Recasts paragraph 1, adds details and comments in paragraphs 2-5 from earnings call

By Dharna Bafna

Feb 24 (Reuters) - First Solar FSLR.O, the largest U.S.-based solar panel maker, projected annual sales below Wall Street estimates, citing customer headwinds such as permitting delays under the Donald Trump administration, sending its shares down nearly 14%.

The company also anticipates a $125 million to $135 million impact from tariffs in 2026, CFO Alex Bradley said in a post-earnings call.

"We've kind of run at a very low utilization rate to try to sort of buy some time to see how these tariffs ultimately get played out," the company said, adding that the decline in gross margin was driven by tariff-related costs and underutilization linked to curtailments at its Series 6 international facilities.

"Many of our customers continue to face both regulatory and commercial challenges, including federal permitting approval delays," First Solar said.

Net sales, however, came in at $1.68 billion for the quarter ended December 31, up about 11.1% from the year-ago period, driven by an increase in the volume of modules sold in the quarter.

The Arizona-based company now expects 2026 net sales to be in the range of $4.9 billion to $5.2 billion. Analysts, on average, were expecting $6.12 billion, according to data compiled by LSEG.

First Solar reported net income for the fourth quarter of $4.84 per share, compared with $3.65 a year ago.

(Reporting by Dharna Bafna in Bengaluru; Editing by Alan Barona and Sherry Jacob-Phillips)

((Dharna.Bafna@thomsonreuters.com))