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PG&E E-9 vs E-6 vs E-1 tariffs

Discussion in 'Technical' started by pgrovetom, Jul 26, 2009.

  1. pgrovetom

    pgrovetom New Member

    Joined:
    Mar 10, 2009
    Messages:
    4
    Does anyone have any input on comparing the PG&E E-1, E-6 TOU and E-9 TOU A and B rate schedules for a combined Solar PV and Tesla?

    I am just completing a 12,600/9924 Watt (STC/CEC) Solar PV system and buying a Tesla Roadster. I've been examining and building simplified spreadsheets trying to roughly analyze the PG&E E-9 A/B TOU (experimental rate schedule for Electric Vehicles) versus the recently ruined E-6 TOU versus the flat non-TOU E-1 rate schedules in selecting which schedule that is the lowest cost when combining Solar PV and a Tesla electric car and the timing of charging and electric usage timing that is practical.

    I'm curious if anyone has found, developed or done any kind of analysis or come up with simple rules of thumb given all the variables. Its a messy Excel problem and I'm considering just writing software to compare the schedules given the variables and data. In addition, E-9 appears to have a separate meter option but separating the PV and home and Electric charging outlet seems odd.

    The data includes the tariff schedules from Baseline ( which is not the same for everyone), 100-130%, 130-200%, 200-300% and over 300% for usage amounts and kWhr rates. These are different for E-1, E-6 and E-9 and three levels Peak, Partial Peak and Off Peak that vary from Summer/Winter, M-F/S-S and time of day. Then the PV system power can be sold into PG&E but produces its power for about 5-6 hours tailing off at each end that must be applied.

    There must be a tool that allows usage over time, charging with time, Pv output with time over a year, user inputs and then uses the PG&E tariff tables and estimates yearly/monthly usage daily curves, cost, PV contribution etc.. It could be done with Excel but is rather messy. Writing PC software seems easier to me and more flexible.

    Has anyone looked into this and share their knowledge and conclusions or possibly a tool so I don't have to develop my own.

    thanks for any thoughts

    Tom
     
  2. Serge

    Serge Member

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    Queens, NY
  3. EVnut

    EVnut Darell, the EVnut

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    Davis, CA
    I've been back and forth through this for years. Without solar, E9 is the hands-down winner. Charge at night, and you're golden. With Solar, E7 was much better for me since it allowed much higher credit for my generation, though my charging cost doubled. Now that E7 has (again) gone away, and E6 is the only other option, there is simply *no* easy way to figure out what is best. It depends so much on your usage pattern, that there's no spreadsheet that will determine what works best. The good news is that you CAN switch, so I'd just take a stab at it. Use it for a year, and you'll at least have some relevant data, and can switch if you realize it is wrong for you.

    Good luck!
     
  4. pgrovetom

    pgrovetom New Member

    Joined:
    Mar 10, 2009
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    Writing software E-1,6,9A,9B comparisons

    I'm buying a Tesla Roadster and just installed my 12Kw Solar PV system and I'm trying to determine which tariff makes sense since with an EV and Solar, I have my choice of E-1,E-6,E9A or E9B.

    I first looked at the tariff tables and thought about a spreadsheet to compare them. After giving it some thought and how crazy it looks, I decided to write a basic program to allow the user to enter his data such as baseline, solar power hourly profile for winter and summer, power usage 24 hour profile also for summer/winter/M-F/SatSunHolidays (an approximation). I hard coded the current tariff tables for peak, partial peak and off peak also by summer/winter/M-F/SatSunHolidays for E1,E-6,E-9A and E-9B and am debugging the calculations. It will calculate every hour of day of the year by month adding usage and deducting solar excess based on the tables, accumulate each month and calculate the bill, print them and print the yearly totals. I've taken two AC clamp meters on my PG&E main L1/L2 feeds and am characterizing my usage which includes a well pump, 2 booster water pumps, 5 pool pumps ( filter/solar, Jacuzzi jets and waterfalls) and everything that is significant. I'll cut down my vampire power and create profiles based on programming my various pumps as best I can and feed the data in. Hopefully it will give me either obvious big differences if I tune everything to use power at the right time or small differences and tell me it doesn't matter. I'll report the tariff results once I get it done. Once I clean up the rather hacked code :eek: I'd be happy to share it.

    Tom
     
  5. TEG

    TEG TMC Moderator

    Joined:
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    Messages:
    17,250
    Location:
    Silicon Valley
    Are those with existing E7 "grandfathered in" or are they being converted to E6?

    When I got solar, E7 wasn't available so I "defacto" went to E6, and have been with it ever since. I think the recent/temporary E7 was effectively only available to new solar installs, and not available for E6 customers to switch into.
     

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