Those numbers sound about right, but the real problem for solar in Germany is how it inflates the cost, and the intermittency. The capacity factor is just a readout of those problems.
Germany is one of the major economies with the very worst solar resources in the world. So it might actually make a lot of sense for them to build a bit of nuclear instead of stringing HVDC from Spain or Italy or wherever is sunnier. Or not, it's a very tricky projection! These costs are changing quickly, and any nuclear build is a bet not only on the current costs of technologies, but a bet on the future 30-60 years of costs.
