Usually, applicants under the 2005 program have to pay a fee upfront, called a credit subsidy, to compensate the government for the risk it runs by guaranteeing such a loan. Those fees can be costly, and few companies have applied. But the Energy Department said on Thursday that it had $170 million, approved under the budget deal of April 2011, that it would use to pay all or part of those subsidies.

That would make the 2005 program more like the loan guarantee program financed by the American Recovery and Reinvestment Act of 2009, in which the government paid the subsidy. The solar module maker Solyndra borrowed $527 million under that program before it went bankrupt, prompting several government investigations.

It was unclear how much in loans the department could guarantee with the new money. The size of the subsidy depends on the government’s assessment of the risk. The government could also decide to pay only a portion of the credit subsidy.

Based on previous loan guarantees, however, the volume of loans is likely to run at least into the hundreds of millions of dollars.

Among the applicants whose loan guarantees were not completed before the clock ran out on the 2009 program was First Solar, which had sought a $1.93 billion loan; the company is still facing financing problems. Another company whose application was not approved by the deadline was SolarCity, but that company said it had found private financing and withdrawn its application.