Market conditions are bad for solar now but this move by Siemens to leave solar power could be a bellwether. The amount of installed renewable energy in wind and hydro dwarfs that of solar. In addition to planning to sell their solar businesses, Siemens is also leaving Desertec, a consortium of countries and huge companies who want to build ginormous solar thermal plants in the Middle East and North Africa. The problem with solar thermal is that it needs water, something which is always problematic in deserts. Solar photovoltaic, by contrast, uses practically no water.
I think the predominant form of renewable energy will end up being wind.