Improving Solar Generation Efficiency with Solar Modules

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OPEN 2012
Pasadena, California
Project Term:
03/28/2013 - 09/27/2016

Technology Description:

The California Institute of Technology (Caltech) is developing a solar module that splits sunlight into individual color bands to improve the efficiency of solar electricity generation. For PV to maintain momentum in the marketplace, the energy conversion efficiency must increase significantly to result in reduced power generation costs. Most conventional PV modules provide 15-20% energy conversion efficiency because their materials respond efficiently to only a narrow band of color in the sun’s spectrum, which represents a significant constraint on their efficiency. To increase the light conversion efficiency, Caltech will assemble a solar module that includes several cells containing several different absorbing materials, each tuned to a different color range of the sun’s spectrum. Once light is separated into color bands, Caltech’s tailored solar cells will match each separated color band to dramatically improve the overall efficiency of solar energy conversion. Caltech’s approach to improve the efficiency of PV solar generation should enable improved cost-competitiveness for PV energy.

Potential Impact:

If successful, Caltech’s solar system would convert greater than 50% of incoming light energy into electrical power at a cost well below $1/watt.


Cost-effective PV systems would enable increased U.S. renewable energy use. As electric vehicles become more popular, the ability to power those using renewable energy would decrease our reliance on foreign oil.


Replacing energy systems powered by coal would provide an immediate decrease in greenhouse gas emissions, of which electricity generation accounts for over 40%.


Cost-effective renewable energy alternatives would reduce electricity rates for consumers in locales with renewable portfolio standards or greenhouse gas emissions targets.


ARPA-E Program Director:
Dr. Michael Haney
Project Contact:
Prof. Harry Atwater
Press and General Inquiries Email:
Project Contact Email:



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