OPEN 2015
Golden, Colorado
Project Term:
04/22/2016 - 03/31/2021

Critical Need:

Solar photovoltaic (PV) power is the most widely used type of solar power. It offers a clean, renewable source of electricity at increasingly competitive costs. However, solar PV represents only 1.1% of U.S. power generation capacity. Innovations to enhance solar PV performance and reduce its cost could accelerate adoption of PV, which will help reduce greenhouse gas emissions in the United States. Currently, traditional single junction solar cells have a maximum solar-to-electricity conversion efficiency of about 26%. However, multijunction solar cells have a higher possible efficiency and could significantly increase this conversion rate, thereby making solar PV a more cost-effective generation option. In a multijunction cell, each junction produces an electric current in response to different wavelengths of light. By using multiple materials, the solar cells can also absorb a broader range of wavelengths more efficiently, allowing the solar cells to generate more electricity per cell. The main drawback of these systems is that multijunction cells cost far more than traditional single junction cells.

Project Innovation + Advantages:

This project team, led by the National Renewable Energy Laboratory (NREL), will employ hydride vapor phase epitaxy (HVPE), a fast growth technique used to produce semiconductors, to lower the manufacturing cost of multijunction solar cells. Additionally the team will develop new materials to be used in the HVPE process, enabling a chemical liftoff method that allows reuse of substrates. The chemical liftoff will mitigate costs of substrates, further reducing the overall system cost. NREL’s approach will leverage this improved HVPE technology to produce thin, flexible, highly efficient multijunction cells, with very high power at low cost. III-V PV has several inherent advantages over other PV materials, including higher efficiency, low temperature coefficients, and low material usage. The novel combination of HVPE growth of multijunction solar cells and substrate reuse could result in more cost-effective, higher performing multijunction solar cells, which could ultimately lower the cost and increase the efficiency of PV systems. These innovations could spur greater adoption of PV systems and reduce reliance on fossil-fuel power generation.

Potential Impact:

If successful, the NREL project team will develop highly efficient PV cells that could enable greater utilization of emissions-free solar power.


Improved solar technologies can help diversify U.S. sources of power generation and reduce reliance on fossil-fuel based power.


The team’s highly efficient solar cells enable greater power conversion in PV systems without increasing the physical footprint of the systems. This could accelerate adoption of PV, which will help reduce greenhouse gas emissions in the United States.


The team’s innovations could significantly decrease the cost of multijunction solar cells, which could improve the overall cost effectiveness of solar systems.


ARPA-E Program Director:
Dr. James Zahler
Project Contact:
Dr. Aaron Ptak
Press and General Inquiries Email:
Project Contact Email:


MicroLink Devices
Colorado School of Mines

Related Projects

Release Date: