Optical losses chiefly effect the power from a solar cell by lowering the short-circuit current. Optical losses consist of light which could have generated an electron-hole pair, but does not, because the light is reflected from the front surface, or because it is not absorbed in the solar cell. For the most common semiconductor solar cells, the entire visible spectrum has enough energy to create electron-hole pairs and therefore all visible light would ideally be absorbed.

Sources of optical loss in a solar cell.

There are a number of ways to reduce the optical losses:

• Top contact coverage of the cell surface can be minimised (although this may result in increased series resistance). This is discussed in more detail in Series Resistance;
• Anti-reflection coatings can be used on the top surface of the cell.
• Reflection can be reduced by surface texturing.
• The solar cell can be made thicker to increase absorption (although any light which is absorbed more than a diffusion length away from the junction will not typically contribute to short-circuit current since the carriers recombine).
• The optical path length in the solar cell may be increased by a combination of surface texturing and light trapping.