Actually, out here in California, the installations are happpening.  On the one hand, the tax breaks are not as good and energy prices appear stable for the near future, so the economic case is more difficult to make.  But in many areas there are large arrays alreadu in use for commercial and agricultural applications, with lots more on the way. There are established firms to handle them and economies of scale really do kick in.  And since best place to install them often are over parking lots, you get covered parking as well. <grin>