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High-Temperature Dual-Junction Topping Cells

Yale University

Dual-Junction Solar Cells for High-Efficiency at Elevated Temperature

Program: 
ARPA-E Award: 
$2,540,000
Location: 
New Haven, CT
Project Term: 
07/15/2014 to 12/31/2017
Project Status: 
ALUMNI
Technical Categories: 
Critical Need: 

There are two primary methods for capturing and using sunlight today: direct conversion of sunlight to electricity using photovoltaic (PV) solar panels, or focusing sunlight onto a fluid that is used to drive a steam turbine in concentrated solar power (CSP) systems. Storing hot fluid in CSP systems is a less expensive way to generate electricity when the sun is not shining compared to storing electrical energy from PV in batteries. However, PV uses just part of the solar spectrum at high efficiency, while CSP systems use the entire solar spectrum but at low efficiency. Combining the best elements of these two technologies could provide a means to get the most out of the full solar spectrum, generating both electricity and storable heat (for later use) within the same system. Developing hybrid solar energy systems that perform both functions at the same time could provide electricity at cost comparable to traditional sources, whether the sun is shining or not.

Project Innovation + Advantages: 

Yale University is developing a dual-junction solar cell that can operate efficiently at temperatures above 400 °C, unlike today's solar cells, which lose efficiency rapidly above 100°C and are likely to fail at high temperatures over time. Yale's specialized dual-junction design will allow the cell to extract significantly more energy from the sun at high temperature than today's cells, enabling the next generation of hybrid solar converters to deliver much higher quantities of electricity and highly useful dispatchable heat. Heat rejected from the cells at high temperature can be stored and used to generate electricity with a heat engine much more effectively than cells producing heat at lower temperatures. Therefore, electricity can be produced at higher overall efficiency for use even when the sun is not shining.

Potential Impact: 

If successful, Yale University's high-temperature solar cells could be used in the next generation of hybrid solar converters, enabling more efficient utilization of the full solar spectrum than possible with either photovoltaic or concentrated solar power independently.

Security: 

Developing new hybrid solar systems that generate both electricity and dispatchable heat at the same time could provide domestically-sourced power at costs comparable to traditional sources, whether or not the sun is shining.

Environment: 

Replacing energy systems powered by fossil fuels would provide an immediate decrease in greenhouse gas emissions, 40% of which come from electricity generation today.

Economy: 

Cost-effective, dispatchable solar energy alternatives would stabilize electricity rates for consumers as the penetration of renewable energy increases in the coming years.

Contacts
ARPA-E Program Director: 
Dr. Michael Haney
Project Contact: 
Dr. Mark Reed
Partners
Emcore Corporation
National Renewable Energy Laboratory
Release Date: 
2/6/2014