Xantrex XW and Utility AC disconnect

newenergy
newenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
Here's a requirement from the Utility - cliff's notes at end

"When installing a battery back-up system the required AC disconnect
device must be electrically connected such that when the AC disconnect device
is in the open position the battery back-up system may also be bypassed using a
manually operated bypass switch. This will allow for the dedicated sub-panel
supplied by the battery back–up system to be fed directly from the main electrical
service panel. This bypass capability ensures that in the event that LADWP locks
out the PV system, and the battery back up mode initiates, the manual operation
of the bypass switch will allow all loads to still be fed from the LADWP grid. In the
event of a LADWP power outage the bypass feature does not affect the ability of
the battery back-up system, solar panels, and inverter to be used to supply
power to the critical loads connected to the dedicated sub-panel."

Cliff's: When the Utility AC disconnect is open, the circuits for dedicated backup must be able to be fed by the grid.

The Utility disconnect must be a separate device that has a switch handle and is lockable in the open position.

So, this must go in between the inverter AC Inv OUT and the AC breakers in the Power Distribution Panel, right? Then when the disconnect is locked open and the bypass breaker is switched, the dedicated subpanel will be fed by the utility, right?

And, if that's the case, is the wiring going to be a problem, having to go out of the distribution panel, through the disconnect and then back in?

Thanks.

Comments

  • dsp3930
    dsp3930 Solar Expert Posts: 66 ✭✭✭✭
    Re: Xantrex XW and Utility AC disconnect

    Here's what I believe it is saying:

    In the event the power company decides to come out and lock your AC disconnect, you must be able to provide power from your main panel to your sub from the grid. If they break your AC1, then you have no way to power your sub panel after your batteries die.

    Basically, this means you just need to run a 60A dual pole 240v circuit from your main directly to you sub panel. You might place the new breaker right next to your Xantrex 60A dual pole that feeds your sub. (you can put a metal linkage between them that only allows one to be on at a time if desired) Then, if for any reason your Xantrex bites it, or the utility decides to lock your feed out, you can flip the switch and be back in business on your sub-panel.

    Steps to power sub from main if in lockout by Utility
    1) AC1 breaker at MAIN and PDP to OFF
    2) Load breaker at SUB to OFF
    3) SUB to MAIN breaker ON
    4) MAIN to SUB breaker ON

    Steps to revert back to normal (assuming AC lockout is re-enabled)
    1) MAIN to SUB breaker OFF
    2) SUB to MAIN breaker OFF
    3) Load breaker at SUB to ON
    4) AC1 breaker at MAIN and PDP to ON


    As a side note/bonus: In this configuration you can shut your main breaker off, disconnect your AC1 at the main panel, and open both the main to sub connection and the Xantrex sub panel load connection if desired. This will effectively feed your main panel and your sub off of the XW load line. Note: Be _careful_ with this. There is no anti-islanding protection on the Load line from the Xantrex. You must make sure you are disconnected from the grid. When you reconnect to the grid, make sure to disconnect the main to sub panel connection before turning your main panel AC1 breaker and main breaker back on.

    Steps to power sub and main from Xantrex LOAD if in lockout by Utility
    1) MAIN breaker OFF (no power into main from Utility)
    2) AC1 breaker at MAIN and PDP to OFF
    3) SUB to MAIN breaker ON
    4) MAIN to SUB breaker ON

    Steps to revert back to normal (assuming AC lockout is re-enabled)
    1) MAIN to SUB breaker OFF
    2) SUB to MAIN breaker OFF
    3) AC1 breaker at MAIN and PDP to ON
    4) MAIN breaker ON (power into main from Utility)


    I attached a quick/rough example of what I am referring to.
  • newenergy
    newenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: Xantrex XW and Utility AC disconnect

    If you kept your Main to Sub ON and your Sub to Main ON while you were in "lockout" would you still be feeding power to the grid? When they lock it out, they put a pad lock on it and don't want anyone to be able feed power from that property.

    Also, if you (not me, but my customer) can defeat the anti-islanding that wouldn't be ok, even if they had to defeat a linkage between breakers.


