low cost, low tech, low maintenance desalination idea

don't know if this tech idea is used or even economically feasible: 

green house with a shallow pool inside in desert/steppe area, 

where salt water in flowed into pool, 

sun makes shallow salt water warm inside green house

sun dries salt water, 

salt stays in pool, 

water vapor goes up and is collected in filters in ceiling, 

water vapor cools down and becomes water fluid, 

water fluid is pumped out, 

salt is collected with excavator