In the case of BrightSource’s concentrated solar power site near...

In the case of BrightSource’s concentrated solar power site near Ivanpah in the Mojave Desert, there are some 350,000 mirrors that focus light on three boiling towers (each about 40 stories high). The plant cost $2.2 billion to build, with most of the money coming from a US Department of Energy loan, and sizable investments from NRG Energy and Google. The three plants have a total capacity of 392 megawatts and an annual production of around 1,000 gigawatt-hours of reasonably priced electricity.

This plant produces produces 392 megawatts base load what do you propose they do with the excess energy being produced ?
Just earth it ?
Turn the mirrors away from the sun or use it to store potential energy in the form of elevated water for use when the sun ain't shining ?
I would go with the latter but that is just me.
50 years ago I still had ten years before I was even born.