The funding is aimed at bridging the financing gaps that companies trading in such adolescent technologies often face, mirroring an earlier loan guarantee program targeting developers of large-scale solar projects.

Indeed, the new offering is far smaller than the $16bn in loan guarantees the Energy Department provided to utility-scale solar projects in the wake of the financial crisis, including Ivanpah, Crescent Dunes, Agua Caliente and Desert Sunlight.