Washington -- The Treasury Department's inspector general has opened an investigation of a $528 million government loan to Solyndra Inc., the now-bankrupt solar panel manufacturer once cited as a model of the Obama administration's clean energy program.

A spokesman said Thursday that the inspector general is reviewing the role and actions of the Federal Financing Bank, a government corporation supervised by the Treasury Department. The bank provided the low-interest loan to the Fremont, Calif.-based company.

The Treasury investigation is the latest government inquiry into the collapse of Solyndra, which filed for bankruptcy last month.

The FBI has executed search warrants at Solyndra's headquarters and talked to top executives. The Energy Department's inspector general and the House Energy and Commerce Committee also are investigating Solyndra and the DOE's Energy Loan Program, which has provided billions in loan guarantees to renewable energy companies.

On Wednesday, ﻿Obama administration officials denied Republican charges of White House interference in the loan guarantee to Solyndra, warning that the company's failure should not lead the nation to abandon a potential multitrillion-dollar solar energy market to China.

"I can't imagine we would be willing to cede what is undoubtedly one of the largest, if not the largest, industries in the world for the next several decades," Jonathan Silver, executive director of the Department of Energy's Loan Programs Office, told the House Energy and Commerce Committee.

The Fremont firm's bankruptcy has embarrassed the administration and given a black eye to its push for "green jobs" and alternative energy. Solyndra's plant closed Aug. 31 and nearly all its 1,179 workers were laid off. The FBI raided the plant last week and questioned executives.

The committee postponed until next week testimony from Solyndra Chief Executive Officer Brian Harrison and Chief Financial Officer W.G. Stover Jr. at their request. They are expected to be grilled about why they assured Congress the company was viable while telling investors and the Energy Department that company revenues were expected to drop.

Silver said private investors who loaned $1.1 billion for the Fremont facility were also taken by surprise. He pinned blame for the bankruptcy on more than $20 billion in direct investment by the Chinese government in solar manufacturers that now dominate the industry.

U.S. market share in solar energy has plunged from 40 percent in 1995 to 6 percent today, Silver said. In the past six years, China's market share has soared from 6 percent to 54 percent.

Plummeting prices of solar panels from China and weakening demand from financially stressed European governments forced two other bankruptcies of U.S. solar manufacturers last month, Evergreen Solar in Massachusetts and SpectraWatt in New York. BP Solar in Maryland stopped manufacturing last spring.

With Solyndra, the companies represent a fifth of U.S. solar panel manufacturing capacity.

Rushed loan

At Wednesday's hearing, committee Republicans described the loan as a costly boondoggle from President Obama's $800 billion stimulus legislation. The loan originated in the George W. Bush administration, but evidence indicates it was rushed as part of the stimulus.

Republicans released excerpts from staff e-mails at the Energy Department and the White House Office of Management and Budget indicating that officials felt pressured to hurry the loan so that it could be announced at a groundbreaking event in Fremont on Sept. 4, 2009, that included Energy Secretary Steven Chu, a UC Berkeley professor and former director of the Lawrence Berkeley National Laboratory.

Vice President Joe Biden, beamed in by satellite, gave a speech for the event, saying the loan guarantee was "exactly what the Recovery Act is all about." Obama also touted the plant on a visit there in May 2010.

On March 10, 2009, Biden's then-chief of staff Ronald Klain sent an e-mail to the Office of Management and Budget staff wanting to "chat on Monday about the DOE flag in here on Solyndra. ... If you guys think this is a bad idea, I need to unwind the W(est) W(ing) QUICKLY."

Three days later, an e-mail between agency staff warned, "this deal is NOT ready for prime time." Other staff e-mail cited the "time pressure we are under to sign-off on Solyndra," and requested that the loan announcement be postponed.

Work done in Bush era

Committee Democrat Ed Markey of Massachusetts acknowledged that the loan was "expedited" as part of a broad effort to get stimulus money out the door as fast as possible, but he was "unconvinced" that there was any wrongdoing, citing three years of due diligence, much of it conducted by civil servants during the Bush administration.

Republican Brian Bilbray of Carlsbad (San Diego County) also said he did not believe there was "an intentional misdeed," but he blasted government officials for hyping the project and having "blind faith" in anything renewable. Bilbray said the Solyndra failure could tarnish more-viable solar projects elsewhere.

Solyndra first applied for a loan in 2006 after bipartisan passage of the 2005 Energy Policy Act, intended to wean the country from foreign oil. On Jan. 8, 2009, just before Obama took office, a federal government credit committee remanded the loan for further study, saying a recommendation would be "premature at this time."

Department of Energy officials said the credit committee, comprised of civil servants, did not reject the loan and by March 2009 voted to send it forward after reviewing an independent engineer's report and a market analysis.

Rep. Joe Barton, R-Texas, said "the only thing that changed" between the time the committee remanded the loan and approved it "was the president changed."

Line of creditors

Republicans also charged that the administration broke the law under the Energy Policy Act, which prohibits the government from subordinating a taxpayer-backed loan to loans by private investors. The administration agreed last fall to restructure the loan and to put taxpayers in line behind an additional $75 million ponied up by private investors.

Silver, who formerly worked for a hedge fund, said that giving the company a "fighting chance" and completing the facility gave taxpayers a better chance of recouping some of their money, and that the government remains ahead in line of the $1.1 billion in private investment should any money be salvaged.

The Associated Press contributed to this report.