Realized that my solar charge controller has watt readings for its load terminal that I can access with some simple code.

So, thought I'd use this to compare my 24V Aims pure sine wave inverter with the smaller 12V Black and Decker modified sine wave inverter I've been using to run the satellite modem. The latter has the overhead of a 24V buck converter. I've heard pure sine wave can be more efficient, but the Aims consumes 17 watts even when nothing's plugged into it.

Which can run the satellite modem most efficiently over a full day, assuming it's powered off for 6 hours at night but the inverter is left on? Any bets?

(I've previously measured the satellite modem using 34-40 watts on the AC side.)

I only get one sample per second from the charge controller, and the Aims inverter fluctuates a lot as it generates the sine curve. Query at the wrong time and it's pulling 0 watts. (An oscilloscope would be handy right about now; my little Labrador board can't handle this much power.)

So, I wrote a script to take a bunch of measurements over an hour of light internet usage. Hopefully I'll get enough data for a smooth result.

Clearly the Aims is more efficient!

Although I wonder if the bit of a leveling off at the end may be due to it needing less power to beam data to the satellite due to clouds or orbit or whatever.

Finally, here's the Aims running with nothing plugged into it.

Wow, you can see the polling rate and the 60 hz AC come into and out of phase...

And over those 6 minutes, the average watts used seems to be 4. Better than the 17 in the manual, but still almost as many as my laptop uses.

So, leaving the Aims on all the time, and turning off the satellite modem for 8 hours at night would use only 32 watt-hrs more than turning off the Aims. Compare with the worst solar production I had last winter, which was 100 watt-hrs.

(I had 6 days last winter under 500 wattt-hrs.)