, SMUD, Pasadena, Riverside, etc) have consistently lower rates than their for-profit peers, even with the usual management issues with a long term government project. In LADWP a manager making $300K is a scandal. In SDG&E/Sempra the top can make $5-10 milliion and charge higher rates.

SDG&E in particular has a clear incentive to prioritize fossil fuel use. They're owned by Sempra which is an unregulated company that just happens to own natural gas pipelines and generating stations supplying SDG&E territory. If you were a SDG&E executive, the way up to a much higher compensation is clearly to get promoted to Sempra. So, will anybody with power at SDG&E make efforts to reduce fossil fuel use and encourage more self and other generation that doesn't profit Sempra? No, it's to keep the gas flowing from the electric & gas utility side.

[DrChaos]

What tools do you use that led you to the conclusion that TOU-DR-P is the optimum for you ? Are they quantitative tools ? Spreadsheets ? Other ?

When I found out, and pretty much what I'd already guessed as a blinding flash of the obvious, that most of the residential PV decision for most folks was financial, I then saw an important part of the decision process would require a way to accurately compare what a residential electric bills would be both before and after PV additions under various available tariffs, with considerations for knowing or at least defining things as unknowable for the future.

I didn't do an exact to the penny model---gathering the data was too hard and besides as I've mentioned before reproducing SDG&E's computations on the combination of tiered & TOU doesn't seem at all obvious.

It was more of an informed guess (we call it "physical intuition" in science, meaning something coming from the rear orfice that happens to be right more often than you'd naively expect). I looked at typical consumption/produciton in my TOU periods. Winter doesn't matter that much, all plans are about 1c diff from super-off peak, to off-peak to on-peak.

Looking at my consumption & production with either EVTOU2, DR-SES, TOU-DR-P and TOU-DR, I would end up at essentially zero energy charges any which way, with the hard money charges being dependent on NBC's, taxes and min bills which wouldn't change between any of the rate plans. The SDG&E online rate recommender said the same thing.

TOU-DR-P gives me most psychological comfort and least risk: Except for only a tiny number of days per year, which are disseminated a day ahead, the on peak vs off-peak difference is but one cent. So I wouldn't have to stress daily about the 2x increment in EV-TOU2 or other TOU plans at 4pm. And with the high level of rate arbitrage to super off peak I'm more likely to bank up extra energy credits in case the winter usage minus production is particularly high, or if I decide to get air conditioning.

And my motivation for solar was not entirely financial---I am interested in environmental improvement, which is one reason why I have an EV (other is that it's fun). Without an EV, solar would be uneconomical for me and I didn't do it as I was pretty frugal in consumption ($60-70 a month).

[Ampster]

No as there was no need for me as I already have 2 electric cars, but that would be farily easy to add.......

I am in Sonoma and get a True Up payback from SCP much like you do from MCE so the economics of over paneling are different for us. Two EVs also help soak up some of those extra Coulombs.

[Ampster]

........
SDG&E in particular has a clear incentive to prioritize fossil fuel use. They're owned by Sempra which is an unregulated company that just happens to own natural gas pipelines and generating stations supplying SDG&E territory. If you were a SDG&E executive, the way up to a much higher compensation is clearly to get promoted to Sempra. So, will anybody with power at SDG&E make efforts to reduce fossil fuel use and encourage more self and other generation that doesn't profit Sempra? No, it's to keep the gas flowing from the electric & gas utility side.

Unlike PG & E, which most likely will sell off their natural gas business as part of the bankruptcy. I do have to credit SDG & E for the improvements they made to their portion of the grid that made it less prone to cause fires.

[J.P.M.]

Have you overlaid some scenerios of a two EV family who drives say 50 or 100 miles a day and therefore could consume 25 kWhrs per day at off peak?

No, but assuming you are asking a serious and sincere question and not simply being your usual argumentative self, for the SDG & E published tariff schedules, I can easily model the effects on net usage and the effects changes or charges such as you write of will have on a bill for any billing period or periods and so for a billing year for adding/changing usage or generation, or on a mixture of both usage and/or generation in any amount or combination for any hour or hours in an 8,760 hr. year under any current or prior published SDG & E tariff. Took a while, but I believe I got there - at least the errors I discover now when checking a spreadsheet est. against an actual bill are way down.

But, I've been at such things since ~ 2007.

Why are you limiting off peak consumption to 25 kWhs. ?

The process is not conceptually difficult. It takes little more than a bunch of spreadsheets with ~ 9,000 or less rows, or ~ 36,000 rows or less if you use the 15 minute data, some detailed knowledge of a POCO's billing practices and rate policies as done and approved by the CPUC, and some patience. Mostly a PITA getting the details and minutia right - especially when SDG & E is a lot less than helpful and forthcoming. Cooperative neighbors helped me by providing copies of bills to check my stuff against and find stuff I screwed up on.

I think of a spreadsheet and go by each hour or less time period. It sounds daunting but once the climate zones, daily allowances and a few other things keyed in correctly for a particular account, it mostly comes down to a copy job of two 168 hour weeks - one for summer, one for winter, plugging/adjusting for 5 holidays, and getting the billing schedule dates right, mostly for tiered rate effects.

[Ampster]

No, but assuming you are asking a serious and sincere question and not simply being your usual argumentative self........

No argument here.

Why are you limiting off peak consumption to 25 kWhs. ?

No limitation implied. Use any assumption you want. The subject of this post is "Leveraging TOU rates with an EV" and I thought you might want to make a contribution to the topic.

[J.P.M.]

No limitation implied. Use any assumption you want. The subject of this post is "Leveraging TOU rates with an EV" and I thought you might want to make a contribution to the topic.

Yea, I read that. I also read the text of the post. The way I read and interpreted the text of the post, I saw Richard's question as related to his desire for discussion of a more general outline of how to leverage TOU rates to minimize the final POCO bill come true-up.

Without going too deeply into how I have a method that can do pretty much just that, and more capabilities I didn't describe but that may still be useful to some, and in order to not get too far off topic, I attempted to very briefly outline a method I'm pretty sure works for me and can work for others in N. County San Diego for use as a tool.

In so doing, I attempted to describe something that may resemble a general outline of the method.

I offer it on a take it for what it's worth basis.

As for what you call an assumption, I saw your you're question to me as being pretty specific with respect to the number of vehicles and the number of off peak kWh (and not super off peak BTW). My question was an attempt to get information in order to try to understand why all the specificity which I saw as somewhat irrelevant - sort of like describing the color of two cars involved in an accident. I asked because I wanted to make sure I didn't miss something you were trying to get at.

The general method I (very) briefly outlined will handle changes caused by your specific conditions, or any changes that cause a 25 kWh/day in off peak usage.

For most residential PV, I see no need to describe what causes the usage change(s) or the time(s) of those changes to determine what changes in billing those different/changed conditions may cause - just when they occur and their magnitude. Why they occur is optional.