, nuclear is cheaper once infrastructure is paid off.

The marginal costs for renewables - that is the cost of producing one more MWh if the plant is up and running - is zero. With merit-order pricing, this is their market price. Nuclear cannot compete with that price. Also, while wind energy provides cheap base load, solar electricity production matches the daily demand curve very well. Because of this, it needs less of relatively expensive storage. It was never the plan to use pure nuclear power - that would have been way to expensive. It was always only meant for base load, which is a small fraction of the daily peaks or the daily average demand. Because of that, it was never planned to replace most fossil energy with nuclear - it would have been way too expensive. Nuclear was touted as cheap base load, remember?

Germany’s problem is an entirely different one: Consevative goverments have deliberately obstructed and hampered the extension of renewable energy and power networks. This still needs to happen, and is costing money now. And the conservative government, again, lowers prices and network fees for big companies, and charges citizens for that. That’s why it is expensive.