You can't just connect 20 cable's from Africa to the European grid and expect it to work, that's not how the grid works. And I'm truly surprised that many people on HN seem to think it would.
Source: I work in utilities and one of my current focus area's is creating software to help expand the net to cope with the addition of new renewable sources and EV charging stations. And even that is posing a massive challenge on a relatively small and local scale. I couldn't imagine the impact of this fantasy of just plugging in some cables from Africa somewhere.
Edit: This incident is an example of how sensitive all this stuff is:
https://www.bloomberg.com/news/articles/2021-01-27/green-shi...