TOU for SCE in Southern California analysis

[J.P.M.]

Iso: Check your PM's.

J.P.M.

[insaneoctane]

That last graph was incorrect, I did it a little differently this time and replaced it, so click on it again if you care... It's more of a "peanut butter" approach in that it spreads the $258 credit evenly in dollars over the 12 months. That buys you a little less in the Summer time as rates are higher, but it allows me to have extra kWh even in Dec when I am running high usage vs production....

Also, I'm working on kind of a neat chart, but it's a pain in the @$$ because Excel really doesn't want me to do it. I wanted to take the one that shows the composition of kWh used/gen each month by type/rate and add in the actual $ value. The graph is scaled to kWh, but I wanted $ to appear within the color portion. I'm starting to do it, I'm attaching a preview. I've only done it for Jan/Feb and then I jumped to August to see if it is comprehensible...not sure, what do you guys think? The idea is that 215kWh can be worth $98.86 (Aug, on-peak, gen), yet 306kWh can be worth $91.69 (Aug, off-peak, Used). Take a look, the graph wants to show the kWh for labels (that's what you see for most), but I've started to replace them with a link to the actual $ equivalent.

tou_analysis_2015.03.07.JPG

[insaneoctane]

Here's a good visual for the full year effect of each TOU for my usage...Kind of interesting, if you look a the red (TOU-D-B) that plan has a $16 flat rate associated with it, and you can see those ratchets knock the graph quickly up every month. Clearly, that doesn't improve my situation much over my standard RATE-D tiered plan I'm on now.

tou_analysis_cum_2015.03.07.JPG

[insaneoctane]

Not claiming complete, but ready to have anyone willing take a look at my spreadsheet. Here's a couple notes:
1. It is xlsm because it contains some VB code for holiday calculations; for TOU you need both weekends and holidays to be at a different rate. I realize this might concern people who are particularly sensitive to downloading from unknown sources. Not much I can do for you other than assure you that it's legit and you can make your own choice!
2. I tried to generalize all the inputs with the standard Excel orange/beige background with blue text
3. To try your own data, you'd have to fill in the following:

• Day of month that your bill starts
• 12 months of hourly dates, unless your data works with my dates. I started Nov 16, 2014 and took it to Nov15, 2015.
• Hourly generation numbers, in kW
• Hourly NET numbers, in kW (My output is NET to grid, so I have to calculate USE by adding NET + GEN, where GEN is negative
• Appropriate Rate schedules; I have tabs for each and have 4 schedules modeled, in many cases there aren't too many inputs (on the right side, again, the special color and format will help you id the inputs)

That's it in a nutshell. I don't know if anyone will actually look at this, it was great for me. I'm not going to pretend it's elementary, or easy to adopt to someone else's data or POCU. I hope it's interesting and/or helpful to some.

Here's the link on Google Drive:
Solar_TOU_Rev_M12.xlsm

[silversaver]

Not claiming complete, but ready to have anyone willing take a look at my spreadsheet. Here's a couple notes:
1. It is xlsm because it contains some VB code for holiday calculations; for TOU you need both weekends and holidays to be at a different rate. I realize this might concern people who are particularly sensitive to downloading from unknown sources. Not much I can do for you other than assure you that it's legit and you can make your own choice!
2. I tried to generalize all the inputs with the standard Excel orange/beige background with blue text
3. To try your own data, you'd have to fill in the following:

• Day of month that your bill starts
• 12 months of hourly dates, unless your data works with my dates. I started Nov 16, 2014 and took it to Nov15, 2015.
• Hourly generation numbers, in kW
• Hourly NET numbers, in kW (My output is NET to grid, so I have to calculate USE by adding NET + GEN, where GEN is negative
• Appropriate Rate schedules; I have tabs for each and have 4 schedules modeled, in many cases there aren't too many inputs (on the right side, again, the special color and format will help you id the inputs)

That's it in a nutshell. I don't know if anyone will actually look at this, it was great for me. I'm not going to pretend it's elementary, or easy to adopt to someone else's data or POCU. I hope it's interesting and/or helpful to some.

