President Obama's last year in office was a record year for solar industry job growth, but things haven't been quite the same since Trump took a dump on the industry by imposing tariffs on foreign solar panels for no substantiated reason.
After declaring that foreign solar panels somehow pose a threat to "national security," Trump imposed tariffs as high as 30 percent on foreign panels and that has cost the industry nearly 20,000 jobs over the past two years according to the Department of Labor.
From Forbes:
[Solar] energy jobs have stagnated and dipped for two consecutive years since the Department of Energy’s initial report, with a loss of 10,000 jobs in 2017 followed by a further 8,000 in 2018. Although some job losses were foreseen as a result of project finalizations in several states, the biggest contributing factor was President Trump’s tariffs on solar panels . The first shot fired in what would become a wide-ranging trade war with China in 2018, the U.S.’ decision to add a 30% tariff on foreign-produced solar panels had a negative effect on its domestic solar industry, which heavily relies on cheap imports. [...]
The months immediately preceding the application of the tariffs saw solar panel imports explode as foreign manufacturers and U.S. developers alike looked to get ahead of any potential problems. Despite their future-proofing attempts, the growing uncertainty created by the tariffs led to many developers canceling and freezing billions of dollars of investments and projects.
To put this into perspective, the coal mining industry only employed 53,000 people in 2018 so this would be like Trump destroying more than a third of all coal mining jobs.
Republicans liked to say that President Obama was engaged in a "war on coal" but no policy his administration implemented led to anywhere near the amount of lost jobs that Trump's policies have destroyed. It would actually be far more fair to say Trump is engaged in a "war on solar" than it was to say President Obama waged a "war on coal."
And this doesn't even stem from environmental or regulatory policy or even national security policy. Trump may have cited "national security" to justify his tariffs, but he more or less imposed them on a whim. Imposing these tariffs did not save the environment from smog or reduce premature deaths due to exposure. There's no substantive policy reason for killing nearly 20,000 jobs in the solar power industry.