This system, also called photovoltaic systems (PV), converts solar energy into electrical energy. Light is emitted by small particles called photons. These particles carry a certain energy. This transported energy is used by plants in photosynthesis, collectors in heating water, and solar panels in generating electricity. In order for an electric current to form, electrons must move on a conductive wire. The semiconductor materials used in solar cells are sensitive to sunlight. When light falls on these materials, the energy in the light causes the negatively charged electrons to move. This movement creates an electric current. Solar panels are used more and more every day. Solar cells or panels provide free electricity in areas far from the power grid. However, many people who want to use energy without harming the environment prefer solar panels.