Solar rods: A close-up view of Solyndra’s cylindrical solar cells.
The cylindrical design also allows the solar panels to absorb more light. Solar panels work best when light hits them directly, such as when the sun is directly overhead. To get more power from solar panels, they’re often mounted on tracking systems that keep each panel pointed at the sun all day. But these tracking systems don’t work in high winds, add cost, and take up space that could be occupied by other solar panels. The cylindrical solar cells provide another way to increase the power from a solar panel. At any point in the day, some part of the curved surface is facing the sun more or less directly, and therefore absorbing a large share of that light.
The trade-off, of course, is that the other side of the cylinder is shaded. With highly reflective white roofs, however, this is less of a problem. Light passes through the same spaces between the cylinders that allow wind to flow through. It reflects off the roof and is absorbed by the shaded side of the solar cells. Also, the other surfaces of the solar cell absorb some diffuse light from the sky.
This adds up to greater energy production over the course of a year than a conventional system, the company says. Combined with low installation costs, this significantly lowers the cost of solar power. Gronet says that within a few years, the company plans to produce solar systems that generate electricity competitive with the average cost of electricity in the United States (about 10 cents per kilowatt-hour) by optimizing manufacturing and increasing production volumes.
The company, however, does not plan to expand out of the commercial rooftop business, where its specialized design has an edge. Other solar-panel technologies may prove more affordable for other applications, such as residential installations and large-scale projects for utilities.