14 September 2020
US AFRL invests in NREL solar cell project
The US Air Force Research Laboratory (AFRL) is investing in a technique developed at the National Renewable Energy Laboratory (NREL) to adapt space-based solar technology for terrestrial applications.
As III-V solar cell technology is extremely efficient, it is commonly used to power satellites in Earth’s orbit and many of NASA’s missions to Mars and other planets. However, it is expensive for terrestrial use. NREL has therefore spent the last several years working on a way to make the cells cheaper to manufacture.
The method pioneered at NREL relies on dynamic hydride vapor phase epitaxy (D-HVPE). The earlier version of HVPE used a single chamber where a chemical was deposited, the substrate removed, the chemical swapped out for the next, and the substrate returned to the deposition chamber. D-HVPE uses a multi-chamber reactor, significantly speeding up the process.
“The investment here is specifically to make a pilot-production reactor,” says Aaron Ptak, a senior scientist in the National Center for Photovoltaics at NREL. “This will enable us to prove that the D-HVPE technology can be scaled to meet the needs of Department of Defense customers.”
Until now, the Department of Energy’s Solar Energy Technologies Office and the Advanced Research Projects Agency–Energy have funded NREL’s work on D-HVPE.
AFRL serves as the primary scientific R&D center for the United States Air Force. Last year it announced the creation of the Space Solar Power Incremental Demonstrations and Research project, which intends to capture solar energy using highly efficient solar cells and transmit the collected energy to Earth.
Using a laboratory-scale reactor, NREL researchers can make a III-V solar cell measuring 2-inches in diameter. The production-scale reactor will allow the manufacture of industry-standard cells 6-inches in diameter. The larger reactor is expected to be installed at NREL in July 2021.
Kyma Technologies Inc of Raleigh, NC, USA (which provides crystalline nitride materials, crystal growth and fabrication equipment, and devices) will work with NREL researchers to help design the reactor for the D-HVPE system. The firm specifically has expertise in HVPE equipment. Ceres Technologies Inc (which provides process equipment for the semiconductor and solar industries) of Saugerties, NY, will manufacture the reactor for NREL. The two companies have previously partnered on other projects.
“Bringing Kyma in gives us some extra HVPE knowledge that’s really useful here,” Ptak says. “It was kind of natural to deal with Kyma because they understood the HVPE process and they already had an existing relationship with Ceres to help build semiconductor equipment to the specs that are required for industry and now for national labs.”