Heavy clouds and zero wind, for weeks? That's a once-a-century freak event. Just build gas peaker plants if you are worried about it. You could even add carbon capture, but constructing it might emit more than it will ever capture...
I assume you never tried measuring the output of a solar panel when it's cloudy. It's 10-15% of a sunny day. Closer to not working than working.
On a rainy day that drops closer to 20%.
As an aside - cloudy days avoid a problem I have with shade. In winter, at 3:30pm, the sun goes behind a tree and my production plummets to near zero. If there's cloud cover the sunlight is far more dispersed and there's no "shade".
And you’re still able to power your entire home? What if the rain lasts for a few days, which is pretty common in many places.
I did have one rainy day back in the middle of Winter that was 16% but that will end up being literally the worst day of the year.
Our energy grid can't currently handle the ability to charge electric haulers locally at any scale let alone to move an entire city's worth of energy, so the solution is not to 85x the national electric grid all at once.
But to give them due credit, they believed in this vision and put in the hard work to make sure it became true.
That's literally CCP state controlled communism !! More specifically, that's what the The Gansu–Zhejiang UHVDC project has as an overhead transmission line length (2,370 km in international units).
* https://www.sciencedirect.com/science/article/pii/S014206152...
* https://www.bbc.com/future/article/20241113-will-chinas-ultr...
A common battery for grid level storage is pumped hydro - that is, use the peak power during the day(s) to push water from the bottom of an elevation to the top, and hold it there - bonus points if it captures water delivered from other solar processes (evaporation -> rain)
The overwhelming majority of generation and storage is best deployed at the point of use.
Grid scale anything, is a massive inefficiency.
The only reason grid and city scale is so prevalent in public discourse is because this is the only electricity the utility is paid for, and they are very actively impeding any other solution.
In the US, there is a very large inventory of flat roof industrial buildings, in the industrial parks that are using huge amounts of electricity. Covering all of those roofs with solar (especially here in the west US) would prevent a tremendous amount of grid scale generation, and implementing storage there would eliminate a large part of the transmission line upgrades the utilities are calling for.
The biggest problem in the US isn't technical, it's the governments desire to primarily support the solutions that are best at serving utility shareholder returns, instead of the technically superior solutions.
It's quite common in Australia for commercial and residential.