Microinverter Line Power Reference

Hopefully not asked before, but ... might it be possible to use a pure sine wave 220/240V generator to provide the reference voltage/60 cps for a grid-tied system, along with electronics/switching to shunt the panel output to another load(s) so as not to back feed the generator, so that the panels could be used when line power is not available? Does a pure sine wave generator have stable enough voltage and cps to enable the microinverters?


  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Microinverter Line Power Reference

    Actually it has been asked before, as well as similar concepts including synching to generators (standard and inverter type) or off-grid inverters.

    No, it won't work.
    You could generate a signal that will fool the micro into thinking it has proper Voltage and frequency available, but you will not have the 'electrical mass' of the grid available. The load equivalent will not react fast enough to take the output of the inverter; you will never switch it in time to prevent the power qualification from going out of spec. Electronics sufficient to do so properly ends up being choice #3, and even that has problems associated with it.

    Using a generator to synch is a sure-fire way to burn up a generator.

    Using an off-grid inverter can work, but there are problems. Such as will it back-feed charge the batteries, and if so is there any way to regulate the charge? Most of the time the answer is "no", but a few OGI's can be AC coupled and will work. SMA's Sunny Island, for example, especially when used in conjunction with their GTI's. Xantrex/Schneider/Conext XW series will too, if you can stand the bugs.

    SMA, btw, also has a GTI with a built-in emergency power outlet that allows it to generate some 120 VAC directly during daylight hours without any batteries. It's new, not entirely useful, but is a definite sign of things to come.

    Trying to skip the batteries is a very popular notion these days it seems. But the batteries (or indeed utility) are there to even out the differences in power generation vs. power usage and really they do it very well. Without them you get power during sunlight hours only, which is not that advantageous.
  • stephendvstephendv Solar Expert Posts: 1,571 ✭✭
    Re: Microinverter Line Power Reference

    SMA have a hybrid PV + diesel generator solution, but it seems aimed at industrial scale/village power supply: http://www.sma.de/en/industrial-systems/hybrid.html

    (don't know anything more about it, other than what's in the promotional material)
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