It makes me wonder whether they want a solution to the problem at all. Europe is north enough that in some countries you can probably get rather long streaks of

It makes me wonder whether they want a solution to the problem at all. Europe is north enough that in some countries you can probably get rather long streaks of time where solar just won't work. If you only have 6-7 hours of daylight and they are likely to include lots of clouds and snowfall then I don't see how solar is going to be a replacement for anything. Wind might be, but wind requires an extraordinary amount of area to cover an entire country reliably.