| 1. What is photovoltaics? Photovoltaic systems are solar systems that produce electricity directly from sunlight. The term "photo" comes from the Greek "phos," meaning light. "Voltaic" is named after Alessandro Volta (1745-1827), a pioneer in the study of electricity after whom the term "volt" was named. Photovoltaics, then, means "light electricity." Photovoltaic systems produce clean, reliable electricity without consuming any fossil fuels. They are being used in a wide variety of applications, from providing power for watches, highway signs, and space stations, to providing for a household's electrical needs. 2. What is the difference between "solar energy" and "photovoltaics?" Photovoltaics is a form of solar energy. The term solar energy can refer to something as simple the energy gathered in your parked, sealed car (your solar collector) which is then converted to heat. Solar energy is often used to heat houses directly through passive means (sun enters window, room warms). Solar energy is also often used to heat water (a solar collector is mounted in direct sunlight, which warms a heat transfer fluid, which in turn heats the water in your hot water tank).
Photovoltaics refers specifically to the practice of converting the sun's energy directly into electricity using photovoltaic cells. Photovoltaic cells are often referred to as PV cells or solar cells. 3. What are the components of a PV system?
4. How do the photovoltaic panels work? A solar panel (module) is made up a number of solar cells. Solar cells are generally made from thin wafers of silicon, the second most abundant substance on earth, the same substance that makes up sand. To make the wafers, the silicon is heated to extreme temperatures, and chemicals, usually boron and phosphorous, are added. The addition of these chemicals makes the silicon atoms unstable (their electrons less tightly held). When photons of sunlight hit a solar panel, some are absorbed into the solar cells, where their energy knocks loose some of the modified silicon's electrons. These loose electrons are forced by electric fields in the PV panel to flow along wires that have been placed within the cells. This flow of electrons through the wires is electricity, and will provide power for whatever load we attach (a calculator, a light bulb, a satellite, etc.)
5. What if I want electricity at night or on cloudy days? Introducing batteries to a PV system allows electricity to be stored when the sun is shining. This electricity can then be used to provide power after the sun goes down. Page 2 >> | 
