Please forgive me if this is a stupid question - but is heavily investing in solar electricity a good idea in Europe considering the variation in climate throughout the year?

Energy demand is highest in the Winter, when mean monthly sunshine hours are at the lowest.

Even in Nice (the very south of France) where I assume this difference would be smaller, there's still a big gap between 347.5 mean hours in July and 139.3 mean hours in December (https://en.wikipedia.org/wiki/Nice#Climate).

Surely we'd need to heavily invest in backup generation capacity that would be dormant for the vast majority of the summer then heavily in use over the winter?

Admittedly I have a very limited amount of knowledge in this area - but wouldn't wind or tidal power generation be a better bet here (well, Europe anyway)?