Official Southern California Edison thread

[garygid]

When you finally understand ONE month's billing, you can then try to understand how one month's excess generation (if any) would carry over to the following month's billing.

If the excess is "purchased" each month, the credit might just be handled as a +/-$ figure for each month. However, with a remaining (excess) credit for the entire billing year (if any), is that excess handled with a "true-up" at the end of the billing year, as is done by some PUs with Net-Metering?

 

[xtremeflyer]

So I did some more of my own math.. This Level 1/Level 2 thing during the SUMMER is great. The amount of money you make in Level 2 solar is so beneficial that I wouldn't want to mess with it.

For my July Bill, my total was -$3.03, if I use the TOU-T-TEV tariffs and assume I charge the Leaf 270kWhs, my new bill total becomes $18.34, a difference of $21.38. That means that the extra 270kWh = 8c/kWh

But for Winter time it is different. Since I'm not generating as much solar and I'm not getting the amazing Level 2 benefit during on peak, my November bill was $28.29. If I add in the 270kWh for the Leaf, my new bill becomes $71.34. That means that the extra 270kWh = 16c/kWh

So, Summer TOU-T-TEV = Good, Winter TOU-T-TEV = Bad

 

[mwalsh]

So, Summer TOU-T-TEV = Good, Winter TOU-T-TEV = Bad

Have you guys compared this rate to simply going on TOU-D-T, the standard TOU schedule?

 

[Boomer23]

So, Summer TOU-T-TEV = Good, Winter TOU-T-TEV = Bad

So if your LEAF driving is equal for summer and winter, your overall rate is an equal blend of the two rates, 12 cents, right? I guess we could maximize the benefit by driving the LEAF more in the summer and our ICE car more in the winter, but who really wants to do that?

Of course, it might make some sense if we use the heater a lot. The heater in a Prius doesn't really lower your efficiency, but the heater in a LEAF is the biggest drain on the battery.

 

[xtremeflyer]

So, Summer TOU-T-TEV = Good, Winter TOU-T-TEV = Bad

Have you guys compared this rate to simply going on TOU-D-T, the standard TOU schedule?

If I use TOU-D-T, I would get 10.3c in July and 14.1c in November.. So TOU-T-TEV might be better for me in the summer and TOU-D-T better in the winter, but I think you can only change once every 12 months.

 

[smkettner]

I plan to just use them all and see how it falls out over the next couple years.
Hard to really do a calc for me until I get real TOU data. And if work adds an evse I may not even go TOU.

 

[Boomer23]

I'll write to Jordan at SCE and ask him to explain why they count our negative kWh as positive in my TOU-D-T billing, and how that jives with his explanation to me last Monday.

Jordan Sugar, PEV Analyst at SCE responded to my email this morning, telling me that he's researching the answers to our questions with subject matter experts within the company. I'll be sure to follow up with you guys when he gets back to me.

 

[Boomer23]

I'll write to Jordan at SCE and ask him to explain why they count our negative kWh as positive in my TOU-D-T billing, and how that jives with his explanation to me last Monday.

Jordan Sugar, PEV Analyst at SCE responded to my email this morning, telling me that he's researching the answers to our questions with subject matter experts within the company. I'll be sure to follow up with you guys when he gets back to me.

Latest word is that an internal meeting will be held within SCE next week with various subject matter experts to address the questions we've raised.

 

[tbleakne]

So I did some more of my own math.. This Level 1/Level 2 thing during the SUMMER is great. The amount of money you make in Level 2 solar is so beneficial that I wouldn't want to mess with it.

I understand better now how negative peak usage during the summer really pays off for you if you are at Level 2. The more you charge your car, the lower the Baseline allocation for peak time, and the very high level 2 peak rates more than compensate for slightly more level 2 for the car.

It seems to me SCE's justification for including negative peak usage in the Baseline allocation is probably a focus on grid usage rather than grid generation. Negative usage means you are using the grid to "park" your solar surplus, so by this thinking even negative usage should force one toward Level 2. As you have discovered, however, this policy can payoff for the customer with plenty of excess solar.

My solar spreadsheet now includes these corrected baseline calculations. It looks like my modest solar is only rarely going to be enough to kick me into that negative peak Level 2 that is paying off for you. One reason that I did not fully appreciate is the fact that Peak applies 10AM-6PM M-F, NOT weekends. This means 2/7 of each month's solar production is recorded in off-peak time. Those with good south-facing roofs also get some off-peak production before 10AM. Since most everyone will have positive net off-peak usage, this fraction of solar will subtract from the off-peak usage, reducing how much you exceed Baseline rather than increasing it.

I agree we want to be very careful what we ask for.

 

[mwalsh]

Richard Cromie from Edison was at that CSE meeting last night. He had a real good chart as part of his presentation that covered the TOU-T-TEV rate structure. I'm hoping to get a copy of it today.

