Of course, French nuclear plants have the opposite problem: they're limited in their ability to do anything other than a constant base load supply, even though

Of course, French nuclear plants have the opposite problem: they're limited in their ability to do anything other than a constant base load supply, even though they do much more load following than say US nuclear power. So France has to dump surplus electricity at low-load times and then import power at peak times. I don't think mixing wind, solar and nuclear will fix this either - France's peak demand and its highest net imports are during winter cold spells, when solar and probably also wind output is at a low.