The US Air Force Research Laboratory (AFRL) is investing in a National Renewable Energy Laboratory (NREL) solar cell technique to help bringing down manufacturing costs of III-V high efficiency solar cells so these can be used for widespread installations on earth and not be limited for space related uses alone.
NREL underlines that III-V solar cells are extremely efficient solar cells produced using flexible gallium arsenide manufacturing process. These are commonly used to power satellites in earth's orbit and for NASA's missions to mars and other planets. Now using a technology called dynamic hydride vapor phase epitaxy (D-HVPE), NREL aims to fabricate these solar cells in a 'high-throughput, low-cost manner'.
The D-HVPE technology involves depositing chemical vapors onto a substrate using a multi-chamber reactor. With AFRL's support, the US government laboratory says it wants to make a pilot-production reactor which can help scale the technology to meet the needs of Department of Defense customers.
A production-scale reactor can lead to manufacturing of industry-standard cells 6 inches in diameter, going beyond the 2 inches diameter cell produced by a laboratory scale reactor. The largest such reactor is expected to be installed at NREL a year later in July 2021.
Working together with NREL to design the reactor will be North Carolina based semiconductor supplier Kyma Technologies that's also a HVPE equipment specialist. The reactor itself will be manufactured by New York based systems integration company Ceres Technologies.
AFRL is collaborating with NREL through its Air Force Research Laboratory Space Vehicles Directorate unit to bring down the high cost of solar cell fabrication processes with a view to eventually be able to deploy these high-efficiency cells in broader civilian and commercial applications. NREL Lead Researcher Kelsey Horowitz counts ships, electric vehicles or portable devices for its various intended uses.
"The maturation of D-HVPE technology will build upon AFRL's other research developments with the goal of providing game-changing renewable power solutions to the warfighter," explained AFRL Senior Physicist David Wilt. "For example, space-solar-beaming, central to AFRL's Space Solar Power Incremental Demonstrations and Research (SSPIDR) project, needs affordable high efficiency solar cells such as those produced by D-HVPE. Scientists at AFRL anticipate using these next-gen solar sails to gather the sun's energy, convert it to radio frequency and beam it to a receiver on earth."
On its website, NREL said about D-HVPE. "Using this system, we have demonstrated single-junction GaAs solar cells with >25% conversion efficiency grown and growth rates exceeding 5 micron per minute. We are developing monolithic two-junction devices with target efficiencies >30%, with three-junction devices being planned for the future. In addition, we are pursuing high-quality top cells for integration with high-efficiency crystalline Si solar cells with an expected tandem cell efficiency >30%."
In April 2020, NREL achieved its highest solar conversion efficiency with 47.1% for a six-junction III-V solar cell fabricated under concentrated illumination (see NREL claims close to 50% efficiency for 6 junction solar cell).