Sracked solar cells could achieve more than 50 percent efficiency and 5 cent per kilowatt hour costs in 3 to 5 years

Semprius has come up with three key innovations for cheaper solar power.

1. a cheap, fast way to stack cells
2. a proprietary way to electrically connect cells
3. a new kind of glue for holding the cells together.

In its designs, Semprius uses tiny individual solar cells, each just a millimeter across. That reduces costs for cooling and also helps improve efficiency.

In addition to being fast and precise, the approach also makes it possible to reuse the expensive crystalline wafers that multijunction solar cells are grown on. Eventually the company hopes to stack two multijunction devices, for a total of five or six semiconductors with a “very high performance, beyond 50 percent efficiency,” says Scott Burroughs, vice president of technology at Semprius. He says the company hopes to achieve this in three to five years.

The cells will be more costly than conventional ones. Sarah Kurtz, a principal scientist at the National Renewable Energy Laboratory, says costs won’t come down until production happens at a large scale.

With economies of scale, however, such cells could improve the economics of solar power. At a scale of 80 to 100 megawatts a year of manufacturing capacity, a cell with 50 percent efficiency would make it possible to reach costs of less than five cents per kilowatt-hour.

A stacked solar cell made by Semprius.

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