Many flat roofs in the U.S. could be generating electricity if they were covered with photovoltaic cells. But traditional solar panels are still relatively expensive to instal. Solyndra in Fremont, Calif., hopes to cover the rooftops with solar tubes instead.

Solyndra is churning out thin-film cells made of copper, indium, gallium and selenium. The film is wrapped into a cylindrical shape and encased in glass that seals out moisture and concentrates sunlight. “We are collecting light from all angles, even collecting diffuse light,” says founder and CEO Chris Gronet, thereby converting more of it into electricity. Because the arrays of cylinders do not have to be angled toward the sky or anchored against the wind, as flat panels must be, “we have half the installation cost and can install in one-third the time,” he says.

Gronet declined to comment on the cylinders’ price or reliability, but some installers are already buying in. In November, Phoenix Solar AG, near Munich, Germany, committed $615 million to purchase Solyndra’s product. The company has 10 prototype installations in Germany and in five U.S. states.