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Can 225vac from Solar flow back to grid?

  1. Apr 10, 2013 #1
    Note, this is in the USA, where the street lines are 4,800vac (I think?)...and the lines from the pole are 220VAC to the panel.

    For example, let's say I'm making 225vac from a DIY solar array (connected to my main panel), and the amount of energy I'm currently producing is more than what I'm consuming at my house (and there is no net metering setup...just solar panels with inverters pushing 225VAC connected to my panel). Assuming (since I'm in the USA) that the power coming from the street to my panel is 220VAC, and the power at the line is much higher (4,800 right?).......can my excess (unused) current get to my neighbor's house?

    I always thought it could not, because the line at the street is MUCH higher voltage. However, someone said it can, because the transformer at the pole would simply take the 225VAC and step it up so it could flow back into the grid, and be used by someone else in the neighborhood. Is that right? Will the transformer step the voltage UP?? Like I said, I thought it would not....but someone recently corrected me and said it will. Anyone know for sure??

  2. jcsd
  3. Apr 10, 2013 #2
    Depending on how you have it wired, yes.

    the transformers work in both directions, and chances are the 220v line feeding your house feeds several others as well at a common connection point.

    if you have your inverters directly tied to the incomming panel, you really need to install proper equipment before that setup injures or kills a serviceman.
  4. Apr 10, 2013 #3
    Thank you. Interesting. I did not know the transformer at the pole works both ways....or that the 220vac at my house is on the same line as other homes on the street (possibly).
    Last edited: Apr 10, 2013
  5. Apr 10, 2013 #4
    Some meters are one way only. Most I have run across are 2 way (rotary)

    your 125VAC is half the leg of a 220v line.. it can still backfeed that single phase back into the grid in case of a power outage.

    automatic shutoff or "islanding" islanding is where the inverter passes through the grid power, but if the grid goes away it keeps supplying power to the house but not back to the utility.

    Yes, most AC systems can run in reverse,the chances of you powering your block without the inverters shutting down for overload are pretty slim, but there are pretty strict codes related to systems like yours that dictate the type and how the equipment is installed, and most require a seprate disconnect on the outside of your home for the utility to use, like if they need to work on the local lines they WILL come flip off your power through that disconnect in case your transfer system malfunctions and keeps the lines live while they are working.

    a lot of people do what you describe, and if you get caught with an unauthorized setup it will be quite a headache for you.
  6. Apr 10, 2013 #5
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