NREL Researchers Improve HVPE for Potential Low-Cost III-V Solar Production

Hydride vapor phase epitaxy (HVPE), which has been around since the 1950s may have gotten an upgrade from NREL researchers who devised dynamic HVPE or D-HVPE to produce III-V solar cells. D-HVPE uses a dual-chamber reactor. The substrate moves back and forth between the chambers, vastly reducing the time to make a solar cell. According to the NREL, a single-junction III-V solar cell that takes an hour or two to fabricate using metal organic vapor phase epitaxy (MOVPE, which originated in the 1960s) can be made in just two minutes using D-HVPE.

NREL-- GaAs solar cells produced using D-HVPE

NREL– GaAs solar cells produced using D-HVPE

D-HVPE Holds Potential for Inexpensive III-V Solar Cell Production

The researchers speculate that the new kind of HVPE could eventually produce III-V solar cells such as gallium arsenide (GaAs) that currently are $100 to $300 per watt to produce. Such solar cells are used in spacecraft where, weight and efficiency, not cost are the primary issues. The world record conversion efficiency for a single junction gallium arsenide solar cell is 28.8%.

The NREL researchers say that the newly devised HVPE system needs much improvement before it can be taken out of a lab and made into a pilot production system. “We have an R&D technology that works really, really well. We have designs for a pilot-scale reactor, but we have no way to get from A to B. It’s going to be very capital intensive to get to that step,” Aaron Ptak, an NREL senior scientist said.

Kelsey Horowitz, part of the Techno Economic Analysis Group in NREL’s Strategic Energy Analysis Center, leads the tech-to-market effort to get D-HVPE commercialized. Horowitz, has predicted that solar cells made with D-HVPE technology could generate electricity at 20-80 cents a watt. According to Horowitz, that price won’t happen until they can produce the solar cells in much larger quantities, and that’s at least five years away.