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Big-Picture question for you net-metering folks

Discussion in 'Model S: Battery & Charging' started by AudubonB, Apr 30, 2013.

  1. AudubonB

    AudubonB Mild-mannered Moderator Lord Vetinari*

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    I've been trying to come to terms with the concept of sharing 'my' electrons with a real utility company. In our Arizona home, not here! Here, all my PV electricity gets dumped into my own 9-ton battery bank.

    At any rate, can someone clue me into the reality of what I understand to be the case, as follows:

    In most states, 'real' utility companies will - because laws so mandate - pay you on an avoided-cost basis for you solar (or hydro or wind or hamster cage) electricity. But they understandably place restrictions on how much you can sell to them. My question, then, is how do utilities create this limit? Is it on historical usage (last 12 mos., for example)? Is it on the size of your service - 100A / 200A / 400A / 800A ?

    Is there one great big fudge factor going on here?

    I would be very interested in your real-life examples. I do plan to emplace as many PV panels as my service permits in our Arizona house. Here, I'm limited by the size of my charge controllers, a limit that does not apply to those of you on-grid....which I'm guessing is, not counting me, d*mn close to 100% of this forum....
     
  2. dj905

    dj905 Member

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    In my case (Ontario, Canada), the utility has established a maximum "rated" output of 10kW for a household PV grid-tied system. The system is tied to a separate meter, and the nameplate ratings of the grid tied inverters cannot exceed 10kW. In my case, I have two 5kW inverters, but I have a total of 14kW of panels on several roof surfaces so that I can maximize power output, even though I am limited to 10kW max at any point in time.

    I have been generating over 15,000 kWh per year so far.

    david
     
  3. NuclearPowered

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    Aps or srp?

    Sent from my XT907 using Tapatalk 2
     
  4. AudubonB

    AudubonB Mild-mannered Moderator Lord Vetinari*

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    In my case, APS.

    - - - Updated - - -

    That's a 41 kWH per day mean! Pretty impressive, esp. considering you're 3/8 of 2/3 of squiddly-nothing during, say January..... :)
     
  5. Cosmacelf

    Cosmacelf Active Member

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    Many utilities do a net metering on a yearly cycle. If you generated more electricity than you use over a year they will either ignore the extra power they get from you, or pay you for the electricity at wholesale rates which is a lot lower that it costs you to generate the electricity. So it generally isn't useful to generate more electricity than you can use.
     
  6. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    It all depends on the laws in your state.

    If the power company could get away with it, they'd happily use your co-generated current for free, but state laws tell them how much they must pay.
     
  7. kmporter

    kmporter Member

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    APS offers two solar plans, net metering and net billing. The net billing plan is very similar to what Cosmacelf described, except that it is on a monthly basis. And, IMO it is not as attactive as the net metering plan. In this plan, for every kWh that you over-produce and feed back into the grid, you are credited a kWh. When the bill comes, your kWh credits offset the number of kWh you purchased from APS on a monthly basis. I am not aware of any limit on this. But, any credits you have at the end of the year get dropped (not sure why?). And, to complicate things, I am also on the TOU plan. So, the credits are distributed in 2 buckets, peak and off-peak. Generally, by the beginning of summer I have some peak credits accumulated from previous months (I never have off-peak credits rollover). But, after about a month or so of running the A/C, they get consumed and I won't see anything rollover until late in the year. Other than losing your credits at the end of December, it seems like a fair plan to me.

    Kevin
     
  8. AudubonB

    AudubonB Mild-mannered Moderator Lord Vetinari*

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    Thanks, Kevin. On the record, would you post what you mean by "TOU"? Off record - check your PMs, please.

    As you write, you rarely have off-peak credits roll over. That makes sense: I wouldn't think you'd ever have much, as PV panels aren't famous for generating lots of kWh during the night.... ;)
     
  9. kmporter

    kmporter Member

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    TOU stands for "Time of Use". With APS, I am on a plan that has peak hours of 9 am - 9 pm M-F. So, I do generate some off peak electricity before 9 am on weekdays and all weekend long. But, it's not enough to offset my nighttime use (especially when charging the MS at night).
     
  10. mknox

    mknox Well-Known Member

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    You are referring to the microFIT program (FIT = Feed in Tariff), and it's a pretty sweet deal. The utility will pay 54.9 cents/kWh generated.
     

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