Wiring an inverter (or 2) to a stand alone AC Breaker box

router102router102 Registered Users Posts: 5
Question.... I'm building the first phase of my off grid project. My battery bank and control panel will be located in a shed I constructed next to the house. I'm wanting to wire male receptacles to plug into the inverters (1 2500 watt MSW and 1 3000 watt PSW) with Romex 12/3 house wire, then tie them in to a stand alone AC breaker box mounted in a closet, with 4- 15 amp breakers, then from there I want to run a few outlets to various rooms in the house. That way I wouldn't have to go outside and unplug the cords to service anything, or have extension cords running from the shed to the house. I haven't been able to find much on the internet on how, or if, this can be done. Or a diagram/schematic of the proper way to wire the panel? Any help with this would be appreciated. Perhaps a site where they show how to wire the inverters to the box? Any thoughts?

Comments

  • BB.BB. Super Moderators, Administrators Posts: 30,625 admin
    Welcome to the forum Router102,

    Can you tell us a bit more about your needs and design? What your planned loads are, how big of battery bank (volts, AH), solar panels, backup AC genset (if any), etc.?

    In general, you would wire the output of your AC Inverter to a "main panel". Then wire from the main panel (with appropriate circuit breakers and wiring) to your point of use. That is (usually) well covered in the standard electrical codes (like the NEC--National Electric Code).

    However, when you have AC inverters, their size, type, and individual configurations (neutral bonding to earth/safety ground, their power output designed for hard wire or "outlets", possible backup AC power connections, if the inverters are designed to "sync" to each other or be separate AC mains/output circuits) can make this all fairly complex.

    I like to backup a moment to what are your power needs--Where the system will be installed, your AC (and DC) power needs, size of solar array, size of battery bank, size of inverters/AC charger(s), AC mains and AC genset, etc.

    Your AC inverters are fairly large--And a system this size would generally be a 48 volt battery bank (for various reasons)--But getting two "smaller" AC inverters, I "fear" you are looking at 24 volts (or even 12 volt) DC battery bank.

    But the simple answer to your question is (most likely) to connect each AC inverter to its own AC main panel, and wire out branch circuits (i.e. 15 amp 120 VAC breaker on 14 AWG wiring, 20 amp 120 VAC breaker and 12 AWG wiring, if 120/240 VAC output breaker on dual breakers to 240 VAC loads like well pump, etc.) to your loads. You (normally) would not mix/match the output of your two separately derived power sources (the two AC inverters) to one AC panel to your loads.

    But specifics really matter here. And I suggest your do your paper design(s) first--Before you start spending any money. It is very easy to get lost in the details, then figure out you "cannot get here from there".

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • router102router102 Registered Users Posts: 5
    Thanks for your response, but most of it I didn't understand. :)
    My 1st phase is simple as far as what I want to run. My refrigerator, Desktop PC, small LED t.v and a few low wattage lamps.
    Power supply is 200 watts solar and 1500 watt (max) wind turbine. I plan on using the Aims 3000 watt Pure sign wave inverter for the refrigerator and limited pc use.. The Aims modified sign wave 2500 watt will power the lights and any cell phone chargers, ect. Would it be simpler to just run the 4 extension cords to 4 receptacles?
  • router102router102 Registered Users Posts: 5
    Sorry... I also have 6-12 volt Vmax 100 ah batteries wired for 24 volts....this is a 24 volt setup
  • router102router102 Registered Users Posts: 5
    "You (normally) would not mix/match the output of your two separately derived power sources (the two AC inverters) to one AC panel to your loads.".... yes, this is what I suspected....Thanks
  • router102router102 Registered Users Posts: 5
    I already have all the equipment here..440 amp 10,000 watt charge controller, disconnect box, brake switch, rectifier, 4 resistor dump load.... I bought the large charge controller because I plan on adding in the future. 
  • BB.BB. Super Moderators, Administrators Posts: 30,625 admin
    An Energy Star Refrigerator and Desktop computer usually push you into the medium sized solar power system--This is not a small system to fiddle around with spare parts and wiring.

    For the sake of design here--I really like to design a "balanced" power system. And to design a balanced power system--You really need to define the loads you want to supply.

    For your system--You have "relatively large" AC inverters. Almost no solar panel power. And a medium size wind power turbine (which, for the sake of a typical design, we ignore until the battery+solar is designed first).

    To measure your AC loads--Get a Kill-a-Watt type meter (some libraries even loan them out for free). It will tell you the basic numbers (peak average Wattage). And how many Watt*Hours per day you will need to supply.

    And very quickly, you will find that you will need to conserve energy to make a "cost effective" solar power system. For a typical off grid solar power system, it costs you almost 10x as much for solar power as utility power... If you where paying $1.00 to $2.00+ per kWH vs $0.10 to $0.20 that is typical in the US--You would be looking at replace your 30 year old refrigerator with a modern Energy Star fridge. And replace the desktop computer with a Laptop instead (or modern energy efficient small computer+LED monitor).

    I know that most people try to avoid the math--But the math+numbers from your kill-a-watt meter is really pretty easy. And with those numbers, it makes designing a system that will meet your needs much easier--And will save you a lot of money, time, and frustration.

    If you are willing to work with us, we should be able to walk you through the questions and design pretty quickly. Then, we can start talking about the details of the system hardware.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,214 ✭✭✭✭✭
    Definitely get the Kill-a-Watt  and measure each load over a 24 hour time. I think the last button toggles between watts and time. You need this data as it will keep you in sink with your budget.
    If you are still building, many just run a small solar system to power their tool batteries and phones. They use the generator for large loads and and air compressors. Some of the folks I have worked with just roll a camping trailer in and use that for refrigeration/living.
    Running a full size electric refrigerator is really a distraction at the building stage for many, in my opinion.

    Keep reading and look at this forums FAQ's. 

    Hey Bill !  mail in your in-box, I know you are swamped!  We are out to the Mavericks in an hour to see the Big Waves on the coast along with the totally insane people who ride them!

    http://www.sfgate.com/sports/jenkins/article/Mavericks-surf-contest-draws-an-all-star-cast-6818752.php


    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • BB.BB. Super Moderators, Administrators Posts: 30,625 admin
    Have fun David.

    Hope you find a good place to watch.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,214 ✭✭✭✭✭
    It is live here.  The bar was 9 deep at 9am.  Not that I was in line....
    http://titansofmavericks.com/
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • mike95490mike95490 Solar Expert Posts: 8,799 ✭✭✭✭✭
    Beware of putting a mod-sine inverter into a standard AC breaker box.  Mod-sine generally cannot tolerate either L1 or L2 being tied to ground,
      And, unless you have Sync cables for the inverters, you should only connect 1 inverter to a breaker box, Out of phase inverters can overload the neutral return line (white wire in the romex)
    Powerfab top of pole PV mount | 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 ,

  • just startingjust starting Registered Users Posts: 235 ✭✭✭
    The Magnum RD2824 is an MSW off grid inverter it requires a NGB in a breaker panel just for thought make sure you call the inverter manufacturing co to verify if you can do it that way
    200ah LiFePO4 24v Electrodacus Sbms40 quad breaker chest freezer to fridge- Samlex PST 1524 - Samlex pst3024  - 1hp shallow well pump-Marey 4.3 GPM on demand waterheater - mama bear Fisher wood burning stove, 30" fridgarair oven ,fridegaire dishwasher  Unique 290l stainless D.C. Fridge-unique 120l portable fridge/freezer 
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