Just a few years ago, solar thermophotovoltaics (STPV) was more of a theory than an actuality. The idea behind STPV is that the efficiency of solar modules will improve significantly if certain materials are used to trap the sun’s heat before it reaches the module. Photovoltaics, however, have always had certain limitations, as they can convert only a portion of sunlight into electricity. Since 1961, this limit—known as the Shockley-Quiesser limit, was thought to cap a solar cell’s efficiency around 32 percent.
But last week, an MIT research team reportedly surpassed this theoretical limit.
In this experiment, materials were placed between the sun and solar cells to improve module efficiency—an idea that seems, at first, counterintuitive to how silicon solar cells work. The team used a fairly low-efficiency module in the test to demonstrate the beneficial effects of STPV, which absorbed energy and heat into a preliminary component before it was radiated to the solar cell.
This thermophotovoltaic solar technology creates impressive potential for solar energy harvesting—even on cloudy days. The additional materials of the STPV modules functions as a mini storage system for solar thermal energy, providing a more uniform energy flow as clouds cover and pass the sun. In other words, STPV could offer continuous power.
Solar thermophotovoltaics is not yet market ready, but we can expect to see steps taken to make larger variations of the experimental unit and the manufacturing process economically viable. As we continue to see advancements in photovoltaic technology like STPV, solar systems will continue to increase their return on investment.