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Thread: Solar - Generator connection

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    Solar - Generator connection

    I get an email yesterday asking me if I will go out and inspect a generator/solar installation. They were not sure if it was hooked up correctly by the generator installers. The generator was installed after solar. City inspection - passed. POCO review of installation - passed. Took me a few minutes since I have hardly done any solar work to figure out what was wrong. The load center is inside behind the meter and ATS.

    Not sure how they didn't have problems. Been in for about 3 years I belive.

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    Most likely they have not had problems because there has never happened to be an outage or load test of the generator while the PV was producing and the active local load was less than the the PV output.
    If there was never a reason for the GTI to try to backfeed the generator, there would be no symptoms.
    That or the generator output did not meet the 5 minute stability and precision test for the GTI to lock on and start producing.

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    Where is the pv connection relative to the generator connection? I assume you are getting at that the pv is on the load side of the generator? I know it's wrong, and I wouldn't try it, but probably the inverter would shut down before any damage was done.
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

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    Quote Originally Posted by electrofelon View Post
    Where is the pv connection relative to the generator connection? I assume you are getting at that the pv is on the load side of the generator? I know it's wrong, and I wouldn't try it, but probably the inverter would shut down before any damage was done.
    Not necessarily. I used to teach an off grid lab with a Sunny Boy, Sunny Island, and Generac genset. The SB ran just fine with the genny as the "grid".

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    Array > inverter > load center < ATS < POCO/Generator is the arrangement.

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    Quote Originally Posted by ggunn View Post
    Not necessarily. I used to teach an off grid lab with a Sunny Boy, Sunny Island, and Generac genset. The SB ran just fine with the genny as the "grid".
    I remembered you said that in a previous thread - hence, I didnt say the inverter would not synch to it What I said was the inverter would likely shut down before any damage was done. That is, even if the inverter did synch up to the genny, if demand went below production, the inverter would drive up frequency and/or voltage and THEN shut down. That is my hypothesis anyway. Anyone want to take one for the team and try it?
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

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    Quote Originally Posted by electrofelon View Post
    I remembered you said that in a previous thread - hence, I didnt say the inverter would not synch to it What I said was the inverter would likely shut down before any damage was done. That is, even if the inverter did synch up to the genny, if demand went below production, the inverter would drive up frequency and/or voltage and THEN shut down. That is my hypothesis anyway. Anyone want to take one for the team and try it?
    Just on theory, it would be the generator that would drive up frequency, and the inverter that would drive up voltage. Right?

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    Quote Originally Posted by electrofelon View Post
    I remembered you said that in a previous thread - hence, I didnt say the inverter would not synch to it What I said was the inverter would likely shut down before any damage was done. That is, even if the inverter did synch up to the genny, if demand went below production, the inverter would drive up frequency and/or voltage and THEN shut down. That is my hypothesis anyway. Anyone want to take one for the team and try it?
    I think it would be a race. I wouldn't count on the inverter shutting down before frying control circuits in the generator.

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    Quote Originally Posted by ggunn View Post
    I think it would be a race. I wouldn't count on the inverter shutting down before frying control circuits in the generator.
    But the inverter would shut down at what, 63 hz? I would conjecture that the inverter operation window is a lot less than the generator "damage window." Like I said, I am, not going to try it.
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

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    Are there any code issues? Or are they just operational?

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