Dangerous to leave string connected?

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  • maxpower
    Junior Member
    • May 2020
    • 3

    #1

    Dangerous to leave string connected?

    Long story, but I have a roof mounted PV system that has been worked on by multiple contractors. It has never been fired up, and I'm the one who has been working with the utility company to get it connected. They are coming to inspect and set the REC meter and requested:
    Solar backfed breaker is in the ON position
    All breakers in combiner boxes are in the ON position
    Inverter is programmed and DC disconnect is in the ON position
    The correct One Line Diagram and Site Map are in the info tube on site
    The actual as-built system size matches the approved application
    The correct placards are installed.
    The meter socket is wired correctly (inverter is wired to top of meter socket)

    There are 12 260w panels in a string on the roof, going to a DC disconnect (in off position), then to the inverter (off), then to AC disconnect (off). The panels themsleves were currently left disconnected in two places. I connected the string, and turned the DC disconnect to ON, and also tried to turn on my Inverter, and the AC disconnect going to the socket meter (no REC meter installed).

    Question 1: was this dangerous for me to undertake? My electrician made it seem like it would be ok, but he also doesn't specialize in solar work and was mainly stepping in to help complete the project.
    Question 2: the inverter (SunnyBoy 6.0) won't light up, which I understand could be due to a number of problems that likely require an electrician to troubleshoot...but if there are any basics I should know, please share.

    And finally, to my main question, seeing that there could be multiple issues at play way beyond my understanding, I decided not to do anything further on the system myself, other than switch the AC and DC disconnects back to OFF and turn the (apparently non-functioning) inverter off. The string is still connected to itself, however. I did not want yank free any connections, given that it is sunny out and I understand that means the panels are still generating DC (which I know is more lethal than AC). So, as it stands now, am I safe leaving the system as it currently stands while I wait to have an electrician come out? Or are there any precautions I should be taking?

    Thank you!
  • inetdog
    Super Moderator
    • May 2012
    • 9909

    #2
    The panels themsleves were currently left disconnected in two places.
    The inverter will not power up unless there is DC present at its input. Once that is seen and available to power the electronics, the inverter will start trying to qualify the input from the grid on the AC side.
    In other words, the inverter will power up and show status if it sees DC only, but not if it sees AC only.
    SunnyBoy 3000 US, 18 BP Solar 175B panels.

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