Solar energy could be the top source of electricity by 2050, aided by plummeting costs of the equipment to generate it, a report from the International Energy Agency (IEA), the West's energy watchdog, said on Monday.

IEA Reports said solar photovoltaic (PV) systems could generate up to 16 percent of the world's electricity by 2050, while solar thermal electricity (STE) - from "concentrating" solar power plants - could provide a further 11 percent.

"The rapid cost decrease of photovoltaic modules and systems in the last few years has opened new perspectives for using solar energy as a major source of electricity in the coming years and decades," said IEA Executive Director Maria van der Hoeven.

Solar photovoltaic (PV) panels constitute the fastest growing renewable energy technology in the world since 2000, although solar is still less than 1 percent of energy capacity worldwide.

The IEA said PV expansion would be led by China, followed by the United States, while STE could also grow in the United States along with Africa, India and the Middle East.