Sunrise/Sunset inverter operation normal?

RavsRavs Registered Users Posts: 13
I have a 6kw SMA inverter, and I am somewhat mystified why the engineers at Sunpower allow the inverter to click on and off multiple times during morning wake-up and evening shutdown. 20 times a day must be taking it's toll on the contactor and electronic components, right? I'm ready to put a astronomical timeclock on the AC side to inhibit this behavior? Am I crazy?


  • BB.BB. Super Moderators, Administrators Posts: 31,070 admin
    Re: Sunrise/Sunset inverter operation normal?

    Hmmm... Don't know. SMA is one of the best mfg. out there so I cannot believe that this would do something that would cause early life failure because of the start up/shut down that happens every day.

    Has the installer/vendor said all of this is normal? My older Xantrex GT inverter does not make any clicking noises during start-up/shut-down.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • boBboB Solar Expert Posts: 980 ✭✭✭✭
    Re: Sunrise/Sunset inverter operation normal?

    Is it a Sunpower or SMA inverter ?? Probably doesn't hurt anything as there is probably little or no current being switched through the contacts during those times. Might wear out a spring or something but they're usually made to be able to handle more switchings than the life of the product anyway.

    Still, it should be smarter than this. How often does it wait before switching off and back on again ?? Are you sitting there watching it do this that early in the morning, or is there some data logging you can see or something ??

  • RavsRavs Registered Users Posts: 13
    Re: Sunrise/Sunset inverter operation normal?

    The clicking happens when there is sufficient daylight to energize the inverter near sunrise at about 275-300 volts DC from the PV array but 0 watts as read on the inverter cover, and the clicking sounds like a power contactor closing followed by a change in pitch of the inverter transformer (presumably the inverter coming on-line and "loading"), and then cuts out. After several cycles like this, there is finally sufficient daylight to maintain a closed contact and grid tie condition, albeit only a few watts. Good point that the contact is under no or very low load and not a "deteriorating" condition due to low load, but I need to dig into it with my installer and perhaps there is a retard setting in the software (not accesible to me) to delay power up in the morning (and reverse in the evening). Maybe it's because I am an electrical engineer that I am sensitive to this condition and because the inverter is mounted in the basement that I can hear it clicking twice a day!

    I have the system monitored by a WEL device, but because there is very little load, it does not appear on my logger graphs because all I measure is net power in and out to the grid, and during startup and shutdown there is very low output to grid to measure.
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