New Discovery Could Revamp Solar Power

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"The process combines the light and heat of solar radiation."

Engineers from Stanford University have discovered and demonstrated proof of concept for a process called photon-enhanced thermionic emission (PETE) that can combine the light and heat of solar radiation to generate electricity.

Nick Melosh led the research group that figured out that coating semiconducting material with a thin layer of cesium allowed the material to use both light and heat to generate electricity. Melosh said that the work is a conceptual breakthrough in that it demonstrates a new energy conversion process.

In traditional solar cells the heat from unused sunlight and inefficiencies in the cells means they lose more than 50% of the initial solar energy reaching the cell. Harvesting the wasted heat energy has been a problem because high temperatures are needed to power heat-based conversion systems. Solar cell efficiency quickly decreases at higher temperatures.

The new physical process isn't based on photovoltaic mechanisms and can work at very high temperatures. Most silicon solar cells don't work by the time the temperature is 100 C, but the PETE device's peak efficiency is well over 200 C. Another advantage is that the materials used to build a device are cheap and easily available.

Rooftop solar panel's don't get hot enough for the PETE device to be most efficient, so the researchers say that the devices would work best in solar concentrators such as the parabolic dishes used in large solar farms. These dishes can reach 800 C.

Melosh says that the PETE process has the potential to achieve 50% efficiency or more under solar concentration and could reach 55 or even 60% if combined with a thermal conversion cycle.

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