Solar is cheaper, even at high latitudes like in northern europe, even for baseload application with big battery buffers right next to the solar farm.

Honestly, that sounds extremely unlikely. I don't live that far north in europe, and while I manage about 0kWh on my residental panels on a yearly basis. Thanks to seasonal changes, I would either need 4 more rooftops to keep the power on during january, or I would need to bank something like 700kWh to make it through 3 winter months. That's not counting the electric car, or heating. Heating would roughly quadruple the numbers (being almost entirely clustered when solar isn't producing), and the car would add roughly another house on top (assuming 50% is charged away from home).

Quick maths that I did because I wanted to try going off-grid: I would need ~100m2 of solar panels, and 2500kWh of battery storage. Or on a national level, 63 TWh of storage as well as just under a 1000km2 of solar panels if everyone lived as low-footprint as we do. And that's just housing, it doesn't include commercial buildings or industry.

The big buffers next to the solar farm are actually quite tiny. The largest under-construction battery park in the netherlands banks about 1200 MWh. With an average househould consumption, that's just about enough to carry some ~4000 2-person households through the 3 winter months, assuming you put down enough solar to meet your yearly energy household energy demands (which we don't have). They're obviously not meant for long-term storage, but long-term storage is exactly what you need to make solar work.

And nuclear doesn't have any of these issues. The only issue is that it's expensive, because we stopped building them.