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TOU Metering Calculator

Discussion in 'Energy, Environment, and Policy' started by Runt8, May 24, 2017.

  1. Runt8

    Runt8 Member

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    Location:
    Colorado
    In preparation for my Model 3, I've been researching what options my energy provider has available. They are currently running a TOU Metering pilot program that charges higher rates from 4-8PM, and lower rates from 8-4PM. I'm curious if it makes sense for me to switch once I start charging an EV every night (or possibly even switch now, as other than cooking dinner we don't use much power between 4-8PM).

    Does anyone know of a good TOU calculator available online? Or am I stuck with using an Excel spreadsheet? :eek:

    Thanks!
     
  2. MorrisonHiker

    MorrisonHiker S 90D 2017.28 c528869

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    Are you in Xcel territory? If so, there's a thread here and a spreadsheet you can use to calculate your potential savings: Xcel Time of Use Rates in Colorado

    The times you listed don't match up with Xcel's but you could easily modify the spreadsheet to your needs.
     
  3. Runt8

    Runt8 Member

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    #3 Runt8, May 24, 2017
    Last edited: May 24, 2017
    I use IREA. Normal rates are $0.113, peak goes up to $0.27:eek:, and off-peak down to $0.073. The outrageous peak rate has me concerned, as it seems much higher than other plans I've seen. I'll take a look at the link you sent - thanks!
     
  4. MorrisonHiker

    MorrisonHiker S 90D 2017.28 c528869

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    Yikes. Those rates are definitely higher than Xcel. At least IREA is a coop and you get that refund check every year. ;)
     
  5. brucet999

    brucet999 Active Member

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    When I got my Tesla, I was on SoCalEdison tiered rates which got up to 34 cents per kWh in tier three. I called SCE customer service and they were able to go back to certain representative weeks of my choosing during the preceding year, both summer and winter, and tell me what I had actually been charged and then calculate what it would have cost me under TOU. I found out that TOU would have been slightly cheaper than tiered rates for my usage.

    Now, instead of charging Blue Max pushing me into higher rate tiers, I can charge at super-off-peak rates from 10pm to 8am and on weekends.
     
    • Helpful x 1
  6. Nosken

    Nosken Member

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    Location:
    Lincoln, CA
    Northern California PG&E EV-A TOU Rates are:
    Total Energy Rates ($ per kWh)
    Summer
    PEAK $0.45389 PART-PEAK $0.24986 OFF-PEAK $0.12225
    Peak (2-9 p.m.) and Partial-Peak (7 a.m.-2 p.m. and 9-11 p.m.) Off-Peak (11 p.m. to 7 a.m)
    Thank goodness I have Solar, and can "sell" it back at the higher rates.
    There is a great iPhone App that will use your PG&E account and help you analyze rate plans. My PG&E Toolkit Lite on the App Store
     
    • Like x 1
  7. Runt8

    Runt8 Member

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    Wow, guess I shouldn't complain about my rates.

    I called IREA, they don't have any way to analyze hourly usage, so I would be stuck with manually checking the meter at specific times, or getting a whole home energy monitor.
     
  8. ItsNotAboutTheMoney

    ItsNotAboutTheMoney Well-Known Member

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    If you are on TOU, you pretty much always need a high percentage off-peak to save money.
    To make it work the on-peak pricing has to be quite punitive. Also, don't expect to save much.

    If x is fraction off-peak then break-even is
    0.113=(1-x)*0.27+x*0.073
    x ~= 0.797

    So you need to be 79.7% off peak to break even on TOU.

    How easy that would be would depend:
    - what's your normal usage?
    - could you shift any heavy electrical loads like HVAC, laundry and dishwashing off-peak?
    - would weekends be off-peak?
    - would holidays off-peak?
    - how many miles would you be charging your Model 3 at home?
    - would there be any additional monthly service charge to be on this plan?

    If it's _only_ 4pm-8pm weekdays peak that sounds like a decent deal and you could get a pretty high percentage if your household wouldn't be electrically busy during that period.

    We have 7am-12pm and 4pm-8pm at peak price.
    We have a Volt and our garage average (which is almost all the Volt) is 219.25kWh/month.
    Home average over past 12 months 453.5kWh/month.
    Heat is oil (still...).
    Not much A/C use here: window units; normally limited to a couple of months per year - not even in yet.
    Laundry and cooking electric.
    No luxurious wasters like a heated pool or hot tub.
    Laundry and dishwasher (almost) always done off-peak.

    Over the past year we've averaged 85% off peak, with shifting of electricity. (Actually 79.5% off-peak and 5.5% 12pm-4pm shoulder, but on our tariff the shoulder is charged at the lower rate).

    One thing to consider about that high peak cost on TOU: solar on an unshaded west-facing roof would be more valuable. ;)
     
    • Informative x 1
  9. Runt8

    Runt8 Member

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    Thanks for the reply! Very good information, especially the break even point.

    As for shifting usage to off-peak times, that's the million dollar question (or at least several hundred dollars...). On the plus side, we already run the washer, dryer, and dishwasher at night, and the car would almost exclusively be charged overnight as well. However, I would guess that most HVAC happens during peak times (everyone is at work or school during the day), and the majority of time spent using the electric range is peak time as well. I seriously doubt we can get almost 80% of our usage to happen during off-peak hours unless I'm underestimating the effect of a BEV (peak hours include weekends as well, which makes it more difficult).

    It does seem like the only way to know for sure is to monitor usage for several months to get real numbers. Been looking into whole home electric monitors but haven't found one that works for me yet (the lack of space in my circuit breaker box is problematic).

    Thanks again for the awesome information!
     
  10. brucet999

    brucet999 Active Member

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    You still have a "dumb" meter?
     
  11. Runt8

    Runt8 Member

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    It's "dumbish" - they can check it remotely, but apparently there's no monitoring capabilities. If I join the TOU program they would have to install a different meter (and then charge me $5 a month for the privilege).
     

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