New Stacked Cells Pop The Lid Off Solar Efficiency

Solar-power researchers are always trying to squeeze more power out of their devices. After all, more power from solar cells effectively lowers the overall cost, and a more cost-effective cell will make solar photovoltaics more competitive with other forms of electrical generation.

One company claims to have come up with a system that could propel solar into another dimension of efficiency.

Earlier this year, Semprius Inc., a Durham, N.C.-based manufacturer, announced its new four-junction, four-terminal, stacked solar cell that uses the company’s proprietary microtransfer printing process.

The process is unique in that it joins cells with processors built on different kinds of semiconductor materials. The new stacked cell is composed of a three-junction microcell that is stacked on top of a single-junction germanium microcell using the company’s high-speed microtransfer process.

By using four junctions, the stacked cell is able to capture light across a broader swath of the solar-light spectrum. Capturing more light means more electricity and much greater efficiency than conventional silicon and thin-film, single-junction solar cells.

Semprius claims the new stacked cells can achieve solar-efficiency rates of greater than 50 percent, which is more than double the industry standard. Higher efficiency rates also effectively lower the cost per kilowatt-hour to generate electricity. At the rate claimed by the manufacturer, these cells could generate electricity at less than 5 cents per kilowatt-hour, which is competitive with the cost to generate electricity from natural gas.

About the Author

Rick Laezman

Freelance Writer

Rick Laezman is a Los Angeles-based freelance writer who has been covering renewable power for more than 10 years. He may be reached at

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