Is my 1000W Xantrex inverter too much inverter?

thorsnessthorsness Solar Expert Posts: 52 ✭✭✭
My modest solar-Honda generator powered system at the cabin consists of a single PV panel, two 12 volt AGM batteries, a controller, Vector battery charger, transfer switch and a 1000W Xantrex inverter. We only use the batteries to power lights (all CF) and a CD player. With all the lights on, inside and outside, and the CD player going (rare) the demand is about 200W max. The more common draw is about 60W and almost always less than 100W. If running the vacum or a saw, I start the Honda. I was reading in the NAWS catalog that relatively small demands, such as we call for, while using a 1000W inverter, actually use more power since it is such an inefficient use of the inverter.
My question: would I be better off with a 300W inverter? Along this line, I saw the Morningstar 300W inverter in the same catalog and noted that it doesn't use a cooling fan. This would be beneficial since when we open up our cold cabin in the winter (maybe 10*f or colder sometimes inside), the cooling fan howls and squawks if I turn on more than one small CF light.
Thanks, as usual.



  • n3qikn3qik Solar Expert Posts: 741 ✭✭
    Re: Is my 1000W Xantrex inverter too much inverter?

    Yes you are correct about the draw of the inverter.

    May want to look at 12 VDC CFL. as another option.

    Now, lets ask this, are you currently drawing down the batteries to fast/deep. If the current setup is working, leave it alone.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Is my 1000W Xantrex inverter too much inverter?

    in general yes. 1stly pay close attention to the base draw of the inverter as an indicator of if and how much you may save in comparison to another inverter. that's 'may' because it also depends on inverter efficiencies, especially at the power levels you will typically operate at and that can vary too, for what good would it do you to get say a 300w inverter that may only be at or around the same efficiency % for the same power levels.
    maybe too wordy?
    100w inverter at 93% eff at best and 87% near the area of power you draw at.
    another inverter at best getting 88% will have about the same effect as the other inverter and may not be worth the expense.
    the same could be applied to the base loss of the inverters as it can vary so compare and judge for yourself if there's a savings if it's worth the investment to you to buy it.
  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Re: Is my 1000W Xantrex inverter too much inverter?

    Sell your 1kw inverter, (or save it for growth later) and install the Morningstar. I use the MS and have been very happy with it. We tend to run much like yourself,,, with all the loads on, we are drawing under 100 watts, and the MS does it quiet efficiently.

  • 2manytoyz2manytoyz Solar Expert Posts: 373 ✭✭✭
    Re: Is my 1000W Xantrex inverter too much inverter?

    Another thing to consider is the idle current (parasitic load). Since I have a small solar array, this is an issue for me. Those with a massive array, this simply falls into the noise level.

    I compared my various inverters, and posted the numbers here:

    Things learned.

    1. Big inverters might draw less idle current than a smaller inverter.
    2. A MSW inverter might have a lower idle current than a PSW.
    3. Assume nothing, measure!

    If a big inverter has about the same parasitic load as a smaller one, and if the efficiency curve (as discussed) keeps you off the edges of the curve, go with the BIGGER inverter. No reason not to. And if you suddenly decide you want to run another widget, it has the ability.
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