[Robert A Cook PE]

When you subtract out night, weather, efficiency, angles, and other factors, your net solar harvest is about 10 watts per square meter.

No, no. It would be nice, but no.
The sun provides 1362 (yearly average) to the top of atmosphere (TOS) IF the receiver is perpendicular to the sun's rays.
In the northern summer, 1310 watts.m^2.
In the northern winter, the sun provides 1420 watts/m^2.

At sea level, on an average day BETWEEN 45S and 45N latitudes, the sun might provide 1000 watts/m^2, for about 6 hours per day, IF the solar cells track the sun continuously.
For a flat plate laying horizontally (roof top, for example), the panel only gets 3/4 of that 1000 watts/m^2.

[ctdonath2]

That’s exactly what I’m getting at. Now keep going from there:
You’ve worked it down to 750W/m^2.
At 6 hours a day that’s 188.
An optimistic 20% efficiency harvests 37.
Roughly 1/3 lost to weather conditions and you’re at 24.
Allow for other mundane losses and you’re under 20 watts average.
Then throw in random malfunctions etc.

Hence my “10w/m^2” rule of thumb.