Alta sets seventh consecutive single-junction solar cell efficiency record, at 29.1%

Alta Devices of Sunnyvale, CA, USA (a subsidiary of Hanergy Thin Film Power Group Ltd of Beijing, China since 2014) in November set a new solar energy conversion efficiency record for gallium arsenide (GaAs) single-junction solar cells (for the seventh consecutive time since 2010), certified by German solar energy testing laboratory CalLab at Fraunhofer ISE (Institute for Solar Energy Systems) at 29.1% (an increase from its 28.9% record announced in July). This is also the 13th cell or module solar efficiency record achieved by Alta (joining its single-junction solar module efficiency record of 25.1%).

Alta focuses on GaAs because of its unique advantages such as intrinsic high efficiency, excellent UV and radiation resistance, flexibility and low weight as well as its ability to generate electricity at high temperatures and in low light. The firm’s solar technology is hence suited to powering products that need autonomous power such as small satellites, unmanned aerial vehicles (UAVs), electric vehicles (EVs) and autonomous vehicles (AVs).

In addition to Alta’s technical advances (which push the limits of energy density), the firm’s manufacturing economics enable formats and form factors that were previously not possible, it is claimed. GaAs is typically expensive to produce, but Alta invented a manufacturing technique that develops extremely thin layers (about 1µm thick - a fraction of the thickness of other GaAs solar cells). By utilizing a very thin layer of material with the highest energy density possible, the amount of material needed is low. System costs can hence be dramatically reduced.

Alta recently launched its Gen4 AnyLight solar technology, boosting power-to-weight ratio by 160% over its third-generation technology. Continuous advances in power-to-weight ratio are critical for future small satellites, autonomous UAVs, electric vehicles, and autonomous sensors, notes the firm.

Also, NASA is testing Alta’s solar technology at the International Space Station (ISS) in order to evaluate it for future low-Earth orbit missions, including powering CubeSats.

“NASA’s interest in Alta’s record-setting performance demonstrates that our technology withstands some of the most challenging environments endured by autonomous systems in space, high altitude, and on land,” says CEO Jian Ding.

Following years of collaboration, the US National Aeronautics and Space Administration (NASA) Marshall Space Flight Center (MSFC) selected Alta to participate in the MISSE-X (Materials International Space Station Experiment) flight investigation launched in November on board the NG CRS-10 mission. The goal of this test is to evaluate new solar cell and package technologies in support of future NASA missions requiring solar cells with high efficiency, high packing density, and very low mass.

Alta engineers worked with MSFC scientists and vendors to develop an array of nine solar cells with innovative packaging materials. The cells were fabricated and delivered to NASA for testing during first-half 2018. Integration into the MISSE sample carrier was carried out at the Alphaspace facility in Houston, Texas in August, and the experiment was transported to the International Space Station by the NG-10 Antares rocket on 17 November. The solar cells will be installed into a zenith-facing position on the station in the coming weeks.

After one year of exposure, the solar cells will be returned for evaluation. NASA and Alta have developed scientific models to simulate how the solar cells may be affected by their on-orbit exposure, and the final sample evaluation will allow the teams to refine their models, enhancing the accuracy of predictions related to solar cell and package performance in future, longer missions.

“The High Efficiency, Low-Mass Solar Cell Systems experiment exposes candidate solar cells to the space environment,” says NASA. “In addition, thin polymeric films, developed as cover slide materials for these solar cells, are exposed as separate samples, to measure atomic oxygen erosion yield and transmission changes due to ultraviolet radiation. The test results will be especially important for the design of small but highly capable spacecraft needed to explore our solar system.”

See related items:

Alta Devices raises its GaAs single-junction solar cell efficiency world record to 28.9%

Alta Devices launches Gen4 solar cell, targeting UAVs and autonomous vehicles

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