While I'm at it, here is this ...

While I'm at it, here is this link to Wikipedia's solar flash evaporator page. http://en.wikipedia.org/wiki/Solar_desalination#Types_of_solar_desalination One challenge they mention is "The challenge still existing in the field today, is to achieve the optimum temperature difference between the solar-generated vapor and the seawater-cooled condenser, maximal reuse of the energy of condensation, and minimizing the asset investment". On board some ships, there is about a 1 centigrade difference between steam temperature and water temperature. By having the warm flow along the length of the tubes before they enter the green house/evacuated tube heating array, it would be about the best that could be hoped for. While the link states that using vertical alignment of the tubes allows maximum heating, tilting the green house for this type of system would have the same effect and possibly allow a greater area of exposure to direct sun light. Just have to wait and see I guess.