Solar Technology related terms beginning with P.
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- Packing Factor : The ratio of array area to actual land area or building envelope area for a system; or, the ratio of total solar cell area to the total module area, for a module.
- Panel : See photovoltaic (PV) panel.
- Parallel Connection : A way of joining solar cells or photovoltaic modules by connecting positive leads together and negative leads together; such a configuration increases the current, but not the voltage.
- Passivation : A chemical reaction that eliminates the detrimental effect of electrically reactive atoms on a solar cell's surface.
- Peak Demand/Load : The maximum energy demand or load in a specified time period.
- Peak Power Current : Amperes produced by a photovoltaic module or array operating at the voltage of the I-V curve that will produce maximum power from the module.
- Peak Power Point : Operating point of the I-V (current-voltage) curve for a solar cell or photovoltaic module where the product of the current value times the voltage value is a maximum.
- Peak Power Tracking : see maximum power tracking.
- Peak Sun Hours : The equivalent number of hours per day when solar irradiance averages 1,000 w/m2. For example, six peak sun hours means that the energy received during total daylight hours equals the energy that would have been received had the irradiance for six hours been 1,000 w/m2.
- Peak Watt : A unit used to rate the performance of solar cells, modules, or arrays; the maximum nominal output of a photovoltaic device, in watts (Wp) under standardized test conditions, usually 1,000 watts per square meter of sunlight with other conditions, such as temperature specified.
- Phosphorous (P) : A chemical element used as a dopant in making n-type semiconductor layers.
- Photocurrent : An electric current induced by radiant energy.
- Photoelectric Cell : A device for measuring light intensity that works by converting light falling on, or reach it, to electricity, and then measuring the current; used in photometers.
- Photoelectrochemical Cell : A type of photovoltaic device in which the electricity induced in the cell is used immediately within the cell to produce a chemical, such as hydrogen, which can then be withdrawn for use.
- Photon : A particle of light that acts as an individual unit of energy.
- Photovoltaic(s) (PV) : Pertaining to 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.
- Photovoltaic (PV) Conversion Efficiency : The ratio of the electric power produced by a photovoltaic device to the power of the sunlight incident on the device.
- Photovoltaic (PV) Device : A solid-state electrical device that converts light directly into direct current electricity of voltage-current characteristics that are a function of the characteristics of the light source and the materials in and design of the device. Solar photovoltaic devices are made of various semiconductor materials including silicon, cadmium sulfide, 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 electric 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 smallest environmentally protected, essentially planar assembly of solar cells and ancillary parts, such as interconnections, terminals, [and protective devices such as diodes] intended to generate direct current power under unconcentrated sunlight. The structural (load carrying) member of a module can either be the top layer (superstrate) or the back layer (substrate).
- Photovoltaic (PV) Panel : often used interchangeably with PV module (especially in one-module systems), but 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 sunlight into electricity by the photovoltaic process, including the array and balance of system components.
- Photovoltaic-Thermal (PV/T) System : A photovoltaic system that, in addition to converting sunlight into electricity, collects the residual heat energy and delivers both heat and electricity in usable form. Also called a total energy system.
- Physical Vapor Deposition : A method of depositing thin semiconductor photovoltaic films. With this method, physical processes, such as thermal evaporation or bombardment of ions, are used to deposit elemental semiconductor material on a substrate.
- P-I-N : A semiconductor photovoltaic (PV) device structure that layers an intrinsic semiconductor between a p-type semiconductor and an n-type semiconductor; this structure is most often used with amorphous silicon PV devices.
- Plates : A metal plate, usually lead or lead compound, immersed in the electrolyte in a battery.
- P/N : A semiconductor photovoltaic device structure in which the junction is formed between a p-type layer and an n-type layer.
- Pocket Plate : A plate for a battery in which active materials are held in a perforated metal pocket.
- Point-Contact Cell : A high efficiency silicon photovoltaic concentrator cell that employs light trapping techniques and point-diffused contacts on the rear surface for current collection.
- Polycrystalline : See Multicrystalline.
- Polycrystalline Silicon : A material used to make photovoltaic cells, which consist of many crystals unlike single-crystal silicon.
- Power Conditioning : The process of modifying the characteristics of electrical power (for e.g., inverting direct current to alternating current).
- Power Conditioning Equipment : Electrical equipment, or power electronics, used to convert power from a photovoltaic array into a form suitable for subsequent use. A collective term for inverter, converter, battery charge regulator, and blocking diode.
- Power Conversion Efficiency : The ratio of output power to input power of the inverter.
- Power Density : The ratio of the power available from a battery to its mass (W/kg) or volume (W/l).
- Power Factor (PF) : The ratio of actual power being used in a circuit, expressed in watts or kilowatts, to the power that is apparently being drawn from a power source, expressed in volt-amperes or kilovolt-amperes.
- Primary Battery : A battery whose initial capacity cannot be restored by charging.
- Projected Area : The net south-facing glazing area projected on a vertical plane.
- P-Type Semiconductor : A semiconductor in which holes carry the current; produced by doping an intrinsic semiconductor with an electron acceptor impurity (e.g., boron in silicon).
- Pulse-Width-Modulated (PWM) Wave Inverter : A type of power inverter that produce a high quality (nearly sinusoidal) voltage, at minimum current harmonics.
- PV : See photovoltaic(s).
- Pyranometer : An instrument used for measuring global solar irradiance.
- Pyrheliometer : An instrument used for measuring direct beam solar irradiance. Uses an aperture of 5.7° to transcribe the solar disc.