ABSTRACT
A photovoltaic (PV) cell converts sunlight directly into electricity. A number of materials are photoelectric: Light is absorbed, and an electron acquires kinetic energy to move it to another energy level within the material. Today, the primary materials for PV cells are semiconductors, although researchers are trying other materials, even organic polymers. A PV cell is used in things from small items such as calculators and watches to large installations for electric utilities. Even though PV systems are expensive, there are a number of applications in which they are cost effective, especially for stand-alone systems some distance from the utility grid, mobile jobs such as construction signs, and even for low power (50-200 W) close to the grid. A PV system has the following advantages and disadvantages:
PV has another major advantage for the production of electricity because PV cells and wind do not require water, in contrast to conventional thermal steam plants, even those powered by nuclear reactors.
