WASHINGTON » President Barack Obama’s visit to the Solyndra solar panel factory in California last year was choreographed down to the last detail — the 20-by-30-foot American flags, the corporate banners hung just so, the special lighting, even coffee and doughnuts for the Secret Service detail.

“It’s here that companies like Solyndra are leading the way toward a brighter and more prosperous future,” the president declared in May 2010 to the assembled workers and executives. The startup business had received a $535 million federal loan guarantee, offered in part to reassert U.S. dominance in solar technology while generating thousands of jobs.

But behind the pomp and pageantry, Solyndra was rotting inside, hemorrhaging cash so quickly that within weeks of Obama’s visit, the company canceled plans to offer shares to the public. Barely a year later, Solyndra has become one of the administration’s most costly fumbles after the company declared bankruptcy, laid off 1,100 workers and was raided by FBI agents seeking evidence of possible fraud.

Solyndra’s two top officers are to appear Friday before a House investigative committee where, their lawyers say, they will assert their Fifth Amendment right against self-incrimination.

The government’s backing of Solyndra, which could cost taxpayers more than a half-billion dollars, came as the politically well-connected business began an extensive lobbying campaign that appears to have blinded government officials to the company’s financial condition and the risks of the investment, according to a review of government documents and interviews with administration officials and industry analysts.

While no evidence has emerged that political favoritism played a role in what administration officials assert were merit-based decisions, Solyndra drew plenty of high-level attention. Its lobbyists corresponded frequently and met at least three times with an aide to a top White House official, Valerie B. Jarrett, to push for loans, tax breaks and other government assistance.

Administration officials lay the blame for Solyndra’s problems in part on the global collapse in the price of solar energy components, which forced the company to sell its innovative solar panels at less than it cost to manufacture them. Some lawmakers on Capitol Hill question whether the firm’s executives may have engaged in a cover-up of their precarious financial condition, allegations the company denies.

But industry analysts and government auditors fault the Obama administration for failing to properly evaluate the business proposals or take note of troubling signs already evident in the solar energy marketplace.

“It was alarming,” said Frank Rusco, a program director at the Government Accountability Office, which found that Energy Department preliminary loan approvals — including the one for Solyndra — were granted at times before officials had completed mandatory evaluations of the financial and engineering viability of the projects. “They can’t really evaluate the risks without following the rules.”

The Energy Department’s senior staff has acknowledged in interviews the intense pressure from top Obama administration officials to rush stimulus spending out the door.

“We had to knock down some barriers standing in the way to get these projects funded,” Matthew C. Rogers, the Energy Department official overseeing the loan guarantee program, said in March 2009, just days before Solyndra got its provisional loan commitment.

During the period when Solyndra’s loan guarantee was under review and management by the Energy Department, the company spent nearly $1.8 million on Washington lobbyists, employing six firms with ties to members of Congress and officials of the Obama White House. None of the other three solar panel manufacturers that eventually got federal loan guarantees spent a dime on lobbyists.

Energy Department officials said the lobbying had no impact on their decisions.

But Solyndra, which had been among 143 companies to express an interest in a loan guarantee and 16 that were asked to submit a formal application, ended up securing the first financial commitment. Solyndra’s loan guarantee was the highest of the four companies.

Tim Harris, the chief executive of Solopower, which got a $197 million loan guarantee last month to build solar panels in San Jose, Calif., said his company had never considered employing a Washington lobbyist to grease the application.

“It was made clear to us early in the process that that was clearly verboten,” Harris said. “We were told that it was not only not helpful but it was not acceptable.”

If there was a single bet made by the Obama administration that would determine the success or failure of its investment in Solyndra, it centered on the global price its competitors pay for one of earth’s most common elements: silicon.

Solyndra’s unique tube-shaped solar panels — which harvest early morning and evening light for electricity instead of just midday sun — do not rely on silicon. But it assumed its competitors would continue to pay a relatively high price for silicon, allowing Solyndra to charge the premium required to turn a profit on its panels. It was an assumption Obama officials bought into. But industry experts outside the federal government, going back to 2008, were predicting silicon prices were headed for a steep fall.

Damien LaVera, an Energy Department spokesman, said administration officials realized the Solyndra plan posed some certain risks. The loan program was designed to help finance cutting-edge projects that could not otherwise find enough private-sector investors.

“But we did not just take what this company was telling us,” LaVera said. “We did the analysis on our own and decided it was a good bet.”

But Shyam Mehta, a senior analyst at GTM Research who follows the solar energy industry, said that he questions just how careful this review was, given the obvious warning signs.

“There was just too much misplaced zeal at the Department of Energy for this company,” Mehta said.

Solyndra executives, seeking an edge in the competition for federal loan guarantees, began employing Washington lobbyists in 2008. The company stepped up its efforts in early 2009, retaining McBee Strategic Consulting. Five lobbyists employed by the McBee group eventually worked on Solyndra’s behalf, including Michael Sheehy, a former top aide to Rep. Nancy Pelosi of California, the House Democratic leader. Solyndra has paid McBee Consulting $340,000 since 2009.

Steve McBee, the firm’s founder and a former Senate aide, did not return calls seeking comment, but in an April 2009 press release he said that his firm could help technology companies gain a chunk of the projected bonanza of $100 billion in federal money for clean-energy projects.

McBee said that lobbying was not allowed as part of the process. But in early 2009, the firm filed a disclosure form saying it was retained by Solyndra to lobby on stimulus act spending related to the Energy Department’s loan guarantee program.

In January 2010, four months after the federal loan was finalized, Solyndra executives and lobbyists pressed Gregory S. Nelson, an aide to Jarrett, a senior adviser to Obama, for a meeting to boast about progress at the plant financed with federal money and to discuss a possible second loan, according to White House emails. That meeting occurred Jan. 15, 2010, records show. White House scheduling officials later began talks with Solyndra that led to Obama’s visit in May.

But signs were increasing in 2010 that the company’s business plan was imploding. The dive in silicon prices, which had started in late 2008, accelerated by the end of 2010. Solyndra sales were growing, but so were its losses. It was forced to slash prices much lower than its costs in order to compete with conventional silicon panel producers.

Trade publications began to question whether Solyndra would survive — even its own accountant in March 2010 said it had “substantial doubt about its ability to continue as a going concern.”

But Solyndra and its lobbyists continued to provide assurances to the White House and the Energy Department, which still could have stopped the flow of federal money that was being given out for construction of a new factory.

“We have no intention of going out of business,” David Miller, a Solyndra executive, wrote to Nelson, the White House aide, in July 2010. Miller, added in May 2011, as the cash crunch had severely worsened, that “we have good market momentum.”

Nelson wrote back encouraged.

“Fantastic to hear that business is doing well,” he said, according to a May 2011 email released by the White House. “Keep up the good work.”