Grid Tie minimum inverter voltage?

System
System Posts: 2,511 admin
in Grid Tie and Grid Interactive Systems #1
I have 8 (12v) 125 watt panels that I would like to use for grid tie system. However, I notice the input voltage for Fronius Grid Tie Inverters is minimum 150v and for many other grid tie inverters the mnimum voltage is higher than that. If all the 12v panels above are wired in series the maximum operating voltage is about 136v. The open circuit voltage is about 165v. Does this mean I can use this strring of panels with the Fronius Inverters or should I be looking for a grid tie invereter with lower input voltage? Any tips on this would help! Thanks!
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  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    #2
    Re: Grid Tie minimum inverter voltage?
    If all the 12v panels above are wired in series the maximum operating voltage is about 136v.

    gogreen,

    That value may be based on the STC Vmp spec for the eight modules wired in series, but the MPP voltage will drop as the modules warm up when exposed to the Sun. Figure on a realistic MPP voltage to be ~85% to 90% of the STC spec.

    Good luck!
    Jim / crewzer
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  • Roderick
    Roderick Solar Expert Posts: 253 ✭✭
    #3
    Re: Grid Tie minimum inverter voltage?

    In my opinion, there's a hole between the low voltage of standalone (battery) systems, and pure grid-tied, and your array may fall into that.

    Our array is supposed to have a max power STC voltage of 216 volts, but in practice, I see that it's about 205 volts. I have never seen it operate below 200V, even though the inverter is supposed to be good down to 170V.

    I don't know if the cost is bearable to you, but if you can get enough panels to make the max power voltage be 175 or 200V, that would be what I would do.

    I hear there are also 110V inverters, but have never actually seen one. If so, the input voltage requirements might be lower.
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