President Donald Trump approved a plan to enact tariffs on imported solar cells and modules, committing an unforced error that promises to raise the price on one of the most promising renewable-energy sources. 

Circling the wagons: The move was precipitated by two struggling solar-panel manufacturers who petitioned the International Trade Commission last year to enact the protections. They argued that US producers were being unfairly harmed by the influx of cheap photovoltaics, particularly those arriving directly or indirectly from China. In late October, ITC commissioners recommended that the president impose import limits and tariffs.

Anti-competitve: The tariffs appear to be a clear-cut case of protectionism, propping up a US industry that Chinese rivals have out-competed in the marketplace. China’s solar sector has been instrumental in driving down the cost of panels, bringing the cost of solar energy neck and neck with fossil fuels (at least before you take into account the inherent intermittency and storage challenges associated with solar).

Bottom line: The Solar Energy Industries Association previously warned that the tariffs could double the price of solar panels and eliminate tens of thousands of jobs. They will kick in after nations exceed certain volumes, starting at 30 percent in the first year and falling 5 percent per year for the next three years.