Global renewable electricity capacity has overtaken coal to become the world's largest installed power source for the first time.

The International Energy Agency says that last year, renewables accounted for more than half of the increase in power capacity.

Half a million solar panels were installed every day in 2015 and, in China, two wind turbines were set up every hour.

The IEA's Executive Director Fatih Birol has heralded the change as a turning point in clean power generation.

"We are witnessing a transformation of global power markets led by renewables".

Power surge

A total of 153 gigawatts of renewable power capacity was installed during 2015, more than the entire electricity generating capacity of Canada, according to the IEA’s new report.

Renewable energy sources, such as wind, solar and hydro power are central to efforts to combat climate change.

While the actual amount of power produced by renewable sources is still lower than that from coal, the speed of progress in building renewable capacity shows the huge sums being invested in the area.

Image: Daily Telegraph/IEA

In 2015, renewables accounted for 23% of global power production, compared with almost 40% from coal plants.

This is because renewable power plants do not constantly generate at full capacity with sources like wind and solar able to generate at their maximum output only when weather permits.

The IEA forecasts that rapid renewable expansion will continue, with 825 gigawatts of capacity expected to be built by 2021. That projection is a 13% rise on the IEA’s own projection just a year ago.

Growth will be concentrated in emerging and developing economies, with Asia taking centre stage. China was described as the “undisputable global leader of renewable energy expansion” by the IEA.

“In the next five years, the People’s Republic of China and India alone will account for almost half of global renewable capacity additions,” Fatih Birol said.

Drop in costs

Average global generation costs for new onshore wind farms fell by an estimated 30% between 2010 and 2015, while those for big solar panel plants fell by two-thirds.

Mr Birol said this would help further expansion, “This cost reduction trend, which is expected to continue, will be a key factor in driving renewable deployment.”