Which of the following describes a photovoltaic cell?

A photovoltaic cell is fundamentally defined as a device that converts light energy into electrical energy through the photovoltaic effect. When light, typically sunlight, strikes the surface of the cell, it excites electrons within the material (usually silicon), creating an electric current. This process is central to solar power technology, as it directly allows the harnessing of solar energy into usable electrical power, which can then be utilized to power devices or fed into the electrical grid.

The other options do not accurately capture the essence of what a photovoltaic cell does. For instance, while heat can be involved in some solar energy systems, a photovoltaic cell primarily converts light to electricity rather than serving as a heat power source. Similarly, a photovoltaic cell itself is not an energy storage system; batteries or similar devices serve that purpose. Lastly, while monitoring sunlight levels can be part of a solar power system's overall management, it is not a function of the photovoltaic cell itself. Therefore, the defining feature of a photovoltaic cell is its ability to produce electricity directly from exposure to light.