No, there is nothing special technologywise, it's a regulation thing. The thinking goes something like this: The million or two of balcony power plants installe

No, there is nothing special technologywise, it's a regulation thing. The thinking goes something like this: The million or two of balcony power plants installed in Germany help the installer's energy bill but the, let's be generous, 2 GWh per year produced are only a drop in the overall bucket, most local produced excess will not even leave your street before consumed. Furthermore, consider that Germany alone produces around 600 TWh of electrical energy per year. But Germany's grid is part of the European grid and yeah, 2 GWh don't even move the needle.