Solar power on track to be world's largest electricity source by 2050

Meanwhile, the IEA's report indicates the cost of solar power worldwide is expected to drop to four cents per kilowatt hour (kWh) by 2050. In the U.S., electricity costs about 13 cents per kilowatt hour for residential power and seven cents for industrial power.

IEA Executive Director Maria van der Hoeven stressed in a statement that her agency's two reports do not represent a forecast. As with other IEA technology roadmaps, they detail the expected technology improvement targets and the policy actions required to achieve those goals by 2050.

However, van der Hoeven noted that the cost of solar system hardware is rapidly declining.

"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," she said. "However, both technologies are very capital intensive: almost all expenditures are made upfront. Lowering the cost of capital is thus of primary importance for achieving the vision in these roadmaps."

Rooftop solar panel installations could cut utility profits by 15% or more over the next eight years, according to the federally funded report (download PDF) that studied two prototypical U.S. utilities -- one in the Southwest and the other in the Northeast.