In early 2016, the International Energy Agency (IEA) projected that, starting that year, the world would add just 50 gigawatts of added solar energy capacity per year. And in 2017, solar's growth rate would level out and start to decline.

But as one clean energy researcher points out, the IEA may have gotten it wrong about solar's potential for growth — not just this year, but every year since 2002.

The IEA publishes annual projections about the growth rate of solar energy in its World Energy Outlook.