Policymakers and investors alike need a clear road map to capitalize on the true potential of solar energy, the Paris-based International Energy Agency said.

IEA published a report Monday finding that solar energy resources could combine to become the world's largest source of electricity by 2050, while at the same time offsetting more carbon dioxide emissions than the United State currently puts out.

"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," IEA Executive Director Maria van der Hoeven said in a statement.

Van der Hoeven cautioned, however, that most of the investments needed in solar photovoltaic and solar thermal power are made up front and investors may be wary if the road map to development is clouded by bureaucracy.

"Where there is a record of policy incoherence, confusing signals or stop-and-go policy cycles, investors end up paying more for their investment, consumers pays more for their energy, and some projects that are needed simply will not go ahead," she said.

The IEA report finds China and the United States, respectively, leading in the development of solar photovoltaic technology. Solar thermal energy developments are gaining ground in very sunny skies, such as those in Africa and the Middle East.