Here's the link on Google Drive:
Solar_TOU_Rev_M12.xlsm

thank you

[J.P.M.]

Iso: I was unable to download anything past the first page.

[sensij]

Thank you for sharing your work. There are a couple things in it that catch my attention and I'm digging more deeply to understand. Some initial comments though:

1) It is good that you see the difference between two plans with negative annual balances is only in the fact that additional energy could have been consumed at no charge. Just to be clear, the actual financial credit that would be available to you at the annual true-up (end of the "relevant period" as SCE calls it) is the same no matter what your negative balance appears to be. It is just the (kWh generated - kWh consumed) * the net suplus compensation rate (NCSR, shown here). The result is that if your usage is as you project, the money in your packet at the end of the year would be the same for either -D-A or -D-T.

2) Your usage shows some interesting patterns (see picture of daily usage, from Column E of the spreadsheet), with much lower kWh used in July and in November. You are showing >25% less usage in July than in either June or August, which seems atypical to me. The July pattern in particular contributes substantially to the benefit of TOU-A for you, as I would calculate it. Why is your usage so much lower in that month?

daily usage.JPG

3) The signs in Column C seem to have been changed from the PVWatts (or SAM ) output. The negative values in their output when the sun isn't shining are to account for the energy used by the inverter even when there is no power to invert, and should be positive values in the sign convention you adopted. You seem to have just zeroed these out in your adjusted column D... it might not make much difference, but wanted to point it out.

[insaneoctane]

Thank you for sharing your work. There are a couple things in it that catch my attention and I'm digging more deeply to understand. Some initial comments though:

Thank you for your feedback.
1. Although I am not looking to use my system to make money, I didn't realize that the NSCR program was *so* one sided! (ie <$0.05/kWh surplus) . It definitely shows that I should find a good use for my over production besides selling it back to SCE, so thanks for that.

2. Gut reaction to your observation about two low usage periods would be that we were out of town for extended period during those dates. If we were to stay and have a higher July, I still believe that TOU-D-A is the clear winner.

3. Although I don't remember flipping the sign on my data, I certainly might have. That decision was many calculations ago! I also did zero out the inverter when it was very close to zero and I will check if that has any significant play on results.

Again, thanks for taking the time to review!

JPM- I am curious if you are still having issues reading the file?

[sensij]

I've spent some more time with the TOU-D-A calculations and the spreadsheet produces the same result I would get. If it saves some time for others looking at it, of the 19 columns in the S to AK range for TOU-D-A, only three are really needed to get at the end result... T, AF, and AI, corresponding to basic TOU charges, the 0.10/kWh "credit", and the fixed monthly charge. The rest appear to be for data presentation in the charts.

I'm not sure the TOU-D-T calculations are correct. The baseline allocation in that plan needs to be divided among the different TOU categories (off-peak, on-peak) according to the monthly use in that category, and the tiers are calculated from there. For example, in a month with 400 kWh baseline allocation, with 60% off-peak and 40% on-peak usage, there would be 240 kWh of baseline allocation in off-peak and 160 kWh of allocation in on-peak before moving into the next tier. I haven't followed the spreadsheet's TOU-D-T calculations used closely enough to be 100% sure, but I don't see that accounted for. See Special condition 7 on page 12 of the tariff for more information.

[J.P.M.]

Thank you for your feedback.
1. Although I am not looking to use my system to make money, I didn't realize that the NSCR program was *so* one sided! (ie <$0.05/kWh surplus) . It definitely shows that I should find a good use for my over production besides selling it back to SCE, so thanks for that.

2. Gut reaction to your observation about two low usage periods would be that we were out of town for extended period during those dates. If we were to stay and have a higher July, I still believe that TOU-D-A is the clear winner.

