The best power generation system of the 21st century

Finally bothered too look up the data. Current levelized costs put wind as the cheapest per kWh. Solar is next. Then natural gas, then coal, then biomass, community solar, and rooftop solar, and then it's nuclear power.
www.lazard.com/media/438038/levelized-cost-of-energy-v100.pdf

Good thing we don't make policy from internet polls.

Before you ask, that doesn't include subsidies or a carbon tax.

atompunk al la fallout would be nice

Cost isn't all.

Consider, please, how much space one individual wind plant or solar panel plant takes up. Enormous amounts of land are used for wind, solar and biomass. ESPECIALLY biomass.

Going off of data from power plants from western and central Europe, (source: go look at a few) the density of electricity produced (gigawatthours per square kilometer) is around 3000 for  third and third and a half generation nuclear power plants. Compared to the worst wholesale source of energy, biomass harvest and combustion (which has a very low efficiency, and therefore has about 1 GWh/km². Even then, I'm taking into account the EXTREMELY optimistic variables for biomass, including perfect environment, climate, drying and the absolute best plant for amount of energy produced per square kilometer (that would be miscanthus sinensis)) is 3000 times less space efficient. Solar and wind is around a few hundred times less efficient. And note especially that currently, our pressurized water reactors are working below 5% fuel efficiency. That is, they get less than 5% of the energy out of an amount of enriched fission fuel. This technology will improve dramatically, as the first fourth generation reactors are coming online, including sodium-cooled fast reactors.
Last time I checked, nuclear was roughly on par with plain old coal burning in the terms of MW produced per cost of building the power plant. And in that analysis by lazard, it's a cumulative cost based on maintenance alone, not on manufacture cost. Solar, wind and biomass have poultry returns relative to nuclear or combustion.

Then, of course, is the fact that solars don't work at night, and wind doesn't blow all the time. The best application of solar is in individual amounts; on residential housing with dedicated power management systems (including accumulators), on specialized systems and vehicles and in otherwise inaccessible locations. It is a colossally stupid decision from a grid-level perspective. Solar panels lose efficiency with higher temperatures, have costly maintenance and horribly environmentally unfriendly manufacture and, worst of all, without subsidies and push from environmentalists, it would be economically unfeasible to create any non-experimental solar farms.
The age of solar power will come with the advent of orbital industry, but we haven't gone that far yet. Solar power is the thing of dyson swarms and space manufacture out in the vastness of space. There's plenty of space in, well, space, where the solar panels won't take up agricultural land and cast shades.

TL;DR: It may be cheap to produce power, but it takes a damn lot of space, and everything costs a lot to build. Solar and wind are also horrible for the power grid.

Is this turning into a fight? I must do something...

You make allot of good points, but i do have one major counter argument. That is mainly that as most structures and societies exist now, much like with the materialism and consumerism we express in product consumption, we like wise are hilariously wasteful in energy consumption as well. Many people simply forget to turn their lights off or unpower appliances and items all the time, burning many more watts than necessary. Additionally even if the families are over all conscientious about their consumption, the simple design of many homes and apartments that are old/designed cheaply/designed replaceable put a much smaller emphasis on energy efficiency in regards to heating.

Now when the thread talks about 21+ power, that in my opinion might cover secondary colonies as well. In that regard efficiency is utmost important. Likewise the precious room needed for power production is not so limited on exo bodies. So yes Nuclear is indeed the best bang for sqaure buck, but secondary supplies should not simply be written off.    

Why do you assume that solar panels on earth will be put on pastures? There's perfectly good deserts, and hey, deserts are exactly the place you'd want to put solar panels.

Storage is cheap and getting cheaper (take pumped hydro).

And space is only a problem if you dramatically underestimate solar output. If we stick with the 22% efficiency we're currently getting with cheap panels (bilayer and more might increase that to 40%, possibly more), and we're looking at 7 work-hours a day in the Mojhave and 1kw/m, and we assume 5% growth on our 28691657770 MWh/annum current total energy use, that's a square 231km on one edge. Presuming all the panels are flat on the ground. We could do better with trackers, but generally they make things more expensive.

Let's throw in 10% more energy on top of that just to account for storage inefficiency and energy losses when producing hydrogen (or whatever) for vehicle fuel. 242.5km x 242.5km. Of course, it wouldn't be one big array, it'd probably be lots of scattered arrays from LA to Lubbock to Salt Lake City. From one array, you might be able to see a couple others on a clear day. All in the driest, sunniest, most god-forsaken land in the west.

I'm not saying it'd be small, but I am saying that it's not taking up anyone's farmlands.