For instance, here in Greece, we have more than 300 days of sunlight per year, it would be great even if solar panels were implemented by companies or individuals themselves.
It does not matter how many days of sun you get but how much of that energy you can harvest, and Greece despite being all sunny and so for tourism it lags well behind a lot of countries by actual potential.
Excluding the islands, you only get 4 hours on average spread through that day, so you would need to either program all your activities during peak hours or a ton of batteries.
I'm not an expert on this field by any means, I'm not exactly sure on how exactly solar panels work and how efficient they are. However, as you've also mentioned, Germany and other nearby countries can't take advantage of the sunlight, due to their climate. I live in Crete, which is sunny for most of the day (And for most of the year), the same thing doesn't occur in north Greece though (Thessaloniki for instance).