SolarCity Corp. employees install solar panels on the roof of a home in Kendall Park, New Jersey in 2015.(Michael Nagle/Bloomberg)

The shares of companies in the renewable energy business plunged Wednesday after Donald J. Trump’s victory, and shares of coal companies soared on anticipation the president-elect would make good on vows to revive the industry’s fortunes.

The shares of the nation’s largest maker of solar panels, First Solar, fell 6.5 percent by 10:30 a.m, and shares of one of the world’s largest manufacturers of wind turbines, Vestas Wind Systems, dropped about 10 percent. SunPower stock slid about 18 percent.

By contrast, the shares of Peabody Energy, the nation’s largest coal company, now in bankruptcy proceedings, jumped more than 50 percent.

By midday, renewable energy stocks had recovered some of their lost ground.

Trump has repeatedly vowed to scrap the Obama administration’s proposed Clean Power Plan, which would lay out a program for utilities to reduce carbon emissions. Trump has also vowed to “bring back coal”  whose main rivals in generating electricity are natural gas generators and wind and solar power producers. Solar currently enjoys a 30 percent investment tax credit that phases out by 2023. Wind energy projects also receive tax credits, though those are already beginning to be phased out.

Exactly what Trump will do about this is unclear, but investors on Wednesday were quick to anticipate possible reductions in tax breaks for wind and solar.

President Trump entered the White House with an environmental policy agenda opposed to that of the Obama administration and many other nations that have pledged support to the Paris climate agreement. The Washington Post's Chris Mooney breaks down what a Donald Trump presidency will mean when it comes to climate change. (Daron Taylor/The Washington Post)

One reason to worry: On Oct. 31, Trump issued a policy statement in which he pledged to “cancel all wasteful climate change spending.” He did not specify what that would entail.

Many analysts said the markets overreacted to the Trump victory because many of the trends toward wind and solar are deeply entrenched in law and politics.

Wind and solar energy generators “have support that extends beyond the typical red blue lines. I don’t know that there would immediately be any kind of tail off of renewable energy,” said Michael Ferguson, a director in the U.S. energy infrastructure group at S&P Global Ratings.

Wind energy has strong support among Republicans as well as Democrats. In an interview with Yahoo News in late August, Sen. Charles Grassley (R-Iowa) said he would protect the wind tax credit. ““If he wants to do away with it, he’ll have to get a bill through Congress, and he’ll do it over my dead body,” Grassley said.

The American Wind Energy Association said more than 80 percent of all wind farms are in Republican congressional districts. AWEA also seized on Trump’s victory speech comments early this morning that “we’re going to rebuild our infrastructure, which will become, by the way, second to none. And we will put millions of our people to work as we rebuild it.” AWEA said in a statement that wind power “is some of the best infrastructure America has ever built and we are on track to doubling it from today’s levels by 2020.”

“The vast majority of federal policies affecting various clean tech verticals are ‘on autopilot’ rather than changing wildly under different administrations,” according to a note Wednesday by analysts at the investment advisory firm of Raymond James. “Furthermore, most of these policies are bipartisan and non-controversial in nature. Thus, there is no objective basis for concluding that the Trump administration will be actively hostile.”

It said, however, that “the major exception” to that is the Obama administration’s carbon emissions policy, inscribed in its proposed Clean Power Plan. Without that plan, there could be negative pressure on renewable energy firms after 2020.

But analysts weren’t clear about how Trump could revive coal. “This was a central campaign promise,” Ferguson said. “He hoped to bring back coal jobs to Appalachia and other areas but the weakness in the coal industry to date hasn’t really been brought about by environmental regulations. It’s been more a function of gas prices being as low as they are.”

Ferguson said that he was “sure the rollback of environmental regulations would aid that. But as long as gas prices are cheap natural gas is going to be more competitive.”