using single phase inverters in a three phase building

Good evening all,
I live in Kingston Jamaica where we have a Delta Grid, so our single phase installations are 110v between phases (110+110=220vac) and our three phase is 110vac-110vac-190vac (high leg). No manufacturer makes a three phase inverter which will interconnect with the delta grid unless you put a transformer with delta/star which adds about $3-4k usd to the bill. My question is for a 25kw PV system can i use five 5000w single (split phase) phase inverters on the two 110 legs and not connect anything to the 190vac leg ..

sincerely,

Robin

Comments

  • inetdoginetdog Posts: 3,121Solar Expert ✭✭✭✭
    Re: using single phase inverters in a three phase building

    You can use single phase inverters on the two 110 legs, yes. But the power company may not be OK with the imbalance that will cause on their system (unless most of that energy will actually be going to feed your own 110v loads on site.)
    Most of the major GTI manufacturers I have looked at (including SMA) offer individual inverters that are designed to wire between two hot lines (which in your case would be any two) at a voltage of ~ 220 or 240 volts. Using those you could connect to the high leg (just not from the neutral) as well as to the 110/220 legs.
    Some of these inverters may, so satisfy some regulator requirements that may not apply in your case, be designed so that they need a center point reference input even though they will not be delivering any current to it. That would be the center tap in the case of 110/220 single phase and the neutral in the case of 190Y/110 three phase (which is not what you have...)
    SMA SB 3000, old BP panels.
  • reckless1reckless1 Posts: 29Solar Expert
    Re: using single phase inverters in a three phase building

    Thanks inetdog...


    robin
  • ggunnggunn Posts: 1,973Solar Expert ✭✭✭
    Re: using single phase inverters in a three phase building
    inetdog wrote: »
    You can use single phase inverters on the two 110 legs, yes. But the power company may not be OK with the imbalance that will cause on their system (unless most of that energy will actually be going to feed your own 110v loads on site.)
    Most of the major GTI manufacturers I have looked at (including SMA) offer individual inverters that are designed to wire between two hot lines (which in your case would be any two) at a voltage of ~ 220 or 240 volts. Using those you could connect to the high leg (just not from the neutral) as well as to the 110/220 legs.
    Some of these inverters may, so satisfy some regulator requirements that may not apply in your case, be designed so that they need a center point reference input even though they will not be delivering any current to it. That would be the center tap in the case of 110/220 single phase and the neutral in the case of 190Y/110 three phase (which is not what you have...)

    I'll just add that some of these high leg arrangements are open delta with a much smaller transformer driving the high leg than the other two. In those situations the power company may not even want you to interconnect with the high leg.
  • RudyRudy Posts: 1Registered Users, Users Awaiting Email Confirmation
    In a grid tie system (220/380, Y, Argentina), is it possible to connect a delta output inverter (no grounded) or iIam obligated to use an inverter with a Y output? My idea is the delta should not be a problem, connected to the phases of the Y system. which are at 380 volts, but I want to be sure. In the Y system I only have single phase loads. Evntually a 3 phase electrical motor. Thanks for your help. Rudy.
  • Dave AngeliniDave Angelini Posts: 3,770Solar Expert ✭✭✭✭
    If you want to be sure you will need to check what is customary or required by the utility.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

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