Quarterly additions to U.S. utility-scale solar power capacity dropped below 1GW for the first time since 2015 in this year's third quarter (Q3), according to the Solar Energy Industries Association (SEIA) and Wood Mackenzie Power & Renewables. Section 201 import tariffs were the root cause.

Overall, newly installed U.S. solar power capacity dropped 15 percent year-over-year in Q3. The report authors note there's a lot in the utility PV project pipeline, however.

“Developers originally planning to bring projects online in Q3 2018 were forced to push out completion dates to Q4 2018 or Q1 2019 due to uncertainty around tariffs,” highlighted Wood Mackenzie Senior Analyst Colin Smith. “We did, however, see utility PV procurement outpace installations fourfold in Q3, showing that despite the tariffs causing project delays, there is substantial growth ahead for the U.S. utility PV sector.”

Looking for a strong Q4 for utility PV

Wood Mackenzie expects that many of the projects that have been delayed will come online by year-end. As a result, the report authors expect 3.5 GW of utility-scale PV capacity will come online n Q4 2018, the largest quarter for utility PV installations since Q4 2016.

Turning to the residential solar market, new installations were essentially flat or rose marginally for the third consecutive quarter on both a year-over-year and quarterly basis. 2017 saw the residential PV market contract 15 percent year-over-year.

Nevada and Florida were bright spots in terms of new residential and solar PV installations in Q3, according to the Q3 U.S. Solar Market Insight Report.

New non-residential solar PV capacity dropped year-over-year but rose quarterly in Q3. Growth set a new record-high in New York and also was strong in California's commercial sector. More than 400 MW of non-residential PV capacity was installed in Minnesota, building on a rising trend.

“If not for the tariffs, the U.S. solar market would undoubtedly look better today than it does now,” said Abigail Ross Hopper, SEIA’s president and CEO. “However, as this report shows, this is a resilient industry that cannot be kept down for long. With smart policies in place, the potential for the solar industry is hard to overstate.”

Looking ahead to Q4, the report forecasts a total of 11.1 GW of new PV installations will come online by the end of 2018. Longer term, Wood Mackenzie Power Renewables and SEIA expect total U.S. installed PV capacity to more than double over the next five years, with more than 14 GWdc installed annually by 2023.

Highlights from the report: