TOU for SCE in Southern California analysis

[J.P.M.]

The Eagle device (~$100), made by Rainforest Automation, talks directly to a smart meter and makes your usage data available for logging... either directly into csv, or uploading to the cloud. No calibration problems since it is getting data from the meter itself. It is compatible with most SDG&E, SCE, and PG&E meters. I transfer my data to PVOutput.org at 5 minute intervals, although it is capable of reporting much faster. You can see my consumption data here... the PV production data will be added soon. Click a date to see the detail... the defauly view is intended for production data, which I don't have yet.

It is pretty easy to see by looking at the chart when the fridges, heater and other cyclic loads come on. Loads like the microwave, electric oven, and humidifier are also easy to spot. I've started using a Kill-A-Watt to mapping out my baseline usage, usually around 170 W, or over 200 when the fountain is running, and have accounted for around 100 W of it so far.

Thanx for the insight. Honest.

[sensij]

The Eagle device (~$100), made by Rainforest Automation, talks directly to a smart meter and makes your usage data available for logging... either directly into csv, or uploading to the cloud. No calibration problems since it is getting data from the meter itself. It is compatible with most SDG&E, SCE, and PG&E meters. I transfer my data to PVOutput.org at 5 minute intervals, although it is capable of reporting much faster. You can see my consumption data here... the PV production data will be added soon. Click a date to see the detail... the defauly view is intended for production data, which I don't have yet.

It is pretty easy to see by looking at the chart when the fridges, heater and other cyclic loads come on. Loads like the microwave, electric oven, and humidifier are also easy to spot. I've started using a Kill-A-Watt to mapping out my baseline usage, usually around 170 W, or over 200 when the fountain is running, and have accounted for around 100 W of it so far.

[J.P.M.]

I definitely will. I'm "that" type. My current rate plan, RATE-D with just tiers was *EASY* compared to all the TOU stuff we just did here. I had a slick spreadsheet for my ROI that when I got my monthly bill, I added one new row. Each month I filled in about ~6 key parameters from the bill and the spreadsheet calculated what my bill *would* have been prior to solar. In order for it to work correctly, I had to validate baselines #'s and rates each time. The quick way I found to do this was to have it calculate my bill based off my actual usage (which I pull independently from my TED 5000 device- I've got that fairly automated too with an automatic URL generated by Excel) and if my estimated bill is within a couple pennies, I've validated my baselines and rates without digging deep...we know how often they make little changes. In the last 4 bills it's either been spot on or within a penny. Then, once I see what I "saved" (with vs without solar), I write myself a check to a separate (high-yield) savings account I've got setup. The idea is that I'll pay myself back for my solar installation, month by month based off my actual ROI.

Now, with the new TOU-D-A rate plan that I've just changed to, I should be able to do something similar based on all the work I've already done to support this thread and the decision, but with hourly data needed to calculate/validate things, it won't be a single row in Excel anymore! Maybe a summary row on a separate spreadsheet and I'll archive the underlying data somehow. Funny how I got this whole ROI/spreadsheet really dialed in, so what do I do? Go make a big change like a rate change and have to start over!

What you write sounds real familiar. I found comparing spreadsheet predictions to actual bills is a very helpful/powerful checking tool. It also highlighted to me all the strange interactions and stuff my mother (or SDG& E) never told me. I'm lucky in that several neighbors share their bills/usage with me. No one is on T.O.U. yet.

I don't fear the spreadsheet part of making sense of T.O.U., but getting a realistic and representative set of usage vs. time data is something I'm still thinking/working toward.

Regards,

[insaneoctane]

Just keep checking.

I definitely will. I'm "that" type. My current rate plan, RATE-D with just tiers was *EASY* compared to all the TOU stuff we just did here. I had a slick spreadsheet for my ROI that when I got my monthly bill, I added one new row. Each month I filled in about ~6 key parameters from the bill and the spreadsheet calculated what my bill *would* have been prior to solar. In order for it to work correctly, I had to validate baselines #'s and rates each time. The quick way I found to do this was to have it calculate my bill based off my actual usage (which I pull independently from my TED 5000 device- I've got that fairly automated too with an automatic URL generated by Excel) and if my estimated bill is within a couple pennies, I've validated my baselines and rates without digging deep...we know how often they make little changes. In the last 4 bills it's either been spot on or within a penny. Then, once I see what I "saved" (with vs without solar), I write myself a check to a separate (high-yield) savings account I've got setup. The idea is that I'll pay myself back for my solar installation, month by month based off my actual ROI.

Now, with the new TOU-D-A rate plan that I've just changed to, I should be able to do something similar based on all the work I've already done to support this thread and the decision, but with hourly data needed to calculate/validate things, it won't be a single row in Excel anymore! Maybe a summary row on a separate spreadsheet and I'll archive the underlying data somehow. Funny how I got this whole ROI/spreadsheet really dialed in, so what do I do? Go make a big change like a rate change and have to start over!

[J.P.M.]

Thanks. I am sure there are better resources for SCE tariffs, but I certainly will help where I can.

You're Welcome.

I wouldn't sell myself short on that one. Think about this: If there were real good sources for information, don't you think you'd have found them by now after all the effort ?

FWIW, I think my stuff is pretty good for SDG & E and it can replicate most tiered bills within a few cents exclusive of weird local taxes, but I've not seen stuff as accurate. I'm working on T.O.U., but I really feel that's a matter of production income vs. the expense of time of use and lowering usage and time of use until cost matches or is lower than revenue.

