Two of the main obstacles to the widespread adoption of solar energy are cost and efficiency. However researchers at the Durham, North Carolina-based startup Semprius have found a way to tackle both these issues by simply stacking solar cells. The technique enables Semprius to produce solar panels with efficiencies as high as 50% (compared to the industry standard of 25%).
Semprius makes its super efficient solar cells by stacking different semiconducting materials that collect different frequencies of light. The technique is inexpensive, it doesn’t require any radical redesign, and it can be done with pre-existing manufacturing techniques and equipment.
An article from Technology Review states that Semprius has achieved three key innovations: a cheap, fast way to stack cells, a proprietary way to electrically connect cells, and a new kind of glue which holds the cells together. In its current designs, Semprius uses tiny individual solar cells, that are just a millimeter across in order to aid cooling and increase efficiency.
Semprius manufactures its semiconductor materials using conventional techniques, but it stacks several different layers to create solar panels that can captures more energy from sunlight. Semprius has made two prototypes: One with an efficiency of 43.9 percent and the other, using slightly different materials, with an efficiency of 44.1 percent. Eventually the company hopes to stack two multijunction devices (a total of five or six semiconductor layers) for 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.