 

[Boomer23]

I'm overdue for posting an update on the topic of solar PV owners with TOU-D-TEV rates.

My contact, the analyst at SCE's PEV group, basically confirmed our understanding of how Tier 1 allocations are calculated, with the example below.

In regard to Solar PV production, which is NOT addressed in the example below, he confirmed that, as we already knew, SCE allocates the absolute value of our usage and our solar generation to calculate Tier 1 usage. There is really no explanation for why this is done, except to say "The brief answer is that using the absolute value of the net usage was determined to be the best and most consistent approach to treating baseline allocations across multiple possible conditions".

EXAMPLE:
The TOU-D-TEV rate has three separate peak periods (on-peak, off-peak, and super off-peak), and each period has two tiers. Your baseline allocation is split among these three periods, based on how much energy you use in each period that month. These “peak allocations” are then multiplied by 130% to determine the Tier 1 allowance for each period (the tariff defines Tier 1 as all usage up to 130% of that period’s baseline allocation). Any usage beyond the Tier 1 allowance is billed at the higher Tier 2 amount.

The following example shows how usage is allocated into Tier 1 and Tier 2.

Column A (Monthly Baseline Allocation) is the daily baseline allocation for the season multiplied by the number of days in the month (10.2 kWh * 30 days)

Column B (Daily Usage) shows the customer’s actual usage for each peak period during this particular month. The customer used a total of 540 kWh this month.

Column C (Peak Percentage) divides the kWh used during each period by the total kWh used during the month

Column D (Peak Allocation) multiplies the Peak Percentage by the Baseline Allocation (Column C * Column A)

Column E (Tier 1 Allowance) is the Peak Allocation multiplied by 130%

Column F (Tier 1 Usage) is the amount of peak usage that falls into Tier 1

Column G (Tier 2 Usage) is the peak usage in excess of Tier 1 (Column B minus Column F)



For my part, I plan to wait and see what we see on our upcoming bills in sunnier months and when we start charging our EVs. Our greater negative costs for our Peak generation may offset much of the Tier 2 usage during Off Peak and Super Off Peak periods.

 

[garygid]

So, assuming On-Peak "B" is -90 (over-generation) instead of 90.
How does the table change?

 

[Boomer23]

So, assuming On-Peak "B" is -90 (over-generation) instead of 90.
How does the table change?

I think it wouldn't change at all, Gary. Since for tier calculations, SCE considers over generation equal to usage, the table would look the same. However, on your monthly bill, the 90 kWh of net generation would show up as negative dollars.

BUT, here's another thought. Since SCE's meter only sees NET generation, what if I charged my EV during the day instead of at night? I'd charge it enough during On-Peak so that, combined with my on-peak household usage, the SCE meter never sees net generation, nor usage. That way, my Tier 2 usage would only be based on my net usage, which would be zero during Peak, and less than the Tier 2 cutoff during Off Peak. And there would be almost no usage during Super Off Peak. So maybe my usage would always be in Tier 1. Now, I wouldn't get any negative dollars to compensate my bill, but I might stay in Tier one all year, or at least during the sunny months.

Interesting thought exercise. And it makes me wonder if SCE is really going to encourage us to use power from midnight to 6 am, like they would like us to.

 

[xtremeflyer]

I think it wouldn't change at all, Gary. Since for tier calculations, SCE considers over generation equal to usage, the table would look the same. However, on your monthly bill, the 90 kWh of net generation would show up as negative dollars.

BUT, here's another thought. Since SCE's meter only sees NET generation, what if I charged my EV during the day instead of at night?

Interesting thought exercise. And it makes me wonder if SCE is really going to encourage us to use power from midnight to 6 am, like they would like us to.

Actually, during the summer months you WANT Tier 2 during On-Peak. It's so lucrative for those of us with solar. But during the winter months, I think you might be on to something, at least charging during the day enough that your Off-Peak and Super Off-Peak don't hit Tier 2. Of course, I'm at work during those hours, so I wouldn't be able to try it out really.

 

[garygid]

Well, each PU is paying differently for over-generation, so your SCE strategy does not work for SDG&E (seems to pay very little).

 

[mwalsh]

Can you break this down for me in the simplest of terms....I'm having a real hard time getting my head around what you're talking about.

 

[xtremeflyer]

Can you break this down for me in the simplest of terms....I'm having a real hard time getting my head around what you're talking about.

Look at Boomer's chart and assume that the 90 kwH during Peak was negative. Now lets say instead of charging your vehicle all in Super Off-Peak, you chart 50kwH of that during Peak.

Your new numbers would be
-40 On Peak, 300 Off Peak, 100 Super Off Peak

SCE uses absolute values, so your Monthly Usage would now be 440 (40 + 300 + 100) instead of 540.

