Overloaded Inverter

sundownrsundownr Solar Expert Posts: 25
If I were to put 5 each, 300W solar panels on a typical 1000W inverter what damage, if any, would I do to the inverter? Would not the inverter simply use up to its rated input capability?

Thanks.

Comments

  • RCinFLARCinFLA Solar Expert Posts: 1,393 ✭✭✭✭
    Re: Overloaded Inverter

    If you are talking about a grid tied inverter then it won't hurt.

    The inverter will run up to its rated limit. Most of the time panels will not be producing maximum panel output so large panels will help produce more output in morning and afternoon angled sun exposure.

    If this is battery based then an MPPT controller will only run up to its rated power limit. You have to make sure batteries are large enough AH rating to take max current. A PWM controller may be damaged depending on if unit has overcurrent limit circuitry.
  • sundownrsundownr Solar Expert Posts: 25
    Re: Overloaded Inverter

    Thanks RCinFLA. This is what I thought.

    It would then seem wise, in any battery based, solar system, to regulate current...
  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Re: Overloaded Inverter

    Pretty much, we work on a "balanced" system design. Size of load (peak, WH per day) defines the battery bank. The Battery Bank size defines the solar array wattage. And the local needs (distance to array, available solar panel Imp/Vmp/Array Size) define the Solar Charge Controller needs (PWM, MPPT, battery bank voltage 12/24/48, etc.).

    But instead of talking about the recommendations in an abstract way--What are your needs. We can talk about the questions and choices towards your needs.

    A hard requirement is usually less confusing when we discuss the details.

    Once you have gone through a design cycle (even if you don't build it)--Then all of the rules of thumbs and recommendations make more sense.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Overloaded Inverter

    current is somewhat regulated whether we want it that way or not. you have to size the power going into the cc or inverter so that you don't waste any of that expensive pv power by having a current limit reached. often times in such a case that the pv levels must be that high as to hit the current limitations of either a cc or inverter then it's time to either get a new high powered model or add another cc or inverter to handle the excess. now that was general speak and specific conditions may dictate what the best option may be for your circumstance and is also a matter of choice on your part.
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Overloaded Inverter
    sundownr wrote: »
    If I were to put 5 each, 300W solar panels on a typical 1000W inverter what damage, if any, would I do to the inverter? Would not the inverter simply use up to its rated input capability?

    Thanks.

    The way I read your question, you are talking off-grid and are asking what would happen if you connected 1500 watts of panel, directly to an inverter, no batteries, no controller etc.
    If this is correct, than at best, it won't work, and at worst, you have a fire.
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Overloaded Inverter
    The way I read your question, you are talking off-grid and are asking what would happen if you connected 1500 watts of panel, directly to an inverter, no batteries, no controller etc.
    If this is correct, than at best, it won't work, and at worst, you have a fire.
    Sorry, that's just not correct. In the first place, if there are no batteries, then it's not off-grid. In the second place, the inverter (OG or GT) will draw current up to its maximum and then the MPPT circuit will dial down the load on the PV to limit the current input to the inverter. Even if it didn't and the inverter were damaged, it wouldn't cause a fire; the inverter would shut down and open-circuit the array.

    In high latitude locations with frequent cloud cover, overloading an inverter by 50% is not uncommon. One has to be careful about max voltage at low temps when doing string sizing, of course.
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Overloaded Inverter
    ggunn wrote: »
    Sorry, that's just not correct. In the first place, if there are no batteries, then it's not off-grid. In the second place, the inverter (OG or GT) will draw current up to its maximum and then the MPPT circuit will dial down the load on the PV to limit the current input to the inverter. Even if it didn't and the inverter were damaged, it wouldn't cause a fire; the inverter would shut down and open-circuit the array..

    Re-read his original post. "If I were to put 5 each, 300W solar panels on a typical 1000W inverter what damage, if any, would I do to the inverter?"
    There is much we don't know, including what, if anything this poster may or may not know about such systems. It's not all that uncommon to have folks ask if they can directly wire PV to off grid inverters. What voltage are the panels? What is a "Typical 1000 watt inverter"? Sounds like it COULD be off grid he's asking about, or indeed it COULD be GT, but he doesn't tell us one way or the other. Dare we assume one way or the other? What happens when you supply a "typical 1000 watt inverter" meant to run on 12VDC?, (again he doesn't tell us) with perhaps 30 or higher unregulated volts directly from the panels? There IS a limit to the input voltage before the smoke rolls out.
    We should never assume details the OP does not tell us, especially when he or she is asking questions such as these, but we can questions and hope to get answers, and until we get those answers, I stand by my post.
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Overloaded Inverter
    Re-read his original post. "If I were to put 5 each, 300W solar panels on a typical 1000W inverter what damage, if any, would I do to the inverter?"
    There is much we don't know, including what, if anything this poster may or may not know about such systems. It's not all that uncommon to have folks ask if they can directly wire PV to off grid inverters. What voltage are the panels? What is a "Typical 1000 watt inverter"? Sounds like it COULD be off grid he's asking about, or indeed it COULD be GT, but he doesn't tell us one way or the other. Dare we assume one way or the other? What happens when you supply a "typical 1000 watt inverter" meant to run on 12VDC?, (again he doesn't tell us) with perhaps 30 or higher unregulated volts directly from the panels? There IS a limit to the input voltage before the smoke rolls out.
    We should never assume details the OP does not tell us, especially when he or she is asking questions such as these, but we can questions and hope to get answers, and until we get those answers, I stand by my post.
    No skin off my nose, but on the face of it with no other information, simply connecting 1500 Watts of PV to a 1000 Watt inverter is not necessarily a problem at all.
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