Anti-reflective coating in solar cells

The light which falls on a solar cell first makes contact with the shiny surface of the cell.  This results in the light getting reflected.  Thus, this the energy of the light rays are also lost along with the reflected rays.  Hence, it is essential that all photovoltaic cell have an effective anti-reflective coating which prevents the light from getting reflected. 

A reflective coating ensures that the energy from all the rays incident on the photo voltaic cell is made available for conversion into electricity thereby increasing the efficiency of the cell.

Anti reflective coatings are similar to the coatings used on camera lenses.  They interfere with the process of reflection by creating another light wave which is out of phase with the reflected wave.  This causes the reflected waves to cancel each other out and no energy is lost through reflection. This phenomenon is called destructive interference.

The thickness of the anti-reflective coating is critical.  It should be perfectly selected so that the light from the surface of the anti-reflective coating is out of phase with the light reflected from the surface of the photocell. 

Another method of preventing light from getting reflected off the surface is by texturing the surface of the photocell.  This causes the light to get reflected multiple times by the textured surface and a greater amount of the energy in light is captured by the photo cell.  This is called "light trapping"