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A Challenge for you guys

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  • A Challenge for you guys

    Hi, I have a situation that I don't have a solution to. Maybe you can help.

    1.I use 1200 kwh a month with no solar panels.
    2. Google sunroof project says my site can support a 3kw system
    3. Pvwatss says approx 400kwh a month generation for my site from a 3kw system.

    so, net metering plan at (1200kwh use - 400kwh generation) * 11.7 cents perkwh for net metering plan
    =$93.6 a month.

    With no solar panels 1200kwh * 7.8 cents per kwh = $93.6 a month.

    I'm not making this up. In my scenario solar doesn't make financial sense.

    Here is my question. Is there any way to have a system that uses both the grid AND batteries, but is NOT a net metering plan?

  • #2
    Let me expound.
    I want to keep my 7.8 cent plan
    i don't want to give free energy to the grid since I won't be on a net metering plan

    Unfortunately I use almost no electricity during the day. Between 6am and 6pm I use only 2 kwh per day.

    So I need all my electricity at night when the solar panels are not making energy.

    Is there a solution to this problem?


    • #3
      The expense and maintenance of batteries drives the cost to about $1.70 per kwh

      in actuality, a cheap generator & a transfer switch is a better deal for backup power than batteries.
      Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
      || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
      || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A



      • #4
        You have lots of options, on/off/hybrid. With enough money, anything is possible. Making something possible and keeping it cost effective and at the same time with a minimum of lifestyle disruption is the challenge.

        What it seems you don't have at this time is enough information to make intelligent choices.

        I wouldn't call what you have a problem as much as I'd call it a situation. But if it is a problem, any solution starts with an understanding of the situation. Any understanding of the situation takes education - the kind best obtained on your own.

        Is there a cost effective way to what sounds like a hybrid system ? Probably not. At $0.078/kWh, making even grid tied PV cost effective will be a real challenge.

        Start your self education with the following:

        - Get a copy of "Solar Power Your Home for Dummies". 20 bucks or so at bookstores/Amazon.
        - Read it.
        - Screw Google and their mickey mouse stuff. Stick with PVWatts and learn it's finer points. Your roof or property's solar production potential is too easy to model and perhaps estimate without the need to resort to averages and that Google stuff which, for an individual residence looks like a waste of time, or at least unnecessary.
        - Make sure you are very familiar with your POCO's rate plans and net metering plans. Often, the devil is in the details. Most folks don't take the time or make the effort to do that in a thorough fashion and so often miss details and opportunities or perhaps worse, wind up making and using bad/incorrect assumptions that cost money.
        - Any consideration of cost effectiveness will need some consideration of what a system will cost both upfront and for ongoing maint. (like batteries for off grid applications) and things like how long you intend to live where the system will be located. Get familiar with the economics of something called life cycle costing and time value of money principles.
        - Do as you please but when you look at off grid, do so without wearing rose colored glasses. And if you do go off grid, know you've been advised it's not all sweetness and light of the type that tree huggers and those with skin in the game would like you to believe. Sounds (reads) like you do not know how much toil, treasure and lifestyle adjustment is necessary to live off grid.
        - If net metering is available, and if you can make it work as your education and opinion leads you, do it. It's about the only realistic way to get close to a scenario where residential PV has any chance of being cost effective, especially with your low rates. My guess is a hybrid system with batteries will not be economically viable. Your self education will likely confirm that guess.

        After the above self education, com e back here and read threads here that discuss off grid/battery system. Then come back here again with all your newly acquired self education and ask questions to fil in any knowledge gaps that still exist. Doing it that way will make the questions more informed, save time and make the answers you get a whole lot better and informative.
        Last edited by J.P.M.; 09-08-2018, 12:53 PM.


        • #5
          Originally posted by Clumsy Ninja View Post
          Here is my question. Is there any way to have a system that uses both the grid AND batteries, but is NOT a net metering plan?
          Sure; it's called self consumption. You can get systems (like the Powerwall) set up to do just that. They are not cost effective unless your power is >30 cents/kwhr or so.

          At 7 cents a kwhr it's not an option if you want to save money.


          • #6
            Thank you all. So my suspicion is correct.

            Because all my energy use is night time use, and because my energy is only 7.8kws,

            Then solar would NOT be cost effective for me.

            It's slwhat I though but I wanted to get your input. Thanks.