> Norway has so much hydroelectric capacity that it doesn't matter, though.

We have substantial DC interconnects to countries that have little or no hydro so our prices are no not much different from the rest of Northern Europe. Any excess solar would be sold to Europe just like excess hydro is now. It could also be used to drive pumped storage to ensure that the reservoirs are full for the winter.

The nice thing about hydroelectric is that the energy you use from photovoltaics during the summer means you don't have to drain the dams as much during summer, which means you'll have more power in store for winter (unless you've decided to sell it to Europe first). There's also at least one hydroelectric plant in Norway that supports storing energy by pumping water into the basin, although that feature is rarely used.