Getting water from the sea up to the desert would be a huge challenge in California, and right on the coast isn’t very sunny for most of it.

I'm not sure what they're attempting to describe in the article but so far seems to me like a child's toy compared to a proper multi-stage flash distillation plant (which uses multiple stages and decreased pressures at each stage to massively decrease energy requirements) -- and even those should use more energy than reverse osmosis plants.