The solar power industry — which has created tens of thousands of jobs in recent years — is bracing for a shakeup after President Donald Trump slapped tariffs on imported solar panels and modules.

The impact of the 30 percent tariff remains uncertain. The manufacturers that requested a trade investigation last year say the tariffs give them a fighting chance against foreign competitors. But much of the industry warns that they will push up project costs and make building solar energy farms less attractive.

That could mean slower employment growth in a sector that has expanded at more than 20 percent annually in recent years. There were about 260,000 solar workers in the United States at the end of 2016 — five times the size of the coal mining industry — according to the Solar Foundation's latest annual jobs census.

A slowdown in the deployment of big, utility-scale clean energy projects would come at a time when the White House is promoting planet-warming fossil fuels like coal and backing away from international efforts to fight climate change.

"The fact is that if you put high tariffs on solar panels you're going to kill demand for solar," Abigail Ross Hopper, CEO of the Solar Energy Industries Association, told CNBC in an interview prior to the decision. "We grew our jobs 17 times faster than the rest of the economy."

Imposing tariffs could create as many as 6,400 solar manufacturing positions, but job losses in other parts of the industry would almost certainly exceed those gains, an independent analysis by Bloomberg New Energy Finance performed for Utility Dive found.

Nonmanufacturing jobs account for about 85 percent of the U.S. solar workforce, including electricians, welders and engineers designing and building the solar farms.

These are also well-paying jobs with the median advertised wage for solar installers, electricians and engineers at about $25 to $29 per hour, according to the Solar Foundation.

Source: The Solar Foundation

The tariffs apply to imported solar cells, the individual components that convert light into electricity, and solar modules, or groups of cells.

But other manufacturers in the supply chain could take a hit, said Ross Hopper. Those include U.S. companies that make frames for solar panels, equipment to convert electric currents and trackers that allow arrays to follow the sun throughout the day.

The Trump administration's decision marks the conclusion of a trade case brought last spring by bankrupt solar manufacturer Suniva, and later joined by SolarWorld, a cell maker whose German parent company announced it was insolvent last year. They claimed that a flood of cheap foreign solar cells and modules made it impossible for many U.S.-based manufacturers to compete.

"Over the last 5 years, nearly 30 American solar manufacturers collapsed; today the President is sending a message that American innovation and manufacturing will not be bullied out of existence without a fight," Suniva said in a statement.

The U.S. International Trade Commission, an independent and bipartisan panel, ruled in September that imports from China and elsewhere did indeed cause harm to American companies.

In its decision on Monday, the Office of the U.S. Trade Representative said China used a series of "state incentives, subsidies, and tariffs to dominate the global supply chain" and carve out a leading role in solar cell and module manufacturing.

The Obama administration twice placed tariffs on solar imports from China, but Chinese companies skirted the penalties by moving production to neighboring countries. The Trump administration's tariffs close that loophole by applying tariffs to all solar cell and module imports.

The tariffs announced by the Trump administration on Monday are much lower than the penalties Suniva and Solar World requested. The companies recommended applying a tariff of 25 cents per watt on solar cells and 32 cents per watt on modules.

The tariffs the Trump administration adopted — 30 percent in the first year that the penalty is applied — adds 10-15 cents to imported cells, according to MJ Shiao, head of Americas Research at GTM Research, a green tech analysis firm.

A 10-cents-per-watt tariff could reduce construction of large, utility-scale solar farms by 9 percent, GTM estimates.

The tariff drops by 5 percentage points each year, ending at 15 percent. The tariffs kick in after 2.5 gigawatts of solar cells have been imported. That's roughly equal to the output of 11.5 million solar panels, according to a 2016 estimate by the Department of Energy.