The fallout from a trade probe is rippling through the U.S. solar industry, delaying projects and threatening to slow the renewable energy transition

On top of an old coal mine in western Pennsylvania, developers were preparing to install the first of 237,000 new solar panels — a living embodiment of the transition away from fossil fuels into clean energy. Just as the Maple Hill solar farm was getting underway, things came to an abrupt halt.

The $30 billion U.S. solar industry is being ensared in a trade probe that's leaving projects like Maple Hill in limbo and threatening to slow down — possibly even derail — the country's shift to renewable power. The panels crucial to the solar farm in Portage, Pennsylvania, were being made in Thailand. But the threat of tariffs, equal to as much as 239% of the equipment's value, forced the supplier to halt shipments.

"Solar projects across the country, including ours, just got stopped in their tracks," said Tom Rumsey, senior vice president of Competitive Power Ventures, the developer behind Maple Hill.

The fallout is rippling through the industry. NextEra Energy Inc. is warning a huge number of its projects could be delayed, while SOLV Energy is shelving five planned installations and laying off 500 workers. The Public Service Company of New Mexico said planned renewable projects may cost more and won't be operating until after next summer.

At least 65% of U.S. solar capacity set to come online in 2022 and 2023 is now at significant risk of cancellation or delay, according to an advocacy group fighting the trade probe.

And that's just based on the announcement of the investigation, which could take a year to complete.

If the Commerce Department decides to expand tariffs, the consequences would be even more far-reaching. The duties would hit Malaysia, Thailand, Vietnam and Cambodia — countries that supply the U.S. with 80% of its imported modules. While it's possible that other nations could help fill some of the supply gap and new domestic manufacturing may eventually spring up, the turbulence could take years to settle. The upheaval would likely jeopardize President Joe Biden's green ambitions, including his goal to decarbonize the electricity sector by 2035.

Why the Energy Transition Is Facing Setbacks

The probe represents just the latest setback for the nation’s energy transition. The solar industry is already confronting Biden administration policies that hamper shipments of key equipment, and legislation to expand critical tax credits is stalled in Congress. Meanwhile, wind power is under threat as turbine makers struggle to translate soaring demand into profit, U.S. coal use is surging and Biden is imploring oil companies to produce more crude.

"I believe that the president, at his core, is a climate and justice champion," said Suzanne Leta, head of policy and strategy at rooftop company SunPower Corp. "But we're not quite seeing the urgency we need in order to meet that objective.”"Read more: Experts say Biden's signature climate goal is all but dead.

Solar generation was earmarked to potentially provide 40% of the nation’s power under Biden’s climate plans. Now, 83% of companies surveyed by the Solar Energy Industries Association say deliveries of panels have been delayed or canceled because of the trade probe. The group estimates that 318 projects totaling 51 gigawatts of solar capacity are being impacted. That's equivalent to the electricity generated by more than 51 nuclear reactors.

Many analysts say it's too early to quantify what impact the possible duties would have on U.S. greenhouse gas emissions, though modeling provided by the solar association suggests an extra 364 million metric tons of carbon dioxide could be unleashed by 2035 — equivalent to the annual release from 97 coal plants.

"This is a lost opportunity," said SOLV Chief Executive Officer George Hershman.

The solar industry "is well positioned to meet the demand," he said. "We have an administration that all of us in the industry supported. We wanted this administration with this agenda. And to think that we’re two years in, and we're talking about laying off solar workers. These are really self-inflicted wounds."

In Pennsylvania, Maple Hill was originally planned as a 127-megawatt solar farm. The company now has just 20 megawatts worth of panels on hand and little chance of nabbing more quickly.

"We literally have a project with a quarter of the panels installed or in storage — with the remaining panels in flux," said Rumsey of Competitive Power Ventures. "It's fully permitted. You're paying for the land, your construction team is mobilized, you have your interconnect. All you’ve got to do is construct it."

What the Commerce Department Is Weighing

The Commerce Department is evaluating whether companies are unfairly skirting 10-year-old duties on Chinese solar cells and modules by assembling the gear in Malaysia, Vietnam, Thailand and Cambodia.