It would be possible if you have a huge well-connected grid, spanning thousands of kilometers, with low costs of sending energy over long distances and small en

It would be possible if you have a huge well-connected grid, spanning thousands of kilometers, with low costs of sending energy over long distances and small energy loss (ideally, spanning multiple timezones, or connecting sunny regions and windy regions with the less renewable-friendly ones). There has been some research into this topic, but we're not there yet. First, the connectedness of e.g. EU grid is not that high. Second, it's a very political subject in a way (everyone wants to be energy independent on its own, without needing to import too much). Finally, IMO Europe is not that big to be sustainable on its own regardless of weather (which is often similar on large part of continent).