Solar power now accounts for more installed capacity than any other form of electricity generation, according to new data out Tuesday.

“About half a million solar panels were installed every day around the world last year,” the Paris-based International Energy Agency said in a new report on the renewables sector, as emerging markets in particular bet heavily on green power. China also installed the equivalent of two wind turbines every hour last year.

In total, over half the new power capacity installed last year—153,000 megawatts, or 153 gigawatts—was renewable-sourced. That’s a 15% increase from the previous year, and three-quarters of it came in the shape of wind (66 GW) or solar photo-voltaic (49 GW).

Capacity is what a plant can theoretically produce. Actual generation remains much lower, due to the basic unpredictability of resources such as sunlight and wind. But even on levels of actual generation, the IEA said renewables would close the gap rapidly going forward.

“We are witnessing a transformation of global power markets led by renewables and, as is the case with other fields, the center of gravity for renewable growth is moving to emerging markets,” said Dr. Fatih Birol, the IEA’s executive director.

The IEA said the share of renewables in the generation mix would rise to 28% within six years, from 23% at the end of last year. It raised its forecast for green power output in that timeframe by 13% “due mostly to stronger policy backing in the U.S., China, India and Mexico.”

Another factor expected to help is a continued fall in costs: the IEA reckons the cost of solar PV will fall by a quarter, and the cost of onshore wind will fall by 15%. Lower capital costs mean that an installation can break even with lower load rates.

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While climate change policy plays a large role in countries’ policy choices, especially in the wake of the Paris summit last year, the IEA pointed out that cutting air pollution and diversifying energy supplies are just as important some some countries. In China, in particular, renewables are helped by the fact that overall energy demand is growing rapidly, and renewables are the only option for meeting demand in places where pollution is already a hard constraint.

In China and India, where the fastest growth in green power is expected, it will still cover less than half of the overall increase in electricity demand. By contrast, in developed economies, renewables will grow faster than overall generation.