What about STORING excess power and delivering it during the day at a same level ? That is a critical part! I remember last time it was too expensive.

At temperate latitudes, summer/winter is a bigger deal than day/night. To the point where it makes sense to orient fixed panels tilted south and you still get a 2-3x difference in daily capacity between the seasons.

Related is the other comments here that mention air-conditioning is largely a non-issue if you spec for year-round solar. If you are generating 3x as much energy in July compared to January, and January can power your house, then the A/C is basically free.

You can buy a full day's worth of energy storage with an array of LiFePO4 batteries for less than the typical 3% estimate of annual home improvement and maintenance costs you should be budgeting for as a homeowner. The cost problem usually comes from the labor and every solar installation company seemingly being ran by scam artists.

Thats whats driving the buildout in places like spain.

Solar power is in curltailment most days, so to make money solar operators need to add batteries to take free energy and shift it to the ultra expensive parts of the day.

grid-scale batteries are accelerating more rapidly than anyone thought a few years, it’s not really seen as an unsolvable problem anymore

Because solar energy production doesn't just vary by time-of-day, it also varies seasonally. Where I live, winter solar production collapses due to decreased daylight hours and cloud cover. At the same time, energy use skyrockets due to heating demand.

We would need a lot of batteries to be able to charge during the summer and drain during the winter!

Tell me you didnt read the article without telling me.