is the generation of voltage or electric current when a solar cell is exposed to sunlight. When a solar cell is subject to the sunlight, the absorbed amount of light generates electric energy, while remaining sunlight is reflected. This effect makes solar panels useful, as it is how the cells within the panel convert sunlight to electrical energy.
The photovoltaic effect was first discovered in 1839 by Alexandre Edmond Becquerel. When doing his experiments he involved wet cells, and he noted that the voltage of the cell increased when its silver plates were exposed to the sunlight.