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Low-Cost Hetero-Epitaxial Solar Cell for Hybrid Converter

Massachusetts Institute of Technology (MIT)
Spectrum Splitting for High-Efficiency Photovoltaic and Solar Thermal Energy Generation
ARPA-E Award: 
Cambridge, MA
Project Term: 
05/15/2014 to 07/31/2015
Project Status: 
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: 
MIT is developing a high-efficiency solar cell grown on a low-cost silicon wafer, which incorporates a micro-scale heat management system. The team will employ a novel fabrication process to ensure compatibility between the indium gallium phosphide (InGaP) solar cell and an inexpensive silicon wafer template, which will reduce cell costs. MIT will also develop a color-selective filter, designed to split incoming concentrated sunlight into two components. One component will be sent to the solar cells and immediately converted into electricity and the other will be sent to a thermal receiver to be captured as heat. This will allow the simultaneous availability of electricity and heat. By leveraging the InGaP system, MIT's solar cells will be more tolerant to high temperature operation than today's PV cells and allow recovery of more useful higher temperature waste heat through the micro-scale heat management system. The solar cell and heat recovery system will enable more efficient use of the entire solar spectrum to produce dispatchable renewable electricity.
Potential Impact: 
If successful, MIT's system will integrate solar cells and thermal receivers to enable optimal use of the entire solar spectrum for dispatchable energy generation from sunlight.
Developing new hybrid solar systems that generate electricity and heat at the same time could provide power at costs comparable to traditional sources, whether or not the sun is shining.
Replacing energy systems powered by fossil fuels would provide an immediate decrease in greenhouse gas emissions, 40% of which come from electricity generation today.
Cost-effective, dispatchable solar energy alternatives would stabilize electricity rates for consumers as the penetration of renewable energy increases in the coming years.
ARPA-E Program Director: 
Dr. Eric Schiff
Project Contact: 
Dr. Jurgen Michel
Release Date: