Note that there are significantly fewer CSP installations in the United States than PV installations, this difference limits the robustness of conclusions, and in particular, there are very few projects using certain CSP technologies. On average, based on evidence from the United States, tower systems have the greatest CSP land use requirements on both a capacity and energy basis. Towers use 50 per cent more direct land than troughs on a capacity (MW) basis, and use 20 per cent more on a generation basis.