The technology of trapping the Sun’s energy by using solar cells has been around for some time. Each solar cell has the capability to produce just a small amount of energy; hence the cells are usually arranged in a large area on rooftops to get the required amount of energy.
Unfortunately, space limitations mean that some houses cannot get the required power because there is insufficient space for the necessary solar cells. It is therefore great news to hear that scientists have discovered a new technology of concentrating more solar energy in a relatively small space.
The chemical engineers at MIT are using carbon nanotubes to concentrate solar energy as much as 100 times more so than it is possible to achieve with regular photovoltaic cells. The carbon nanotubes are hollow carbon atom tubes that can be used as antennas that concentrate light energy, effectively creating more powerful yet relatively smaller solar arrays.
These antennas can be used to focus the concentrated energy on photovoltaic cells, which means that you will not need to cover your entire roof with photovoltaic cells to get enough energy. Basically, solar panels convert photons into electric current. The nanotube antenna concentrates more photons that can be directed to the solar panels, enabling the generation of more current.
The researchers refer to the antenna as ‘solar funnel’. These ‘funnels’ can be used in various places where a concentration of light is required, such as in night-vision goggles.
The nanotube antenna funnel is made of a fibrous rope that is just 10 micrometers long and 4 micrometers thick, which contains around 30 million carbon nanotubes. The team of researchers made a fiber with two nanotube layers, each having different electrical properties – bandgaps.
Electrons can be found at different energy levels in any material. A photon striking a surface excites electron to higher level of energy. The energy level difference between the electron and the hole it leaves behind is called bandgap.
The inner layer of the antenna has lower bandgap while the outer layer has a higher bandgap. The researchers have not used the antenna to develop a photovoltaic cell but they intend to. In such a device, the ‘solar funnel’ would focus the photons before solar cells convert them to electricity.
Such devices would create a better alternative to the conventional solar panels. They will be cheaper because the prices of nanotubes are getting lower.