At least three.

km

American

You can't mix units like that

I'd want to say "about a week", but I learned not to overestimate people, so probably 5 days top

Technically nuclear came from a different star. The sun won't create those kinds of heavier elements until it burns through its hydrogen and helium fuel to start fusing its way up to lead, and I don't think it's massive enough to actually reach the kind of supernova collapse required to smash lesser elements together into heavier elements than that in any significant amount. So technically, fission is the only the form of energy that isn't based on solar. It's just the still-cooling-embers leftover from someone else's dying star, a whole bunch of billions of years ago. I guess you could say the sun's gravity at least attracted it all into this general vicinity though, at least until the Earth's own gravity started pulling its own weight.

except for geothermal which comes from the Earth’s rotational momentum

emm that is not the source of geothermal energy..

Didn't the molten core also originate in some way from the sun?

...and it's still 20 years away.

Do you mean something like the Mojave Solar Project, which has produced 5.1 million MegaWatt hours since 2015?

https://en.wikipedia.org/wiki/Mojave_Solar_Project

Or do you mean something like a smaller scale, e.g. home use? Look up Parabolic Solar Collector.

Or are you thinking of an Heliostat? https://en.wikipedia.org/wiki/Heliostat Something like the Solar Two, https://en.wikipedia.org/wiki/Heliostat#/media/File:Solar_two.jpg

Dyson swarms would be more feasible. Heat rejection on a sphere would give an engineer a complete meltdown.

First a Dyson Ring; have you read any of the Ringworld series by David Niven? And for the time being solar panels, solar architecture, cardboard solar fucking ovens, solar deathray from a satellite dish, etc, etc, etc.....