    The grid bypass in the PDP allows the grid to power the sub, no?

    and a disconnect between the inverter out and the PDP should make it impossible for the system to feed power to the grid, right?
  • RCinFLA
    RCinFLA Solar Expert Posts: 1,484 ✭✭✭✭
    Re: Xantrex XW and Utility AC disconnect

    Wow, that must have been written by an engineer.

    First I thought it was talking about a fire shut off, then I think bypass mode transfer switch.

    It is always good to have a bypass mode around inverter's transfer switch in case the inverter system fails. It allows working on the inverter while there is a bypass transfer around inverter to supply power from grid.

    The XW power distribution panel has the AC input and bypass breakers tied with a pivot rocker creating a transfer switch.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Xantrex XW and Utility AC disconnect

    We had something like that where I used to work... Basically, a series of circuit breakers and keyed lockouts that only the electrician could operate... Can open one set of breakers (medium sized computer room UPS system) and then close another set (grid power to backup subpanel). If done wrong, some tripped breakers and possible smoke).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • dsp3930
    dsp3930 Solar Expert Posts: 66 ✭✭✭✭
    Re: Xantrex XW and Utility AC disconnect
    RCinFLA wrote: »
    The XW power distribution panel has the AC input and bypass breakers tied with a pivot rocker creating a transfer switch.


    The XW bypass in the PDP will not work in this case. (assuming your lockout is between the PDP and the main panel breaker) The utility will be locking the AC1 connection in an OFF state. The XW uses AC1 for passthru, charge, and sell.


    newenergy wrote: »
    If you kept your Main to Sub ON and your Sub to Main ON while you were in "lockout" would you still be feeding power to the grid? When they lock it out, they put a pad lock on it and don't want anyone to be able feed power from that property.

    Also, if you (not me, but my customer) can defeat the anti-islanding that wouldn't be ok, even if they had to defeat a linkage between breakers.


    The grid bypass in the PDP allows the grid to power the sub, no?

    and a disconnect between the inverter out and the PDP should make it impossible for the system to feed power to the grid, right?

    No, with the MAIN to SUB linkage connected, and the LOAD and AC1 disconnected, your sub panel is connected just to the main. (There is no connection enabled between the XW and the sub or main panels)

    It looks like the spirit of the requirement is not violated by using a main to sub connection to me. They do say that you need to be able to do it manually if they cut your AC1. It doesn't look like it says that the main to sub connection has to be automatic and synced with their lockout of AC1. (IE. a dual pole A/B switch on the AC1 lockout)

    No, the grid bypass in the PDP will not do it. (assuming your lockout is between the PDP and the main panel breaker) The XW bypass in the PDP will not work in this case. The utility will be locking the AC1 connection in an OFF state. The XW uses AC1 for passthru, charge, and sell.
  • newenergy
    newenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: Xantrex XW and Utility AC disconnect

    I'm not worried about it being automatic, but about it being defeatable. If you have both breakers in the sub (to loads and back to main) on, then you feed back to util. Maybe they would be satisfied if they are on a linkage that only allows one to be open at a time, but I don't really think they would be (if they knew exactly what was going on). I think they want anything that puts power on their system to be able to be locked out with their lock and under their control.

    Does AC1 mean the Inv OUT or AC OUT in the XW? or the connection in the PDP for the INV 1 and Grid By-Pass breakers?

    If the utility interruption is between the Inv OUT and the PDP it seems like, with the Grid By-Pass on, there is a path from the main, through the By-Pass breaker, to the Inverter Distribution Panel.

    If the interruption is between the Inv OUT and the PDP, and the Grid-bypass is not on in the inverter, and the utility disconnect is open, is there any way power can go from the AC IN Grid terminals in the XW through the ON Inv 1 IN breaker in the PDP and to the main?

    singleline.jpg
  • dsp3930
    dsp3930 Solar Expert Posts: 66 ✭✭✭✭
    Re: Xantrex XW and Utility AC disconnect

    Sorry about the terminology. I have a Midnite E-Panel and not a Xantrex PDP. I just opened my Xantrex doco to get the label right.

