Your personal impression doesn't really matter though. What matters is the statistics.
Of course there is sun in Germany. Yes, there's less. But then it's also cooler which makes the solar panels more efficient. What matters is if it's economical to use solar panels there, which it is. In summer, where some areas will use quite a bit of AC, there's more daylight hours than regions further south. In winter, if you have vertically mounted panels, a nice effect you can get is that the snow reflects extra sunlight from the ground to the solar panel.
Fun fact, even the airport in Longyearbyen in Svalbard, Norway - an island close to the north pole - has solar panels. They're mounted vertically on the walls, since the sun is never very high in the sky. There's no sun at all in winter, but in summer there's sun 24/7.
https://sunpower.maxeon.com/int/case-study/energy-arctic-cir...
It's surprising how much production they get even that far north: "the PV system produces as much as 70 percent of what is typically produced in Germany"
So please don't use your subjective impression about how bright you feel it is to gauge the viability of solar. I can tell you from personal experience, it's not very bright in Svalbard even in summer.
BTW, much of the energy need in winter in northern climates is for heating. It's surprisingly effective to store thermal energy over several months. So it's actually viable to dump heat from excess solar in a thermal reservoir in summer, and use that heat in winter.