The cost of solar energy has fallen to a record $18 per megawatt-hour, making it the cheapest source of electricity in history.

The IEA reported that global solar capacity doubled in the past 12 months, adding 420 gigawatts of new capacity. China led with 180 gigawatts, followed by the US at 65 gigawatts.

“We’re witnessing an energy transition happening faster than anyone predicted,” said IEA Executive Director Fatih Birol.