Total solar insolation at peak is under about 400 watts per square meter. A one square foot panel at 100% efficiency is never [1] going to beat 40-50W even in the best circumstances, at the equator, and ignoring weather... and nighttime.
[1] The sun becoming a red giant is hereby defined as an exception to this statement per the follow-up comments.
- "...heating due to gravitational contraction will also lead to hydrogen fusion in a shell just outside the core, where unfused hydrogen remains, contributing to the increased luminosity, which will eventually reach more than 1,000 times its present luminosity...[135]"
1.3 megawatts per square meter! An entire nuclear power plant on your roof, provided the weather allows, provided weather still exists. The future is bright.
Chances are that the expansion of the sun will have stripped away the weather, along with the roof, the house, and any of the lighter elements of the Earth’s surface.
You are forgetting the efficiency gains future homes will make so they require less power. Partly thanks to the rise of room temperature superconducting.
I get annoyed when commenters make back and forth claims without ever providing any citations so I did a Google and found myself on a NASA page. According to that page it's ~1360 W/m^2 at the top of the atmosphere, but by the time it gets to the surface it seems to average out to only about 340 W/m^2[1].
You misread the source. The average is for the entire planet, parts of which are covered by clouds, and half of which is at night. 1 kW/m^2 is a typical value for peak insolations outside extreme latitudes. If the atmosphere absorbed significantly more than that, you could not see very far.
[1] The sun becoming a red giant is hereby defined as an exception to this statement per the follow-up comments.