Large scale electricity storage is very much a solved problem actually. Bath county for instance has solved the problem since the 80's.

It's just once you take the cost of storage for solar it is no longer the cheapest power source. Our power isn't delivered by our government for the sake of sustainability and benefiting the citizens but by private corporations who want to make profit.

The pumped hydro station I linked cost 4.36 billion USD to construct in 2022 dollars back in 1985. It also has a capacity of 24,000 mWh.

Meanwhile the F-35 project cost the US government 1.7 trillion dollars.

So let's say new pumped hydro plants of a similar size would cost 10 billion dollars just for being excessive. Then let's say the US government didn't fund one jet and instead built pumped hydro storage. Then fuck it, let's say nothing worked out the budget got blown and only a fraction of that were built so only 100 stations were built to make it a nice round number.

That's 2,400 gWh

Idk about you but that is a lot of buffer to make any renewable much more stable. It's actually enough buffer to power the entire country for a few hours and ideally bridge most of the night demand. For more than three times over budget and for the price of one jet for the US military.

It's also worth noting this helps all power generation not just renewables. All power plants prefer to be kept at their most efficient output and not turn off or cool off at night while demand is low. We really just need to have a buffer for when solar isn't active but people are in the early mornings and late evenings.