Driven largely by a boom in solar power, renewable energy expansion has hit record-breaking totals across the globe and is shattering expectations, especially in the United States, where projections were pessimistic just a decade ago.

In 2016, almost two-thirds of new power capacity came from renewables, bypassing net coal generation growth globally for the first time. Most of the expansion came from a 50 percent growth in solar, much of it in China.

In the U.S., solar power capacity doubled compared to 2015—itself a record-breaking year—with the country adding 14.5 gigawatts of solar power, far outpacing government projections. In the first half of 2017, wind and solar accounted for 10 percent of monthly electricity generation for the first time. 

Two reports—one from the International Energy Agency (IEA), which looked at growth in renewables globally, and one from the Natural Resources Defense Council (NRDC), which tracked growth in the U.S.—were published this week, both telling the same story.

“We had very similar findings: 2016, from a U.S. perspective was a great year for renewable energy and energy efficiency,” said Amanda Levin, a co-author of the NRDC report. “China is still the largest source of new power, but in the U.S., we’re seeing an increase in renewables year over year.”

Growth Shatters Past Expectations

The numbers are far higher than the U.S. Energy Information Administration (EIA) predicted a decade earlier. The agency forecast in 2006 that solar power would amount to only about 0.8 gigawatts of capacity by 2016.  

Instead, installed solar by 2016 was 46 times that estimate, the NRDC points out. EIA’s prediction for wind power was also off—the agency predicted 17 gigawatts of wind power, but that figure actually rose nearly fivefold, to 82 gigawatts of capacity.

The agency, likewise, didn’t predict a drop in coal-fired power generation, which plummeted by nearly 45 percent.

Globally, according to the report from the IEA—not to be confused with the EIA—solar was the fastest-growing source of new energy, bypassing all other energy sources, including coal. Overall, the IEA found, new solar energy capacity rose by 50 percent globally—tracking with the rise in the U.S. Adding in other renewable sources, including wind, geothermal and hydropower, clean energy sources accounted for two-thirds of new electricity capacity. The IEA also increased its forecast for future renewable energy growth, saying it now expects renewable electricity capacity will grow 43 percent, or more than 920 gigawatts, by 2022.

Solar’s U.S. Growth Could Hit a Speed Bump

In the U.S., the prospects are similarly positive, despite the Trump administration’s efforts to bolster the coal industry and roll back Obama-era clean energy legislation.

Levin noted one potential damper on that growth. Last month, the U.S. International Trade Commission ruled in favor of two solar manufacturers that are seeking tariffs on cheap imported solar panels. Ultimately, any tariff decision would be made by the Trump administration.

“It would mean a much higher price for solar panels, and it could put a large reduction in new solar being added over the next two to three years,” Levin said.

“States and cities are moving forward on clean energy,” she said. “We think the investments made by states and cities, to not only hedge on gas prices, but to meet clean energy standards, will continue to drive solar even with the decision.”