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  • 120v 240v options

    I purchased a property in the mountains in Colorado and I finally got a chance to look further into the solar system that is currently installed. I knew it was a 120v system but I wasn't sure how the panel in the house was wired (they wired the one leg of 120v to both legs in a 240v panel). I am going to be replacing most of the system since it is too small for what we need but I don't plan on running a new line to the house.

    Currently the batteries and the inverter are in a room in the barn with 2 conductors plus ground running to the house. I was hoping to instal a 240v system because the generator I am looking at using has 240v output, the well pump is 240v and I need some occasional use 240v outlets in the barn/shop, I don't need 240v in the house though. I see a few options:
    1. Install a 120/240 inverter and run the house through an auto-transformer.
    2. Install a 120v inverter, keep the well pump running through an auto-transformer and install an auto-transformer on the generator and 240v outlets in the barn/shop.
    3. Install a 120v inverter and 120v generator, keep the well pump running through an auto-transformer and install an auto-transformer on the 240v outlets in the barn/shop.
    4. Install a 120v inverter and 120v generator, keep the well pump running through an auto-transformer and run the 240v outlets off a second generator.
    5. Install a 120/240 inverter and run new wires to the house.
    6. Any other options I didn't consider.

    Thanks

  • #2
    > one leg of 120v to both legs in a 240v panel
    Good way to set the wires on fire, this overloads the neutral wire with the amps from 2 hots
    Don't try to run the 240 motor from a step-up transformer. Most will not handle the starting surge very well, and saturate the core, eventually the motor will start, but with extra wear.

    Many new 240V inverters will charge batteries via a 240VAC generator, which is way better than most stand alone chargers on 120VAC
    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

    Comment


    • #3
      Originally posted by Mike90250 View Post
      > one leg of 120v to both legs in a 240v panel
      Good way to set the wires on fire, this overloads the neutral wire with the amps from 2 hots...
      This will only happen if the panel's output is wired as MultiWire Branch Circuits (MWBCs), also known as Edison circuits. These will typically run to 15 or 20A circuits together as only three wires (plus EGC), usually one red, one black, and one white for neutral for both circuits. As long as red and black are fed from different phase of a 120/240 volt input to the panel the current in the neutral will never be more than the 15A or 20A of one half of the circuit alone. When both sides are fully loaded the neutral current is zero.
      If you feed both red and black from the same 120V source the neutral may end up carrying twice the current and would have to be twice the size of the other two.
      SunnyBoy 3000 US, 18 BP Solar 175B panels.

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      • #4
        There is one hot and one neutral coming into the panel. The one hot is attached to both hot legs in the panel. So the neutral wire will not end up carrying any more than the one hot wire.

        Comment


        • #5
          Originally posted by ColoradoBound View Post
          There is one hot and one neutral coming into the panel. The one hot is attached to both hot legs in the panel. So the neutral wire will not end up carrying any more than the one hot wire.
          That is true for the feeder (incoming) wires, but see my post for info on outbound feeders and branch circuits.
          Also if you run the single hot to both poles of a 240V main breaker, you can get twice the breaker current through the incoming wire pair.
          SunnyBoy 3000 US, 18 BP Solar 175B panels.

          Comment


          • #6
            Missed that it was about branch circuits. I have not looked at the panel closely enough but I don't think there are any multi wire branch circuits.

            Any opinions on how to wire the new system?

            Comment


            • #7
              Originally posted by ColoradoBound View Post
              I see a few options: . . .
              I'd stick with 240V as much as possible. Something like a Radian inverter would work. You will be able to use your generator to full capacity and run your tools/pump. With the Radian you should not need an autotransformer.

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              • #8
                I plan on using the Conext XW+ inverter and I was thinking that staying 240v as much as possible would be the best way to go. I now just need to see what it would take to get a new cable run to the house.

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                • #9
                  I use the XW6048 and it's an awesome inverter. Never complains
                  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

                  Comment

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