    The AC1/AC IN (Grid) connection needs to have an external lockable disconnect. I am not aware of a requirement that it has to be between the PDP (generation equipment) and the main panel. (though it may possibly be that way in some areas?) So, it seems like having the disconnect between AC1/AC IN (Grid) and the PDP should work -- allowing you to divert the grid connection to the sub panel as desired using the bypass breaker.

    If you have been locked out and the bypass switch is NOT engaged, then there will be no power going to the sub-panel after the batteries and/or solar power being provided is exhausted. Once the bypass switch is manually engaged, there should be no way for your Xantrex inverter to connect with the grid or the sub panel when using the Xantrex PDP.
  • RCinFLA
    RCinFLA Solar Expert Posts: 1,484 ✭✭✭✭
    Re: Xantrex XW and Utility AC disconnect

    ACout and Inverter out are the same. AC1in (and AC2in) have relays that connect them to ACout/Inverter. There are three independent voltage and current sensors on two ACin's and ACout. These tell XW brain which way the current is flowing, and its magnitude and phase, on all ports.

    XW inverter is syncronized to any available grid or generator. The inverter operates in parallel. (Inverter function can be shut off).

    I am still a little confused with the statement:

    "This bypass capability ensures that in the event that LADWP locks
    out the PV system, and the battery back up mode initiates, the manual operation
    of the bypass switch will allow all loads to still be fed from the LADWP grid."

    Does this means if the power company wants to shut your use of inverter/backfeeding totally down then you can bypass the XW out of the connection to grid so you are not left with only battery power to rely on. Guess I'm not sure what scope of the words "lock out" means.

    Anyway, this is what the XW power distribution panel does. I don't recommend non-mechancially ganged breakers as you can accidentally flip bypass breaker (Main panel to Aux panel) while XW inverter is supplying power to AUX panel. The mechanical rocker ganging of the XW output 60 amp breaker and the 60 amp bypass breaker make sure only one is 'ON' at a time.

    XW manuals have some problem with intermixing the use and meaning of 'bypass' and 'passthrough'. Should mean bypassing around XW while other means passing through the XW. One of the manuals uses 'bypass' to mean passthrough with inverter switching shut off.

    It is never good practice, and against code, to require unique knowledge of which breaker to flip first (to prevent sparks from flying). It is true that if done wrong one of the 60 amp breaker will blow open but its not something you want to have happen. (it will likely scare the crap out of you also)
  • RCinFLA
    RCinFLA Solar Expert Posts: 1,484 ✭✭✭✭
    Re: Xantrex XW and Utility AC disconnect

    What looks strange to me in the diagram is why are they putting outside lockout breaker on the XW ACout line instead of the XW AC1in line.

    I think it should be on AC1in line. The way it is wired makes transferring grid to Aux panel difficult. The way it is shown will also allow XW to push power to grid even if outside lockout breaker is opened.

    Perhaps the confusion is with regard to a grid-tie (battery-less) inverter output.
  • newenergy
    newenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: Xantrex XW and Utility AC disconnect

    dsp,

    I think I understand everything from your last post. I had the disconnect on the Inv OUT line before which seemed right to me at the time because it says Inv OUT and all, but it does connect to the sub panel, not the main. So, I moved the disconnect to in between the Grid terminals and the PDP. So that looks right now, without the direct line from main to sub, right?


    RCinFLA,

    "Does this means if the power company wants to shut your use of inverter/backfeeding totally down then you can bypass the XW out of the connection to grid so you are not left with only battery power to rely on. Guess I'm not sure what scope of the words "lock out" means."

    This is right. The utility wants to be able to lockout your system, not just for anti-islanding, but if they just don't like you and your PV (maybe net-metering contract dispute or w/e, but they just don't want you pushing power on the grid)

    And I hope this change straightens out the problems and that locked out the system can by-pass and get util power to sub panel, and grid down can still draw power from batteries (which still get charged from solar), and can not supply power to the grid when locked out or when grid is down.


    Thanks a ton.

    singleline2.jpg