The International Energy Agency (IEA) said last year marked a turning point for renewable electricity, which accounted for more than half the new power capacity installed in 2015.
Installation of renewables was up 15% on the previous year to a record 153 gigawatts, driven largely by record additions of new wind power totalling 66 gigawatts and 49 gigawatts of new solar photovoltaic (PV).
China, a key player in driving renewable installations, saw two wind turbines installed every hour in 2015.
The IEA has significantly upped its five-year growth forecast for renewables, expecting the clean technologies to grow 13% more between 2015 and 2021 than it estimated last year.
This is largely down to strong policy backing in the United States, China, India and Mexico, as well as falling costs.
In the next five years, solar PV costs are expected to drop by a quarter and onshore wind costs will fall by 15%.
While tackling climate change is a significant driver for increasing renewables, cutting severe air pollution and boosting energy security by diversifying supplies are also key - particularly in emerging economies in Asia, the IEA said.
By 2021, renewables are set to generate 28% of the world's electricity, up from 23% in 2015.
Just over a fifth of renewable generation (21%) will come from wind, 9% each from solar and bioenergy, 59% from hydropower and 2% from other technologies by that time.
In total, power from renewables in 2021 is set to exceed 2,600 terawatt hours - an amount equivalent to the total electricity generation of the US and the European Union put together.
But the IEA warned policy uncertainty persisted in too many countries, slowing down the pace of investments, the cost of financing projects was still a barrier in many developing countries and progress in providing heat and transport from renewables was still slow.
Dr Fatih Birol, executive director of the IEA, said: "We are witnessing a transformation of global power markets, and, as is the case with other fields, the centre of gravity for renewable growth is moving to emerging markets.
"I am pleased to see that last year was one of records for renewables and that our projections for growth over the next five years are more optimistic.
"However, even these higher expectations remain modest compared with the huge untapped potential of renewables.
"The IEA will be working with governments around the world to maximise the deployment of renewables in coming years."
Juliet Davenport, chief executive of 100% renewable electricity supplier Good Energy, said: "Renewable energy has been an unbelievable success story around the globe.
"The statistics released today from the IEA show just how far clean technology has come. When I started my company 15 years ago, you could fit the whole UK renewable energy industry into a small room, and now nearly 25% of the UK's power comes from renewables alone.
"The move to a 100% renewable and 'smarter' future is definitely within our grasp. And with advances in battery storage technology continuing at pace, now is an exciting moment."