[RedDevil]

I see those big mirror solar plants as large scale experiments. As such they aren't efficient enough cost wise, though they do prove the concept works.
My gut feeling says they are too large and use lots of one-of or small scale produced parts.
Smaller, mass produced arrays could bring the cost down quite some. I doubt it would ever be enough.
As long as the grid does not get flooded by an overage, home PV panels and large windmills are the way to go.

There will always be fluctuations in power supply and demand. The grid should always try to meet demand.

However, we can nudge demand by varying the electricity cost so smart devices will level it off.
Say your fridge will try to maintain a temperature of around -20 degrees Celsius, but if the electricity cost drops below average by low demand it will cool down to -22 degrees, and if the price rises it allows the fridge temperature to rise to maybe -18 before it finally starts cooling. Likewise for EV charging; not beyond 85% if the price is high.

Some appliances do not lend themselves for this kind of power brokering, but once the incentive is there, you'll find many situations where it can make a difference.
Guide, don't (just) buffer.