Hot Solar Cells: Maximizing Solar Power

The advent of solar panels had sparked a green revolution for clean renewable power, but unfortunately, we are only getting a quarter of the sun's power in electrical energy. MIT is currently developing a new photovoltaic cell that converts heat into wavelengths of light that a solar power can process. The technology converts sunlight into heat, then converts the heat being absorbed by the environment into concentrated wavelengths of light maximizing the energy converted from sunlight.

The device consists of an absorber and an emitter, combined to form an "absorber-emitter" layer. The absorber is made of carbon nanotubes that help funnel sunlight and convert it into heat. Because of the high conductivity of carbon nanotubes, it quickly transfers heat to the second portion, the emitter. The emitter is a photonic crystal, a nanostructure that affects the movement of photons (light particles), which can convert heat into specific concentrated wavelengths of light. The emitter only begins converting photons when the temperature reaches around 1000°C. The device is also equipped with an optical filter that reflects low energy photons back to the emitter, increasing heat and recycling photons.

This method of capturing the sun's energy has the potential of being twice as efficient as conventional photovoltaic cells, but the resources to build these devices are costly. The MIT Technology Review believes the availability of these new solar cells will within the next 10 or 15 years.