Besides, the POCO's seem to feel that they have nothing to gain by explaining things, so they don't.

What you have may not be unique, and it probably will need some tweaking for awhile, but I bet it's pretty accurate for its purpose.

Just keep checking.

[insaneoctane]

Risk nothing, be nothing. Under the Ready, Aim, Fire category - Take the shot. Looks like you've done a lot of homework. You are now one of the go to people for SCE tariffs.

Thanks. I am sure there are better resources for SCE tariffs, but I certainly will help where I can.

[J.P.M.]

FWIW, I just switched my rate plan to Tou-d-a and should be effective in my next billing cycle starting on the 18th. Time to put my wallet where my spreadsheet is.

Risk nothing, be nothing. Under the Ready, Aim, Fire category - Take the shot. Looks like you've done a lot of homework. You are now one of the go to people for SCE tariffs.

[insaneoctane]

FWIW, I just switched my rate plan to Tou-d-a and should be effective in my next billing cycle starting on the 18th. Time to put my wallet where my spreadsheet is.

[russ]

It will change as politics and public opinion changes - not at all permanent. As it is all made up "facts" it is highly likely to be modified.

[insaneoctane]

You keep using "better", but that isn't really true. Right now, TOU-D-A and TOU-D-T are equally good... you will pay the same amount at the end of the year under either. If you were to add more consumption, it is unlikely to preserve your existing hourly distribution, so it is hard to say which plan may be best at that time until you model it (which you can easily do!).

Maybe semantics, but I do believe A to be better. I will admit if everything stays at current predictions, then the plans would be the same result. But, I feel there is uncertainty in my predictions, mostly on the production side. For example, I've only had my solar array online for 4 full months, so I have an estimated my generation to the 85% of a 10k PVWatts model. I may get more output, I make it less output. The more margin that I can get in my cost predictions, the better off I am. But, I feel plan A has more margin and therefore is better based off my current assumptions and predictions. I realize that my spreadsheet and predictions are based off my last years usage profile, I have tried to objectify the decision as to which rate plan to be on. I also realize that I might see more cross over between the rate plans if I varied my usage profile, but with so much hourly data I am not up for that!

[silversaver]

The calculation is never easy, but I'm still suggesting people to go little larger. The worse is by maxing TOU plan and trying to settle with smaller system. The solar price has drop and cost of production is less than $0.10 per kWh for most base on 20yrs output. You know the electricity rate will definitely goes up in next 20yrs and so is the power demand, why start small? You will spend more money in long run by saving a few bucks. It is a simple math without any calculation.

[sensij]

PVWatts does not account for savings time. If it did, you would find a 25 hour day and a 23 hour day in there when the time changed. The west coast is modeled as UTC-8, and right now, we are actually UTC-7. Further complicating it is the fact that the rate tariffs may have DST adjustment included in the hours that do not align with when DST is actually enacted (I'm looking at you, PG&E).

Although your intended use of this spreadsheet may be, in part, to see how much energy you can use before incurring a bill, I hope that other forum members find this earlier in their shopping process. It could become a very powerful tool to help people understand how to offset their bill cost-effectively, and shows that an array sized for something less than 100% of expected energy consumption can still fully offset their electric bill. (rates will change, of course, but TOU is likely to continue in one form or another for the foreseeable future.)

You keep using "better", but that isn't really true. Right now, TOU-D-A and TOU-D-T are equally good... you will pay the same amount at the end of the year under either. If you were to add more consumption, it is unlikely to preserve your existing hourly distribution, so it is hard to say which plan may be best at that time until you model it (which you can easily do!).

One more minor catch... the minimum monthly charge for -D-A and -D-T will be about $1.79 when you are net negative, not $0.93. The $0.93 would apply if, when combined with your other charges, you exceeded that minimum. I am not suggesting that distinction is worth trying to program in.

[insaneoctane]

I got to thinking (uh oh) and wanted to exercise spreadsheet to see that TOU-D-A would eventually become more expensive, mostly as a validation of all the rate plans. Probably because I'm still surprised that the TOU-D-A seems like such an obvious choice for me and I always question obvious (particularly when it seems to be different than most others and contrary to standard "recommendations"). So, I simply scaled my usage from 90% to 150% of actual and using the data table function in Excel (makes this easy), I created a sensitivity chart of the 4 rate plans vs USAGE. Pretty interesting, you'll see that once I exceed 12,230 kWh/yr I'm better off on the RATE-D plan. I labeled my "baseline" usage from 2014 (9060 kWh). It doesn't look like the other plans are ever better for me.

tou_analysis_sensitivity_2015.03.11.JPG

[insaneoctane]

Q: Anyone know if pvwatts data accounts for daylight savings in the hourly export? Since I'm using it as the basis for my solar output predicts, I'm noticing that the recent daylight savings change would be beneficial to TOU-D-A/B rates because the high rates don't start until 2pm and with DST my 2pm+ just got a bit fatter....I looked at the data and I don't see any change in the data to support the output moving at all during March, so I'm thinking not. If that's the case, I've got some additional margin on my numbers.

[insaneoctane]

Actually, that sort of brings up another point... I think the fixed charges associated with each plan need to be paid, there is no way to credit them out by TOU accounting, so even though you are showing a negative number for your TOU-D-A result, there is still likely to be a bill to be paid at the end of the net metering year.

Yes, I do have to pay SCE monthly for the fixed charges and I think you're right that they are a different color of money and can't be erased with production.