I don't think 30% comes close to cutting it. Look up the difference in production for a solar panel in summer vs winter in let's say Berlin. And that's average. Consider extended lowpoints.

Yes, that's exactly why you would over-provision. So the upside of having occasional surplus is that in other times such as winter with less solar, you are more likely to still have enough capacity.

sorry my bad for formulating it badly: less solar and now wind means days or even weeks with no solar and no wind aka "dunkelflaute"

In germany a week long dukelflaute occurs every 2 years.

Sure, power on for 24/7/365 from Solar + Wind + Battery alone is hard; and 99% uptime is more expensive than 95% because of the batteries needed.

However when talking about rural communities that might not have power at all, or run a diesel generator in the evenings, that 95% from clean sources is a good start.

The problem of rural communities having no power is, I think mostly a non issue across most of europe.

Having most of the electrical grid already it makes no sense to scale it back or not connect the few not connected communities

I'm not arguing against renewable I'm arguing against the idea that in most of europe it would be better to use small grids instead of an european wide big grid.

Hydrostorage is cheap if it provides enough energy for more than one small community, having the ability to balance energy production and needs across europe is easier than being at the mercy of local weather.

A good example for that is austria, where the grid has a problem where a better connection between east and west is not finished/buid because of discussions about environmental impact.

This leads to overproduction in one place which can't be transferred to places that need electricity.

https://kommunal.at/wir-haben-ein-strom-problem

And you'll be churning out hydrogen all summer.

sorry my bad for formulating it badly: less solar and now wind means days or even weeks with no solar and no wind aka "dunkelflaute"

In germany a week long dukelflaute occurs every 2 years.

You don't need 30% more panels, you need to store energy for the all usage for about a week.

Oh, you mean a rare eventuality.

Yes, you need some redundant power supply. We should probably be investing more on research about synthetic fuels than we are right now (and shelf-stable flow batteries; hydrogen won't cut it in a micro-scale, even though it's great for national grids), but for a long time everybody will still use fossil fuels for that.

It's not a huge problem right now.