Renewable energy companies in the United States might lose a friend in the coming months.

Conservative Republicans are trying to kill the Export-Import Bank, the independent and self-sustaining federal agency founded during the Great Depression that helps finance the purchase of American-made goods and services by overseas buyers. The bank’s current authorization expires at the close of business on September 30 if Congress doesn’t act.

Ex-Im is pretty obscure – at least, it was before the Republicans targeted it – but the bank drives a fair amount of business. It rang up 3,842 financing authorizations in the 2013 fiscal year – loan guarantees, mostly, but also direct loans and export credit insurance – backing exports worth $37.4 billion. Renewable energy had a $257 million piece of that pie.

And the cost to taxpayers? According to a recent report [PDF] from the Congressional Research Service, after covering operating expenses and loan loss reserves, “Ex-Im Bank provided $1.1 billion to the U.S. treasurey in FY2013.”

That’s right, the taxpayers made money off Ex-Im.

Yet critics say the bank is an affront to free market principles, rewarding the politically well-connected and even putting taxpayer dollars at grave risk. That critique was reflected in this statement by Rep. Jeb Hensarling (R-Texas), the leading voice in opposition to the bank’s continued existence, at a June hearing of the House Financial Services Committee, which he chairs:

“The Bank ostensibly makes loans backed by taxpayers that the private sector is unwilling to make. If private creditors are unwilling to engage in these transactions, it begs the question why should the American taxpayer?”

Supporters reply that one big reason is that companies from other countries are getting similar support. Renewable energy companies add that long project timelines and the new nature of many renewable energy technologies and applications can make obtaining financing nearly impossible overseas.

Those are the arguments made by Steve Wilburn, CEO of California-based FirmGreen, a player in a biogas project at a Brazilian landfill that was aided three years ago by a $48.6 million loan supported by Ex-Im. At a House hearing in June, Wilburn testified that with no financing assistance available from his commercial bank, he was advised by his Brazilian colleague to “contact his ECA” – export credit agency.

“I was embarrassed,” Wilburn testified. “I had to ask him what ECA meant.” Wilburn said he discovered that competitors on the project were dangling finance support from their home country ECAs – Air Liquide though France’s Compagnie Française d’Assurance pour le Commerce Extérieur, and Linde through Germany’s Euler Hermes Kreditversicherungs-AG.

The Novo Gramacho project is now operating, producing fuel-grade biomethane gas that helps power a local refinery as well as food-grade liquid CO2, all with the help of FirmGreen’s VerdeControls plant control software and VerdeWatts energy management system. FirmGreen estimated the project generated 165 U.S. jobs, including those at FirmGreen itself and at other U.S. companies that were involved along the way.

Opponents have tried to focus the Ex-Im debate on the bank’s support for big customers – S&P recently estimated that the bank has supported up to 30 percent of Boeing’s jet deliveries in the past four years, according to a Wall Street Journal story. But Karl Gawell, executive director of the Geothermal Energy Association, said that ignores much of the bank’s work in renewable energy.

“Small U.S. firms involved in new energy technologies, like renewable energy and efficiency, are competing head-to-head against many foreign competitors to sell goods and services in international markets,” Gawell wrote on the National Journal’s Energy Insiders forum. “The Export-Import Bank plays an important role in the competitiveness of U.S. exports and the health, if not survival, of many of the firms that are developing and deploying the energy technologies expected to dominate the global energy markets of the future.

Renewable energy is a focus of the bank’s activities in part because Ex-Im’s charter requires it. Plus, Congress early in the Obama administration specifically targeted 10 percent of the bank’s financing for renewables. It was kind of a crazy directive, since in 2009 just $13 million, or 0.4 percent of the bank’s financing, went to renewables. But the figure grew quickly, reaching $721 million in 2011, 2.2 percent of the bank’s authorizations.

Renewable energy authorizations have since fallen, but Craig O’Connor, director of Ex-Im’s Office of Renewable Energy, said that doesn’t reflect any backsliding on the bank’s commitment.

Renewable energy as a business “is a little lumpy,” O’Connor said in an interview. “In any one year you could have a slip.” More fundamentally, “at the Ex-Im Bank, we’re not controlling our own destiny. We don’t go out and create demand, we reflect it.”

That said, O’Connor beats the bushes to find U.S. companies who might be able to sell goods or services overseas, and to get them in Ex-Im programs if that’s what they need to make exports happen.

U.S.-based companies can also get assistance in doing projects overseas from the Overseas Private Investment Corporation. It operates similarly to Ex-Im, except its charge is to help U.S. companies invest in developing companies.

Just last month, OPIC approved a $230 million loan to help support Arizona-based First Solar’s Luz del Norte solar power plant in Chile. At 141 megawatts, it will be the largest photovoltaic solar plant in Latin America, according to First Solar.

What’s interesting in this case is that just a few years ago several First Solar projects in India were supported by Ex-Im financing aid. With those projects, there was an explicit guarantee of U.S.-made First Solar goods to India (the company has plants in Ohio and Malaysia). With OPIC doing the financing, there’s no such promise with the Chile project.

Camilo Patrignani, CEO of the renewable energy project developer Greenwood Energy, says help from multilateral lenders like OPIC is vital to making projects happen in Latin America as commercial lenders become more comfortable with the space. And he says that even though OPIC deals don’t come with an export guarantee, loans for overseas projects can be good for the United States.

“Of course we all want to see the world turning to clean energy solutions,” Patrignani said in an interview. “Moreover, these are not subsidies. They pay for themselves. And there are direct and indirect benefits. Once you look at the multiplier effect of American companies focusing on Latin America, you see it’s really worthwhile.”

OPIC’s charter is also up for reauthorization this year, but the agency appears safe; a bill focused on electrifying Africa that includes a three-year reauthorization passed the House in May despite majority Republican opposition, and a bipartisan bill in the works in the Senate would re-up OPIC for five years.

As for Ex-Im, while Hensarling is continuing his crusade, there are signs that a campaign by Ex-Im and its supporters – both business and labor – has begun to turn the tide in favor of the bank, particularly in the Senate. Still, according to a recent story in The Hill, “the legislative path for a bill remains murky.”