3. Although I don't remember flipping the sign on my data, I certainly might have. That decision was many calculations ago! I also did zero out the inverter when it was very close to zero and I will check if that has any significant play on results.

Again, thanks for taking the time to review!

JPM- I am curious if you are still having issues reading the file?

Yes as of about 30 sec. ago. I get screen shot of P.1 and a message that says :" Whoops ! There was a problem loading more pages." I cannot access the shown page either. Go Figure. My Luddite brain is stymied.

[sensij]

Yes as of about 30 sec. ago. I get screen shot of P.1 and a message that says :" Whoops ! There was a problem loading more pages." I cannot access the shown page either. Go Figure. My Luddite brain is stymied.

I ran into that problem too, when I tried to use the "Open With" function. When I used the "Download" function, it came through correctly.

[sensij]

If it helps to have a non-google drive option, I moved it into my dropbox, and it can be accessed by request.

[J.P.M.]

If it helps to have a non-google drive option, I moved it into my dropbox, and it can be accessed with this link.

Iso: Got it. Thanx. It may be a bit before I respond. PM on the way.

[insaneoctane]

I've spent some more time with the TOU-D-A calculations and the spreadsheet produces the same result I would get. If it saves some time for others looking at it, of the 19 columns in the S to AK range for TOU-D-A, only three are really needed to get at the end result... T, AF, and AI, corresponding to basic TOU charges, the 0.10/kWh "credit", and the fixed monthly charge. The rest appear to be for data presentation in the charts.

I'm not sure the TOU-D-T calculations are correct. The baseline allocation in that plan needs to be divided among the different TOU categories (off-peak, on-peak) according to the monthly use in that category, and the tiers are calculated from there. For example, in a month with 400 kWh baseline allocation, with 60% off-peak and 40% on-peak usage, there would be 240 kWh of baseline allocation in off-peak and 160 kWh of allocation in on-peak before moving into the next tier. I haven't followed the spreadsheet's TOU-D-T calculations used closely enough to be 100% sure, but I don't see that accounted for. See Special condition 7 on page 12 of the tariff for more information.

Sensij, I'm glad the TOU-D-A appear to match.
As, for the TOU-D-T, I read the tariff sheet you referred to and that is most definitely, not the way I used to calculate baseline. I read the tariff sheet a few times but couldn't really "get" it. Your description is much easier to follow by itself, but can't confirm it matches what I read:

In order to determine the allocation of baseline kWh to each Time-of-Use (TOU) period, the customer’s baseline allowance for the billing period is first allocated to each TOU period based on the ratio of the metered seasonal kWh in the TOU period to the total metered seasonal kWhs in the billing cycle. TOU kWhs are then assigned to each tier by applying the existing tiering parameters. Baseline allowance for distribution to TOU periods is the minimum of the standard allocation as set forth in Preliminary Statement, Part H, or total metered kWh for the billing cycle

Sounds like I've got more work to see if TOU-D-T does anything for me still.....

[sensij]

Sensij, I'm glad the TOU-D-A appear to match.
As, for the TOU-D-T, I read the tariff sheet you referred to and that is most definitely, not the way I used to calculate baseline. I read the tariff sheet a few times but couldn't really "get" it. Your description is much easier to follow by itself, but can't confirm it matches what I read:



Sounds like I've got more work to see if TOU-D-T does anything for me still.....

There is a thread in a Tesla forum that is discussing this at the same level of detail you seek. This post in particular provides an explanation similar to mine, but nowhere do I see how to handle it if your net usage during a particular TOU period is negative, as it would be for you in Peak for most of the year. The thread suggests that if you sign up for the TOU-D-T plan, the calculation in the margin of your bill will explain it, but given the limitations on plan switching I'm not sure it really matters enough for you to try to find out. As you've shown, TOU-D-A is likely to leave you with a net metering credit at the annual true-up, which is the best possible outcome. Only once you have more loads that you plan to add will it be worth re-evaluating, but who knows what the rates will be at that time anyway.