Renewable electricity capacity has overtaken coal to become the world's largest installed power source for the first time after a record-breaking year in which 500,000 solar panels were installed every day. Some 153GW of renewable power capacity - more than the total generation capacity of Canada - was installed last year, making it the fastest growing electricity source, the International Energy Agency said.As a result, worldwide renewable capacity hit 1985GW, or about 31% of global power capacity, pipping coal-fired power, which stands at 1951GW.However, the amount of power produced by renewable electricity generators was still significantly lower than that from coal, accounting for 23% of global power production, compared with almost 40% from coal.The IEA said renewable energy expansion would grow, with 825GW expected to be built by 2021 - 13% more than forecast a year ago - "driven by policies aimed at enhancing energy security and sustainability".Fatih Birol, the IEA's executive director, highlighted the "impressive" recent cost reductions in onshore wind and solar panels that he said were "unthinkable just five years ago" and forecast solar costs would drop by 25% and onshore wind by 15% to 2021."Growth is anticipated to be increasingly concentrated in emerging and developing economies, with Asia taking the centre stage," he said."In the next five years, China and India alone will account for almost half of global renewable capacity additions."While new renewables expansion is primarily focused on wind and solar, by far the biggest existing renewable source remained hydropower.Some 61% of installed renewable capacity and 71% of renewable power output came from hydroelectric sources, according to the IEA. Wind power accounted for 15% of renewable output, bioenergy 8% and solar 4%, according to the IEA. ..