3. Photovoltaic (fo-to-vol-ta-ik) systems are solar systems that produce electricity directly from sunlight. The term "photo" comes from the Greek "phos," meaning light. "Voltaic" is named for Alessandro Volta (1745-1827), a pioneer in the study of electricity for 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. Photovoltaic (fo-to-vol-ta-ik) systems are solar systems that produce electricity directly from sunlight. The term "photo" comes from the Greek "phos," meaning light. "Voltaic" is named for Alessandro Volta (1745-1827), a pioneer in the study of electricity for 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.

4. Photovoltaic Cell -- Thin squares, discs, or films of semiconductor material that generate voltage and current when exposed to sunlight.Photovoltaic Cell -- Thin squares, discs, or films of semiconductor material that generate voltage and current when exposed to sunlight. Module -- Photovoltaic cells wired together and laminated between a clear superstrate (glazing) and encapsulating substrate.Module -- Photovoltaic cells wired together and laminated between a clear superstrate (glazing) and encapsulating substrate. Array -- One or more modules with mounting hardware and wired together at a specific voltage.Array -- One or more modules with mounting hardware and wired together at a specific voltage. Charge Controller -- Power conditioning equipment to regulate battery voltage.Charge Controller -- Power conditioning equipment to regulate battery voltage. Battery Storage -- A medium that stores direct current (DC) electrical energy.Battery Storage -- A medium that stores direct current (DC) electrical energy. Inverter -- An electrical device that changes direct current to alternating current (AC) to operate loads that require alternating current.Inverter -- An electrical device that changes direct current to alternating current (AC) to operate loads that require alternating current. DC Loads -- Appliances, motors and equipment powered by direct current.DC Loads -- Appliances, motors and equipment powered by direct current. AC Loads -- Appliances, motors and equipment powered by alternating current.AC Loads -- Appliances, motors and equipment powered by alternating current.

5. A solar collector is a device for extracting the energy of the sun directly into a more usable or storable form. The energy in sunlight is in the form of electromagnetic radiation from the infrared (long) to the ultraviolet (short) wavelengths. The solar energy striking the earth's surface at any one time depends on weather conditions, as well as location and orientation of the surface, but overall, it averages about 1000 watts per square meter on a clear day with the surface directly perpendicular to the sun's rays.

6. 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.) 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.)

7. Solar thermal energy refers to harnessing the sun's light to produce heat. Heat results when photons, packets of light energy, strike the atoms composing a substance (water, your body, asphalt), exciting them. Solar thermal technologies include passive solar systems for heating (or cooling!) buildings; flat plate solar collectors, often used for providing households with hot water; and solar concentrator power systems. These systems, also known as solar thermal power plants, use the sun's heat to create steam, which then turns a turbine and produces electricity. (Fossil fuel burning power plants also produce electricity by first creating steam in order to turn a turbine.)

8. Photovoltaics is one 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) and converted into 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.