Alright, the rich text reply editor still isn't working for me, so I can't quote people without it fucking up the formatting, but Bofferbrauer's response I can get behind. It is true that future gens of nuclear fission hold a lot more promise than the current gens, and are way safer. Fission isn't a long term solution though, even with the better plants. That Ted Talk I linked in the messed up formatting reply features a chart that explains that at current consumption of energy, there just aren't enough reserves for fission to replace fossil fuels.
I'm not nearly as pessimistic as some of you are on solar. In fact I'm incredibly optimistic. The technology for battery backed 100% renewable grids exists TODAY and in a financially feasible form. All that prevents it is the political will. It requires a reworking of the entire power grid and the power plant business model, so as to make it less a bunch of power plants providing electricity at a cost per Watt to a network of connected homes across huge distances, and more a bunch of networked networks of microgrids generating power locally, and storing it at power plants, which also generate electricity, and instead of selling the electricity per kWh, they sell a monthly service to connect and regulate all the microgrids. So if a storm blocks the sun in a microgrid dependent on solar, that microgrid gets its energy from neighboring microgrids that are having a sunnier day, and battery backs everything up so that if there are a lot of rainy days everywhere for everyone, there's enough extra energy to hold everyone over. A renewable grid can be sustainable, reliable, and not fluctuate wildly, it just needs to be scaled properly and the business model needs to be reworked. Not likely to happen under the current private system, but Bernie wants publicly owned power, which would be the easiest way to organize this.
I like your microgrid idea. In towns, that should be perfectly feasible with every house having solar collectors on their roof. Not so sure about cities, but for those wind farms and solar farms might bridge that gap.
However, the fluctuations will not go away by this. I'll have to find the chart with the German energy production again, because on it you could clearly see what weather that day had just by looking at how the solar or wind energy spiked or dropped. And while they account for about 23% of total power in 2018, when they both spike together, they reach about twice the output of the power plants Germany has, and often in such cases, some part of the power is simply not getting collected since that's way too much to not overload the grid.
Here, you can actually see the power output of each day in Germany: https://www.agora-energiewende.de/en/service/recent-electricity-data/chart/power_generation/06.08.2019/16.08.2019/
You can see the fluctuations very well that come with solar and wind. More conventional power plants will be needed until we have batteries that can store several hundreds of MAh @240V (120V for the US. And that's Mega Ampere Hour, not Milli Ampere Hour @5V or 3.3V like in those puny little powerbanks - so just about 50 billion times bigger), we can't depend on Wind and Solar alone. That works well for towns, but not so much in cities where the consumption is much bigger than could be collected by such means.
Also from that chart, you can clearly see that German is turning off power plants or running them at a lower power output to not overload the grid during daytime or high wind power output at nighttime, otherwise they would probably be net energy exporters. So reasoning that the high price might come from the power imports is most probably wrong, otherwise they would certainly produce more power, as they have the capacity for it. This is one of the main benefits of having some non-renewable energy production: you can turn them on and off at will if needed.
I would say however that there could be a way out: having to force buildings that they need to install a battery which size depends on the power consumption of it. This could become pretty huge batteries in skyscrapers (or several smaller ones), but that way we would escape the need for the megabatteries mentioned above. But who else will get that idea? And more importantly, who would want to put this motion forward politically, no matter which country? I doubt there's much political will to enforce something like this.