Buying bigger inverter than needed.

solarvicsolarvic Solar Expert Posts: 1,071 ✭✭✭✭
I can buy a new fronius IG Plus 3.8-1 inverter about $200 less than the smaller 3.0-1 inverter. Does this make sense when the smaller inverter would work? Maximum usable amp input for the 3.0 inverter is 14 amp which limits me to 1 string.of 16 panels I plan to use. With the 3.8 inverter I still would be limited to the 16 panels in one string. The fronius inverters have 3 power stages and use only as many stages as needed. Do you think the output would be the same for the 3.8 inverter as the 3.0 inverter? The 3.8 inverter The 3.8 inverter can use 17.8 amps which would let me have 2 strings of panels if I decided to add more panels. :Dsolarvic:D


  • BB.BB. Super Moderators, Administrators Posts: 33,319 admin
    Re: Buying bigger inverter than needed.

    I like the extra capacity even if not used... Hopefully the unit will run cooler.

    Since they appear to run three parallel conversion stages--then there should be less losses when there is less solar power available (vs a one stage larger converter with lots of capacitive/switching losses).

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • solarvicsolarvic Solar Expert Posts: 1,071 ✭✭✭✭
    Re: Buying bigger inverter than needed.

    I pulled the trigger and bought the 3.8 ig-plus because I wanted the 600 volt inverter. I have 2 regular lg inverters that have the 500 vdc limit. I needed as high as voltage as I could get as the panels are a little over 250 ft from the inverter and I can get them in 1 string. If I used the regular ig I would have needed to use 2 strings at twice the amps. I probably will have one of my regular IG inverters for sale when I get done. :Dsolarvic:D
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