A photovoltaic cell, also known as a solar cell, is an electronic device that converts sunlight directly into electricity through a process called the photovoltaic effect. When photons from sunlight strike a photovoltaic cell, they may reflect off the cell, pass through the cell, or be absorbed by the semiconductor material. Only the absorbed photons provide energy to generate electricity. When the semiconductor material absorbs enough sunlight, electrons are dislodged from the materials atoms, creating a flow of electricity. A photovoltaic cell is made of semiconductor material, and it is comprised of many layers of materials, each with a specific purpose. The most important layer of a photovoltaic cell is the specially treated semiconductor layer, which is comprised of two distinct layers (p-type and n-type) and is what actually converts the Suns energy into useful electricity through the photovoltaic effect. Photovoltaic cells can be manufactured in a variety of ways and from many different materials, but the most common material for commercial solar cell construction is silicon. Multiple solar cells are often grouped in panels, and panels can be grouped into arrays of different sizes to power water pumps, provide electricity for individual homes, or provide utility-scale electricity generation.