New Solar Cell Device Surpasses Theoretically Predicted Efficiency Limit
A team of researchers at the Massachusetts Institute of Technology (MIT) published a paper last week in the journal Nature Energy that described how they built a working solar thermophotovoltaic device (STPV) that enables solar cells to break through a theoretically predicted ceiling on how much sunlight they can convert into electricity. With this revolutionary new technology, the researchers show the potential of how solar panels can generate even more energy than theoretically determined by harnessing some of the panels’ waste. To learn more about the STPV technology, read on!
Since 1961, the Shockley-Queisser Limit established an absolute theoretical limit on traditional solar cell efficiency regarding energy conversion. A single-layer of silicon cells—the type of cells most widely used in today’s solar panels—has an upper limit of 32 percent. But currently, researchers are studying ways to increase this overall efficiency by using multiple layers of cells or converting the sunlight first to heat before generating electrical power. This latter method uses devices called STPVs, which the MIT team used in their study.
A normal solar cell converts sunlight into energy and delivers it to a storage mechanism while producing heat energy that dissipates and is wasted. The MIT team added a new material layer to the solar cell structure, which enables the device to absorb the heat energy and convert the emitted radiation into light. The converted radiation is emitted in the form of just the right wavelengths of light for the solar cell to capture. This cell configuration and process improve the efficiency and reduce the heat generated in the solar cell. The key to improved efficiency is using a layer of high-tech materials called nanophotonic crystals that can be tuned and configured to emit precisely determined wavelengths of light when heated.
The new technology could double the amount of power generated by solar panels without dramatically increasing cost. However, the next hurdle is determining how STPV technology can be economically scaled.
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