President Trump dealt a blow to the U.S. renewable energy industry Thursday in approving new tariffs on imported steel and aluminum.

Aggressive foreign trade practices are an "assault on our country," the president said, before signing a Section 232 proclamation that slaps a 25 percent tariff on imported steel and a 10 percent tariff on imported aluminum.

Factories have been left to rust, communities have turned into ghost towns, and U.S. national security has been undermined, said Trump. "Now we're finally taking action to correct this long-overdue problem."

While steel company CEOs say tariffs will bring back American jobs, numerous trade experts, industry groups, politicians and even members of the aluminum industry argue tariffs won't revitalize U.S. manufacturing and could harm other segments of the economy in the process. The clean energy industry is one of those segments. 

"Steel and aluminum are important commodities for critical wind, solar and storage components, with few bankable substitute materials available," state Wood Mackenzie Power and Renewables analysts in a forthcoming research note.

GTM Research, MAKE Consulting and Wood Mackenzie collectively calculate the resulting price increase in commodities could potentially result in a 3 percent to 5 percent increase in the levelized cost of energy for U.S. renewable power plants, leading to slightly lowered forecasts for project deployments or slightly lowered project returns.

"While the broader impacts are unknowable, the tariffs will have a direct impact on renewable component costs, both in the form of increases in general electrical products (e.g., wiring, transformers) and in critical components, including: wind turbine towers, solar ground-mount posts and tracker torque tubes, and battery system housing containers," the note states.

Given that the new tariffs are coupled with already-pressured margins, an existing Section 201 tariff on solar modules, the planned step-down of the federal solar Investment Tax Credit and the wind Production Tax Credit, and the potential withdrawal of tax equity as the result of tax reform, analysts write that "the Section 232 tariffs represent yet another headache to mitigate or absorb for renewables."

Tariff flexibility for U.S. "friends"

According to the Solar Energy Industries Association (SEIA), steel and aluminum tariffs could add 2 cents per watt to utility-scale solar projects, which is a significant increase on top of what the association sees as "job-killing" solar tariffs.

President Trump said at Thursday's signing ceremony that solar tariffs have brought back U.S. solar manufacturing plants. However, there is still no evidence of a market resurgence.

“As President Trump prepares to issue an official decision on tariffs for steel and aluminum products, we want to remind him that the net loss of jobs and the cancellation of projects as a result of his solar tariffs are real and causing damage to America’s energy economy," said Abigail Ross Hopper, SEIA president and CEO, in a Wednesday statement.

"There has been very little interest in building substantial new solar manufacturing capacity as a result of solar tariffs," she said. "The actual number of jobs added because of solar tariffs will be negligible under the best of circumstances."

It's possible the impact of the new steel and aluminum tariffs on solar, wind and storage will be softened by exemptions and ongoing trade negotiations, however. 

"We have to protect and build our steel and aluminum industries, while at the same time showing great flexibility and cooperation to those who are friends of ours," Trump said at the signing ceremony.

Canada and Mexico were excluded from the tariffs, while parties continue to discuss changes to the North American Free Trade Agreement. But if the negotiations are unsuccessful, Trump indicated that steel and aluminum tariffs would be placed on America's neighbors, too. 

The U.S. will remain open to modifying or removing tariffs for other nations, Trump added, as long as they aren't deemed a threat to national security and damaging to American jobs. Trading partners and allies, like Australia, will be given strong consideration.

"We will see who is treating us fairly and who is not treating us fairly,” said the president. That assessment includes how much allies are or are not spending on their militaries and to help maintain global stability.

U.S. Trade Representative Robert Lighthizer will be leading the review process before the tariffs take effect 15 days from Thursday.

A "mirror tax" for Tesla?

As the implementation of steel and aluminum tariffs gets underway, Trump said there will additional trade action to come. He specifically cited a tweet from Tesla CEO Elon Musk, in which the tech leader noted that an American-made vehicle going to China has to pay a 25 percent import duty, while a Chinese car coming to the U.S. only pays a 2.5 percent duty.

"We raised this with the prior administration and nothing happened," Musk tweeted. "Just want a fair outcome, ideally where tariffs/rules are equally moderate. Nothing more. Hope this does not seem unreasonable."

Trump responded to Musk today in promising to enact a "reciprocal tax program" or a "mirror tax" at some point in the near future. Under that arrangement, the U.S. would impose the same duty level on another country that that country imposes on the U.S.

“We’re going to be doing a lot of that," Trump said.