Thank you for your help. But if the signal from the satellite is amplified in the modem and the signal sent to the satellite is powered by the modem, then I would guess that when a signal is neither being sent or received there may be only a few watts being used by the modem. Is this true? If not, how is the extra power being used during idle times. Curtis-m below says he uses 9 watts most of the time on his HN 9000.
Honestly, it will depend... With you being off-grid you shouldn't depend on the "average" power usage, but the possible highest usage as well so that you don't overload your personal grid, unless you can predict when the signal will drop out and the modem ramps up transmission power and processing to try and keep a signal lock.
The label on the power brick states (at least on mine) Input at 100-130V @ 2.0A (which at maximum theoretical value is 260w), and the output is listed as 46w.
The only time these modems will use a TON of power is during heavy cloud cover, rain, and when it's acquiring a signal after being powered on, so you may want to plan for possible high wattage surges during those scenarios.
Power usage also depends upon how well your satellite is aimed, as well as general location in your beam assignment.
Information source..... from the written spec.... as I said.... for planning purposes... the only number I believe you can use is Hughes. I didn't look at my brick, but, obviously Corrosives is newer (or older) than this spec sheet since his states a different input current rating.
The difference between the input calculated wattage and rated power consumption is a function of voltage at the input vs the various voltages supplied on the output of the brick. Thus the lower power consumption rating. Since we are not given the output voltages or currents drawn by each of them, we can not calculate backwards into that 46 watt number.
I, obviously can't disagree with what curtis-m says his is drawing. To use a simple analogy, the only precaution I would offer is that inverters, like cars, come in many sizes, shapes, and colors. And as car advertisements all say "your mileage may vary".
Where I will respectfully disagree is that the power usage changes based on external influences such as weather, dish pointing, etc.
A one-watt radio is a one watt radio. When the modem is powered up, the RF carrier (radio) powers up, and uses what it uses and doesn't change.
What does vary, depending on those external influences, is what modulation technique is used to modulate that RF carrier (send and receive data). That is solely a function of the firmware in the modem talking to the NOC to optimize the transmission path. And changing modulation technique, does not have any significant impact on power consumption.
Caveat: There may be some small power consumption change depending on how the firmware uses the chips in the modem for various modulation techniques, but I would expect that to be a very small number in the overall power usage.
It is only a question of how much data can be transported over the link under the current conditions using that one watt radio. When the modem reads the incoming signal, if it is degrading or improving, it will tell the NOC, we need to change the modulation to slow things down or speed things up to optimize usage of the link.
So, Timothy, at the end of the day, it all depends on what approach you want to take to calculate your power needs.