Solar could supply civilization with more energy than fission or fusion (in manmade reactors) ever could. The Sun will produce orders of magnitude more energy than totally fusing all the deuterium or fissioning all the uranium and thorium in the solar system could provide. Far from being a sign of a civilization in decline, the triumph of renewables would be a signpost on the way to becoming a Kardashev 2 civilization that can fully exploit the energy resources of the solar system.
The important shift btw is not from coal and nuclear to renewables, it's from fossil fuels for heating and transportation and industry to electricity. If we figure out how to build fusion power plants safely for cheap in a few decades, we will already have set up our infrastructure to run on electricity instead on carbon. Cutting energy usage is just a nice side effect of switching from 30% efficient ICEs to 80% efficient electric cars and from heating with gas to heating with a heat pump.
Do we have enough rare-Earth minerals to build this many solar panels? What do we do with the panels when they reach the end of their lifecycle twenty years from now? What do we do when it's nighttime in the Sahara?
To cover nights in the Sahara we use some of the absurd excess energy we get from covering the whole desert to make some Hydrogen or Methane and convert that back to electricity. If we don't want PV and gas synthesis for some reason to we can also just store heat in molten salt in solar-thermal installations and drive steam turbines. That's just a bit more expensive than PV today.
I'm not sure why rare Earth minerals would be a bottleneck. They aren't rare in the element abundance sense, just uneconomical to extract, which is why they are being extracted in countries where human rights violations are happening all the time.
The are no rare-Earth minerals in silicon solar cells.
Very deep space missions can't use solar power due to the inverse square fall-off of light from the sun, but even those don't use nuclear reactors. They use radioisotope thermal generators powered by radioactive decay. RTGs don't have any moving parts and can run for decades without maintenance.
I think it's astonishing and delightfully living-in-the-future that solar cells -- once so expensive that only space missions could justify their cost -- are now manufactured by the square kilometer and cheap enough to "farm" electricity here on Earth. If you're pondering speculative technologies of the future, a solar collecting Dyson swarm could provide more energy than all the fissionable materials in the solar system.
Not that so-called renewables will actually solve that, cutting energy usage on the other hand definitely would help.
That dead end technology is one of the few hopes for countering global warming and carbon emissions. And rooftop solar and EV batteries dual-purposing for distributed grid storage are complementary technologies.
"Why can't we bring down the price of nuclear" is a problem with the nuclear industry, and has nothing to do with the REVOLUTIONARY sea change that renewables represent.
And I'm a LFTR fan. Brayton cycle? 100x more available fuel that's breeded? Vastly reduced proliferation risk? "Burn" spent fuel rods? 99% fuel use? Zero meltdown risk with plug and liquid fuel? Scales down to the size of a closet? Very rapid startup/shutdown time? Container degradation was a problem, but whatever. Amazing stuff.
But LFTR and other technologies have zero chance in the open market right now with renewables plummeting in cost to the point that there exist no fossil fuels that are competitive in the marketplace.
Solar/wind is one of the few developments that are counter to our civilization sliding into a polluted, totalitarian, oppressive dystopia. Solar/Wind can enable decentralized power production in the third world, and combined with Starlink and other satellite internet webs will enable so much potential for the third world without the pseudo-oppressive nature of grid and wired communications infrastructure.
It's because nobody is thinking about the starships, for better or worse. People are bad enough at dealing with today's problems.
By increasing energy efficiency by a factor of 2 you easily cut down on energy usage.