I would not have guessed that the solar arrays beneficial effect on precipitation is dependent on them not being too efficient and so releasing more heat than b

I would not have guessed that the solar arrays beneficial effect on precipitation is dependent on them not being too efficient and so releasing more heat than bare desert (which is very reflective). From the article - "The precipitation increase in our solar farm experiments is due to the relatively low conversion efficiency of the panels (15%, typical current conversion efficiency for photovoltaic panels), which results in albedo decrease. However, if solar panel efficiency and the associated effective albedo are high enough to lead to an albedo increase relative to the background environment (as, for example, a 45% efficiency would), the climate impact would be surface cooling with precipitation suppression, similar to the impact of overgrazing in the desert. Assuming an intermediate conversion efficiency higher than 15% for solar panels (e.g., 30% efficiency) results in negligible albedo change and, thus, insignificant climate impacts." [^] http://science.sciencemag.org/content/361/6406/1019 http://science.sciencemag.org/content/361/6406/1019