Energy Secretary Steven Chu, testifying Thursday before a House subcommittee, vigorously defended his department’s loan guarantee and grant programs against charges of poor judgment and political favoritism, rejecting Republican assertions that loans to the Solyndra solar energy company were influenced by politics.

The House Energy and Commerce Committee called the hearing to grill Chu about the programs, focusing on the more than half a billion dollars in loan guarantees given to Solyndra, a solar-panel manufacturer that went bankrupt at the end of August.

Chu strongly denied that he made any decision on Solyndra based on political considerations.

Republican lawmakers pressed Chu to explain the decision to give Solyndra $535 million in federal loan guarantees. Democrats charged that the grilling reflected House Republicans’ aversion to supporting clean-energy technologies that might antagonize the oil and coal industries.

“A central focus of the investigation is to understand why [the Department of Energy] did what it did and how we find ourselves with this taxpayer-funded debacle,” said Rep. Fred Upton (R-Mich.), the House Energy and Commerce Committee chairman. “The number of red flags about Solyndra that were raised along the way — many from within DOE — and either ignored or minimized by senior officials is astonishing.”

“What did Secretary Chu know about the situation at Solyndra, when did he know it, and how did he act on this information, if at all?” Upton asked.

Rep. Joe Barton (R-Tex.) said, “I happen to continue to support a loan guarantee program for alternative energy . . . but I cannot continue to support it if we cannot get assurances that this is a history that is not going to be repeated.”

But Rep. Henry Waxman (D-Calif.), the committee’s ranking Democrat, said that while an oversight investigation into the Solyndra loan was warranted, he objected to the way the inquiry was run by Upton and Rep. Cliff Stearns (R-Fla.), chairman of the subcommittee of oversight and investigations.

“It is time for the Republicans to stop dancing on Solyndra’s grave and get serious about energy policy,” Waxman said.

In prepared remarks for the hearing of the subcommittee on oversight and investigations, Chu said pointedly that “we appreciate the support the loan programs have received from many members of Congress — including nearly 500 letters to the Department — who have urged us to accelerate our efforts and to fund worthy projects in their states.”

Opening the hearing, Stearns said it was “readily apparent that senior officials in the Obama administration put politics before stewardship of the taxpayers’ dollars.” He said the panel’s goal is to “determine why the department and the administration tied themselves so closely to Solyndra and why they are so desperate to prop up this company.”

Waxman charged that Republicans resisted release of exculpatory documents, provoked a “gratuitous conflict” with the White House and released “cherry-picked e-mails” that smeared an Obama fundraiser. He also called for rejection of what he described as the GOP’s “anti-science and anti-progress policies” promoted by their oil and coal industry allies.

Citing credit lines offered to Chinese companies by the China Development Bank as well as various incentives and public financing in more than 50 other countries, Chu said the loan guarantee programs funded by the 2009 economic stimulus bill were needed to “provide support to cutting-edge clean energy industries that involve technology and market risks.”

“Countries like China are playing to win in the solar industry,” Chu said.

In response to questions, Chu deflected suggestions that the Energy Department should have known in advance that Solyndra was a bad bet. He said the company was hit by a sharp drop in the price of solar panels — 40 percent in one year and 70 percent over three years, he said.

“The range of predictions being made by financial analysts . . . the average of those were not expecting those prices to plummet,” Chu said. “These companies and others got caught in a very bad tsunami.”

Republicans asked whether the Energy Department should have stopped extending loan guarantees to Solyndra after the company ran into cash problems in October 2010.

Chu said the department believed that it made sense to help fund the company while it finished constructing its manufacturing facility. At one point, he said, the department faced a difficult choice of whether to let the company go into “immediate bankruptcy” or try to keep it going so that it might have a chance of survival.

GOP lawmakers also pressed Chu on the decision to let equity investors who put $75 million into Solyndra once it ran into liquidity problems be first in line to recover money in the event of a bankruptcy. They said by doing so, the Energy Department was violating legal guidelines.

Chu said the law barred giving private investors or lenders precedence in the original financing arrangements, but that once the company ran into financial trouble it was necessary to give new investors preference and that other agencies, such as the Overseas Private Investment Corp., have done the same thing.

“It was a difficult decision, and we were always always focused on that path that could get as much taxpayer recovery as possible,” Chu said.

Republicans grilled Chu about whether he knew of George Kaiser, a major contributor to the 2008 Obama campaign whose family foundation was a major investor in Solyndra and who had made frequent visits to the White House. Barton asserted that “everybody and their dog knew who he was.”

Chu said that at the time he approved the loan guarantee to Solyndra, he did not know who Kaiser was, but that he does now. He stressed that “we did not communicate with the White House about whether we should approve a loan. . . . That was our responsibility.”

When Waxman asked whether the loan guarantee to Solyndra was a “political favor,” Chu replied: “It was absolutely made only on the merits.”

Chu also said the fact that Congress appropriated $10 billion to cover credit risk showed that it knew ahead of time that a significant number of loan guarantee recipients possibly could go bankrupt. “Congress knew of the risks,” he said.

Rep. Edward J. Markey (D-Mass.) charged that committee Republicans were focusing on Solyndra because fossil fuel industries were threatened by the possibility that solar and wind could become competitive with oil and coal.

“Republicans attacked solar energy because they say it’s too expensive,” Markey said. “But Solyndra failed because the price of solar energy has become too cheap.”

Markey and other Democrats asserted that taking risks like the one associated with Solyndra was necessary because of China’s substantial help for its own solar panel manufacturers. Waxman said, “I don’t believe in surrender.”

Rep. John Sullivan (R-Okla.) later asked Chu whether he would give loan guarantees to Solyndra knowing what he knows now. “Knowing what I know now? No,” Chu said. “But you don’t make decisions and fast-forward two years. I wish I could do that.”

Republicans on the House Energy and Commerce Committee have been harshly critical of the Energy Department and the White House after obtaining reams of administration e-mails concerning the department’s decision to help Solyndra, even after the company started having liquidity problems.

The e-mails released so far have shown an administration where some of President Obama’s economic advisers fought against the program, while the Energy Department struggled to get deals approved quickly.

The White House also has released letters, many written by congressional critics of the Energy Department and the loan guarantee program, supporting loan guarantee requests.

Many Republican lawmakers have suggested that the loan guarantees were given to Solyndra because of the company’s political connections in the White House.

But Chu said in his opening remarks that “the final decisions on Solyndra were mine, and I made them with the best interest of the taxpayer in mind.” He added, “I did not make any decision based on political considerations.”

Instead, he said, the original loan guarantee “was based on the analysis of experienced professionals and on the strength of the information they had available to them at the time.” He noted that private investors had put more than half a billion dollars of their own money into Solyndra and that the company was praised as one of “50 most innovative companies” by the Massachusetts Institute of Technology’s Technology Review in February 2010.

Chu also defended the department’s decision to continue supporting Solyndra even after it told the administration that it needed emergency funds in the face of a cash shortage.

“The Department faced a difficult decision: force the company into immediate bankruptcy or restructure the loan guarantee to allow the company to accept emergency financing that would be paid back first if the company was still unable to recover,” Chu said in his opening statement.

“Immediate bankruptcy meant a 100 percent certainty of default, with an unfinished plant as collateral,” he said. “Restructuring improved the chance of recovering taxpayer money by giving the company a fighting chance at success.”

Chu added, “While we are disappointed in the outcome of this particular loan, we support Congress’ mandate to finance the deployment of innovative technologies, and believe that our portfolio of loans does so responsibly.”

Staff writer William Branigin contributed to this report.