Your allocation percentages would be 9%, 68% and 23%, giving you a tier one allowance of
36kW On Peak, 270kW Off Peak, 91kW Super Off peak. This would keep almost all of your energy in Tier 1.

 

[mwalsh]

Nope, even worse trying to comprehend it after a lunchtime glass of wine. I'll try again tomorrow, sober.

 

[Boomer23]

Can you break this down for me in the simplest of terms....I'm having a real hard time getting my head around what you're talking about.

Let's see if I can make it clearer. It is confusing stuff and others may be having a hard time with it as well.

Also, I'm not the sharpest knife in the drawer, so you other guys, please check me out on this.

This is for folks with solar PV systems and we're looking at the TOU-D-TEV rate, which is said the be the best rate for those planning to charge an EV, IF you don't have a separate SCE meter for the EVSE circuit. (It turns out that the dual meter panels that allow you to use the TOU-EV-1 rates are way expensive, large and costly to install, so most folks will find them prohibitive).

Examples of the TOU-D-TEV rates per kWh for Summer are:
On-Peak: Tier 1: 19 cents, Tier 2: 55 cents
Super Off-Peak: Tier 1: 10 cents, Tier 2 16 cents.
There are also winter rates and an Off-Peak period as well.





So here we go into the complex part:
We'd like to keep all of our usage in Tier 1 as much as possible. Tier 1 rates apply to your usage up to 130% of your baseline allocation. Then you pay Tier 2 rates for all usage above that for the month. An example of a baseline figure is 306 kWh per month. So all of your usage below 306 X 1.3 = 398 kWh will be in Tier 1.

SCE allocates your Tier 1 usage, in this case 398 kWh, to the three time periods based on your percentage of usage by time period.

Now, here's the crux of the issue: We'd hope that SCE would only count the power that we actually pull FROM SCE in these calculations. Many of us make enough power with our solar PV systems that we wouldn't go into Tier 2 at all in sunny months. BUT, using Time Of Use meters, SCE also measures how much power we send back TO their grid. Surprisingly, SCE also counts these UNUSED kWh, which are due to over-generation, as if they were power USAGE in calculating the Tier 1 limit. To be super clear here, SCE adds the kWh SENT BACK to SCE to the kWh USED to calculate the usage applied to Tier 1. So the more power we generate during On-Peak, when it's sunny, over and above the amount we use in our homes, the more likely we'll be to be billed Tier 2 rates for our Off-Peak and Super-Off Peak time periods. Because of the fact that we generated more solar power, we're more likely to find that we are billed the Tier 2 rate for much of our EV charging (AND for much of our evening household usage in the Off-Peak period). That just doesn't seem right!





Now, it needs to be said that all of the kWh sent back to SCE are given a negative sign on your bill. So the negative charges at those nice high 55 cent rates in summer, will more than offset the 16 cents for the kWh used at night during Super Off-Peak. I think that this is what xtremeflyer calls the lucrative effect of SCE's pricing plan.

However, in a Net Metering agreement, if I end up, including charging my EV, having a net usage of zero kWh at the end of my 12 month measuring year, but if I have a net negative dollar bill due to the high negative costs built up because I sent a lot of kWh back to SCE during Peak times, will SCE pay me for those negative dollars? Or will they say that they don't owe me anything because I used a net of zero kWh for the year? I suspect that the case will be the latter, and this seems to agree with reading I've done on the web.

I'm now wondering how to log as FEW "overgeneration" kWh as possible. Remember that SCE's meter doesn't "see" kWh that your solar PV system generates but that you use at the same time. An example is the kWh that you use to cook during sunny days. At those times, you are just using solar power that you are generating, and SCE never even sees that power. So what if I charge my EV during the day time, when the sun is shining? These kWh used for charging my EV wouldn't impact my Tier usage calculation at all. Of course, I also wouldn't see the large negative charges for Tier 2 overgeneration that would add large "credits" to my bill.

I haven't done the math on this yet, so it's still just an idea.

We'll need SOME overgeneration during summer months to build up a "bank" of negative kWh for winter charging, but we could do much summer charging during Peak periods in order to stay in Tier 1 for the month.

I'm interested in this because SCE's method of calculating Tier 1 limits is getting me to think about charging during Peak times, which is against SCE's intention, I'm sure, because they have excess capacity at night. If I decide to charge during the day because of SCE's billing scheme, I'll be keeping my excess power generation during PEAK hours away from other grid users for their air conditioning, etc, which is counter to what we want to do as a community.

It may also be worthwhile to look at other available rate schedules from SCE to double check that they wouldn't result in better rates after all.

 

[mwalsh]

Thanks for the long explanation. I get it now. I'm not sure how I feel about it, but I get it.