“The federal government has brought a knife to a gun fight,” Mr. Bowles said. “Its support is completely out of proportion to the support displayed by China — and even to that in Europe.”

Stephanie Mueller, the Energy Department press secretary, said the department was committed to supporting renewable energy. “Through our Loan Program Office we have offered conditional commitments for loan guarantees to 16 clean energy projects totaling nearly $16.5 billion,” she said. “We have finalized and closed half of those loan guarantees, and the program has ramped up significantly over the last year to move projects through the process quickly and efficiently while protecting taxpayer interests.”

Evergreen did not try to go through the long, costly process of obtaining a federal loan because of what it described last summer as signals from the department that its technology was too far along and not in need of research and development assistance. The Energy Department has a policy of not commenting on companies that do not apply.

Evergreen was selling solar panels made in Devens for $3.39 a watt at the end of 2008 and planned to cut its costs to $2 a watt by the end of last year — a target it met. But Evergreen found that by the end of the fourth quarter, it could fetch only $1.90 a watt for its Devens-made solar panels. Chinese manufacturers were selling them for as little as $1.60 a watt after reducing their costs to as little as $1.35 or less per watt.

Evergreen’s joint-venture factory in Wuhan occupies a long, warehouselike concrete building in an industrial park located in an inauspicious neighborhood. A local employee said the municipal police had used the site for mass executions into the 1980s.