Anyone hoping for answers about Solyndra, the bankrupt solar-panel maker, was disappointed Friday. The chief executive and chief financial officer of the company repeatedly took the Fifth Amendment as members of a House subcommittee asked scathing questions. “How does a company go from having the president of the United States visit it to having the F.B.I. come in and confiscate its files?” asked Rep. Joe Barton, a Texas Republican. Meanwhile Republicans are using Solyndra as an argument for delaying further loan guarantees for solar projects, which must break ground by Sept. 30 to be eligible.