...
For a cheap solar energy solution, how about this: Take a bunch of desert. Cover it in a layer of insulator, then (on top) metal, black paint, water, and glass. When the Sun comes up, it will heat the paint very quickly (~20 – 100 C / hr.), causing the water to become high-pressure steam. With double-paned glass and good insulation, the heat will be trapped well enough for steam to reach many hundred degrees C. That steam can then run an old-fashioned steam turbine.
...
But the temperature during the night can fall very low afaik. Meaning large amount of water (thick layer) would never heat up properly during the day, making the entire project inefficient.
How about switching to PoS or PoS hybrid instead?