More than half of new power capacity added last year came from renewable energy sources like wind and solar power, beating fossil fuels for the first time, according to a new report.

The report from the Intentional Energy Agency called 2015 a turning point because renewables now represent 23% of global power generation. That share is expected to grow to 28% by 2021 thanks in large part to market forces and a shift in global policy in favor of renewable energy, according to the report.

“We are witnessing a transformation of global power markets led by renewables,” says Fatih Birol, IEA executive director, in a press release. “However, even these higher expectations remain modest compared with the huge untapped potential of renewables.”

Policymakers are increasingly introducing rules to encourage the adoption of renewable power and phase out the highest polluting fossil fuel plants, particularly coal-fired power plants. In the U.S., for instance, the Clean Power Plan has led many states to phase out coal-fired power plants and replace them with natural gas or renewable power plants. Chinese President Xi Jinping has called for his country to peak carbon dioxide emissions by 2030 and has pushed rapid installation of wind and solar power. China alone has driven 40% of the world’s growth in renewable power, according to the IEA report.

But much of the transition to renewable power would likely occur even in the absence of regulation as the cost of many renewable power sources have declined rapidly in recent years thanks to technology advances and increased competition. The cost of photovoltaic solar power—the most common type of solar panel found at most power plants and on homes—has fallen 70% over the past decade and is expected to continue to decline in the coming years.

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Write to Justin Worland at justin.worland@time.com.