This week, an advocacy group called The Solar Foundation released its ninth annual solar jobs report. In 2018 the industry contracted, shedding 8,000 solar jobs, or a loss of about 3.2 percent from 2017. The solar industry employed 242,343 people in 2018, the report said.

The solar industry is the largest renewable energy employer in the US and the second largest energy employer behind the oil and gas industry. Wind and coal trail far behind solar in terms of the number of people employed. (For comparison, coal mining lost 2,000 jobs between 2016 and 2017 , although that industry employs only slightly more than 50,000 people.)

2018 marks the second year in a row that the solar industry has posted job losses. In 2017, The Solar Foundation's report showed that employment contracted by 3.8 percent. The foundation only counts solar jobs where at least 50 percent of a person's time is dedicated to solar energy.

The Solar Foundation's report attributes this slack in the market to the solar tariffs ordered by the Trump administration in January 2018. Those tariffs were the result of months of uncertainty in the year prior, as two foreign-owned but US-based solar manufacturers argued to the International Trade Commission that tariffs on cheap imported solar cells and modules were necessary to maintain their business in the US.

"This uncertainty led to project delays, especially for the larger, utility-scale installations," the Solar Foundation's report notes.

Additionally, state-level policies and economic conditions in states with well-established solar industries contributed to job losses. California and Massachusetts lost the most jobs in the solar industry. California, which holds 40 percent of US solar capacity, saw jobs decline in part due to the fact that the state's utilities were under less pressure to add renewable capacity in 2018 after making significant strides in adding renewable capacity in previous years. In Massachusetts, the delay of a program to compensate PV system owners (the Solar Massachusetts Renewable Target, or SMART, program) added to market uncertainty and led to job losses, according to the Solar Foundation.

Not all news was bad in 2018, however. Florida, Illinois, Texas, New York, Ohio, and Washington all added significant numbers of solar jobs, according to the report, despite the overall US dip in solar employment.

Currently, the solar industry's jobs are centered around construction, project development, wholesale trade, and distribution. The Solar Foundation found that three-quarters of solar industry jobs are found in those categories, while manufacturing represents just 14 percent of US solar jobs. Engineering, legal, and financing jobs constitute five percent of solar industry jobs.

Looking to the future, the Solar Foundation is optimistic. The report surveyed many solar industry employers, and based on those employers' plans to hire or fire in 2019, the Solar Foundation believes that the industry will see a seven-percent increase in jobs, year over year, in 2019.

But the foundation counters its optimism in the report with a warning: "The urgent challenge of climate change means the progress we have seen to date is not nearly enough. The report continues, "Solar energy will need to develop and expand even faster in order to reduce carbon emissions to sustainable levels. If this can be achieved, a host of additional benefits will follow, including new solar job growth."