Ray Kurzweil was right—again.

The International Energy Agency declared solar photovoltaic power “the new king of electricity” onOctober 14, stating in its annual World Energy Outlook that “solar PV is consistently cheaper than new coal- or gas-fired power plants in most countries, and solar projects now offer some of the lowest cost electricity ever seen.”

Kurzweil told us more than a decade ago this would happen. Hardly anyone believed him. Kurzweil is the inventor and futurist best known for his writings on the singularity, the moment when machine intelligence surpasses human intelligence and it becomes possible to upload our brains. “There will be no distinction, post-Singularity, between human and machine," he has written.

Many of his predictions are based on applying Moore’s Law to technologies other than computer chips and following that idea where it goes. Back when photovoltaic tech was impossibly inefficient, he observed that it was doubling in performance every two years or so; he extrapolated from there.

Result: Depending on which year you take as the baseline, he was forecasting over a decade ago that global photovoltaic capacity in 2019 would be 448 gigawatts or that in 2020 it would be 1,120 gigawatts. Reality is right in between. The IEA’s estimate for 2019 (the actual number still isn’t available) is 633 gigawatts; the forecast for 2020 is 770 gigawatts.

You could argue that Kurzweil’s forecast range was very wide, but remember that he was making these calls when global photovoltaic capacity was only seven to 15 gigawatts. Remember also that he didn’t claim to predict the future of oil, gas, or coal prices or the future of energy demand as the world economy expanded, all of which would affect demand for solar technology.

Making outlandish predictions that tend to come true is largely the story of Kurzweil’s life, as Fortune noted four years ago. This news is a reminder of what writer David Z. Morris advised: Ignore him at your peril.