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  • cpereira
    Junior Member
    • May 2015
    • 1

    #1

    Not sure if it can be done

    Background Information:

    To get started this is not for a system to be installed in the US. This is something I want to apply in Nicaragua, Central America due to the high cost of electricity.

    -Going fully off grid is not an option due to the cost of the solar systems in the country
    -Running a Grid-tied system is a huge risk (see the reason below)
    -Current electric bill is at around $500 a month

    Idea:

    I want to create a system where I can save money by using solar power without completely depending on Solar due to the cost of implementation. I want to gradually grow my solar array before I can go fully off grid. I want to install the solar panels with a battery bank as my family is not at home all the time. What I want from that is that my home runs from the Solar Panels and the Batteries once we start using electricity and once that is not enough then it goes into the grid. The risk here is that there is only one electric company which does not allow the use of two way meters. Their meter actually reads any output from my solar array as if I was pulling from the grid instead (Solar array is currently disconnected). What I want to achieve is that my house fully disconnects from the grid when I have enough power in the battery bank, but automatically switches to grid once there is not enough power.

    This would allow me to save some money, and eventually I would go fully off grid once I am able to grow the solar array enough for that.

    Please let me know if you have any ideas on how to achieve this.
  • Mike90250
    Moderator
    • May 2009
    • 16020

    #2
    You are not going to like the answer.

    First, what is your monthly electric bill? 300KWh 500Kwh
    Divide by 30 (number of days in a month, we're looking for your daily usage)

    Say your daily usage is 10Kwh (easy to scale)

    You need a battery that can hold 4 days of power, or about 40Kwh of battery.

    A common 6v, 200ah golf cart battery contains 1,200wh (1.2Kwh)

    So you need about 33 batteries of this type (don't buy anything yet, we're just getting started.)

    What's that price ? they only last 5 years, then you buy new ones. Does that save you any money ?


    The other question, to not run the meter backwards, is a feature in the inverter called
    Grid Support, or Load Shaving Schneider Electric Conext XW inverters can do this, and I think other brands could too.
    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

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister

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