Solar Junction Announces Development of 4J Space Cells

Solar Junction, provider of the highest efficiency commercially available multi-junction solar cell for terrestrial concentrated photovoltaic (CPV) applications, is announcing an ambitious plan to become the world’s leading provider of solar cells for space power applications. Solar Junction is rapidly developing a fully lattice-matched, four-junction (4J) space cell product enabled by its proprietary dilute nitride technology platform, with predicted air mass zero (AM0) efficiencies exceeding 33% by 2016. Solar Junction presented at the 2015 Space Power Workshop in Manhattan Beach, California (May 11-14), where it announced to the aerospace community its recent progress in developing next-generation space solar cells.

Solar Junction is currently producing a high efficiency three-junction (3J) space cell using its dilute nitride material as the bottom active junction on a GaAs substrate. 2014 saw the first commercial shipment of Solar Junction’s 3J space cell, with AM0 efficiencies exceeding 31%, and the 3J product is undergoing qualification. During the 2015 Space Power Workshop, The Aerospace Corporation presented radiation degradation results from two Aerospace AeroCube picosats currently on-orbit (since June 2014) carrying Solar Junction 3J space cells. The results demonstrate that dilute nitride materials have radiation hardness comparable to conventional cells and show great promise for Solar Junction’s next-gen space products.


Image provided by The Aerospace Corporation (AeroCube-6 A/B)

IV curve

Data provided by The Aerospace Corporation

Early prototypes of Solar Junction’s next-gen 4J space cell with an industry-standard Ge bottom junction have reached AM0 efficiencies of 31%. By late 2016, Solar Junction plans bring to market its 4J, lattice-matched, dilute nitride, Ge bottom junction space cell with a minimum average efficiency of 33%.

4J cell

Since introducing its terrestrial CPV technology over seven years ago, Solar Junction has proven that dilute nitrides can be produced in high volume on 6-inch wafers with industry leading manufacturing yields and significant cost savings using molecular beam epitaxy (MBE). Solar Junction is now poised to enter the space photovoltaics market. Its proprietary dilute nitride technology is lattice matched on both Ge and GaAs substrates, provides a range of bandgaps between 0.9 eV and 1.4 eV, and is the only technology platform that enables low-cost monolithic growth beyond three junctions.

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