SunPower Corp. dropped a “guidance bomb” that’s dragging down shares of solar manufacturers.

The second-largest U.S. panel producer told analysts Tuesday night that it expects to lose as much as $175 million this year, a shift from May when it expected to earn as much as $50 million. The shares plunged the most in more than seven years.

SunPower said demand for utility-scale solar projects is slowing, while competition in the panel market is dragging down prices. While its 2016 revenue forecast is unchanged at $2.8 billion to $3 billion, it now sees gross margins coming in at 9.5 percent to 11.5 percent instead of 13 percent to 15 percent, according to generally accepted accounting principles.

The change took analysts by surprise. Ben Kallo, an analyst at Robert W Baird & Co., said he was “blindsided” by the unexpected reversal, during the company’s earnings call after the close of regular trading Tuesday. And Michael Morosi, an analyst at Avondale Partners LLC, called the shift a “guidance bomb” and downgraded the shares to the equivalent of hold from buy in a research note Wednesday.

SunPower shares slumped 30 percent to $10.31 at the close in New York, the most since November 2008. The company also announced plans to close a manufacturing plant in the Philippines and is firing 15 percent of its workforce.

Other solar manufacturers also declined. First Solar Inc., the biggest U.S. solar manufacturer, fell 7.2 percent to $38.66, the lowest since September 2013, and Canadian Solar Inc., the world’s second-biggest panel maker, slipped 8.9 percent to $13.16, the lowest since August 2013.

Tom Werner, SunPower’s chief executive officer, attributed the revised forecast to several macroeconomic conditions, including the paucity of tax-equity financing, a flood of assets being peddled by the bankrupt clean-energy giant SunEdison Inc., and aggressive pricing by industry newcomers.

“I understand the concern,” he told analysts on the call, “but these changes materialized in the last few months.”

Patrick Jobin, an analyst at Credit Suisse Group AG, said in a research note Wednesday that the factors “should have been apparent many months ago.”

‘Problematic’

“The cuts are problematic in their own rights, but the bigger issue for the stock from here is management credibility and lack of apparent stability in the core business,” said Jobin, who dropped his target price to $12 from $32.

Werner said weakness in the utility-scale market emerged over the past few months, in part because the December extension of U.S. federal tax credits reduced utilities’ urgency to sign contracts and SunEdison’s bankruptcy in April increased investors’ perceived risk.

“Certainly 2017 will be a difficult year in power plants,” Werner said on the call. “The power plant market is unlikely to improve in America in the next few quarters. It will in time.”

©2016 Bloomberg News

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