We have all seen calculators with solar cells, that enable the device to work without any batteries, and can be used for unlimited time period as long as there’s enough light.
These solar cells that are present in calculators and many other devices are also called photovoltaic (PV) cells. As the name depicts, these cells have the capability of converting sunlight directly into electricity.
A group of cells can also be connected together electrically, fitted into a frame to form a solar panel. Moreover, these solar panels can be combined together to form larger solar arrays, similar to the ones operating at Nellis Air Force Base in Nevada.
Photovoltaic cells are made up of special material called semiconductors such as silicon, which is currently used most commonly.
When light falls on to the cell, a certain amount of the light is absorbed by the semiconductor material. The energy of the absorbed light is then transferred to the semiconductor. The energy is used to loosen up the electrons, allowing them to flow freely, and thus create electricity.
PV cells also have one or more electric fields that force electrons freed by light absorption to flow in a certain direction making a current. Thus by inserting metal contacts on the top and bottom of the PV cell, we can direct the current for some external use. This current, combined together with the cell’s voltage due to the built-in electric fields, defines the power that the solar cell can produce.
This is the basic process through which photovoltaic cells work, but clearly there’s much more to it, which will be explained in the proceeding articles.