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Key PV Industry Terms


Amorphous Silicon (a-Si) – A thin-film PV silicon having no crystalline structure.


Array – A collection of electrically connected photovoltaic (PV) modules.


BIPV – See Building Integrated Photovoltaic.


Building Integrated Photovoltaic (BIPV) - Structural materials are combined with PV material to create the roof, walls and windows of a building.


Cadmium Telluride – Thin films material deposited on glass.


Capacity – The total number of ampere-hours that can be withdrawn from a fully charged battery at a specified discharge rate and temperature.


CdTe – See Cadmium Telluride.


Chemical Vapor Deposition (CVD) - Chemical Vapor Deposition is the most common thin film deposition method in advanced semiconductor manufacturing; deposited species are formed as a results of chemical reaction between gaseous reactants at elevated temperature in the vicinity of the substrate; solid product of the reaction is deposited on the surface of the substrate; used to deposit films of semiconductors (crystalline and non-crystalline), insulators as well as metals; variations of CVD processes include Atmospheric Pressure CVD (APCVD), Low Pressure CVD (LPCVD)and Plasma Enhanced CVD (EPCVD), Metal-Organic CVD (MOCVD) and others.


CIGS – See Copper Indium Gallium Diselenide.


CIS – See Copper Indium Diselenide.


Concentrator – A photovoltaic module that uses optical elements to increase the amount of sunlight incident on a PV cell.


Conversion Efficiency – The ratio of the electrical energy produced by a photovoltaic cell to the solar energy impinging on the cell.


Converter – A unit that converts a dc voltage to another dc voltage.


Copper Indium Gallium Diselenide CIS) – Thin films material deposited on either glass or stainless steel substrates.


Copper Indium Diselenide (CuInSe2 or "CIS") - Has an extremely high absorptivity, which means that 99% of the light shining on CIS will be absorbed in the first micrometer of the material.


Crystalline - A material that has atoms arranged in an ordered periodic array.


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


CVD – see Chemical Vapor Deposition.


Deposition - A process used to deposit a thin layer of insulating or conductive material onto the wafer or other substrate.


Direct Current (dc) – Electric current flowing in only one direction.


Doping - Adding a controlled amount of impurities to a material in order to modify some intrinsic characteristic, e.g., resistivity/conductivity, melting point.


Efficiency – The ratio of output power (or energy) to input power (or energy. Expressed in percent.


Flat Glass - All types of glass (rolled, float, plate, etc.) produced in a flat form, regardless of the method of production. The most common method of producing flat glass today is the float process. A method for the production of high-quality sheet glass whereby a ribbon of molten glass is fed across a bath of heated liquid, usually molten tin, in a carefully controlled atmosphere. The process was developed by the UK firm Pilkington Brothers.


Flat-Plate Array – A PV array that consists of non-concentrating PV modules.


Grid – Term used to describe an electrical utility distribution network. “Off the Grid System” would refer to a system that is not drawing from or sending to the electrical utility distribution network.


Inverter – In a PV system, an inverter converts dc power from the PV array/battery to ac power compatible with the utility and ac loads.


Irradiance – The solar power incident on a surface. Usually expressed in kilowatts per square meter. Irradiance multiplied by time equals Isolation.


Kilowatt (ks) – One thousand watts. A unit of power.


Kilowatt Hour (kwh) – One thousand watt-hours. A unit of energy. Power multiplied by time equals energy.


Life-Cycle Cost – The estimated cost of owning and operating a system for the period of its useful life.


Load – The amount of electric power used by any electrical unit or appliance at any given time.


Module – The smallest replaceable unit in a PV array. An integral, encapsulated unit containing a number of PV cells.


Monocrystalline Silicon - A type of silicon that has a single and continuous crystal lattice structure with almost no defects or impurities.


Multicrystalline Silicon - A type of silicon that is cast into ingots using grains of monocrystalline silicon. The ingots are then sliced into wafers and used in the manufacturing of mircrochips and photovoltaic cells.


N-Type Silicon – Silicon material that has been doped with a material that has more electrons in its atomic structure than does silicon.


Panel – A designation for a number of PV modules assembled in a single mechanical frame.


PECVD – See Plasma Enhanced Chemical Vapor Deposition.


Photovoltaic - A process where sunlight is converted to electricity.


Photovoltaic (PV) Cell – The treated semiconductor material that converts solar irradiance to electricity.


Photovoltaic System – An installation of PV modules and other components designed to produce power from sunlight and meet the power demand for a designated load.


Plasma Enhanced Chemical Vapor Deposition (PECVD) is a process where plasma is used to lower the temperature required to deposit film onto a wafer.


Polycrystalline Silicon – A material used to make PV cells which consists of many crystals as contrasted with single crystal silicon.


Power (Watts) – A basic unit of electricity equal (in dc circuits) to the product of current and voltage.


PV – see photovoltaic.


PVD – See sputter coating.


Semiconductor – A material that has a limited capacity for conducting electricity. The silicon used to make PV cells is a semiconductor.


Silicon – A brownish semiconductor material that is used to make photovoltaic cells and most semiconductor wafers.


Solar Cell – See Photovoltaic Cell.


Sputter Coating – A vacuum evaporation process which physically removes portions of a coating material called the “target’, and deposits a thin, firmly bonded film onto an adjacent surface called the “substrate”. The resulting coating is held firmly to the surface by mechanical forces.


Stand-Alone PV System – A photovoltaic system that operates independently of the utility grid.


Substrate – A materails that is the basis for subsequent processing operations in the fabrication of semiconductor devices.


Subsystem – Any one of several components in a PV system (i.e. array, controller, batteries, inverter, load).


Tempered Glass - Special process of solidification of a glass sheet in order to make it particularly resistant to breakages. The process may be physical (thermal) or chemical. In the former, the glass sheet is heated to a temperature just below its softening point and then immediately cooled by special jets of cold-air. These harden the surface of the glass, giving the inside more time to cool. This allows the external layer to crystallize into a wider lattice while the inside solidifies with greater compression than in the crystal lattice. The result is a sheet of glass which is two or three times stronger than untempered glass and which, upon breakage, shatters into tiny pieces with blunt edges (the most common applications are for automotive glass). The chemical process, on the other hand, is based on the so-called ion-stuffing technique. Different chemical elements possess different ionic radii and therefore different densities. Hence, if glass containing sodium is cooled slowly in a salt bath of molten potassium, the sodium ions will migrate from the glass to the salt, while the potassium ions will move to the surface of the glass where, due to their wider radium, they create a denser and therefore stronger surface layer (of no less than 0.1 mm). Glass sheets which have been chemically tempered are five to eight times stronger than those which have not undergone any tempering process.


Thin-Film PV Module – A PV module constructed with sequential layers of thin film semiconductor materials. Typical manufacturing processes are CVD and Sputter coating with CdTe and CIGS. The advantages of Thin-Films are low materials and processing costs. See also Amorphous Silicon.


Tracking Array – A PV array that follows the path of the sun. This can mean one-axis, east to west daily tracking, or two-axis tracking where the array follows the sun in aximuth and elevation.


Volt (V) – The unit of electromotive force that will force a current of one ampere through a resistance of one ohm.


Watt (W) – The unit of electrical power. The power developed when a current one ampere flows through a potential difference of one volt; 1/746 of a horsepower.


Watt Hour (Wh) – A unit of energy equal to one watt of power connected for one hour.