Scientists Pinning Hopes On Heat To Improve The Efficiency Of Solar Powered Devices
January 20, 2014 09:03 AM EST
Scientists are devising a new approach in which heat will play a vital role in increasing the efficiency of solar powered devices. The new approach, developed by MIT researchers will use sunlight to heat a high-temperature material whose infrared radiation would then be collected by a conventional photovoltaic cell.
The process of collecting infrared radiation by conventional photovoltaic cell would improve the performance because it makes it possible to take advantage of wavelengths of that usually go waste.
According to researcher this could also make it easier to store energy for later use.
A traditional silicon-based solar cell "doesn't take advantage of all the photons." The reason is that the energy conversion of a photon into electricity requires the photon energy levels to match. Although silicon's bandgap - a characteristic of the photovoltaic (PV) material, responds to many wavelengths of light, it misses quite a few.
To overcome the limitations, researchers inserted a two-layer absorber-emitter device which was made of novel materials between the sunlight and the PV cell. The novel materials included carbon nanotubes and photonic crystals.
The inserted intermediate material collected energy from a broad spectrum of sunlight that would heat the process. Upon heating a piece of iron that glowed red hot, emitted light of a particular wavelength turning to match the bandgap of the PV cell mounted nearby.
"The efficiency would be significantly higher -- it could ideally be over 80 percent." said Evelyn Wang, author of the study, in a press release.
The researchers said the system combined the advantages of solar photovoltaic systems with solar thermal systems. The combination gave an advantage for delayed use as heat can be stored more easily than electricity.
The process has been described in the journal Nature Nanotechnology.