Jargon Buster

Alternating Current (AC) – A type of electrical current, the direction of which is reversed at regular intervals or cycles. In the United Kingdom, the standard is 100 reversals or 50 cycles per second, Hertz (50). Electricity transmission networks use AC because voltage can be controlled with relative ease.

Amorphous Silicon – A thin-film, silicon photovoltaic cell having no crystalline (regularly repeating) structure. Manufactured by deposition of layers of doped silicon on a substrate.

Ampere (amp) - A unit of electrical current or rate of flow of electrons. One volt across one ohm of resistance causes a current flow of one ampere.

BIPV (Building-Integrated Photovoltaics) – A term for the design and integration of photovoltaic (PV) technology into the building shell, typically replacing conventional building materials. This can include the replacement of facades, glass, skylight systems or other increasingly innovative manners.

Crystalline Silicon – A type of photovoltaic cell made from a slice of single-crystal silicon or polycrystalline silicon.

Direct Current (DC) – A type of electricity transmission and distribution by which electricity flows in one direction through the conductor, usually relatively low voltage and high current. To be used for typical 120 volt or 220 volt household appliances, DC must be converted to alternating current, its opposite.

Electric Circuit – The path followed by electrons from a power source (generator or battery), through an electrical system, and returning to the source.

Electric Current - The flow of electrical energy (electricity) in a conductor, measured in amperes.

Electrical grid – An integrated system of electricity distribution, usually covering a large area.

Electricity – Energy resulting from the flow of charge particles, such as electrons or ions.

Energy – The capability of doing work; different forms of energy can be converted to other forms, but the total amount of energy remains the same.

Energy Audit - A survey that shows how much energy used in a home, which helps find ways to use less energy.

Flat-Plate Photovoltaics (PV) – A PV array or module that consists of nonconcentrating elements. Flat-plate arrays and modules use direct and diffuse sunlight, but if the array is fixed in position, some portion of the direct sunlight is lost because of oblique sun-angles in relation to the array.

Frequency – The number of repetitions per unit time of a complete waveform, expressed in Hertz (Hz).

Gigawatt (GW) – A unit of power equal to 1 billion Watts; 1 million kilowatts, or 1,000 megawatts.

Grid-Connected System – A solar electric or photovoltaic (PV) system in which the PV array acts like a central generating plant, supplying power to the grid.

Inverter – A device that converts direct current electricity to alternating current either for stand-alone systems or to supply power to an electricity grid.

Joule – A metric unit of energy or work; 1 joule per second equals 1 watt.

Kilowatt (kW) - A standard unit of electrical power equal to 1000 watts, or to the energy consumption at a rate of 1000 joules per second.

Kilowatt-Hour (kWh) – 1,000 thousand watts acting over a period of 1 hour. The kWh is a unit of energy. 1 kWh=3600 kJ.

Life - The period during which a system is capable of operating above a specified performance level.

Load - The demand on an energy producing system; the energy consumption or requirement of a piece or group of equipment. Usually expressed in terms of amperes or watts in reference to electricity.

Load Circuit - The wire, switches, fuses, etc. that connect the load to the power source.

Load Current (A) – The current required by the electrical device.

Megawatt (MW) – 1,000 kilowatts, or 1 million watts; standard measure of electric power plant generating capacity.

Megawatt-Hour – 1,000 kilowatt-hours or 1 million watt-hours.

Multicrystalline – A semiconductor (photovoltaic) material composed of variously oriented, small, individual crystals. Sometimes referred to as polycrystalline or semicrystalline.

N-Type – Negative semiconductor material in which there are more electrons than holes; current is carried through it by the flow of electrons. This is then combined with a P-Type system to create a diode.

Ohm – A measure of the electrical resistance of a material equal to the resistance of a circuit in which the potential difference of 1 volt produces a current of 1 ampere.

Orientation – Placement of the solar cells with respect to the cardinal directions, N, S, E, W.

Parallel Connection - The standard method of joining solar cells or photovoltaic modules in smaller systems formed by connecting positive leads together and negative leads together; such a configuration increases the current, but not the voltage. In larger commercial systems an array will consist of several parallel series each of which will go through a separate inverter.

Photon - the photon is the elementary particle responsible for ‘light energy’ or electromagnetic phenomena. It is the carrier of electromagnetic radiation of all wavelengths, including in decreasing order of energy, gamma rays, X-rays, ultraviolet light, visible light, infrared light, microwaves, and radio waves.

Photovoltaic(s) (PV) – The direct conversion of light into electricity.

Photovoltaic (PV) Array – An interconnected system of PV modules that function as a single electricity-producing unit. The modules are assembled as a discrete structure, with common support or mounting. In smaller systems, an array can consist of a single module.

Photovoltaic (PV) Cell - The smallest semiconductor element within a PV module to perform the immediate conversion of light into electrical energy (direct current voltage and current). Also called a solar cell. Not to be confused with a solar thermal cell.

Photovoltaic (PV) Device - A solid-state electrical device that converts light directly into direct current electricity. Solar photovoltaic devices are made of various semiconductor materials including silicon, cadmium suphide, cadmium telluride, and gallium arsenide, and in single crystalline, multicrystalline, or amorphous forms.

Photovoltaic (PV) Effect – The phenomenon that occurs when photons, the ‘particles’ in a beam of light, knock electrons loose from the atoms they strike. When this property of light is combined with the properties of semiconductors, electrons flow in one direction across a junction, setting up a voltage. With the addition of circuitry, current will flow and electrical power will be available.

Photovoltaic (PV) Generator – The total of all PV strings of a PV power supply system, which are electrically interconnected.

Photovoltaic (PV) Module - The essentially planar assembly of solar cells and ancillary parts intended to generate direct current power under un-concentrated sunlight. The structural (load carrying) member of a module can either be the top layer (superstrate) or the back layer (substrate).

Photovoltaic (PV) Panel - Normally used interchangeably with PV module. More accurately used to refer to a physically connected collection of modules (i.e., a laminate string of modules used to achieve a required voltage and current).

Photovoltaic (PV) System - A complete set of components for converting