Solar power still amounts for a small share of net electricity generation around the world. In the USA, for instance, as of December 2014 it was responsible for just 0.45% of the total electricity produced.
Things are changing quite quickly, however, and if the German think tank Agora Energiewende is right, faster than expected.
The main obstacle to a more widespread adoption of photovoltaic so far, has been cost: solar used to be very expensive compared to coal or gas, but, according to Agora — that recently commissioned a study on the subject to the Fraunhofer Institute for Solar Energy Systems — this is no longer true.