TOU for SCE in Southern California analysis

[Gmoney!]

Yah i doubt ill qualify for that. I'll be producing more than consuming during day but that EV will use up a ton at night which i'll buy back at .11 cents but still will probably go over 130%.. Is it calculated monthly or daily?

Guess i was wrong, got my SCE bill for last month...

Before TOU-A, bill was $410
On TOU-A, bill is now $180

I use 1384kwh

1044 of them are super off peak
268 off peak
72 peak

As for credit, I am getting 330kwh at lil over 10 cents so credit of $34

Not sure how this will work when I get solar but something tells me i'll be a lil more in the negative than i projected. We will see, i am not al that sure how accurate the pvwatt production prediction will be.

[J.P.M.]

I agree that it is a credit against future usage.

In my real life example, having been through a one year TOU-EV cycle with SCE, I did NOT have positive net generation for the year. However, I had an ending credit at the end of the year, due to the favorable effect of solar generation and the TOU plans, but they did not pay me anything for that ending credit, since I did not have positive net generation for the year.

Which seems to make sense, and perhaps another advantage of T.O.U. - enabling a combination of reduced usage and heads' up time of usage to allow a user and owner of a smaller system to have some further control to offset an equal or greater portion of their bill.

[wrlsguy]

I'm pretty sure that's a credit against future usage, not money in your pocket for overgeneration.

I agree that it is a credit against future usage.

In my real life example, having been through a one year TOU-EV cycle with SCE, I did NOT have positive net generation for the year. However, I had an ending credit at the end of the year, due to the favorable effect of solar generation and the TOU plans, but they did not pay me anything for that ending credit, since I did not have positive net generation for the year.

[insaneoctane]

I would agree, I would look at it as a credit for futre usage. But, it's also true, that after the 12 month true-up period, per AB-71, SCE would have to send me a check if it still shows they owe me money. I'd likely turn on the A/C a little more in the summer or consider a hot tub that I've been avoiding if I truly saw the credit at the end of the true-up period and it was more than a few bucks.

[silversaver]

just for record. If you have overgeneration, regardless of getting the check or roll over to next cycle, SCE pays you $0.049 per kWH. Your are not getting the kWh credit but cash value after annual true up period. I think taking the check is better choice since you are getting the same dollar value why roll into next billing cycle.

[J.P.M.]

Although I failed to comment yet, on my post above (#23), something interesting about the graph:
3rd month (March), shows that I consumed more than I generated (682C vs 623G), yet I got a credit (-$23.79). This illustrates the power of the TOU if it can work for you...

FYI, in case it's not obvious, the "used" or "consumed" amount is the raw consumption amount, NOT net (gereration does not effect the raw amount).

I'm pretty sure that's a credit against future usage, not money in your pocket for overgeneration.

[insaneoctane]

Although I failed to comment yet, on my post above (#23), something interesting about the graph:
3rd month (March), shows that I consumed more than I generated (682C vs 623G), yet I got a credit (-$23.79). This illustrates the power of the TOU if it can work for you...

FYI, in case it's not obvious, the "used" or "consumed" amount is the raw consumption amount, NOT net (gereration does not effect the raw amount).

[DanS26]

Am I missing something here?

You already said you have a TED5000 system. If you set up the TED for solar capture and have TOU set up properly then it will be obvious over a period of a few months and a few different TOU plans which one is advantageous for your household usage patterns. Why reinvent the wheel?

Download TED data to spreadsheet and do a boatload of analysis.

[J.P.M.]

Yes, 10,000kWh.
Also, I understand that PVWatts isn't ideal for this, but I really don't know how else to predict my hourly generation. If I had 1 year of past data, I'd just use that and it would be a great starting point for me....but I don't have that. If you have a better suggestion for predicting hourly generation data, I'm all ears!

Forget about the ears. Now see this:

I appreciate your situation. Mine isn't a whole lot different.

