When the sun sets, Solar thermal power keeps going (Score 1)

Quite the contrary: the high temperature heat collected by CSP systems (Concentrating Solar Power) can be stored for later use in cheap media such as gravel. Storage for upkeep of electricity production during the night is economically feasible, storage for bridging longer periods is not. It is cheaper to have a fuel-fired auxiliary boiler in the system for the occasional instances when the stored heat is exhausted.