I should add, that's just for the largest US plant.
The Kashiwazaki-Kariwa monster in Japan, with seven reactors, was capable of producing nearly 8,000 MW on just ~1,000 acres. Or upwards of 50 to 80 times what the best utility solar installations today can produce at max output on the same amount of land.
The Solar Star installation could end up being the best solar comparison right now (completed in June). At max capacity, it might narrow the ratio such that the Japanese plant is capable of producing 50 to 60 times the power on the same land.
Solar star is theoretically capable of about a terawatt on about 4k acres, so that makes the reactor about 15-20 times as efficient. Still a huge difference, but don't hype the numbers too much.
I can't find any source suggesting the Solar Star is capable of 1 TW output with 4000 acres. SunPower's own fact sheet† gives about 1/1500 that capacity for the 3200-acre installation. Where did you hear this?
The Ivanpah plant isn't a great example. The tech is already going obsolete, and it's producing far below theoretical effectiveness. It should be able to produce a terawatt. Fundamentally, it's because solar is immature technology, and nuclear is mature. So what would the efficiency and cost be for a mature solar plant? And how do we get to maturity?
If a solar plant could hit 50% of the energy efficiency on the same land (and the poor-performing Ivanpah plant reveals that it's possible), that raises a question of why we need the cost and complexity of nuclear.
Solar Star (see adventured's comment parallel to yours) may be the current state of the art. It claims 747 MW on 3200 acres. That still doesn't put it in the same league as nuclear.
As a followup, I did some calculations and figure the US averages about 534twh of electricity - say it peaks at 1000twh, which seems reasonable. Both solar and wind appear to be capable of about 1twh per square mile these days, based on existing installations. So 1000 square miles of wind/solar, plus some battery caching, could provide 100% of our typical energy needs. This seems pretty feasible to me.
True, but does it have to be? We can throw more land at the problem. I live in the midwest, where we're starting to see the countryside dotted with windmills. If you can generate a terawatt per square mile, how many do you need?
