In the biggest blow he’s dealt to the renewable energy industry yet, President Donald Trump decided on Monday to slap tariffs on imported solar panels.

The U.S. will impose duties of as much as 30 percent on solar equipment made abroad, a move that threatens to handicap a $28 billion industry that relies on parts made abroad for 80 percent of its supply. Just the mere threat of tariffs has shaken solar developers in recent months, with some hoarding panels and others stalling projects in anticipation of higher costs. The Solar Energy Industries Association has projected tens of thousands of job losses in a sector that employed 260,000.

The tariffs are just the latest action Trump has taken that undermine the economics of renewable energy. The administration has already decided to pull the U.S. out of the international Paris climate agreement, rolled back Obama-era regulations on power plant-emissions and passed sweeping tax reforms that constrained financing for solar and wind. The import taxes, however, will prove to be the most targeted strike on the industry yet.

“Developers may have to walk away from their projects,” Hugh Bromley, a New York-based analyst at Bloomberg New Energy Finance, said in an interview before Trump’s decision. […]