TOU rates and best combination

solar_dave
solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
in Grid Tie and Grid Interactive Systems #1
I currently run on a 9AM to 9PM Mon.-Fri TOU peak rate. I cover my on peak usage pretty easily but not my off peak which gets generated from dawn to 9AM and weekends.

The utility also offers a TOU rate of 12PM to 7PM Mon-Fri. BTW, the rates are lots higher on the short TOU, but who cares if I can cover it all with solar.

Assuming I can cover all the generation for the second plan so I am net zero on peak, should I switch to the shorter on-peak to have more off peak generation available? I still am not net positive on the 9-9 TOU off peak. The down side is I am grandfathered on the 9-9 TOU, and if I do switch off there is no going back.

I suppose I could gather some data and analyze the difference, just thought I could get some ideas here.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,637 admin
    #2
    Re: TOU rates and best combination

    Dave,

    How does your utility charge/bill for Peak vs Off-Peak with your solar GT system?

    My utility simply take takes the power generated/used during the month and multiplies it by the amount used/generated during the time period and adds it all together...

    So, for me, it works best if I generate a whole bunch of power during peak ($0.29 per kWhr summer peak) and consume it during off-peak ($0.09 per kWhr). It basically makes my array look 3x larger than it really is during the peak period (all the money is simply added/subtracted from my 1 year running total account).

    For us, it does get a bit more complex--we have tiered rates... The more power we use, the more we pay for our power. In my case, I use less than the second tier--so I have not figured out how they account for unbalanced usage/generation between TOU periods. It is possible that, for example, if I get an electric car and consume a bunch of power during off peak--that it will push me into a higher rate plan. But I also get paid more money during peak--so I may still be relatively OK (our local utility always takes "murky" billing rules and errors in their favor--nothing strange about that).

    For me, I have a grandfathered TOU plan too which is noon-6pm peak power (instead of partial peaks that run to 9pm--deep dark does not generate solar power for me). In our home, it is pretty easy for us to load shift out of the noon-6pm time period (easy to explain to kids).

    For you, can you load shift out of the shorter TOU peak? And will they give you Peak Money to pay for Off-Peak usage?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #3
    Re: TOU rates and best combination

    In my case it is like 2 separate billing sections, I get credit kWh for any excess I generate applied to on or off peak.

    On Dec. 31 each year they pay back for any excess "banked" kWh at the rate of $0.065 and reset the bank to 0.

    I guess now my real concern is that I do cover the on peak easily but the off peak I still buy some power each month, now the AC is starting to run later into the night.
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  • Jburgess
    Jburgess Solar Expert Posts: 130 ✭✭✭
    #4
    Re: TOU rates and best combination

    Dave,

    The TOU that is 9-9 is frozen, so if you change, you will not be able to go back.

    http://www.aps.com/main/services/residential/rates/Default.html
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #5
    Re: TOU rates and best combination
    Jburgess wrote: »
    Dave,

    The TOU that is 9-9 is frozen, so if you change, you will not be able to go back.

    http://www.aps.com/main/services/residential/rates/Default.html

    Yep as I stated I am grandfathered onto that rate but if I change it is all one way.
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