Given the uncertainties involved, PVWatts is probably as good as most TOOLS for estimating LONG TERM OUTPUT OVER MANY YEARS.

Get the hourly PVWatts output for your system on a spreadsheet. If you're familiar with SAM, that's probably better. Or, run both and take your best shot at something that makes sense to you between the two.

IF you DEFINE a PVWatts hourly estimated output for one year as a long term average output for your system, and multiply each hour's output by that hour's rate from a POCO T.O.U. tariff schedule(s) of your choice, you will have an estimate of annual average revenue from you system. That revenue will then be constant regardless of how much you use, provide the system is not oversized. You can adjust that for annual rate increases as your needs and/or desires dictate. Because the weather will vary, revenue for some years will be more, some less.

For T.O.U., one BIG consideration is to think about and decide (define really) just what an average year's usage will, or ought to look like in terms of quantity of kWh used and time of use, and have a fair probability of being representative of your lifestyle. Once you do that, for better or for worse, high/low, right /wrong, you will be able to estimate the cost of that usage. Again, some years will be more, some less. The variables of changing lifestyles, not to mention how the POCO will probably mess with the peak/off peak times in the future will always compound the uncertainty, but that's life. Sue me.

The difference in the two yearly totals, revenue vs. expense will be how much you'll owe or pay. Again, some years will be more, some less. Think long term and think flexible.

I realize SCE has a dizzying tariff schedule and they are a lot less than forthcoming about helping to make sense of the mess, but the logic above in some form ought to work.

Basically, it's figuring out revenue and expense separately and going from there. Maybe a PITA, but I'm pretty sure the tools exist to do it.

I've got the SDG & E schedule TOU - SES on a spreadsheet of 8,760 + rows. A TOU with bins would be more difficult, but doable.

Take what you want of the above. Scrap the rest.

[Gmoney!]

Yah i doubt ill qualify for that. I'll be producing more than consuming during day but that EV will use up a ton at night which i'll buy back at .11 cents but still will probably go over 130%.. Is it calculated monthly or daily?

[insaneoctane]

I still didnt understand what this .10 cent credit is? Is it if you stay below 130% of baseline after net metering or just based on total consumption?

My interpretation is you will earn up to approximately $30ish credit IF you net consume 130% of your baseline. Ie. Baseline = 300 kWh then 130% is 330 at $0.10 = $33. If you net less, you get less credit.

[Gmoney!]

My calculations also showed TOU A as better. I think if you can shift most your usage to off peak, TOU A will be the better plan eventhough sce claims TOU D is better for solar owners.

I still didnt understand what this .10 cent credit is? Is it if you stay below 130% of baseline after net metering or just based on total consumption?

[insaneoctane]

Also, I think you mean you used 10,000 kWh last year, not 10, right ?

Yes, 10,000kWh.
Also, I understand that PVWatts isn't ideal for this, but I really don't know how else to predict my hourly generation. If I had 1 year of past data, I'd just use that and it would be a great starting point for me....but I don't have that. If you have a better suggestion for predicting hourly generation data, I'm all ears!

[insaneoctane]

Here's one more showing $/month and usage

tou_analysis_b_2015.02.28.JPG

[J.P.M.]

Nicely done so far.

One more time: using PVWatts to compare individual months or years will lead to problems. Part of the reason you are not getting anywhere what PVWatts estimated is because your weather is not the same as what PVWatts uses to ESTIMATE LONG TERM OUTPUT..

Do as you wish. I encourage you to continue your work. But, meant as a friendly suggestion, and in the most respectful way possible, IMO, your ignorance of what PVWatts does, how it uses weather data, and its limitations are leading you to false conclusions and incorrect expectations. I'd just as respectfully suggest, read the PVWatts help info screens and also spend about 20 min. reading info on the net about TMY's - Typical Meteorological Years, and how they are generated and their limitations. You have only knowledge to gain and a few miuntes to lose.

Also, I think you mean you used 10,000 kWh last year, not 10, right ?