AC Watts vs DC Watts

DrewE wrote:

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RMS vs peak and the square root of two have to do with averaging a sine wave and having the equivalent steady-state value over time--integrating over time, basically. AC voltages and currents are generally expressed as RMS values, and these are related to the peak values by the conversion factor. They're expressed as RMS values precisely because it enables one to use standard basic DC laws to compute things like power or Ohm's law and get the correct answers for resistive loads (i.e. if the power factor is 1.0). To do otherwise would basically require calculus rather than arithmetic to figure these things, as indeed often is the case with non-sinusoidal waveforms.

AC power in watts is AC Volts (RMS) times AC amps (RMS) for a resistive load. An AC watt can of course accomplish as much work in a given time as a DC watt, since they're both just watts.

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For e.g. an electric heater, the power consumption is just the wattage, and would I suppose be RMS watts if you wanted to integrate the instantaneous power consumption over the course of one or more AC cycles. Nearly always for power we're talking about more or less steady-state operation, so such integration is assumed.

If the inverter is 100% efficient, by definition the power going in will be the same as the power going out, and your DC power consumption will be exactly the same as the AC power output.
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